Formulated a 2nd order floating based whole body impedance control algorithm, allowing for human robot interaction and push recovery. This new type of impedance is not an approximate model such as linear pendulum model, it calculated all the compliant joints' actions when force applying to the base.
Floating base impedance control when walking
Most of the biped robots are based on fixed base dynamic or kinematic model. This generates a lot of problems including changing the reference leg between stance and swing leg. As a result, it becomes necessary to build three different dynamic models including left leg on the floor, right leg on the floor, and two legs on the Floor at the same time. In order to prevent those problems, floating base model is an suitable and efficient solution. This impedance control is based on floating base kinematic method. There is no need to calculate the complex inverse dynamic solution; instead, what needs is second order kinematic model related to whole body position, velocity, acceleration and the force/torque on contact points. The simulation results are in the below, the biped robot is able to walk and be compliant to those external force applied to the base and balance really well.