Abstract: A backdriveable device for manipulating and measuring limb movement, and a method of use thereof. The device comprises a plurality of forcers, at least one linear guide for constraining the forcers to reciprocate along respective linear trajectories, and a linkage for attachment to a limb of a user, the linkage rotatably connected between the forcers and including two bars rotatably connected together at a vertex. Movement of the forcers along their linear trajectories results in movement of the vertex along a spatial trajectory. In specific embodiments, the forcers are moving coils of a linear motor. The movement and forces applied by the coils can be controlled through a computer interface, providing robotic control of limb movement.