Distributed Estimation for Cooperative Mobile Manipulation

We present a distributed method for the estimation of the kinematic parameters, the dynamic parameters, and the kinematic state of an unknown body manipulated by a decentralized team of mobile ground (planar) robots. The proposed approach relies on the geometry of the rigid body kinematics, the rigid body dynamics, on nonlinear observation, and on consensus algorithms. The only three requirements are that each robot is able to control the 2D wrench exerted locally on the load, it can measure the velocity of its contact point, and the communication graph is connected. The finite time convergence of the strategy is proven and all the robots agree on the same estimated quantities at the end of the procedure. We present also two basic distributed control strategies that are proven to satisfy nonlinear observability conditions needed for the estimation accomplishment. Finally, a numerical test that demonstrates the evolution of the estimation algorithm is given.