A force feedback interface including a haptic accelerator that relieves the computational burden associated with force feedback generation from a force feedback processor. The force feedback processor is preferably a device microprocessor included in the interface device and separate from a controlling host computer for determining forces to be output. The haptic accelerator quickly determines velocity and/or acceleration information describing motion of a user manipulatable object from raw position data received from sensors of the interface device and representing the position of the user object. The velocity and/or acceleration data is used by the force feedback processor in the determination of forces to be output on the user object. The haptic accelerator can in some embodiments also quickly and reliably determine condition forces which depend on the motion of the user object, thus relieving additional computation burden from the force feedback processor and permitting the force feedback processor to focus on determining other types of forces and overseeing the operation of the force feedback interface device.