QuickSilver Makes Joystick Control Easy
QuickSilver Controls, Inc., line of controller/drivers for servo control of NEMA 17, 23 and 34 frame stepmotors accommodates a simple analog joystick input to control position, velocity or torque.
Joysticks are useful for augmenting complex motion control systems for such things as computerized microscopes and vision systems. On the fly, the controller can switch from joystick control to automated control. An example would be using the joystick to pan around a product, pressing the button at several "interesting" points. The controller would be able to memorize these points and move back to them latter for a more detailed inspection.
The addition of this simple feature requires more sophistication from the controller than you might expect. The command from a joystick is anything but smooth. Not only is the analog signal noisy, but so is the hand controlling it. The ends of travel are often non-linear. To inhibit motor movement when the joystick is released, the center position needs a definable dead band. The ratio of joystick movement to output needs to be configurable to allow for such things as fast and slow speed jogging.
QuickSilver's joystick command allows the user to filter, clip and scale incoming analog joystick signal to create a smooth, well behaved output. For example, let us say the user wants to use a joystick to command the servo to go from -2000 counts to +2000 counts. The command will allow the user to:
o Filter Out High Frequency Analog Input Noise
o Choose Amount of Joystick Travel To Use
o Define a Dead Band Around the Joystick Center Position
o Define Number of Counts to Move
o Limit Move Velocity
For more details, see the Application Note "QCI-AN047 Input Mode - Joystick" on QuickSilver's website (www.QuickSilverControls.com).
