The present invention provides a device which can generate commands for controlling a physical therapy apparatus adapted to accept external commands. The device has a base, a motion manipulation portion and a moveable portion of substantially the same shape and dimensions as the portion of the physical therapy apparatus which interacts with at least one part of the body of a patient. The device also includes conversion means for converting stored time-dependent output signals to a series of command signals and means for transmitting the command signals to the physical therapy apparatus. The command signals are produced by the movements of the moveable portion, and, when transmitted to the physical therapy apparatus, can induce the physical therapy apparatus to undergo a series of motions substantially identical to those of the moveable portion.