In this paper, modeling and robust control of force and vibrations of a flexible arm with a non-symmetric rigid tip body are discussed. By using Hamilton's principle and Lagrange multiplier method, dynamic equations of the constrained flexible arm are derived. We analyze the stability of the compliance control and the direct force feedback as the force control of the flexible arm. We construct robust controllers of an optimal controller with low-pass property and an H-infinity controller. Simulations have been carried out.