The soft robotic hands developed in our lab are pneumatically actuated. That means, by opening inflation and deflation valves in a controlled manner, we can control the enclosed air in a particular air-chamber. The valves used are so called “binary valves”, referring to the characteristic that they only can take on two different states – open/closed. This comes with a drawback. If we want to close the fingers of the hand slowly, lets say to grasp an object, we need to open-close-open-close the valves in a bang-bang controlled manner that results in jittery movements of the finger. To enable smooth and slow movements, we would need a way to regulate the air-flow that is introduced when we open the valves.
Proportional valves are a way to tackle this problem. Unlike binary control valves which produce full flow when energized, proportional control valves produce pressure or flow proportional to an electrical signal. In recent years valves of this kind that satisfy our pressure-range requirements have become commercially available.
Description of Work
This thesis involves researching different proportional valves that are suitable for our soft-robot hands. When a specific proportional valve has been selected it needs to be embedded into our hardware. The main goal of this thesis is to develop a suitable air-flow controller that also maintains the characteristics of our current air-mass controller. So to say, a PD-controller in the realm of air-mass and air-flow needs to be developed on the basis of proportional valves.