Integrated design of robotic mechanisms for force balancing and trajectory tracking

Traditionally, mechanisms are driven by constant velocity motors. A real-time controllable (RTC) mechanism refers to the mechanism driven by servomotors, which can be planned and scheduled in real-time. Robot manipulators are typical examples of the RTC mechanisms. The generic task of an RTC mechanism is the trajectory or motion tracking. This paper describes an integrated approach to design an RTC mechanism considering force balancing and trajectory tracking, simultaneously. In particular, a new approach called adjusting kinematic parameter (AKP) for the force balancing of RTC mechanisms is described. The force balanced mechanism has simpler dynamics, and thus facilitates the development of control systems for performing trajectory tracking. This paper demonstrates that the force balanced mechanism by the AKP approach is more promising than those by other approaches in terms of the reduction of joint forces and torques in servomotors, and improvement of the trajectory tracking performance. Based on simulation, this paper also shows the effects of two different control systems: PD and non-linear PD versus the AKP approach and the counterweight approach.

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