Dynamic Analysis and Simulation of a 1-DOF Driven by a Parallel Force/Velocity Actuator (PFVA)

Some work has been done to try to combine force control and velocity control capability into the same actuator design. The objective in trying to incorporate two fundamentally distinct resources (force and motion priorities) into the same actuator is to obtain an expanded spectrum of dynamic responses at the output of the system so that the system may (ideally) operate in pure force control mode or pure velocity control mode or a combination of these modes. Presented in this paper is a design that combines two fundamentally distinct actuators (one using low reduction or even direct drive, which we will call a Force Actuator (FA) and the other with a high reduction gear train that we will refer to as a Velocity Actuator (VA)). The premise of this work is that we could obtain a variety of responses at the system’s output by integrating separate force and motion priorities (Parallel Force/Velocity Actuator) within the same system in-parallel and dynamically “mixing” their contributions. We conceptually describe a Parallel Force/Velocity Actuator (PFVA) based on a Dual-Input-Single-Output (DISO) epicyclic gear train. We then present a dynamic model formulation for a non-linear 1-DOF mechanical system (Slider-Crank Mechanism) that uses a PFVA at the input. Using this dynamic model, we present a numerical simulation. The numerical simulation focuses on two issues, (a) effect of the relative scale change (ρ) between the two inputs on the torques at the two prime-movers and (b) effect of ρ on the dynamic coupling between the inputs. It was observed that as the relative scale change (represented by ρ) was decreased (i.e. the sub-systems tend towards behaving as “equal” systems) the dynamic coupling between the systems increased. In the study of the effect of ρ on the inertia and static torques at the prime-movers, it was noticed that they follow inverse trends.Copyright © 2007 by ASME