BIPROCESSOR CONFIGURATION WITH ALTERNATING HIERARCHY FOR HIGH SPEED PROCESS CONTROL Th. Borangiu and R. Dobrescu Department of Control and Computers, Polytechnical Institute of Bucharest, Romania Abstract. The object of the paper is to present a biprocessor control configuration dedicated to high speed technological processes,such as electrical drives.In the proposed structure, a specialized asynchronous interface connects two INTEL 8085 microprocessors,the first of which performs the frequency con- trol for two electric stepper motors,according to numerical two-axes interpolatin algorithms,while the second works out the optimal controls 7 feedrate,speed) for a class of nonlinear performance indexes,subject to nonlinear constraints of ine- quality type.Any one of the two microprocessors,logically pla- ced on priority based hierarchical levels,can take hold of the master position in the control system and communicate over an 3 t bit data bus with the subordinate processing unit (sla- Real time processing diagrams are worked out,making there- fore possible parallel high speed processing of both complex computing functions and of advanced optimization algorithms. Final remarks are made concerning some practical results,such as the improvement of contouring speed,productivity and cost of machining,in the computerized numerical-adaptive (CNC-AC) control of metal cutting processes. Ke ords. Multiprocessing systems; computer interfaces; nume- d?r control; optimal control; machine tools; microprocessors. INTRODUCTION The development of numerical control systems for machine tools was perma- nently marked by a dichotomy in the design of two basic structures which ensure both technic and economic re- quirements of the machining process: -the numerical control equipment (NC), which interpolates with the necessary precision the programmed trajectory of the interaction point between tool and workpiece; -the adaptive control equipment (AC), which performs the optimization of the cutting process,according to perfor- mance criteria such as productivity. However,an unitary approach of the two control systems in a biprocessor NC-AC configuration seems more satis- factory,both from the point of view of real time parallel processing,and of data transfer procedure between the two structures (Crossley,l979;Forsberg 1977).Since this data transfer updates information used in the application programs of each processor for actua- ting controls (frequency control of stepper motors or speed control for main axis d.c. motor),a general pur- pose application of the biprocessor configuration results in the field of high speed industrial processes,like electric drives. PARALLEL PROCESSING OF NC AND AC FUNCTIONS Real time processing of data is per- formed by two 8085 microprocessors, designated as the NC processor and the AC processor,each of them being connected to dedicated interfaces, and exchanging information through a common asynchronous interface.Thus, the NC processor accesses the part program from a paper tape reader,re- ceives position feedback from the dis- placement transducers and,according to linear or circular interpolation algorithms with tool correction (for this purp0se.a hardware extension is