  Topology optimization methods have widely been used in various industries,
owing to their potential for providing promising design candidates for
mechanical devices. However, their applications are usually limited to the
objects which do not move significantly due to the difficulty in
computationally efficient handling of the contact and interactions among
multiple structures or with boundaries by conventionally used simulation
techniques. In the present study, we propose a topology optimization method for
moving objects incorporating the material point method, which is often used to
simulate the motion of objects in the field of computer graphics. Several
numerical experiments demonstrate the effectiveness and the utility of the
proposed method.
