A family of virtual contraction based controllers for tracking of flexible-joints port-Hamiltonian robots: theory and experiments
This work addresses control challenges for flexible-joint robots, which is an incremental improvement in robotics control methods.
The paper tackles the trajectory tracking problem for flexible-joint robots by proposing a family of virtual contraction-based controllers, guaranteeing exponential convergence to predefined trajectories under potential energy matching conditions.
In this work we present a constructive method to design a family of virtual contraction based controllers that solve the standard trajectory tracking problem of flexible-joint robots (FJRs) in the port-Hamiltonian (pH) framework. The proposed design method, called virtual contraction based control (v-CBC), combines the concepts of virtual control systems and contraction analysis. It is shown that under potential energy matching conditions, the closed-loop virtual system is contractive and exponential convergence to a predefined trajectory is guaranteed. Moreover, the closed-loop virtual system exhibits properties such as structure preservation, differential passivity and the existence of (incrementally) passive maps.