Power assist device using strain responsive means

摘要

In apparatus wherein a massive component, such as the spot film device of an x-ray table, is driven to various positions with an electric motor drive, a handle is attached to the component for urging it in the desired direction. The handle is attached to the component with beams that flex slightly. A piezoresistive strain gage assembly is mounted on one of the beams for developing an error signal in response to the handle being urged in either direction. The signal is amplified and used to control the power assist driving motor. Means are provided for compensating the vertical component of gravitational force when the handle and the object to which it is attached are angulated. Means are also provided for disabling the drive motor if an electronic element fails.