摘要:

Equations of motion are derived for a flexible orbiting spacecraft, consisting of a rigid base body, a flexible beam and a rigid tip body, taking the motion of instantaneous centre of mass into consideration. We consider three kinds of motions, namely, the attitude motion of the base body, the three-dimensional translational vibrations (extension in the longitudinal direction and bendings in the other two directions) and the torsional vibration of the flexible beam due to the existence of the rigid tip body. It is shown that the motion of the base body and the motion of the flexible beam are coupled to each other. The translational vibrations and the torsional vibration of the flexible beam are also coupled through the dynamics of the tip body. One interesting aspect is that, as an effect of the interaction between the rigid base and the beam, a perturbation term appears in the dynamic equation of the flexible beam. It is also made clear that, fortunately, the existence of this perturbation leads only to an increase in the stiffness of thg flexible beam and does not affect damping of the vibration. Finally, the control design problem is mentioned and computer simulations are discussed.

ISSN:0020-7721    

DOI:10.1080/00207729408928955

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A mathematical model of a robot manipulator is described by a set of ordinary, coupled non-linear differential equations. Present theory is insufficient to obtain the exact solution of the equations to control the manipulator. We reduce the complexity of the problem by proposing a model reference system where the Coriolis terms are ignored and where the system of non-linear differential equations is almost decoupled by a careful selection of input torques. We show that the proposed control scheme for the model reference system is stable about a known equilibrium point. We present the simulation study for a two-link rotary manipulator where a model reference system and a control scheme are developed. The simulation results indicate that the solution is stable around a predetermined equilibrium point and that the addition of Coriolis terms in the non-linear differential equation does not change the overall stability of the system. The simulation results indicate that the robot manipulator tracks the desired trajectory.

ISSN:0020-7721    

DOI:10.1080/00207729408928956

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Prsent studies on industrial manipulator control either completely neglect structural flexibility or only consider manipulator link flexibility. Ignoring joint flexibility may cause significant errors in gross motion control if the joint elastic effect is predominant. A control scheme that can effectively compensate for the motion disturbances due to simultaneous existence of link and joint flexibility is presented. The manipulator dynamics is first formulated by a superposition of two models. An assumed modes of vibration is proposed to model the flexible links and a linear torsional spring to model the elastic joint. Then, a non-linear feedback rate servo control system is developed that compensates for the gross motion bias introduced by both joint elasticity and link flexibility. Motion simulation results show that the proposed modelling technique can effectively describe the dynamic behaviour of a flexible-link, elastic-joint robot. They also verify that the proposed controller is robust in that it can satisfactorily suppress the disturbances due to both link flexibility and joint elasticity and yield an accurate gross motion.

ISSN:0020-7721    

DOI:10.1080/00207729408928957

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A two-layer hierarchical structure for urban traffic dispatching control is proposed. The system operates in a heuristic manner and resolved a resource allocation problem in real time, related to the Dial a Ride (DAR) case. To decrease the complexity of the initial large-scale problem of resource allocation, space and time decomposition is performed. The space decomposition allows us to obtain local, low dimensional resource allocation problems. The time decomposition defines a discrete time optimization problem of resource allocation, which is solved by a central dispatching unit (CDU). It performs the resource allocation among the subsystems in accordance with the state imbalance, defined by the different number of unserved requests in the subsystems. The lower layer problems are solved by local dispatching units (LDU) which perform optimal vehicle routing and service of requests in real time. Special procedures, suitable for on-line control, are proposed for obtaining the upper layer solutions and for information transfer between the layers. The behaviour of a taxi system is simulated and the positive influence of the upper layer is shown.

ISSN:0020-7721    

DOI:10.1080/00207729408928958

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An adaptive controller that can provide asymptotic stability for an unknown linear time-invariant continuous system, subject to internal point delays, is presented. The only requireda prioriinformation about the plant is that the order of a time-invariant stabilizing controller has to be known for the case of known parameters.

ISSN:0020-7721    

DOI:10.1080/00207729408928959

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Dynamic phenomena of an intrinsically discrete nature are frequently encountered in complex large-scale man-made systems. Developing efficient control strategies for systems of this kind has become very important. Synchronization of behaviours between many components of such a system can greatly affect the overall performance. The problem of optimal synchronization for a certain kind of discrete event dynamic systems is formulated as a mixed integer linear programming (MIP) problem. In preliminary computational experiments, the resulting MIP problems were found to be easily solvable.

ISSN:0020-7721    

DOI:10.1080/00207729408928960

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The aim of this paper is to develop the concept of regional observability for distributed systems. This original concept is closer to practical considerations since it only requires the observation of the state on a given subregion. We show by means of an example that it is a weaker concept and we describe two approaches. The first one is state space based and can be easily implemented for numerical simulations. Then a second approach leads to the estimation of the state on the considered subregion with a zero residual state.

ISSN:0020-7721    

DOI:10.1080/00207729408928961

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A linear continuous-time system with saturation on controls becomes a non-linear closed-loop system when linear state feedback control law is implemented. Assuming that the system to be controlled is stabilizable, the possibilities for an invariant feedback matrix to make the saturated closed-loop system globally asymptotically stable (GAS) are studied. It is proven that this stability property can be obtained by means of a linear feedback provided the considered system is stabilizable with respect to a Lyapunov function of the open-loop system. It is also shown that the global stability property in a closed-loop can only concern asymptotically or critically stable open-loop systems. However, except for a strictly unstable linear open-loop system, i.e. with at least one eigenvalue with a positive real part, there always exists some linear feedback linear matrix for which the stability domain can be as large as desired, even if the open-loop system is critically unstable. In all previous cases, the suitable feedback matrix is given and can easily be computed. When the closed-loop system cannot be GAS, a simple determination of a non-linear stability domain is given, together with the corresponding algorithm. Further, when the saturated closed-loop system is GAS, the conditions indicating whether this system is dynamically faster (DF) or equivalent (DE) to the open-loop system are given.

ISSN:0020-7721    

DOI:10.1080/00207729408928962

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The well-known Dahlin-Higham controller for a scalar control system with dead time is extended to the control of a class of multivariable control systems using a matrix fraction representation. The main result of this work is the design of a MIMO controller that can achieve simultaneously exact decoupling and time delay compensation. Sufficient conditions under which a MIMO system with equal delays is decoupled and a sufficient readability condition for a MIMO controller are given. Exact decoupling for plants with unequal time delays is achieved by a suitable increase in the time delays of the controller, This results in a highly computationally efficient MIMO controller. Simulation results are given to illustrate the analysis.

ISSN:0020-7721    

DOI:10.1080/00207729408928963

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

It is established that block pulse functions (BPFs) are superior to the delayed unit step function (DUSF) proposed by Hwang (1983). The superiority is mainly due to the most elemental nature of BPFs in comparison to any other PCBF function. It is also proved that the operational matrix for integration in the BPF domain is connected to the integration operational matrix in the DUSF domain by simple linear transformation involving invertible Toeplitz matrices. The transformation appears to be transparent because the integration operational matrices are found to match exactly. The reason for such transparency is explained mathematically. Finally, Hwang claimed superiority of DUSFs compared to Walsh functions in obtaining the solution of functional differential equations using a stretch matrix in the DUSF domain. It is shown that the stretch matrices of Walsh and DUSF domains are also related by linear transformation and use of any of these two matrices leads to exactly the same result. This is supported by an example. It may be noted that for any analysis approach involving any of the PCBFs, the accuracy of the final result is always the same. This is because all the PCBFs are connected to one another by linear transformations.

ISSN:0020-7721    

DOI:10.1080/00207729408928964

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor