Control system for self-propelled working vehicle including vehicle course correction means

• US 5,079,706 A
• Filed: 02/13/1990
• Issued: 01/07/1992
• Est. Priority Date: 12/09/1986
• Status: Expired due to Fees

• Current Assignee: Kubota Corporation
• Original Assignee: Kubota Corporation
• Inventors: Takahara, Kazuhiro, Tanaka, Shigeru, Ito, Katsumi, Yamaguchi, Tetsuo
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Lee, Benny
• Application Number:
  US07/479,189
• Time in Patent Office: 693 Days
• Field of Search: 364/424, 364/443, 364/424.01, 364/424.02, 180/167, 180/168, 180/140, 180/142, 180/233, 180/234, 180/DIG. 900, 37/DIG. 1, 37/DIG. 17
• US Class Current: 701/23
• CPC Class Codes: G05D 1/0033 by having the operator tracking the vehicle either by direct line of sight or via one or more cameras located remotely from the vehicle
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0261 using magnetic plots
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165

Abstract

A steering control system for a self-propelled working vehicle having steerable front and rear wheels. The control system comprises sensors for detecting a directional or orientation error and a sideways error of the vehicle relative to a reference line or lines extending in a vehicle running direction, and a control unit for steering the vehicle in response to signals received from the sensors. The control unit is capable of steering the vehicle in a turn steering mode for turning the front and rear wheels to the same steering angle in opposite directions and a parallel steering mode for turning the front and rear wheels to the same steering angle in the same direction. When the directional error and the sideways error take place simultaneously, the control unit determines directions and angles for turning the front and rear wheels to correct the two errors simultaneously.

Claims

1. A steering control system for a self-propelled working vehicle having steerable front and rear wheels and movable along a propelling target line, said steering control system comprising:

direction detecting means for detecting an inclination of vehicle running direction relative to said target line, said inclination relative to said target line being a directional error;

sideways error detecting means for detecting a distance between said vehicle and said target line, said distance being a sideways error; and

steering control means for steering said front and rear wheels in response to signals received from said direction detecting means and said sideways error detecting means, said steering control means comprising means for steering said front and rear wheels to the same steering angle in opposite directions in only a turn steering mode and for steering said front and rear wheels to the same steering angle in a same direction in only a parallel steering mode;

wherein, when detection by said direction detecting means of said directional error of said vehicle and detection by said sideways error detecting means of said sideways error of said vehicle take place simultaneously and said front wheels are directionally displaced from said target line by a large amount compared with the rear wheels, said steering control means further increases steering angle of said front wheels by a predetermined front wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode; and

when detection by said direction detecting means of said directional error of said vehicle and detection by said sideways error detecting means of said sideways error of said vehicle take place simultaneously and said rear wheels are directionally displaced from said target line by a large amount compared with said front wheels, said steering control means further increases the steering angle of said rear wheels by a predetermined rear wheel offset with respect to positions of said front and rear wheels in said parallel steering mode; and

wherein said steering control system detects a presence of obstacles laterally spaced from the vehicle and thereby corrects deviations from the target line.

2. A steering control system as claimed in claim 1 wherein said steering control means steers said front and rear wheels in said turn steering mode when only a signal of directional error of said vehicle is received from the direction detecting means, and wherein said steering control means steers said front and rear wheels in said parallel steering mode when only a signal of sideways error is received from said sideways error detecting means.

3. A steering control system as claimed in claim 2 wherein at least one of a front and a rear wheel offset amount is determined in accordance with the signal received from the sideways error detecting means.

4. A steering control system as claimed in claim 1 wherein, when only a signal of directional error is received from the direction detecting means, the steering control means steers at least one of the front and rear wheels in the turn steering mode.

5. A steering control system as claimed in claim 1 wherein, when only a signal of sideways error is received from the sideways error detecting means, the steering control means steers the front and rear wheels in the parallel steering mode.

6. A steering control system for a self-propelled working vehicle having steerable front and rear wheels and movable along a propelling target line disposed by a ground path, said steering control system comprising:

light beam emitting means installed on the ground path;

first and second sensor means vertically arranged on the vehicle for detecting a light beam, emitted from said light beam emitting means, from a position transverse of the vehicle;

directional error and sideways error calculating means for detecting, in response to said first and second sensor means, a directional error, said directional error being in inclination of vehicle running direction relative to said target line, and a sideways error, said sideways error being a distance between said vehicle and said target line, respectively with said directional and sideways error calculated from data received from said first and second sensor means;

steering control means for steering said front and rear wheels in response to signals received from said directional error calculating means and said sideways error calculating means, said steering control means comprising a means for steering said front and rear wheels to the same steering angle in opposite directions in only a turn steering mode and for steering said front and rear wheels to the same steering angle in a same direction in only a parallel steering mode;

wherein, when detection by said direction error calculating means of said directional error of said vehicle and detection by said sideways error calculating means of said sideways error of said vehicle take place simultaneously and said front wheels are directionally displaced from said target line by a large amount compared with the rear wheels, said steering control means further increases a steering angle of said front wheels by a predetermined front wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode; and

when detection by said direction error calculating means of said directional error of said vehicle and detection by said sideways error calculating means of said sideways error of said vehicle take place simultaneously and said rear wheels are directionally displaced from said target line by a large amount compared with said front wheels, said steering control means further increases a steering angle of said rear wheels by a predetermined rear wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode.

