The PHD: A Planar, Harmonic Drive Robot for Joint Torque Control
Abstract
Many efforts are underway to extend the abilities of robots into the domain of space, where they can be used to perform simple tasks in environments where it is difficult or dangerous for humans to work. One such effort, the Flight Telerobotic Servicer (FTS) is being undertaken for NASA by Martin Marietta. The FTS is a two arm manipulator system mounted on a mobile platform. A third arm is used to anchor the platform while working. The two manipulators on the FTS are seven degree of freedom arms which will be used to perform a variety of tasks. MIT was contracted, in conjunction with the University of Iowa, to build an accurate simulation of a seven degree of freedom manipulator similar to that proposed for the FTS. This thesis documents the development of that model. In order to perform some tasks, the FTS will need some sort of force control ability. To assist in the development of that ability a robot, the PHD, was designed and built with the capability to be used for two purposes. First, it can be used to perform research on joint torque control schemes, and second it can be used to determine the important dynamic characteristics of the Harmonic Drive gear reducer. The PHD, is a planar, three degree of freedom arm with torque sensors integral to each joint allowing joint torque feedback to be implemented. Preliminary testing using the PHD has shown that a simple linear spring model of the Harmonic Drive's flexibility is suitable in many situations. Future work with the system could include a more detailed Harmonic Drive model, as well as development of joint torque feedback schemes for force control.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1990
- Accession Number
- ADA228691
Entities
People
- Bruce R. Thompson
Organizations
- Massachusetts Institute of Technology