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Other examples are fly-by-wire systems in aircraft which use servos to actuate the aircraft's control surfaces, and radio-controlled models which use RC servos for the same purpose. Many autofocus cameras also use a servomechanism to accurately move the lens. A hard disk drive has a magnetic servo system with sub-micrometer positioning accuracy ...
But if the load were not predictable and became excessive, the motor's speed might vary as a function of the load not just the voltage, and an open-loop controller would be insufficient to ensure repeatable control of the velocity. An example of this is a conveyor system that is required to travel at a constant speed.
Motion control is a sub-field of automation, encompassing the systems or sub-systems involved in moving parts of machines in a controlled manner. Motion control systems are extensively used in a variety of fields for automation purposes, including precision engineering , micromanufacturing , biotechnology , and nanotechnology . [ 1 ]
The system assumes (in the examples) that the plane of the camera and the plane of the features are parallel., [16] discusses an approach of velocity control using the Jacobian relationship s˙ = Jv˙ . In addition the author uses Kalman filtering, assuming that the extracted position of the target have inherent errors (sensor errors).
This example is slightly simplified (no gears between the motor and the load) from the control system for the Harlan J. Smith Telescope at the McDonald Observatory. [6] In the figure there are three feedback loops: current control loop, velocity control loop and position control loop. The last is the main loop. The other two are minor loops.
Settling time to +/- 1% Constant Velocity, or + / - 1 um jitter, after high acceleration or high deceleration respectively, takes an estimated 3 bandwidth periods. For example, a 50 Hz servo bandwidth, having a 1 / 50 · 1000 = 20 msec period, will settle to 1 um position accuracy within an estimated 3 · 20 = 60 msec.
A common example is a vehicle’s cruise control system. When a vehicle encounters a hill, its speed may decrease due to constant engine power. The PID controller adjusts the engine's power output to restore the vehicle to its desired speed, doing so efficiently with minimal delay and overshoot.
A pure feed-forward system is different from a homeostatic control system, which has the function of keeping the body's internal environment 'steady' or in a 'prolonged steady state of readiness.' A homeostatic control system relies mainly on feedback (especially negative), in addition to the feedforward elements of the system.