A method for the design of controllers of constrained manipulators in the presence of model uncertainties is developed. The controller must carry out fine maneuvers when the manipulator is not constrained, and compliant motion, with or without interaction-force measurement, when the manipulator is constrained. At the same time stability must be preserved if bounded uncertainties are allowed in modelling the manipulators. Stability of the manipulator and environment as a whole and the preservation of stability in the face of changes are two fundamental issues that have been considered in the design method. A set of practical design specifications in the frequency domain is presented that is meaningful from the standpoint of control theory and assures the desired compliant motion in the Cartesian coordinate frame and stability in the presence of bounded uncertainties. This approach also assures the global stability of the manipulator and its environment. The consequence of inexact achievement of performance specifications on stability is also specified. Part I concerns the fundamentals of compliant motion, while Part I1 is devoted to the controller design method.

In this paper we discuss an approach to the detection of incidents on freeways. Our techniques are based on the use of a macroscopic dynamic model describing the evolution of spatialaverage traffic variables (velocities, flows, and densities) over sections of the freeway. With such a model as a starting point we develop two incident detection algorithms based on the multiple model and generalized likelihood ratio techniques. We also describe a new and very simple system for processing raw data from presence-type vehicle detectors to produce estimates of the aggregate variables, which are then in turn used as the input variables to the incident detection algorithms. Simulation results using a microscopic simulation of a two-lane freeway indicate that:(1) our algorithms are robust to the differences between the dynamics of actual traffic and the aggregated dynamics used to design the detection systems; and (2) our methods appear to work as well as existing algorithms in heavy traffic conditions and work better in moderate to light traffic. Areas for future work are outlined at the end of the paper.

There are many techniques for designing discrete-time compensators.However, the digital implementation of such designs has not typically been addressed.The nature of digital hardware impacts the computational structure of the compensator and also can affect the original system design parameters.This paper deals with the architectural issues of serialism, parallelism and pipelining in implementing digital feedback compensators.The concepts of serialism and parallelism are shown to involve essentially the same considerationsfor digital compensators as for digital filters.However, the same cannot be said of pipelining, due to the feedback loop.A design technique is proposed for dealing with the problem of compensator pipelining, and several examples of pipelining LQG compensators are presented.* This work was performed in part at the MIT Laboratory for Information and Decision Systems with support provided by NASA Ames under grant The implementation of control algorithms in such digital hardware has raised many new issues. These tend to fall into two categories, one involving the effects of the finite precision and fixed-point arithmetic of small-scale digital systems, and one involving architectural issues. Such questions have not generally been treated in the literature. Therefore some methodology must be established for digital feedback compensator implementation. In other words, we need some way to specify and order the critical computations that must take place in a compensator so that the resulting digital hardware performs as close to the ideal design as is consistent with the expense and speed requirements of the application.We have addressed the issue of finite wordlength due to compensator coefficient rounding and multiplication roundoff in earlier works [1,2].Our general approach has been to examine the concepts already developed for digital signal processing. Then, considering the compensator as a digital filter within a control loop, we can try to apply these ideas. However, the presence of the feedback path itself, and the emphasis on closed-loop performance,has frequently required us to adapt and extend the methods of digital signal processing.In this paper, we will examine the architectural issues involved in -1-compensator implementation, in particular, the notions of serialism, parallelism and pipelining. We will show that the serialism/parallelism concept is essentially identical to that involved in the implementation of any digital system. However, the use of pipelining in digital control systems raises several difficult questions. We will discuss these points in the context of linear-quadratic-Gaussian (LQG) control systems, although they extend easily to maore general cases-.The organization of this paper will be as follows. In Section II, we will briefly review the LQG control problem and describe the resulting ideal compensator equations. The notion of a compensator structure, which is somewhat different than a conventional filter structure, and an adapted notation for describing s...

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