Work position error detecting apparatus

• US 4,831,561 A
• Filed: 06/18/1987
• Issued: 05/16/1989
• Est. Priority Date: 06/19/1986
• Status: Expired due to Fees

• Current Assignee: Tokico Limited (Hitachi, Ltd.)
• Original Assignee: Tokico Limited (Hitachi, Ltd.)
• Inventors: Utsumi, Noriyuki
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Teska, Kevin J.
• Application Number:
  US07/064,201
• Time in Patent Office: 698 Days
• Field of Search: 364/167, 364/469, 364/478, 364/516, 364/559, 364/550, 364/513, 364/560, 356/375, 356/376, 356/385, 356/386, 356/363, 901/7, 901/43, 901/46, 901/47, 250/201, 250/561
• US Class Current: 702/150
• CPC Class Codes: G05B 19/4015 going to a reference at the beginning of machine cycle, e.g. for calibration

Abstract

A work position error detecting apparatus comprises at least three one dimensional sensors for generating outputs dependent on a detected position of a work, where the one dimensional sensors are arranged so that directions in which the position of the work is detected is mutually different among the one dimensional sensors, a memory device for pre-storing outputs of each of the one dimensional sensors at a reference position of the work, and a computing unit for calculating and outputting a position error quantity of the work from the reference position based on outputs of the one dimensional sensors and the outputs of the one dimensional sensors at the reference position pre-stored in the memory device.

Claims

1. A work position error detecting apparatus comprising:

three one dimensional sensors for each detecting a position of a corresponding portion of a work along a corresponding direction and for generating outputs dependent on the detected positions of the portions of said work, said three one dimensional sensors being arranged so that the directions are mutually different among said three one dimensional sensors;

memory means for prestoring reference position data based on outputs of said three one dimensional sensors obtained from said work in a reference position; and

computing means coupled to said three one dimensional sensors and to said memory means for calculating and outputting a position error quantity of said work from outputs of said three one dimensional sensors and said reference position data pre-stored in said memory means.

2. A work position error detecting apparatus as claimed in claim 1 in which said one dimensional sensors are provided on a side of said work.

3. A work position error detecting apparatus as claimed in claim 1 in which said three one dimensional sensors comprise a first one dimensional sensor for detecting a position of a first portion of said work along a direction of a length of said work, a second one dimensional sensor for detecting a position of a second portion of said work along a direction of a height of said work, and a third one dimensional sensor for detecting a position of a third portion of said work along a direction of a width of said work.

4. A work position error detecting apparatus as claimed in claim 3 in which said third one dimensional sensor is constituted by an ultrasonic distance sensor for detecting the position of the third portion of said work by measuring a distance between the third portion and the third one dimensional sensor.

5. A work position error detecting apparatus as claimed in claim 3 which further comprises a fourth one dimensional sensor for detecting a position of a fourth portion of said work along the direction of the height thereof, said second and fourth portions being separated from each other along the direction of the length of said work.

6. A work position error detecting apparatus as claimed in claim 3 which further comprises a fourth one dimensional sensor for detecting a position of a fourth portion of said work along the direction of the width thereof, said second and fourth portions being separated from each other along the direction of the length of said work.

7. A work position error detecting apparatus as claimed in claim 3 in which each of said first and second one dimensional sensors is constituted by an optical sensor for detecting the position of a corresponding portion of said work by receiving a light from a corresponding light source via said work.

8. A work position error detecting apparatus as claimed in claim 7 in which said optical sensor comprises an array of light receiving elements which are arranged with a constant pitch along a direction in which the position of the portion of said work is detected.

9. A work position error detecting apparatus as claimed in claim 1 in which each one dimensional sensor is movable along the direction in which the position of a corresponding portion of said work is detected by said each one dimensional sensor.

10. A work position error detecting apparatus as claimed in claim 9 in which each one dimensional sensor is provided on a table which is movable along the directions of length, height and width of said work.

11. A work position error detecting apparatus as claimed in claim 9 in which said computing means comprises correlation data calculating means for calculating correlation data between deviations of said one dimensional sensors and changes in outputs of said sensors caused by the deviations and for supplying the correlation data into said memory means, said position error quantity being calculated by also using said correlation data.

12. A work position error detecting apparatus as claimed in claim 11 in which said correlation data calculating means calculates correlation data for a plurality of different kinds of work.

13. A work position error detecting apparatus as claimed in claim 1 in which said work is a car body.

14. A work position error detecting apparatus as claimed in claim 13 in which one of said one dimensional sensors detects a position of a pillar portion of the car body along a direction of a length thereof.

15. A work position error detecting apparatus as claimed in claim 13 in which one of said one dimensional sensors detects a position of a wheel house portion of the car body along a direction of a height thereof.