The ability to interact with automation systems is often the roost overlooked aspect of system design and can make the difference between a truly useful, productive system and a source of frustration and inefficiency. Ludl Electronic Products systems have always included features to provide operator interaction with the system. In fact every controller module features a means for stand-alone operation: joystick/digipot for motors, toggle switches for filter wheels and shutters.
Positioning input devices fall into two categories: velocity and displacement devices. A velocity input device controls velocity based upon a variable input. It is analogous to an automobile gas pedal; the more you press, the faster you go. Displacement devices move a discrete distance based on a measured input. In the LEP world the displacement device is known as a digipot. As the digipot knob is turned, digital pulses are read by the controller. For a given pulse sequence the motor is turned a corresponding number of steps.
The LEP XY joystick support provides very fine short distance control with the ability to traverse long distances at high speeds. The exponential velocity/deflection curve is programmable.
LEP offers several digipot types. Typically for focus control applications, the single XY Joystick's digipot functions similar to a focus knob on a microscope. The X'( digipot control is arranged such that it simulates the coaxial control of a standard mechanical microscope stage.