Control arbitration system for a mobile robot vehicle

• US 5,227,973 A
• Filed: 02/26/1991
• Issued: 07/13/1993
• Est. Priority Date: 02/26/1991
• Status: Expired due to Term

• Current Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Original Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Inventors: Marcantonio, Angelo R.
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/661,771
• Time in Patent Office: 868 Days
• Field of Search: 364/424.02, 180/167-169, 318/568.12
• US Class Current: 701/23
• CPC Class Codes: G05D 1/0061 for transition from automatic pilot to manual pilot and vice versa

Abstract

A method of arbitrating between various modes of operation involved in controlling the movement of a robot vehicle from a current position in which the modes are given a sequential priority in such manner that no mode can be activated unless all previous modes in the sequence are not actuated. The sequential priority is abort command, joystick control, object avoidance, missed target procedure, and dead reckoning.

Claims

1. A method for controlling a robot vehicle comprising the following steps in order:

determining whether a target location is being asserted;

determining whether the vehicle has reached a target location;

arbitrating to determine which one of a plurality of modes of operation is to be asserted via a control hierarchy providing priority in descending order to said modes including abort command, joystick control, obstacle avoidance, missed target procedure, and dead reckoning;

controlling the movement of the vehicle in accordance with the arbitrated asserted mode for a given period; and

returning to the first step.

2. A method for controlling a robot vehicle having means for producing first signals representing its position and orientation, and second signals indicating the locations of obstacles, said method comprising the steps of:

determining whether a target location is asserted or not;

deriving from said first signals the position and orientation of the vehicle;

determining whether the vehicle has reached the target location;

computing the heading and distance to the target location from the position and orientation of the vehicle;

computing the steering velocity required to reach the target location from the position and orientation of the vehicle;

computing the drive velocity from the distance between the vehicle and the target location;

determining whether a joystick mode has been asserted;

steering the vehicle in accordance with the steering velocity provided by a joystick control, driving the vehicle at said drive velocity for a given period of time, and returning to said first step if the joystick mode is asserted;

determining whether o not an obstacle is present if the joystick mode is not asserted;

steering the vehicle in accordance with an obstacle avoidance procedure, driving it at said drive velocity for a given period, and returning to said first sep if an obstacle is present;

determining whether the distance between the vehicle and the target location is increasing;

driving the vehicle at said drive velocity and steering it at said steering velocity for a given period, if an obstacle is not present and said distance is not increasing;

halting the vehicle if said distance is increasing, the joystick mode is not asserted, and the obstacle avoidance procedure is not active; and

halting the vehicle if it has reached the target location.

3. A method for controlling the movement of a robot vehicle comprising the steps of:

determining whether the location of a target to which the vehicle is to move is asserted;

obtaining information as to the current position and orientation of the vehicle;

determining whether the vehicle has reached the target;

halting the vehicle if it has reached the target;

computing the distance and heading of the target location, if the vehicle has not reached the target;

deriving a first signal for controlling the steering of the vehicle to the target;

deriving a second signal related to the distance of the vehicle from the target location for controlling the speed of the vehicle;

determining whether a joystick is asserting a steering signal;

controlling the speed of said vehicle with the second signal and the steering signal from said joystick, if present, and returning to the first determining step;

determining whether an obstacle is within the range of the target location, if the joystick is not asserting a steering signal;

moving said vehicle in accordance with an obstacle avoidance procedure if an obstacle is present, and returning thereafter to the first step;

moving said vehicle in response to said first and second signals if an obstacle is not present, and returning thereafter to the first step; and

halting the vehicle and returning to the first determining step, if the distance between the vehicle and the target location is increasing and the vehicle is not moving in response to the joystick or the obstacle avoidance procedure.