Susan Hackwood

A Torque-Sensitive Tactile Array for Robotics

We introduce a new tactile sensor and show its advantages for robotic applications. The tactile array elements are composed of magnetic dipoles (in an elastic medium) whose position and orientation are detected by magnetoresistive sensors. We show that, unlike the existing tactile sensor designs, this device is sensitive to torque as well as to normal and tangential forces. We demonstrate experimentally the fabrication, sensitivity, and repeatability of the tactile elements.

Continuous electrowetting effect

We introduce a new electrowetting effect, continuous electrowetting (CEW), and show its advantages for applications to displays and other electro‐optic devices. We demonstrate experimentally, by using CEW, fast and reversible electrowetting flow on the theoretically predicted scale of ∼10 cm/s for ∼1‐V driving voltage.

Electrowetting switch for multimode optical fibers

Construction and characterization of an optical switch, based on electrowetting and suitable for use with multimode fibers are described. With a 50-μm core, 0.23-N.A. input and output fibers, the measured fiber-to-fiber insertion loss at λ = 0.633 μm was 0.5 ± 0.1 dB for one channel and 2.0 ± 0.2 dB for the other, with cross talk of −22.8 ± 0.5 and <−51 dB, respectively. Response time is ≈20 msec with driving power of ≈25 μW and a voltage requirement of ≤1.0 V. The switch has been tested for over 107 cycles with no observable degradation.

Multi-agent supporting systems (MASS): control with centralized estimator of disturbance

A new type of a swarm, named multi-agent supporting system (MASS), is introduced for supporting structures where the configuration formed by many agents must be maintained even though there exist unknown disturbances. A control system for a MASS is also proposed on the basis of a new estimator of disturbance. The proposed disturbance estimator is described by inverting the stable digital inverse system. With this disturbance estimator, the unknown disturbance acting on each agent in the MASS is cancelled by the input, and influences less the output of the system. A computer simulation has been executed to demonstrate the effectiveness of the proposed method in comparison with the control method without the disturbance estimator.<<ETX>>

Dynamic Sensing for Robots: An Analysis and Implementation

Dynamic sensing is discussed in detail. We have initiated a systematics of robotic sensor design by formulating the general problems and addressing the specific question of how to arrange the sensing elements. We have derived a general relationship between the number and speed of the sensing elements as a function of their response and processing times. We have thus constructed afiber-optic sensor for the fingers of a Unimation Puma 500 robot. The sensor consists of three linear arrays ( each with 12 sensing elements), attached to the edges of the robot fingers in a U shape. The elements are composed of parallel, equally spaced, collimated light beams that pass from finger to finger. Each linear array can be scanned dynamically to provide a 12 X 18 = 256-pixel cov erage of a 2 X 3-cm area.

A color vision system for film thickness determination

The use of color vision as a tool for machine vision provides a powerful means of performing rapid, accurate inspection of microelectronic structures. Since microelectronics fabrication is in large part a thin film technology, and since thin films have characteristic colors, this approach extends the range of optical analysis possible. We have constructed a color vision system used to measure thin film dielectric materials. Color matching is performed rapidly (<100 msecs) and with resolution better than 20 Å. The resolution limit has been so far set only by the samples available for measurement. We have further extended the capability of the system beyond simple color matching to identify true unknown samples whose thickness fall within the range of the original system database. Feed-back control of the illumination has been incorporated into the system; we present data on the effect of shifts in lighting or magnification. Microscopic, as well as broad area measurements (for uniformity) can be made.

A color vision system for microelectronics: Application to oxide thickness measurements

We present a new method of automated inspection of microelectronic structures. The method is based on color rather than black and white vision, and is a first such application of color vision to inspection for microelectronics fabrication. We describe the general method and demonstrate its practical implementation in the measurement of oxide thicknesses. A key result of this work is to have established sensitivity criteria for color detection in microelectronic structures. The resolution achieved allows us to measure differences in oxide thickness to approximately 30 Angstroms or better. By using the Ohta coordinates, our system can discrimimate between cyclically repeating hues. This determination can be done very rapidly (approximately 100 milliseconds) and does not require a complex (and thus expensive) computer system. An additional advantage of our method is the possibility of more easily and flexibly performing oxide thickness measurements in situ, than can be accomplished with standard techniques, such as ellipsometry.

Reentrant-Loop Magnetic-Effect Proximity Sensor For Robotics

We introduce a new proximity sensor and show its advantages for robotic assembly and manipulation of recessed parts. The sensor is based on the Reentrant-loop magnetic effect. We demonstrate experimentally that a simple embodiment of this sensor in a robot hand can detect position and orientation of marked objects within ri5 cm range, independently of the speed of approach.