Lawrence Tognetti's Masters Thesis

Lawrence Tognetti's (L.J.) Masters Thesis

Summary

Haptic interfaces have various applications ranging from training devices to super joysticks for remotely operated robots. Existing marketed haptic interfaces rely on powered actuators to resist motion or apply force to the user, simulating desired virtual boundaries and other haptic features. Due to the size or nature of certain applications, it may not be desirable to use a haptic interface with capabilities of overpowering the human's input. This has opened the area of passive haptic interfaces. Passive haptic interfaces do not use actuators capable of adding energy to the system, but rather utilize actuators that dissipate or redirect user supplied energy. PTER (Passive Trajectory Enhancing Robot) is a two-degree of freedom passive haptic robot test bed, utilizing clutches to dissipate or redirect user supplied energy in order to simulate virtual boundaries. Deficiencies in PTER's actuators have been identified in past research.

This research initially surveys industrial available clutch / brakes, but none are found to suit the project's requirements. Efforts are then turned to redesigning the existing Dynacorp electromagnetic friction clutches. The new clutches incorporate provisions to measure actual applied torque for use with feedback control and rely on a new spring back mechanism to ensure repeatable engagement and disengagement. Careful attention is given to torque measuring sensitivity and endurance strength of the new components. One prototype clutch is built, tested, and modeled. Benefits of closed loop proportional torque control are demonstrated with experiments and advantages of various digital controllers are simulated.

Individual Chapters

Each of the individual chapters are saved in a separate "PDF" file. Below you will find the chapter titles and the link to the file. The appendix information was not included, but please contact me if you desire to review it.

Cover pages & Table of Contents
Chapter 1
Introduction
Chapter 2
Description & History of PTER
Chapter 3
Description of Existing and Alternative Brakes
Chapter 4
Dynacorp Brake Redesign
Chapter 5
Testing & Control
Chapter 6
Conclusion & Future Work
References

Contact

If you have any questions, feel free to contact me (L.J.) at gt0030b@prism.gatech.edu