Co-design of a robotic leg with compliant biarticular actuation

The challenge we currently face in actuation design of robots is that we want high power, high torque ánd high efficiency while staying light and compact. This is a hard challenge, but luckily, we can copy nature. As our muscles have found solutions to the exact same problems! Animals use elasticity and bi-articulation (i.e. muscles spanning over multiple joints) in their bodies to improve efficiency and power/force production.

But currently, most of the robots still use a stiff mono-articulated actuation topology. Why is that?
Designing actuation topologies is complex, as you need to take into account a lot of variables and unknowns, which makes it a field where you need to gain a lot of experience, and you need to iterate a lot to come up with a good design. Thus, elasticity and bi-articulation are often disregarded to reduce design complexity.

We have developed a method that optimises the movement of your robot while also optimising certain variables of the actuation topology, which is called co-design. We have applied it on a robotic leg to optimise for squatting, and we even developed a prototype to validate our co-design results!