Mechanical bandwidth as a guideline to high-performance manipulator design

The mechanical bandwidth of a manipulator ultimately limits its closed-loop bandwidth and so its response in both trajectory and force control. Here, mechanical design strategies are introduced to improve performance, including placing a distinct speed reducer at the joint rather than at the motor shaft, limiting the transmission ratio and properly selecting the contact compliance. The authors define simple models of the transmission for position-in-position-out and force-out and examine the corresponding transfer functions. The bandwidth of each of the simple models (which neglect damping) is approximately equal to the frequency of the first break point in the magnitude of the frequency response which, in turn, is equal to its lowest resonant frequency. The aim is for the open-loop bandwidth to be as high as possible to increase the quickness of the manipulator´s response to commands