A precessional device having independent control of the output torque generated by the device and the oscillation rate of the device is disclosed. The device comprises a rotor supported by an axle wherein the ends of the axle are supported by a circular race. The circular race is rotatable, and may be driven by a motor or other means, thereby controlling the oscillation rate of the device independently of the output torque arising from the rotation rate of the rotor. The motor may be controlled by a control program that adjusts the rotation rate of the circular race to modify the shape of the resistance curve.