7. A steering control system as claimed in claim 6 wherein said steering control means steers said front and rear wheels in said turn steering mode when only a signal of directional error of said vehicle is received from the direction detecting means, and wherein said steering control means steers said front and rear wheels in said parallel steering mode when only a signal of sideways error is received from said sideways error detecting means.

8. A steering control system as claimed in claim 7 wherein one of a front and a rear wheel offset amount is determined in accordance with a signal received from sideways error calculating means.

9. A steering control system as claimed in claim 6 wherein, when only a signal of directional error is received from the directional error calculating means, the steering control means steers the front and rear wheels in the turn steering mode.

10. A steering control system as claimed in claim 6 wherein, when only a signal of sideways error is received from the sideways error calculating means, the steering control means steers the front and rear wheels in the parallel steering mode.

11. A steering control system for automatically propelling of self-propelled working vehicle having steerable front and rear wheels and being movable along a running guide, said system comprising:

wheel drive means for driving at least one of the front and rear wheels;

direction detecting means for detecting a directional error of said vehicle, said directional error being an inclination of vehicle running direction relative to said running guide;

sideways error detecting means for detecting a distance between said vehicle and said running guide, said distance being a sideways error; and

steering control means for steering said front and rear wheels in response to signals received from said direction detecting means and said sideways error detecting means;

wherein, when both said directional and sideways errors exceed predetermined permissible ranges, said steering control means steers said front and rear wheels in an offset steering mode so as to steer said front and rear wheels to different steering angles in the same direction, said front and rear wheels being steered in only a first direction which corrects said sideways error, with said front wheels steered to a greater angle than said rear wheels, where said directional error and said sideways error occur in a same direction, and said front and rear wheels being steered in only the first direction to correct said sideways error with said rear wheels steered to a greater angle than said front wheels, where said directional and sideways errors occur in opposite directions; and

wherein said steering control system detects a presence of objects laterally spaced from the vehicle and thereby corrects deviations from a target line.

12. A method for steering a self-propelled vehicle having steerable front and rear wheels and moveable along a target line, said method comprising the steps of:

detecting an inclination of vehicle running direction relative to said target line, said inclination relative to said target line being a directional error;

detecting a distance between said vehicle and said target line, said distance being a sideways error;

steering said front and rear wheels in response to said directional and sideways error, said front and rear wheel being steerable to the same steering angle in opposite directions in only a turn steering mode and to the same steering angle in a same direction in only a parallel steering mode;

further increasing said steering angle of said front wheels by a predetermined front wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode when said directional and sideways errors are detected simultaneously and said front wheels are directionally displaced from said target line by a large amount compared with said rear wheels; and

further increasing the steering angle of said rear wheels by a predetermined rear wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode when said directional and sideways errors are detected simultaneously and said rear wheels are directionally displaced from said target line by a large amount compared with said front wheels;

wherein said steering system correcting deviations from the target line by detecting a presence of obstacles laterally spaced from the vehicle.

13. A method for steering a self-propelled working vehicle having steerable front and rear wheels and movable along a propelling target line disposed on a ground path, said method comprising the steps of:

detecting light beams, using first and second sensor means vertically arranged on said vehicle, emitted from light beam emitting means installed on the ground path;

detecting an inclination of vehicle running direction relative to said target line in response to said detected light beams, said inclination relative to said target line being a directional error;

detecting a distance between said vehicle and said target line in response to said detected light beam, said distance being a sideways error;

steering said front and rear wheels in response to said directional and sideways error;

said front and rear wheel being steerable to the same steering angle in opposite directions in only a turn steering mode and to the same steering angle in a same direction in only a parallel steering mode;

further increasing said steering angle of said front wheels by a predetermined front wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode when said directional and sideways errors are detected simultaneously and said front wheels are directionally displaced from said target line by a large amount compared with said rear wheels; and

further increasing the steering angle of said rear wheels by a predetermined rear wheel offset with respect to the positions of said front and rear wheels in said parallel steering mode when said directional and sideways errors are detected simultaneously and said rear wheels are directionally displaced from said target line by a large amount compared with said front wheels.

14. A method for automatically propelling a self-propelled working vehicle having steerable front and rear wheels and moveable along a running guide, said method comprising the steps of:

driving at least one of the front and rear wheels with a wheel drive means;

detecting an inclination of vehicle running direction relative to said running guide, said inclination relative to said running guide being a directional error;

detecting a distance between said vehicle and said running guide, said distance being a sideways error;

steering said front and rear wheels in response to said directional and sideways error; and

steering said front and rear wheels in an offset steering mode so as to steer said front and rear wheels to different steering angles in the same direction, said front and rear wheels being steered in only a first direction which corrects the sideways error with said front wheels being steered to a greater angle than said rear wheels, and said directional and said sideways error occur in the same direction, and to steer said front and rear wheels in only the first direction to correct sideways error with said rear wheels steered to a greater angle than said front wheels, where said directional and sideways errors occur in opposite directions, said steering occurring when said directional and said sideways errors exceed predetermined permissible ranges, said steering control system avoiding obstacles laterally spaced from the vehicle by detecting a presence of the obstacles and thereby correcting deviations from a target line.