Autonomous biped walking robots are supposed to explore various unknown environments. This requirement demands a precise control of the actuators such that biped does not cause any damage to itself or the surroundings.

This project is focussed on the force control of the actuators. Presently, two different kinds of force controlled actuators are being studied: Series Elastic actuators and Series Damper Actuators.

Series Elastic Actuator (SEA)

Proposed by MIT Leg Lab, it is an actuator that is connected to the external load through an elastic component, for example, a spring. The desired force on the load is achieved by controlling the deflection of the elastic component. SEA have many desirable properties like high force fidelity, low output impedance, shock absorption capability, etc. The low system bandwidth has greatly limited its further applications in industry.

Series Damper Actuator

The idea of this actuator system is similar to SEA, but the elastic component is replaced with a damper in the actuator system. Accordingly, the desired force is achieved by controlling the relative velocity in the damper rather than the deflection of the elastic component. The introduction of damper endows the system with impact protection, larger bandwidth and output range and better performances, especially at low output force range.