Energy based safety for passive robots performing active interaction tasks

Energy-aware control is a control methodology stemming from ideas in port-Hamiltonian system theory. In this method, setting the energy of the system and its variation gives analytic information that is directly used in the design of the control law, providing a systematic way to ensure important aspects like passivity, stability, and, potentially, safety.
One of the main advantages of energy-aware control is that it can naturally be used for nonlinear systems. One place where such nonlinear dynamics arise is in articulated robots (e.g. cobots) due to their kinematics.

In recent work, an energy-aware adaptive interaction control strategy was developed, by using offline task-based optimisation. The optimisation was cast into a time-varying impedance control framework, to yield an optimal open-loop control action. The open-loop action was supplemented by a low-gain Cartesian impedance controller to reject unmodelled and external disturbances. The strategy uses a novel energy injection approach with tanks for increased safety, which provides a substantial benefit over conventional energy tank approaches.

This project seeks to continue this work, focusing on two aspects, theoretical and experimental:
- investigate/improve the safety aspect by considering the kinetic energy of the robot, in the optimisation as well as the tanks subsystem and budgeting;
- experimental validation on a Franka Emika Panda robot, of
  1. basic task completion (task-based+task-free control);
  2. safety testing during unexpected collisions (interaction energy);
  3. (optionally) iterative feed-forward adaptation.