Title: Electric vehicle steering/drive control method, electric vehicle steering/drive control apparatus, and electric vehicle
Abstract: An electric vehicle steering/drive control method and apparatus having predetermined steering modes defining composite patterns of individual wheel travel paths, whereby the vehicle wheels are controlled independently. The steering modes are determined by different condition equations related to each composite pattern. A steering mode select signal is generated based on a mode selection by a vehicle driver. The steering mode select signal is received by a wheel steering angle computer and a wheel rotation speed computer. Based in part on the steering mode select signal, the wheel steering angle computer generates a signal that is received by a steering motor controller, which in turn controls motors that change the steering angle of the wheels. An actual angle sensor generates a signal based on the actual angle of the wheels and a steering angle comparator receives the actual angle sensor signal. In addition, to move the vehicle in a particular direction and at a particular speed, a speed and direction command signal is also generated based on driver input. This speed and direction command signal is received by a common signal rate of change suppression computer, which generates a signal received by the wheel steering angle computer and a wheel rotation speed computer. Then the wheel rotation speed computer generates a signal based on signals received from the common signal rate of change suppression computer and the steering angle comparator computer. A drive motor controller receives the wheel rotation speed signal and activates drive motors associated with each wheel, thereby causing the wheels to move rotationally.
Patent Number: 6,871,125 Issued on 03/22/2005 to Oshima, et al.
| Inventors:
|
Oshima; Hiroyasu (Kanazawa, JP);
Baba; Kazuaki (Kanazawa, JP);
Imai; Katsuya (Kanazawa, JP);
Yamada; Akihiro (Nonoichi-machi, JP)
|
| Assignee:
|
Kanazawa Institute of Technology (JP)
|
| Appl. No.:
|
294113 |
| Filed:
|
November 14, 2002 |
Foreign Application Priority Data
| Nov 16, 2001[JP] | 2001-351127 |
| Current U.S. Class: |
701/22; 701/41; 180/204 |
| Intern'l Class: |
B60T 008//32; B60L 015//20; B60K 008//00 |
| Field of Search: |
701/22,41,69,89
180/204,408,411,421,234,410,242,244,65.1,65.3,65.8,446,415
|
References Cited [Referenced By]
U.S. Patent Documents
| 5348111 | Sep., 1994 | Williams et al. | 180/415.
|
| 5379220 | Jan., 1995 | Allen et al. | 701/41.
|
| 5404960 | Apr., 1995 | Wada et al. | 180/446.
|
| 5453930 | Sep., 1995 | Imaseki et al. | 701/22.
|
| 5465806 | Nov., 1995 | Higasa et al. | 180/165.
|
| 5996722 | Dec., 1999 | Price | 180/403.
|
| 6449552 | Sep., 2002 | Ohba et al. | 701/89.
|
| 6549835 | Apr., 2003 | Deguchi et al. | 701/41.
|
Primary Examiner: Nguyen; Tan Q.
Assistant Examiner: Tran; Dalena
Attorney, Agent or Firm: Brinks Hofer Gilson & Lione
Claims
What is claimed is:
1. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting one of the steering modes based on a particular driving
condition, and giving a vehicle speed/direction command; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M1 can be expressed as the
condition equations
##EQU52##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2 :√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case in which the turning paths of the wheels inscribe
concentric arcs, is the distance between the center of the concentric arcs
and a point central to the locations of the four wheels.
2. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes comprising at least one
of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
are lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting a steering mode through an operation performed by a vehicle
driver and giving a vehicle speed/direction command by a vehicle driver
based on a particular driving condition;
holding the rate of change of a vehicle speed/direction command signal
resulting from operations performed by the driver to a value smaller than
the lowest value of either of the steering angle command following
performance or the speed of rotation command following performance of the
wheels, thereby adjusting the vehicle speed/direction command signal; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M1 can be expressed as the
condition equations
##EQU53##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2 :√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between th front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
3. A method of operating and electric vehicle having left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting one of the steering modes based on a particular driving
condition, and giving a vehicle speed/direction command; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M2 are equations that can be
expressed as the condition equations
.alpha..sub.1 =.alpha..sub.2 =.alpha..sub.3 =.alpha..sub.4
n.sub.1 =n.sub.2 =n.sub.3 =n.sub.4
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
and,
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively.
4. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes comprising at least one
of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
are lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting a steering mode through an operation performed by a vehicle
driver and giving a vehicle speed/direction command by a vehicle driver
based on a particular driving condition;
holding the rate of change of a vehicle speed/direction command signal
resulting from operations performed by the driver to a value smaller than
the lowest value of either of the steering angle command following
performance or the speed of rotation command following performance of the
wheels, thereby adjusting the vehicle speed/direction command signal; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M2 can be expressed as the
condition equations
.alpha..sub.1 =.alpha..sub.2 =.alpha..sub.3 =.alpha..sub.4
n.sub.1 =n.sub.2 =n.sub.3 =n.sub.4
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
and,
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively.
5. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting one of the steering modes based on a particular driving
condition, and giving a vehicle speed/direction command; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M3 can be expressed as the
condition equations
##EQU54##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +(2L).sup.2
(R-W).sup.2 +(2L).sup.2 :√(R+W).sup.2 +(2L).sup.2 (R+W).sup.2
+(2L).sup.2 :.vertline.R-W.vertline.:.vertline.R+W.vertline..
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
6. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes comprising at least one
of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
are lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to left with
the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting a steering mode through an operation performed by a vehicle
driver and giving a vehicle speed/direction command by a vehicle driver
based on a particular driving condition;
holding the rate of change of a vehicle speed/direction command signal
resulting from operations performed by the driver to a value smaller than
the lowest value of either of the steering angle command following
performance or the speed of rotation command following performance of the
wheels, thereby adjusting the vehicle speed/direction command signal; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M3 can be expressed as the
condition equations
##EQU55##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +(2L).sup.2
(R-W).sup.2 +(2L).sup.2 :√(R+W).sup.2 +(2L).sup.2 (R+W).sup.2
+(2L).sup.2 :.vertline.R-W.vertline.:.vertline.R+W.vertline..
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
7. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to left with
the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting one of the steering modes based on a particular driving
condition, and giving a vehicle speed/direction command; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M4 can be expressed as
##EQU56##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =L:√W.sup.2 +L.sup.2 :0:W
for right turns, and as
##EQU57##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√W.sup.2 +L.sup.2 :L:W:0
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels; and,
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels.
8. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes comprising at least one
of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
are lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle to the right with the right front
wheel as the center of rotation of the turn, and turns to the left with
the left front wheel as the center of rotation of the turn;
selecting a steering mode through an operation performed by a vehicle
driver and giving a vehicle speed/direction command by a vehicle driver
based on a particular driving condition;
holding the rate of change of a vehicle speed/direction command signal
resulting from operations performed by the driver to a value smaller than
the lowest value of either of the steering angle command following
performance or the speed of rotation command following performance of the
wheels, thereby adjusting the vehicle speed/direction command signal; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M4 can be expressed as
##EQU58##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =L:√W.sup.2 +L.sup.2 :0:W
for right turns, and
##EQU59##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√W.sup.2 +L.sup.2 :L:W:0
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between th front
wheels and rear wheels; and,
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels.
9. A method of operating an electric vehicle having left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to left with
the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting one of the steering modes based on a particular driving
condition, and giving a vehicle speed/direction command; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the M5 steering mode can be expressed as
.alpha..sub.1 =.alpha..sub.2 =0
##EQU60##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =0:W:L:√W.sup.2 +L.sup.2
for right turns, and
.alpha..sub.1 =.alpha..sub.2 =0
##EQU61##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =W:0:√W.sup.2 +L.sup.2 :L
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels; and,
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels.
