This paper investigates manipulation tasks with arrays of microelectromechanical structures (MEMS). We develop a geometric model for the mechanics of microactuators and a theory of sensorless, parallel manipulation, a...
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This paper investigates manipulation tasks with arrays of microelectromechanical structures (MEMS). We develop a geometric model for the mechanics of microactuators and a theory of sensorless, parallel manipulation, and we describe efficient algorithms for their evaluation. The theory of limit surfaces offers a purely geometric characterization of microscale contacts between actuator and moving object, which can be used to efficiently predict the motion of the object on an actuator array. It is shown how simple actuator control strategies can be used to uniquely align a part up to symmetry without sensor feedback. This theory is applicable to a wide range of microactuator arrays. Our actuators are oscillating structures of single-crystal silicon fabricated in a IC-compatible process. Calculations show that these actuators are strong enough to levitate and move, for example, a piece of paper.< >
By monitoring or following trails layed on the ground a mobile robot can perform several useful navigation tasks. An example would be following a trail layed on an outward journey in order to later find the way back t...
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By monitoring or following trails layed on the ground a mobile robot can perform several useful navigation tasks. An example would be following a trail layed on an outward journey in order to later find the way back to the starting point. This paper describes the latest stage in the development of a robot navigation system based on laying down and detecting trails of volatile chemicals. Previously a prototype olfactory sensor was developed which showed the feasibility of having a mobile robot follow an odour trail on the floor. This prototype sensor has now been improved by managing airflow in the vicinity of the sensor. This has decreased the sensor response time and improved rejection of spurious odour signals carried by airflow in the room. A simple and effective applicator has also been developed for laying odour trails.< >
Given an arbitrary telecommunications network N our goal is to find the minimum cost for equipment which will enable N to survive an arbitrary link fault. We consider uni-directional and bi-directional ring technologi...
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Given an arbitrary telecommunications network N our goal is to find the minimum cost for equipment which will enable N to survive an arbitrary link fault. We consider uni-directional and bi-directional ring technologies. Basically, our goal is to find minimum cost ring covers for any network N, where a ring cover is a set C of rings such that every link in N is covered by (i.e. part of) at least one ring in C. If a network N is augmented with enough equipment to support a given ring cover C, it can respond to a link failure immediately (and automatically) by routing the disrupted traffic through surviving links in the ring that covers the failed link. We describe an efficient algorithm to find a minimum cost ring cover for uni-directional transmission rings under simplifying assumptions. This algorithm offers a useful heuristic for computing low cost ring covers for existing networks and actual cost functions. We also provide efficient heuristics to find nearly minimum cost ring covers for bi-directional transmission rings. We show that certain versions of the bi-directional problem are NP-complete, hence (presumably) no efficient algorithm exists that always finds a minimum cost ring cover. However, our heuristics perform well in practice.
This paper presents an adaptive control scheme based on a fuzzy logic algorithm and its application to end-effector positioning of flexible-link manipulators. Here, a fuzzy based adaptive controller is considered due ...
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This paper presents an adaptive control scheme based on a fuzzy logic algorithm and its application to end-effector positioning of flexible-link manipulators. Here, a fuzzy based adaptive controller is considered due to its simplicity and the fact that it does not require expressing the controller in terms of the system parameters, as it is necessary in the case of self-tuning regulators. This controller is based on a functional fuzzy model where the consequents are crisp functions represent controllers designed for different operating regimes. The premise is constituted by the fuzzy subsets corresponding to the process parameters estimated in real time. The effectiveness of this new scheme is verified on a clamped free beam and a single-line flexible arm instrumented with piezoceramic sensors and actuators. It is shown that robust performance may be achieved in face of large parameter variations.< >
Experimental results for end-point positioning of multi-link flexible manipulators through end-point acceleration feedback are presented in this article. The advocated controllers are implemented on a two-link flexibl...
