Vehicle docking apparatus and method

• US 4,659,970 A
• Filed: 08/14/1986
• Issued: 04/21/1987
• Est. Priority Date: 08/14/1986
• Status: Expired due to Fees

• Current Assignee: Caterpillar Industrial Incorporated A Ohio Corporation A Wholly-Owened Subsidiary of Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Melocik, Grant C.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ro, Bentsu
• Application Number:
  US06/896,378
• Time in Patent Office: 250 Days
• Field of Search: 318/269, 318/272, 318/273, 318/275, 318/277, 318/279, 318/587, 318/52, 318/139, 318/362, 318/363, 318/371, 318/372, 364/426, 180/65.1, 180/65.3, 180/65.5, 180/65.8
• US Class Current: 318/269
• CPC Class Codes: G05D 1/0223 involving speed control of the vehicle vehicle fittings for automatically controlling, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator B60K31/00
• CPC Class Codes: G05D 1/0225 involving docking at a fixed facility, e.g. base station or loading bay parking aids B62D15/027

Abstract

Automatic guided vehicles are commonly used in industrial material handling operations. Such vehicles must be accurately docked at predetermined stop locations without the guidance or assistance of human operators. The subject apparatus is used in conjunction with a vehicle having a vehicle drive circuit for controllably propelling the vehicle at a velocity responsive to a velocity command signal. At least one ground engaging wheel is equipped with a vehicle brake for controllably stopping the vehicle in response to a brake actuation signal. A position determining element produces a controlled stop signal in response to the vehicle being positioned a predetermined distance from the desired stop location, and an absolute stop signal in response to the vehicle being positioned at the desired stop location. A logic control circuit receives the stop signals and produces a brake actuation signal having a value sufficient to partially engage the vehicle brake and a velocity command signal having a value sufficient to continue to propel the vehicle at a predetermined low velocity in response to receiving the controlled stop signal. The logic control circuit produces a velocity command signal having a minimum value in response to receiving the absolute stop signal.

Claims

1. Apparatus for controllably stopping a vehicle, said vehicle having a vehicle drive means for controllably propelling said vehicle at a velocity responsive to a velocity command signal, at least one ground engaging wheel equipped with a respective vehicle brake adapted to controllably stop said vehicle in response to brake actuation signals, and a transducer means for sensing said vehicle velocity and responsively producing an actual velocity signal, comprising:

a logic control means for producing said velocity command signal and said brake actuation signal in response to predetermined operating conditions;

position determining means for producing a controlled stop signal in response to said vehicle being positioned a predetermined distance from a desired stop location, and an absolute stop signal in response to said vehicle being positioned at said desired stop location; and

wherein said logic control means receives said actual velocity signal, said controlled stop signal and said absolute stop signal, produces said brake actuation signal having a value sufficient to partially engage said vehicle brake and said velocity command signal having a value sufficient to continue to propel said vehicle at a predetermined low velocity in response to receiving said controlled stop signal, and produces said velocity command signal having a minimum value in response to receiving said absolute stop signal.

2. Apparatus, as set forth in claim 1, wherein said vehicle brake is electrically actuated.

3. Apparatus, as set forth in claim 2, wherein said logic control means produces a brake effort command signal, and includes a brake control means for producing said brake actuation signals in response to said brake effort command signal, said brake actuation signals being a pulse signal having a pulse cycle variably responsive to said brake effort command signal.

4. Apparatus, as set forth in claim 3, wherein said brake control means produces a first brake actuation signal having a relatively long pulse duty cycle in response to said brake effort signal having a magnitude in a first predetermined range, and a second brake actuation signal having a relatively short pulse duty cycle in response to said brake effort signal having a magnitude in a second predetermined range.

5. A method for controllably stopping a vehicle, said vehicle having a logic control means for producing a velocity command signal and a brake actuation signal in response to predetermined operating conditions, a vehicle drive means for controllably propelling said vehicle at a velocity responsive to said velocity command signal, at least one ground engaging wheel equipped with a respective vehicle brake adapted to for controllably stop said vehicle in response to said brake actuation signal, and a transducer means for sensing said vehicle velocity and responsively producing an actual velocity signal, comprising the steps of:

producing a controlled stop signal in response to said vehicle being positioned a predetermined distance from a desired stop location;

producing said brake actuation signal having a magnitude sufficient to partially engage said vehicle brake and said velocity command signal having a value sufficient to continue to propel said vehicle at a predetermined low velocity in response to said controlled stop signal;

producing an absolute stop signal in response to said vehicle being positioned at said desired stop location; and

producing said velocity command signal having a minimum value in response to said absolute stop signal.