Ultrasonic apparatus for positioning a robot hand

• US 4,718,023 A
• Filed: 11/27/1984
• Issued: 01/05/1988
• Est. Priority Date: 11/27/1984
• Status: Expired due to Fees

• Current Assignee: Photo Acoustic Technology
• Original Assignee: Photoacoustic Technology Incorporated
• Inventors: Arora, Arvind
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Lastova, John R.
• Application Number:
  US06/675,424
• Time in Patent Office: 1,134 Days
• Field of Search: 364/513, 364/182, 901/46, 901/47, 901/1, 73/625, 73/628, 73/641
• US Class Current: 700/258
• CPC Class Codes: B25J 13/089 Determining the position of the robot with reference to its environment
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 2219/45083 Manipulators, robot

Abstract

A robot positioning apparatus for use with robot devices having a movable portion, wherein the movable portion may be spatially oriented to, and controllably spaced from, a reference surface. Initial locating of the reference surface is accomplished by an approximate positioning subsystem using multiple, angularly oriented units which send and receive acoustic orientation positioning signals in search of the reference surface. Once a return signal is received, switching logic identifies the necessary reorienting of the movable portion to achieve approximately the proper facing relationship of the movable portion to the surface. For precise positioning and ranging after the facing relation is established, a precision positioning subsystem emits an acoustic signal toward the surface, and a response signal is received back from the surface by at least two, and preferably three, receivers mounted upon the movable portion of the robot device. A comparator compares the times of flight of the signals received by the receivers on a pair-wise basis, thereby determining the relative distance of the pair of receivers from the surface, which in turn is a direct indication of the spatial orientation of the compared receivers in relation to the reference surface. The signal time of flight from the surface to the receivers is measured as an indicator of the distance of the receivers from the surface. The movable portion of the robot device is adjusted to maintain some predetermined distance and spatial orientation for the signal receivers mounted on the movable portion, thereby orienting the movable portion with respect to the surface in three dimensions.

Claims

1. Apparatus for positioning a movable portion of a robot device with respect to a surface, comprising:

an approximate positioning subsystem, including,

means for emitting at least two non-colinear approximate positioning signals,

means for receiving a response signal, if any, resulting from the striking of the approximate positioning signals on the surface, said means for receiving being mounted on the movable portion of the robot device,

means for detecting the presence of a first received response signal,

means for adjusting the movable portion of the robot device into an approximate facing relationship to the detected first received response signal; and

a precision positioning subsystem operable when the movable portion is in an approximate facing relationship to the surface, including,

means for emitting a precise positioning signal toward the surface;

means for receiving a return signal originating at the surface as a result of the precise positioning signal striking the surface, said means for receiving being mounted on the movable portion of the robot device and including at least two signal receivers,

means for comparing the times of flight of the return signals received by said signal receivers on a pair-wise basis to create a comparison signal, and

means for adjusting the movable portion of the robot device to maintain predetermined values of the comparison signal.