Force control with hybrid actuator for virtual needle insertion

In virtual reality, some applications demand a fast, stable force response with high strength for use in haptic interfaces. While the existing active and passive actuators cannot fully satisfy these requirements alone, their cooperation could provide better results. This study aimed at the development of a hybrid actuator by combining a DC servomotor and a particle brake. The actuator was tested for multilayered tissue simulation, which required rendering abrupt changes and large forces. The designed controller adjusted the actuator inputs based on their capabilities. The brake provided an average force level while the motor superimposed the finer details on this profile. The hybrid actuator was able to track the force profile very well during virtual needle insertion and removal. It also provided a very rigid feeling when the needle touched the bone.