  We present two distributed methods for the estimation of the kinematic
parameters, the dynamic parameters, and the kinematic state of an unknown
planar body manipulated by a decentralized multi-agent system. The proposed
approaches rely on the rigid body kinematics and dynamics, on nonlinear
observation theory, and on consensus algorithms. The only three requirements
are that each agent can exert a 2D wrench on the load, it can measure the
velocity of its contact point, and that the communication graph is connected.
Both theoretical nonlinear observability analysis and convergence proofs are
provided. The first method assumes constant parameters while the second one can
deal with time-varying parameters and can be applied in parallel to any
task-oriented control law. For the cases in which a control law is not
provided, we propose a distributed and safe control strategy satisfying the
observability condition. The effectiveness and robustness of the estimation
strategy is showcased by means of realistic MonteCarlo simulations.
