Note that, as a consequence of the null angle modulation strategy, the position feedback is positive, that is, a sudden command to move right will produce an initial cart motion to the left followed by a move right to rebalance the pendulum.
12.
A servo system differs from some stepper motor applications in that the position feedback is continuous while the motor is running; a stepper system relies on the motor not to " miss steps " for short term accuracy, although a stepper system may include a " home " switch or other element to provide long-term stability of control.
13.
A tree often provides numerous additional functions including chemical injection points, well intervention means, pressure relief means, monitoring points ( such as pressure, temperature, corrosion, erosion, sand detection, flow rate, flow composition, valve and choke position feedback ), and connection points for devices such as down hole pressure and temperature transducers ( DHPT ).
14.
The telescope mount is altitude over azimuth ( alt-az ) which allows the telescope to be very compact ( relatively speaking ) and provides direct load paths from the telescope down through the structure to the pier and foundations . The drive motors used to move the telescope in azimuth and elevation will be servo motors with position feedback will be provided by linear tape encoders.
