Considering that in most cases the evolution and the actions of a robot are time-and-space-local phenomena, since 1982 the author has developed the concept of local environment (LE), which is the intersection between the global environment (GE) and a given volume (Ck) located around the mobile parts of the manipulator (e.g., a cylinder and two terminal hemispheres for a link). This makes it possible to define a Newtonian potential function Vk(xk) which is useful in modeling (force synthesis). If in the GE the classical perception systems require a large amount of information, the LE-based control can greatly reduce that amount and, therefore, the processing time for local tasks. Bidigital grippers (SAGEM, JPL) and various other devices (IRISA) with four to 32 proximity sensors (emitters/receivers produced by Siemens and Texas Instruments, data transmitted by optical fibers, and processing done in a Zilog Z80 or Intel 8086 microcomputer) are then presented as examples of optical reflectance sensor (ORS) applications. The ORSs analyzed in the paper operate in the near-infrared (950-nm) region.
The processing of ORS signals includes extraction of parameters (detection, range estimation, and even pattern recognition by active infrared reflectance imaging (AIRI)--generating a segmentation into regions by levels or gradients, which is a low-cost and often accurate alternative to gray-level pictures) and closed loop control (obstacle avoidance, centering, orientation, automatic grasping, force synthesis, estimating the speed of an object via a Kalman filter, and velocity control).
The existing applications are in the field of teleoperation (including underwater working and nuclear plants) and extensions to industrial applications are suggested (such as grasping an object on a conveyor belt, tracking a slowly moving target, and giving assistance to the physically handicapped).
The paper is well structured and consists of several sections: (1) basic principles; (2) state of the art; (3) modeling; (4) processing; (5) control; and (6) concluding remarks. It is relatively well documented (28 figures, 20 references), but has not been well prepared for publication, however, as it contains undefined terms (like IR, CCD, LED), superposed notations (e.g., d is used for distance, direction, and derivation), and revision and grammatical errors. Even though the demonstrations are incomplete, it is still a good informative paper.
