MPC-Net: A First Principles Guided Policy Search
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We present an Imitation Learning approach for the control of dynamical systems with a known model. Our policy search method is guided by solutions from Model Predictive Control (MPC). Contrary to approaches that minimize a distance metric between the guiding demonstrations and the learned policy, our loss function corresponds to the minimization of the control Hamiltonian, which derives from the principle of optimality. Our algorithm, therefore, directly attempts to solve the HJB optimality equation with a parameterized class of control laws. The loss function's explicit encoding of physical constraints manifests in an improved constraint satisfaction metric of the learned controller. We train a mixture-of-expert neural network architecture for controlling a quadrupedal robot and show that this policy structure is well suited for such multimodal systems. The learned policy can successfully stabilize different gaits on the real walking robot from less than 10 min of demonstration data.
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