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Experimental results for end-point positioning of multi-link flexible manipulators through end-point acceleration feedback are presented in this article. The advocated controllers are implemented on a two-link flexible arm developed at the Control/robotics Research Laboratory at Polytechnic University. The advocated approach in this article is based on a two-stage control design. The first stage is a nonlinear O(1) feedback linearizing controller corresponding to the rigid body motion of the manipulator. Because this scheme does not utilize any feedback from the end-point motion, significant vibrations are induced at the end effector. To this effect, and to enhance the robustness of the closed-loop dynamics to parameter variations, the inner loop is augmented with an outer loop based on a linear output LQR design that utilizes an end-point acceleration feedback. The forearm of the manipulator is significantly more flexible as compared with the upper arm. Experimental and simulation results validate the fact that the end-effector performance is significantly better with the proposed O(1) feedback linearizing control as compared with the linear independent joint PD control. In addition, the nonlinear control offers other advantages in terms of smaller and smoother actuator torques and reducing the effects of nonlinearities. Close conformation between simulation and experimental results validates the accuracy of the model.
The use of sensors and actuators along the links of flexible-link manipulators is investigated. Piezoelectric ceramics are considered since they may be utilized both as sensors and actuators. Experimental setups have ...
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The use of sensors and actuators along the links of flexible-link manipulators is investigated. Piezoelectric ceramics are considered since they may be utilized both as sensors and actuators. Experimental setups have been developed to study modeling issues and control design approaches for flexible link manipulators with embedded (or surface-mounted) piezoceramics. The addition of piezoceramics allows a higher level of control for vibration damping. It is shown that piezoceramics substantially reduce the vibration of the arm and hence improve the end-effector positioning of the manipulator. The advocated approach for control design is decentralized frequency shaping.< >
Adaptive nonlinear excitation control of large-scale power systems is considered in this paper. The approach used is an adaptive feedback linearizing control to enhance the robustness to unknown or varying interconnec...
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Adaptive nonlinear excitation control of large-scale power systems is considered in this paper. The approach used is an adaptive feedback linearizing control to enhance the robustness to unknown or varying interconnection parameters like equivalent reactances of the transmission lines. Adaptation in estimated parameters is utilized to achieve an asymptotically exact cancellation of terms. Simulation results for a two generator-infinite bus power system are presented to validate the robustness of the adaptive feedback linearizing scheme to unknown interconnections arising due to faults and subsequent line switchings. The performance using the nonadaptive feedback linearizing control is shown to degrade for network configuration variations arising due to transmission line faults. The studies validate the fact that connective stability and robust performance is maintained for unknown interconnection topology using the adaptive feedback linearizing scheme.< >
In this paper, active control of flexible structures through utilization of structure mounted sensors and actuators is considered. Specifically, dynamic feedback design utilizing signals from the accelerometer mounted...
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In this paper, active control of flexible structures through utilization of structure mounted sensors and actuators is considered. Specifically, dynamic feedback design utilizing signals from the accelerometer mounted on the structure is discussed. Furthermore, utilization of piezoceramics for sensing and actuation to provide a higher level of control for vibration damping is investigated. The flexible pointing system considered here is the test-bed at the Army Research Development engineering Center (ARDEC), which is a scaled-down representation of real-life targetting systems. This setup is also a nice benchmark problem for system identification and different control design philosophies. The approaches advocated here are based on Youla's parametrization of stabilizing controllers, Wiener-Hopf design and decentralized frequency shaping. Modelling aspects for the setup, taking all the structural intricacies into account, are discussed. The preliminary results indicate a significant improvement in performance through utilization of these control schemes.
A new fuzzy reasoning is proposed so that the conclusion consists of a function of mean-values on each membership function in antecedent. It is then shown that the constant parameters in conclusion can be rationally d...
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A new fuzzy reasoning is proposed so that the conclusion consists of a function of mean-values on each membership function in antecedent. It is then shown that the constant parameters in conclusion can be rationally designed from the view point of a control theory, if the conclusion is regarded as a sliding controller with the mean values in antecedent as state variables.
The Signal Processing Instructional Facility (SPIF Lab) is an experiment in using in interactive multimedia for teaching concepts related to linear systems theory and signal processing. The goals of the SPIF lab are t...
The Signal Processing Instructional Facility (SPIF Lab) is an experiment in using in interactive multimedia for teaching concepts related to linear systems theory and signal processing. The goals of the SPIF lab are to augment, enhance, and interconnect sophomore, junior, and senior level courses with the common thread of linear systems and transforms by unifying the experimentation medium. In this fashion, physical phenomenon is returned to the forefront of engineering education. The laboratory features powerful Mathematica Notebooks (a form of hypertext) and interactive applications that use dedicated DSP microprocessors.
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