Advanced Robotics Mechatronics System: emerging technologies for interplanetary robotics

The paper describes some of the results from the Advanced Robotics Mechatronics System Project. The objective of the overall project was to examine new technologies for the next generation of space robotics which would deliver reduced system mass and high torque density joints. The development and test of this novel manipulator joint and control architecture was based on the use of ultrasonic motors (USM). These motors were chosen due to their vacuum compatibility and inherent self braking. The joint consists of a single USM driving a harmonic drive and an electronics board used for motor control, joint telemetry gathering and serial communications to the control computer. Multiple joints are connected in parallel to the motor drive bus and sequentially switched to create near coordinated motion. In order to realize this control architecture, a digital USM controller was developed to replace the analog drive electronics. A prototype joint with drive electronics was built and tested at MD Robotics. Test results have shown that USMs with harmonic drives can provide higher torque densities over larger speed ranges when compared to DC motor and conventional planetary gear combinations used in small space robotic arm applications.