Integrating Energy Awareness into Sequence Control

Finished: 2020-07-22

MSc assignment

RobMoSys is an effort on creating an open, multi-domain, modular and sustainable software ecosystem for the European robotics community. As a contribution to the first stage of this project (RobMoSys-EG-IPC), the RaM research group integrated energy awareness in the loop control level to guarantee passivity and enhance safety for both the plant and its environment. This was achieved by designing and implementing energy guards to encompass each loop control component. In the second stage of the project (RobMoSys-EGCS), energy awareness shall be extended from the component level to the system level by integrating it into the complete motion control stack. The purpose thereof is 1) to provide information on fault detection and fault handling to the supervisory and sequence control levels, and 2) to determine system-wide energetic properties for ensuring that not only local, but also global passivity and stability of the controller is achieved. This MSc assignment will contribute to the RobMoSys-EGCS project by targeting energy awareness in the sequence control level.

Complex physical interaction tasks in distributed control systems often still rely on human skills to deal with the complexity. An example scenario could be a Remotely Operated Underwater Vehicle (ROAV) manipulating seafloor samples. This is not a trivial operation due to variations in environment complexity like the weight and size of the samples. Classical sequence controllers are insufficiently capable of autonomously dealing with such tasks in an efficient manner and, therefore, require human intervention. Taking energy information of the interaction between the loop control level, the plant, and the environment as feedback to the sequence control level may resolve this human dependency. A unique benefit is that energy exchange is both universally applicable and intuitive to understand, also for non-experts. Using energetic information of interactions in control is a novel concept that—because of the universality of energy exchange—could enable a sequence controller to ‘feel' physical interactions like a human does. This can potentially lead to improvements in system level properties such as performance, safety, fault tolerance and responsiveness.

The aim of this assignment is to develop an energy-aware sequence controller by integrating the energetic information provided by energy guards of the loop control components. The design should follow a component-based approach, focussing on e.g. composability, reusability, and replaceability. The controller should be modular, intrinsically passive, port based, and functional in a distributed control system. Performance shall be assessed in a distributed control system setup by comparing the energy-aware controller to the same controller without energy awareness.