Patent attributes
Mechanical apparatus includes a rotational assembly, including a frame and a gimbal, which is attached to the frame by first hinges disposed along a first axis and is configured to rotate on the first hinges about the first axis relative to the frame. A rotating element is attached to the gimbal by second hinges disposed along a second axis, perpendicular to the first axis, and is configured to rotate on the second hinges about the second axis relative to the gimbal. One or more strain sensors are disposed on at least one of the first hinges and configured to provide a signal indicative of a rotation of the rotating element about the second axis relative to the gimbal. Control circuitry is configured to monitor the rotation of the rotating element about the second axis responsively to the signal.