The applicability of transputers in controlsystems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transpute...
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The applicability of transputers in controlsystems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transputers. It is found that a control system with transputers offers a great improvement compared with conventional digital controlsystems. Transputers can solve the common problem in control practice, i.e. having very sophisticted controllers but not being able to implement them because they need too much computing time. However, transputers are not an optimal solution for more sophisticated controlsystems because of shortcomings in the scheduling mechanism.
作者：
Cooper, R.A.Control Systems Lab
Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 United States
This paper is concerned with the directional stability of racing wheelchairs on crown roads. Three types of crown compensators are described and evaluated: the push-pull, the push-push, and the pull-pull. It was found...
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This paper is concerned with the directional stability of racing wheelchairs on crown roads. Three types of crown compensators are described and evaluated: the push-pull, the push-push, and the pull-pull. It was found that the push-push and the push-pull types of compensators have the most desirable characteristics, and were, in general, safer than the pull-pull type. In addition, the equations necessary to specify the minimum spring force required to compensate for the downhill turning moment, were derived and compared to the actual preset forces for the various compensators presently in use. It was found that the force required to maintain directional stability was less than that to deflect the crown compensator. This was due to the preference of athletes for additional stiffness needed for disturbance rejection, and to help compensate for any asymmetry in their stroke kinematics.
作者：
Cooper, R.A.Control Systems Lab
Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 United States
This technical note describes a time-saving device for aligning the rear wheels of a racing wheelchair. The newly-developed analog alignment device is compared to the now standard discrete alignment device. The analog...
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This technical note describes a time-saving device for aligning the rear wheels of a racing wheelchair. The newly-developed analog alignment device is compared to the now standard discrete alignment device. The analog alignment device is found to reduce the time needed to align the rear wheels by nearly 75 percent, while increasing the accuracy of the alignment. The device does not noticeably alter the performance of the racing wheelchair and, if installed properly, the device is sufficiently resistant to fatigue.
Maximum-likelihood soft-decision decoding of linear block codes is addressed. A binary multiple-check generalization of the Wagner rule is presented, and two methods for its implementation, one of which resembles the ...
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Maximum-likelihood soft-decision decoding of linear block codes is addressed. A binary multiple-check generalization of the Wagner rule is presented, and two methods for its implementation, one of which resembles the suboptimal Forney-Chase algorithms, are described. Besides efficient soft decoding of small codes, the generalized rule enables utilization of subspaces of a wide variety, thereby yielding maximum-likelihood decoders with substantially reduced computational complexity for some larger binary codes. More sophisticated choice and exploitation of the structure of both a subspace and the coset representatives are demonstrated for the (24, 12) Golay code, yielding a computational gain factor of about 2 with respect to previous methods. A ternary single-check version of the Wagner rule is applied for efficient soft decoding of the (12, 6) ternary Golay code.< >
Maximum likelihood soft decision decoding of block and lattice codes has recently gained renewed interest. This is partially due to the major role of block and lattice codes in block-coded modulation techniques for ba...
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This paper concerns the supervisory coordination and control of concurrent activities in an automated manufacturing facility. In contrast to commonly used simulation models which integrate the control policy with the ...
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This paper concerns the supervisory coordination and control of concurrent activities in an automated manufacturing facility. In contrast to commonly used simulation models which integrate the control policy with the system model, the subsystem state transition logic is represented by a class of controlled Petri nets (CPNs) with external inputs to be determined by the control synthesis algorithm. We formulate the forbidden state control problem in the CPN context and present a computationally efficient algorithm for generating maximally permissive controls which guarantee the system will avoid the forbidden states while permitting a maximal amount of flexibility in the system operation. The problem formulation and control synthesis algorithm is illustrated for an example of AGV coordination, and several classes of manufacturing control problems which can be addressed within this framework are identified.
The notions of fairness and conflicts in live, bounded, and strongly connected Petri nets (PNs) are formally related. The PN model of a resource-sharing concurrent system (RSCS) is conflict free when the firing of an ...
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The notions of fairness and conflicts in live, bounded, and strongly connected Petri nets (PNs) are formally related. The PN model of a resource-sharing concurrent system (RSCS) is conflict free when the firing of an enabled transition does not disable another transition in the net. Conflicts in the PN represent unresolved resource allocation conditions. The PN is fair when the firing of any transition more than a given number of times is a sufficient condition for all the transitions in the net to have fired. When the PN is fair, no process in the system can be starved; that is resources are allocated so that all tokens progress through the net. Although these concepts are not equivalent, it is shown that they are strongly related to each other when the PN model is live, bounded, and strongly connected. A computational method for finding conflicts is presented, and the concepts are illustrated with an example of buffer allocation in a sorting algorithm.< >
Real-world applications of the emerging theory of controlled discrete event systems (DESs) will not be realized until the obstacle of computational complexity is overcome. This paper presents a step in that direction ...
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Real-world applications of the emerging theory of controlled discrete event systems (DESs) will not be realized until the obstacle of computational complexity is overcome. This paper presents a step in that direction by developing a computationally efficient solution for a class of forbidden state problems. We consider DESs which can be modeled as cyclic controlled marked graphs (CMGs), a class of controlled Petri nets (CPNs). The distributed representation of the DES state in terms of the CMG marking permits an efficient specification of the forbidden states in terms of individual place markings. More importantly, we show that the graphical representation of the state transition logic in a CMG can be used to synthesize state feedback logic which is maximally permissive while guaranteeing the forbidden states will not occur. The practical application of the theoretical results is illustrated for an example of automated guided vehicle (AGV) coordination in a flexible manufacturing facility.
The authors discuss the problem of planning a task for a robotic system that consists of a manipulator mounted on a mobile base. The task planning problem is formulated as a nonlinear optimization problem. The cost of...
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The authors discuss the problem of planning a task for a robotic system that consists of a manipulator mounted on a mobile base. The task planning problem is formulated as a nonlinear optimization problem. The cost of point-to-point motion in three-dimensional Cartesian space is decomposed into two components representing the qualitative difference between motion due to the mobile base and motion due to the manipulator system. Task specifications at each end of the motion impose constraints on the endpoint configurations. The resulting regions of feasible positions and configurations are unconnected and nonconvex. Thus, standard algorithms for nonlinear optimization lead to nonextremal solutions. A heuristic method is presented for searching a tree of starting points for a standard numerical algorithm to find a global minimum for the cost function. The problem formulation is illustrated for a three-degrees-of-freedom (DOF) manipulator on a simple two-DOF mobile base, and tradeoffs between base motion and manipulator motion are evaluated with respect to cost function weighting coefficients.< >
In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vector...
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In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vectors are assumed to be subjected to linear constraints The approach presented, is based on the notion of positive invariance of polyhedral sets. Existence conditions for a control law that transfers asymptotically to the origin all initial states in a polyhedral subset of the state space is formulated. Then, a solution to the LCRP is derived solving a non-linear optimization problem
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