Browse Prior Art Database

Position and Velocity Measurement by Optical Shaft Encoders Disclosure Number: IPCOM000148101D
Original Publication Date: 1982-Jun-23
Included in the Prior Art Database: 2007-Mar-28
Document File: 36 page(s) / 1M

Publishing Venue

Software Patent Institute

Related People

Rangan, Kasturi V.: AUTHOR [+2]



This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 10% of the total text.

Page 1 of 36

Position and Velocity Measurement 1

by Optical Shaft Encoders

. - It ,

Copy right @ 1982 Carnegie-Mellon University 1

This work is sponsored by The Office of Naval Research (Contract No. N00014-81.-K-0503)


. .

Kasturi V. Ra ~ D : ~ > I G


by UNtVERS\T\(


Robotics Institute

 Carnegie-Mellon University Pittsburgh, Pennsylvania 15213

23 June 1982

[This page contains 1 picture or other non-text object]

Page 2 of 36

[This page contains 1 picture or other non-text object]

Page 3 of 36

Table of Contents

1. The Measurement System

1.1 Optical Shaft Encoders
1.1.1 Incrementaf Shaft Encoders
1.1.2 Absolute Shaft Encoders
1.2 Position Measurement
1.3 Velocity Measurement

2. Design

2.1 Configuration of joint motors and shaft encoders
2.2 Hardware Limitations
2.3 Anglc(Position) Mcasurerncnt
2.4 Velocity by Change of Position
2.5 Velocity by frequency measurement

3. Implementation and Performance

3.1 Position Measurement
3.2 Velocity Measurement
3.3 Hardwarc Features
3.4 Noise Reduction in Encoder Signals
3.5 Performance Analysis

4. Conclusion

I. A Brief Review of Transducers

1.1 Angular Displacement Transducers
1.2 Angular Velocity Transducers (Tachometers)

[This page contains 1 picture or other non-text object]

Page 4 of 36

[This page contains 1 picture or other non-text object]

Page 5 of 36

A bst fact 1

Accurate measurement of the angular position and angular velocity of thc joints is erkcntial in the control of

a robot manipulator. This report analyses in detail the design and implementation o measurement system

for the CMU Direct Drive Arm using High Resolution Optical Shaft Encoders. methods of angular

velocity measurement--velocity by change ofposition and velocily byfrequency-are and compared.

[This page contains 1 picture or other non-text object]

Page 6 of 36

[This page contains 1 picture or other non-text object]

Page 7 of 36


 This rcport dcscribcs the principlcs involvcd in using optical shaft cncodcrs to surc angular position and velocity. l'hc dcsign,implcmcntation and performance analysis of a systcm built for the

CMU Direct Drivc Arm arc prcscntcd in detail.
l'hc control of a Robot Manipulator involvcs rcading the current state of the ma ator, computing the

dcsircd statc and implcmcnting a control algorithm to achicvc thc dcsircd statc. rrent statc includes joint anglcs, joint angular velocities, joint angular accclcrations, forces and ts, proximity to a workpicce etc. Thc quantitative rncasurement of these parameters is done using tra

 We are concerned here with the mcasurement of joint anglcs and joint a locities. In. robot manipulators wherc joint links arc connccted to driv.e motors through gca her transmission mcchanisms, thc angular displacement of the motor shaft is many times that o link. This makes possiblc high resolution joint par...