Recent technical paper contributed by Greg Zancewicz & Carlos Hoefken at the 5th International Conference on Control and Robotics Engineering. The paper discusses electric actuators adding weight along an articulated robot arm and how the torque and speed limitations impose additional dynamic constraints including useful life of a robot and the extent to which each actuator operates at or near its torque ratings.
Although strain wave, or “harmonic,” gearing can deliver high reduction ratios in a relatively small form factor, it is well known that the technology also impairs the dynamic performance of robot arms due to elastic deformation that occurs even well below the drive’s rated torque.
Torque density is the ratio of the rated torque of a transmission to its weight. Torque density is an especially critical parameter in robot arm design since the weight of the robot arm actuators become part of a distributed load that needs to be moved and positioned along with the primary robot payload.