Path planning and obstacle avoidance algorithms are requested for robots working in more and more complicated environments. Standard methods usually reduce these tasks to the search of a path composed from lines and c...
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ISBN:
(纸本)9789728865832
Path planning and obstacle avoidance algorithms are requested for robots working in more and more complicated environments. Standard methods usually reduce these tasks to the search of a path composed from lines and circles or the planning is executed only with respect to a local neighborhood of the robot. Sophisticated techniques allow to find more natural trajectories for mobile robots, but applications are often limited to the offline case. The novel hierarchical method presented in this paper is able to find a long path in a huge environment with several thousand obstacles in real time. The solution, consisting of multiple cubic splines, is optimized by Particle Swarm Optimization with respect to execution time and safeness. The generated spline paths result in smooth trajectories which can be followed effectively by nonholonomic robots. The developed algorithm was intensively tested in various simulations and statistical results were used to determine crucial parameters. Qualities of the method were verified by comparing the method with a simple PSO path planning approach.
In this paper, a cooperative metaheuristic for the solution of the Unit Commitment problem is presented. This problem is known to be a large scale, mixed integer problem. Due to combinatorial complexity, the exact sol...
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ISBN:
(纸本)9789728865825
In this paper, a cooperative metaheuristic for the solution of the Unit Commitment problem is presented. This problem is known to be a large scale, mixed integer problem. Due to combinatorial complexity, the exact solution is often intractable. Thus, a metaheuristic based method has to be used to compute a near optimal solution with low computation times. A new approach is presented here. The main idea is to couple a genetic algorithm to compute binary variables (on/off status of units), and an ant colony based algorithm to compute real variables (produced powers). Finally, results show that the cooperative method leads to the tractable computation of a satisfying solution for medium scale Unit Commitment problems.
Catching requires the ability to predict the position and intercept a moving object at relatively high speeds. Because catching is a contact task, it requires an understanding of the interaction between the forces app...
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ISBN:
(纸本)9789728865832
Catching requires the ability to predict the position and intercept a moving object at relatively high speeds. Because catching is a contact task, it requires an understanding of the interaction between the forces applied and position of the object being captured. The application of force to a mass results in a change in acceleration. The rate of change of acceleration is called jerk. Jerk causes wear on the manipulator over time and can also damage the object being captured. This paper uses a curve that asymptotes to zero gradient at +/- infinity to develop an impedance controller, to decelerate an object to a halt after it has been coupled with the end effector. It is found that this impedance control method minimizes the jerk that occurs during capture, and eliminates the jerk spikes that are existent when using spring dampers, springs or constant force to decelerate an object.
This paper deals with the robust stabilization of a car-like mobile robot given in a perturbed chained form. A higher order sliding mode control strategy is developed. This control strategy switches between two differ...
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This paper deals with the robust stabilization of a car-like mobile robot given in a perturbed chained form. A higher order sliding mode control strategy is developed. This control strategy switches between two different sliding mode controls: a second order one (super-twisting algorithm) and a new third order sliding mode control that performs a finite time stabilization. The proposed third sliding mode controller is based on geometric homogeneity property with a discontinuous term. Simulation results show the control performance.
For improving the operability of an omni-directional wheelchair provided with a power assist system, the system must be able to adapt to the individual characteristics of the many different attendants that will use it...
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ISBN:
(纸本)9789728865832
For improving the operability of an omni-directional wheelchair provided with a power assist system, the system must be able to adapt to the individual characteristics of the many different attendants that will use it. For achieving this purpose, an innovative human-interface using a touch panel that provides easy input and feedback information in real time of the operation of a power-assisted wheelchair was developed. The system was tested experimentally with many different attendants and the results show that in addition to providing a human friendly interface by using the touch panel system with monitor it can adapt successfully to the particular habits of the attendants.
This paper presents modeling of stepping motor and control design of input pulse timing for the suppression control of vibration. The stepping motor has the transient response of electric current for the pulse input. ...
