The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

A system and an apparatus capable of independently driving movers are described herein. The system and apparatus includes: a track that forms a path for movers; a plurality of movers movably mounted on the track for moving along the path; and a plurality of drive elements fixedly arranged along the track. The drive elements each have a surface that is oriented to contact a driven member of the movers. The drive elements are configured to sequentially engage the driven member of a plurality of the movers to provide controlled independent motion of the movers along the track. The drive elements may be driven by rotary motors. A method of independently driving movers is also described herein.

A system and an apparatus capable of independently driving movers are described herein. The system and apparatus includes: a track that forms a path for movers; a plurality of movers movably mounted on the track for moving along the path; and a plurality of drive elements fixedly arranged along the track. The drive elements each have a surface that is oriented to contact a driven member of the movers. The drive elements are configured to sequentially engage the driven member of a plurality of the movers to provide controlled independent motion of the movers along the track. The drive elements may be driven by rotary motors. A method of independently driving movers is also described herein.

An electrically controllable rotary pressure device includes a rotary pressure means for being inserted to a human body structure to bore a hole therein or to be fastened thereto, a motor for generating torque provided to the rotary pressure means, a power control unit for supplying power to the motor, a central processing unit for controlling the power control unit, a rotational speed sensor for measuring a rotational speed of the motor or the rotary pressure means, a current sensor for measuring a current flowing into the motor, and a torque compensation unit for adjusting the torque by adjusting a control signal from the central processing unit to the power control unit based on the measured current.

According to one aspect of the present invention, there is provided an electrically controllable rotary pressure device, comprising: a motor for providing torque to rotary pressure means; a power control unit for supplying power to the motor; a central processing unit for controlling the power control unit; and a rotational speed sensor for measuring a rotational speed of the motor or the rotary pressure means, wherein the central processing unit comprises an abnormality detection unit for receiving the rotational speed from the rotational speed sensor, and wherein the abnormality detection unit transmits a control signal to the central processing unit when abnormality in the rotational speed is detected, so that the central processing unit interrupts the power supply of the power control unit.

A system and an apparatus capable of independently driving movers are described herein. The system and apparatus includes: a track that forms a path for movers; a plurality of movers movably mounted on the track for moving along the path; and a plurality of drive elements fixedly arranged along the track. The drive elements each have a surface that is oriented to contact a driven member of the movers. The drive elements are configured to sequentially engage the driven member of a plurality of the movers to provide controlled independent motion of the movers along the track. The drive elements may be driven by rotary motors. A method of independently driving movers is also described herein.

A system and an apparatus capable of independently driving movers are described herein. The system and apparatus includes: a track that forms a path for movers; a plurality of movers movably mounted on the track for moving along the path; and a plurality of drive elements fixedly arranged along the track. The drive elements each have a surface that is oriented to contact a driven member of the movers. The drive elements are configured to sequentially engage the driven member of a plurality of the movers to provide controlled independent motion of the movers along the track. The drive elements may be driven by rotary motors. A method of independently driving movers is also described herein.