NASA’s Marshall Space Flight Center has a suite of novel technologies for digital control of electronic machinery. NASA developed the technologies for autonomous assembly of modular space structures. The base technologies in the suite can improve gap sensors and absolute position sensors. They sense position and proximity, and can also wirelessly communicate the information to drive switching and stepper motor operations. Applications for these technologies span a broad range of industrial robotics topics, and they can be combined to perform a variety of functions. Other technologies in the suite can be incorporated into the base technologies to perform additional sensor functions, and serve as a short-range antenna and close proximity transmitter and receiver. The technologies are self-calibrating and have embedded integrity monitoring functions for assured position and proximity readings.
The technologies offer a number of benefits, including low cost because the devices use simple, inexpensive components. They enable absolute position and improved precision compared to conventional position sensing techniques, and provide precise control for multi-phase stepper motors. In addition, they are efficient because the same hardware can be used for measuring and communicating. A small footprint allows for operation in little spaces, such as miniature applications.
Products in the suite include the following:
- The SCAPS (Single Coil Absolute Position Sensor) GAPSYN (Inductive Gap Sensor) digital signal conditioning electronics, which provide ripple-free voltage that is proportional to the position of the sensor. This circuit processes two signals from the position sensor to determine the amplitude of an amplitude-modulated signal and then corrects for gap fluctuations and nonlinearities.
- An absolute limit switch, which takes advantage of the value of the induced voltage and uses a predetermined value of the sensed signal to determine an absolute limit switching point, such as to stop a movable carriage.
- The system for sensing the position of a rotor in a hybrid stepper motor. This is a rate-insensitive (operates at any speed, including zero rate), linear feedback sensor system that can be used for controlling two-phase and multi-phase stepper motors.
- The micro-commanding servomotor controller with greater than 50-million-to-1 dynamic rate range, which senses rotary position of a drive shaft to derive appropriate drive signals for a motor.
- The short-range antenna/close proximity transmitter and receiver technology, which is an inexpensive and effective method of exchanging information over a short distance between two devices when each is equipped with a coil.
Applications for this technology suite include CNC, waterjet, and laser milling machines; pick-and-place machines for semiconductor manufacturing and automated biotech operations; hard disk drives, printers, and scanners; rotary and linear positioning of automotive engine components; profilometers; industrial robots in which raster, head, and substrate are in close proximity; and robot-assisted surgery.