10. A method of operating an electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of drive
motors, comprising the steps of:
preparing a plurality of different steering modes comprising at least one
of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
are lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
selecting a steering mode through an operation performed by a vehicle
driver and giving a vehicle speed/direction command by a vehicle driver
based on a particular driving condition;
holding the rate of change of a vehicle speed/direction command signal
resulting from operations performed by the driver to a value smaller than
the lowest value of either of the steering angle command following
performance or the speed of rotation command following performance of the
wheels, thereby adjusting the vehicle speed/direction command signal; and,
controlling the steering angle and rotation of speed of each wheel
separately, in accordance with a condition equation for performing
steering/drive operations according to the selected steering mode and
vehicle speed/direction command, thereby effecting steering/drive control
separately for each wheel,
wherein the condition equations required to perform steering/drive
operations according to the M5 steering mode can be expressed as
.alpha..sub.1 =.alpha..sub.2 =0
##EQU62##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =0:W:L:√W.sup.2 +L.sup.2
for right turns, and
.alpha..sub.1 =.alpha..sub.2 =0
##EQU63##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =W:0:√W.sup.2 +L.sup.2 :L
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels; and,
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels.
11. A method of operating and electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of steering and
drive motors, comprising the steps of:
controlling the rotation of each of the steering motors and drive motors in
accordance with condition equations that can be expressed as
##EQU64##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2 :√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case in which the turning paths of the wheels inscribe
concentric arcs, is the distance between the center of the concentric arcs
and a point central to the locations of the four wheels; thereby
controlling the steering angle and speed of rotation of each wheel such as
to perform steering/drive operations according to a steering mode M1,
wherein the travel paths of the right and left rear wheels follow in the
travel paths of the right and left front wheels, respectively.
12. A method of operating and electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of steering and
drive motors, comprising the step of:
controlling the rotation of each of the steering motors and drive motors in
accordance with condition equations that can be expressed as
.alpha..sub.1 =.alpha..sub.2 =.alpha..sub.3 =.alpha..sub.4
n.sub.1 =n.sub.2 =n.sub.3 =n.sub.4
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively; thereby controlling
the steering angle and speed of rotation of each wheel such as to perform
steering/drive operations according to a steering mode M2, wherein the
travel paths of the front and rear wheels lie parallel to each other.
13. An electric vehicle steering/drive control method for an electric
vehicle wherein steering/drive control is effected through separate
steering and drive motors for each of a left front, right front, left rear
and right rear wheel, characterized in that the rotation of the steering
motors and drive motors is controlled in accordance with condition
equations that can be expressed as
##EQU65##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√W.sup.2 +L.sup.2 :0W
for right turns, and
##EQU66##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√W.sup.2 +L.sup.2 :L:W:0
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels; thereby controlling the
steering angle and speed of rotation of each wheel such as to perform
steering/drive operations according to a steering mode M4, wherein the
vehicle turns to the right with the right rear wheel as the center of
rotation of the turn, and turns to the left with the left rear wheel as
the center of rotation of the turn.
14. A method of operating and electric vehicle having a left front, a right
front, a left rear and a right rear wheel, and a plurality of steering and
drive motors, comprising the step of:
controlling the rotation of each of the steering motors and drive motors in
accordance with condition equations that can be expressed as
.alpha..sub.1 =.alpha..sub.2 =0
##EQU67##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =0:W:L:√W.sup.2 +L.sup.2
for right turns, and
.alpha..sub.1 =.alpha..sub.2 =0
##EQU68##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =W:0:√W.sup.2 +L.sup.2 :L
for left turns, where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels; thereby controlling the
steering angle and speed of rotation of each wheel such as to perform
steering/drive operations according to a steering mode M5, wherein the
vehicle turns to the right with the right front wheel as the center of
rotation of the turn, and turns to the left with the left front wheel as
the center of rotation of the turn.
15. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising at least one of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a wheel steering angle computation means for receiving the steering mode
select signal, and based on the vehicle speed and direction command
signal, computing steering angles for the steering motors in accordance
with condition equations required to perform steering/drive operations
according to the select steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and, based on the vehicle speed/direction command signal,
computing wheel rotation speeds for the drive motors in accordance with
condition equations required for performing steering and drive according
to the selected mode;
a steering motor control means for controlling rotation of the steering
motors, based on the computed steering angles; and,
a drive motor control means for controlling the rotation speeds of the
drive motors, based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M1 can be expressed as the
condition equations
##EQU69##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2 :√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of each wheel.
16. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a command signal rate-of-change suppression means for holding the
rate-of-change of the vehicle speed/direction command signal to a value
smaller than the lowest value of either a steering angle command following
performance or a speed of rotation command following performance of the
wheel, for generating an adjusted vehicle speed/direction command signal;
a wheel steering angle computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing steering angles for the steering motors, based on condition
equations required to perform steering/drive operations according to the
selected steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing, therefrom, wheel rotation speeds based on the condition
equations required to perform steering/drive operations according to the
selected steering mode;
a steering motor control means for controlling rotation of the steering
motors based on the computed steering angles; and,
a drive motor control means for controlling rotation of the drive motors
based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M1 can be expressed as the
condition equations
##EQU70##
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2 :√(R-W).sup.2 +L.sup.2
:√(R+W).sup.2 +L.sup.2
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
17. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheels, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising at least one of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a wheel steering angle computation means for receiving the steering mode
select signal, and based on the vehicle speed and direction command
signal, computing steering angles for the steering motors in accordance
with condition equations required to perform steering/drive operations
according to the selected steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and, based on the vehicle speed/direction command signal,
computing wheel rotation speeds for the drive motors in accordance with
condition equations required for performing steering and drive according
to the selected mode;
a steering motor control means for controlling rotation of the steering
motors, based on the computed steering angles; and,
a drive motor control means for controlling the rotation speeds of the
drive motors, based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M2 can be expressed as the
condition equations
.alpha..sub.1 =.alpha..sub.2 =.alpha..sub.3 =.alpha..sub.4
n.sub.1 =n.sub.2 =n.sub.3 =n.sub.4
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
and,
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively.
18. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a command signal rate-of-change suppression means for holding the
rate-of-change of the vehicle speed/direction command signal to a value
smaller than the lowest value of either a steering angle command following
performance or a speed of rotation command following performance of the
wheels, for generating an adjusted vehicle speed/direction command signal;
a wheel steering angle computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing steering angles for the steering motors, based on condition
equations required to perform steering/drive operations according to the
selected steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing, therefrom, wheel rotation speeds based on the condition
equations required to perform steering/drive operations according to the
selected steering mode;
a steering motor control means for controlling rotation of the steering
motors based on the computed steering angles; and,
a drive motor control means for controlling rotation of the drive motors
based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M2 can be expressed as the
condition equations
.alpha..sub.1 =.alpha..sub.2 =.alpha..sub.3 =.alpha..sub.4
n.sub.1 =n.sub.2 =n.sub.3 =n.sub.4
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
and,
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively.
19. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising at least one of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a wheel steering angle computation means for receiving the steering mode
select signal, and based on the vehicle speed and direction command
signal, computing steering angles for the steering motors in accordance
with condition equations required to perform steering/drive operations
according to the selected steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and, based on the vehicle speed/direction command signal,
computing wheel rotation speeds for the drive motors in accordance with
condition equations required for performing steering and drive accordance
to the selected mode;
a steering motor control means for controlling rotation of the steering
motors, based on the computed steering angles; and,
a drive motor control means for controlling the rotation speeds of the
drive motors, based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M3 can be expressed as the
condition equations
##EQU71##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +(2L).sup.2
(R-W).sup.2 +(2L).sup.2 :√(R+W).sup.2 +(2L).sup.2 (R+W).sup.2
+(2L).sup.2 :.vertline.R-W.vertline.:.vertline.R+W.vertline..
