Self-piloting vehicle

• US 4,816,998 A
• Filed: 12/20/1982
• Issued: 03/28/1989
• Est. Priority Date: 02/05/1979
• Status: Expired due to Fees

• Current Assignee: AB Volvo
• Original Assignee: AB Volvo
• Inventors: Ahlbom, Sten H. N.
• Primary Examiner(s): Werner, Frank E.
• Assistant Examiner(s): Underwood, Donald W.
• Application Number:
  US07/451,509
• Time in Patent Office: 2,290 Days
• Field of Search: 180/167, 180/168, 180/79, 180/79.1, 340/23, 340/24, 364/424, 364/436, 364/433, 33/141 R, 33/141.5, 33/142, 33/1 N, 33/1 PT
• US Class Current: 701/23
• CPC Class Codes: B66F 9/063 Automatically guided
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00

Abstract

A self-pivoting vehicle with steering wheel(s) and driving wheel(s), possibly combined, a drive motor and a steering means for pivoting said steering wheel(s). At least one measuring wheel rolls freely against the floor under the vehicle, or two such wheels are journalled at different points on the vehicle for measuring off distances rolled. A computing unit and steering mechanism pivot said steering wheel. The computing unit receives measured values from the measuring wheel(s) for computing the deviation of the vehicle by dead reckoning from a predetermined desired trajectory for the vehicle, and gives off a steering angle signal for deviation correction to the steering mechanism.

Claims

1. In a vehicle which is self-piloting including a steering mechanism for controlling said vehicle motion, a control system for providing steering commands to said vehicle comprising:

means for measuring the change in position of said vehicle in two coordinates including first and second spaced apart free wheels which rotate in response to vehicle movement, and first and second sensors for providing pulses in response to a given rotation of said wheels;

a computer connected to receive position change pulses from each of said sensors, said computer including a programmed trajectory for said vehicle, said computer programmed to calculate from said pulses

(a) a change in attitude Δ

φ

travelled by said vehicle during a time Δ

t as (φ

₁ -φ

₂)/Δ

t where φ

₁ is the attitude at the beginning of Δ

t, and φ

₂ the attitude at the end of Δ

t,

(b) a change in side error in time Δ

t as S₁ -S₂ where S₁ and S₂ are the distances between the midpoint of the wheels and the programmed trajectory at the beginning and end of Δ

t, and

(c) a steering angle from said change in attitude and side error; and

motor drive means coupled to said steering mechanism and connected to receive a signal from said computer representing said steering angle whereby said vehicle trajectory is controlled to follow said programmed trajectory.

2. In a vehicle which is self-piloting including a steering mechanism for controlling said vehicle motion, a control system for providing steering commands to said vehicle comprising:

means for measuring the change in position of said vehicle in two coordinates including first and second spaced apart free wheels which rotate in response to vehicle movement, and sensors connected for providing pulses in response to a given rotation displacement of said wheels;

a computer connected to receive position change pulses from each of said wheels, said computer including a programmed trajectory for said vehicle, said computer programmed to calculate from said pulses

(a) a radius of curvature for an arc R travelled by said vehicle,

(b) a length of said arc,

(c) a steering angle from said length of arc and radius of curvature, and said programmed trajectory according to ##EQU6## where φ

₁ is the initial attitude of the vehicle at the beginning of said arc, Δ

t the time of travel over said arc;

φ

₂ is the attitude after Δ

t;

S₁ is the distance between the programmed trajectory and midpoint of the wheels at the beginning of said arc;

S₂ is the distance between the programmed trajectory and midpoint of the wheels at the end of said arc;

a, b, c, d and f are constants;

δ

g=arctan (1/R); and

δ

a is the actual value of steering angle; and

motor drive means coupled to said steering mechanism and connected to receive a signal from said computer representing said steering angle whereby said vehicle trajectory is controlled to follow said programmed trajectory.

3. In a vehicle which is self-piloting including a steering wheel controlled by a servo motor to change the trajectory of said vehicle, apparatus for providing steering commands for steering said vehicle along a predetermined trajectory comprising:

first and second spaced apart wheels, each having a rotation sensor located on said vehicle which rotates in response to said vehicle movement, each of said sensors generating a pulse in response to a given angular displacement;

first and second counters for receiving each pulse produced from a respectively connected sensor;

a computer connected to monitor the contents of each of said counters, said computer including a programmed trajectory for said vehicle travel and programmed to compute from said counters'"'"' contents

(a) the length of arc of travel of said vehicle,

(b) the radius of arc of said vehicle, and

(c) a new steering angle based on said programmed trajectory and said length and radius of arc; and

,

digital to analog converter means connected from said computer to said servo motor, whereby a steering angle signal is provided by said computer based upon said vehicle movement and said programmed vehicle trajectory.