Stephen J Tenniswood

US Patent:

6180939, Jan 30, 2001

Filed:

Dec 4, 1998

Appl. No.:

9/205742

Inventors:

Myles Markey - Ann Arbor MI
Dale R. Greer - Novi MI
Stephen James Tenniswood - Rochester MI
Jesper Christensen - Freising, DE

Assignee:

Perceptron, Inc. - Plymouth MI

International Classification:

H01J 724

US Classification:

250238

Abstract:

A temperature compensation system (300) is provided for compensating measurements from a sensor (240). A temperature transducer (310) is placed in close proximity to a manufacturing workstation as a means of measuring the ambient temperature associated with the workstation (200). A reference workpiece (100) is placed within a sensing zone of the sensor (240). The system (300) includes a temperature compensating module (320) that is connected to the sensor (240) and to the temperature transducer (310) for determining a baseline measurement of the reference workpiece at a reference temperature. The temperature compensating module (320) is further adapted for collecting a plurality of measurements of the reference workpiece over a plurality of temperatures for establishing a relationship between these measurements and their corresponding temperature values. In addition, a workpiece measuring module (330) is also connected to the sensor (240) and to the temperature transducer (310) for measuring a first workpiece at a first temperature, whereby the sensor measurement is compensated for temperature using this relationship. In this way, the temperature compensation system (300) compensates the sensor measurement for physical changes in any of the components of the workstation that are caused by fluctuations in ambient temperature.