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
20. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a command signal rate-of-change suppression means for holding the
rate-of-change of the vehicle speed/direction command signal to a value
smaller than the lowest value of either a steering angle command following
performance or a speed of rotation command following performance of the
wheel, for generating an adjusted vehicle speed/direction command signal;
a wheel steering angle computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing steering angles for the steering motors, based on condition
equations required to perform steering/drive operations according to the
selected steering mode;
a wheel rotation steed computation means for receiving the steering mode
select signal and the adjusted vehicle speed/direction command signal, and
computing, therefrom, wheel rotation speeds based on the condition
equations required to perform steering/drive operations according to the
selected steering mode;
a steering motor control means for controlling rotation of the steering
motors based on the computed steering angles; and,
a drive motor control means for controlling rotation of the drive motors
based on the computed rotation speeds,
wherein the condition equations required to perform steering/drive
operations according to the steering mode M3 can be expressed as the
condition equations
##EQU72##
.alpha..sub.3 =.alpha..sub.4 =0
n.sub.1 :n.sub.2 :n.sub.3 :n.sub.4 =√(R-W).sup.2 +(2L).sup.2
(R-W).sup.2 +(2L).sup.2 :√(R+W).sup.2 +(2L).sup.2 (R+W).sup.2
+(2L).sup.2 :.vertline.R-W.vertline.:.vertline.R+W.vertline.
where
.alpha.1, .alpha.2, .alpha.3, and .alpha.4 are the steering angles for the
right front, left front, right rear, and left rear wheels, respectively;
n1, n2, n3, and n4 are the wheel rotation speeds for the right front, left
front, right rear, and left rear wheels, respectively;
L is the distance between each wheel and a center line X between the front
wheels and rear wheels;
W is the distance between each wheel and a center line Y between the right
wheels and the left wheels; and,
R, for the case wherein the turning paths of the wheels inscribe concentric
arcs, is the distance between the center of the concentric arcs and a
point central to the locations of the four wheels.
21. An electric vehicle steering/drive control system wherein
steering/drive control is effected through separate steering and drive
motors for each of a left front, right front, left rear and right rear
wheel, comprising:
a steering/drive command means, comprising
a steering mode selection means for generating a steering mode select
signal corresponding to a steering mode selected by a vehicle driver from
among a plurality of different steering modes, comprising at least one of
an M1 steering mode wherein the travel paths of the right and left rear
wheels follow the travel paths of the right and left front wheels,
respectively;
an M2 steering mode wherein the travel paths of the front and rear wheels
lie parallel to each other;
an M3 steering mode wherein the rear wheel turning path relative to the
front wheel turning path is an inside wheel difference path;
an M4 steering mode wherein the vehicle turns to the right with the right
rear wheel as the center of rotation of the turn, and turns to the left
with the left rear wheel as the center of rotation of the turn; and,
an M5 steering mode wherein the vehicle turns to the right with the right
front wheel as the center of rotation of the turn, and turns to the left
with the left front wheel as the center of rotation of the turn;
a vehicle speed/direction command means for generating a vehicle
speed/direction command signal responsive to operations performed by the
driver;
a wheel steering angle computation means for receiving the steering mode
select signal, and based on the vehicle speed and direction command
signal, computing steering angles for the steering motors in accordance
with condition equations required to perform steering/drive operations
according to the selected steering mode;
a wheel rotation speed computation means for receiving the steering mode
select signal and, based on the vehicle speed/direction command signal,
computing wheel rotation speeds for the drive motors in accordance with
condition equations required for performing steering and drive according
to the selected mode;
a steering motor control means for controlling rotation of the steering
motors, based on the computed steering angles; and,
a