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ISBN:
(纸本)9789728865825
This paper presents modeling of stepping motor and control design of input pulse timing for the suppression control of vibration. The stepping motor has the transient response of electric current for the pulse input. Therefore, the motor model considering the transient response of the current is built. The validity of the proposed model is verified by comparing the model considering the transient response of the current with the one without its consideration. Design of the pulse input timing in the method of the four pulse drive is realized to achieve the desired angle without vibration and overshoot using an optimization method. Finally, the effectiveness of the proposed method is demonstrated by comparing simulation results with experiments.
in this paper we develop a modified MRAC strategy for use on plants with unmodelled high frequency dynamics. The MRAC strategy is made up of two parts, an adaptive control part and a fixed gain control part. The adapt...
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ISBN:
(纸本)9789728865849
in this paper we develop a modified MRAC strategy for use on plants with unmodelled high frequency dynamics. The MRAC strategy is made up of two parts, an adaptive control part and a fixed gain control part. The adaptive algorithm uses a combination of low and high pass filters such that the frequency range for the adaptive part of the strategy is limited. This reduces adaptation to unexpected high frequency dynamics and removes low frequency gain wind-up. In this paper we consider two examples of plants with unmodelled high frequency dynamics, both of which exhibit unstable behaviour when controlled using the standard MRAC strategy. By using the modified strategy we demonstrate that robustness is significantly improved.
The rendezvous problem between autonomous vehicles is formulated as an optimal cooperative control problem with terminal constraints. A major approach to the solution of optimal control problems is to seek solutions w...
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ISBN:
(纸本)9789728865832
The rendezvous problem between autonomous vehicles is formulated as an optimal cooperative control problem with terminal constraints. A major approach to the solution of optimal control problems is to seek solutions which satisfy the first order necessary conditions for an optimum. Such an approach is based on a Hamiltonian formulation, which leads to a difficult two-point boundary-value problem. In this paper, a different approach is used in which the control history is found directly by a genetic algorithm search method. The main advantage of the method is that it does not require the development of a Hamiltonian formulation and consequently, it eliminates the need to deal with an adjoint problem. This method has been applied to the solution of interception and rendezvous problems in an underwater environment, where the direction of the thrust vector is used as the control. The method is first tested on an interception chaser-target problem where the passive target vehicle moves along a straight line at constant speed. We then treat a cooperative rendezvous problem between two active autonomous vehicles. The effects of gravity, thrust and viscous drag are considered and the rendezvous location is treated as a terminal constraint.
Predictive and optimal process control using finite Markov chains is considered. A basic procedure is outlined, consisting of discretization of plant input and state spaces;conversion of a (a priori) plant model into ...
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ISBN:
(纸本)9789728865849
Predictive and optimal process control using finite Markov chains is considered. A basic procedure is outlined, consisting of discretization of plant input and state spaces;conversion of a (a priori) plant model into a set of finite state probability transition maps;specification of immediate costs for state-action pairs;computation of an optimal or a predictive control policy;and, analysis of the closed-loop system behavior. An application, using a MATLAB toolbox developed for MDP-based process control design, illustrates the approach in the control of a multivariable plant with both discrete and continuous action variables. For problems of size of practical significance (thousands of states), computations can be performed on a standard office PC. The aim of the work is to provide a basic framework for examination of nonlinear control, emphasizing in on-line learning from uncertain data.
Heaps models are powerful models for concurrent timed discrete event systems. They admit linear description using dioid algebras. Inspired by supervisory control of logical discrete event systems we introduce parallel...
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ISBN:
(纸本)9789728865825
Heaps models are powerful models for concurrent timed discrete event systems. They admit linear description using dioid algebras. Inspired by supervisory control of logical discrete event systems we introduce parallel composition of heap models, called synchronous product, to formally describe the action of supervisor (represented by another heap model) on the system. This additional explicit concurrency for naturally concurrent heap models is useful for studying supervisory control in the algebraic framework of dioid algebras. Timing aspects of supervisory control, i.e. optimal timing of the controller, is studied based on residuation theory.
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