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This paper addresses the trajectory tracking control problem of a nonholonomic wheeled mobile robot in presence of modeling uncertainties. A trajectory tracking controller is proposed by combination of an adaptive feedback linearizing controller and an adaptive robust PID control law. A SPR-Lypunov stability analysis demonstrates that tracking errors and parameters estimation errors are globally uniformly...
This paper discusses methods to avoid collisions between a robot and an obstacle, based on distance feedback given by a laser Time Of Flight (TOF) sensor. Two solutions are presented: the former (GCT: Geometry Consistent Trajectory) preserves the geometrical properties of the trajectory, while the latter (TCT: Time Consistent Trajectory) aims at preserving the time properties of the trajectory. Both...
In this paper, based on the theory of sliding mode control and fuzzy logic control, a new fuzzy sliding mode controller with a fixed-order compensator (FSMC&C) has been presented for application to seismically excited building structures. The major advantages of this method over the conventional sliding mode control are as follows: (i) it make trade-offs between control efforts and specific response...
Feedback linearization approach and Lyapunov tool are used to construct an adaptive control law achieving asymptotical tracking of the desired geometric path in the presence of parameter uncertainties. Backstepping technique is used to obtain the control effort in the torque level. The advantage of the control scheme lies in that it removes the restrictions of the desired longitudinal velocity of...
This paper proposes a new nonsmooth nonregular feedback control to stabilize nonholonomic chained systems. Firstly, a discontinuous nonlinear coordinate transformation and a discontinuous input transformation are constructed to change nonholonomic chained systems into controllable linear systems. Secondly, an invariant set and a switching logic are explicitly constructed to process with the singular...
This paper treats the chaos synchronization problem of chaotic Chua circuit system. Based on LaSalle invariance principal, the proposed controller is featured that (a) only single variable information of the master system is needed; (b) the control law is a simple linear controller with low gain. Finally, the effectiveness of the proposed control law is also illustrated by the numerical simulation...
In this article, an internal and an external synchronization have been investigated, in the presence of uncertain parameters. The proposed controller is designed to synchronize the movement of robot group following the same desired trajectory. To this effect, using a consensus algorithm, we provide an adaptive control under two different schemes. In the mutual synchronization topology, robots network...
The ubiquity of PID controllers in the industry has remained mysterious until now. We provide here a mathematical explanation of this strange phenomenon by comparing their sampling with the the one of “intelligent” PID controllers, which were recently introduced. Some computer simulations nevertheless confirm the superiority of the new intelligent feedback design.
The notion of strong observability is generalized for nonlinear systems. It allows to write the state of the system as a function of the measurable outputs and their time derivatives only, therefore allowing the construction of an unknown-input observer once such derivatives are estimated. It is shown that the output based control design problem for robust finite-time state stability for nonlinear...
In this paper, a novel concept of model based fault tolerance control (FTC) is presented. The FTC is achieved by 2-DOF control strategy: feedback control and feed forward control. Robustness issues are handled by the optimal feedback control and the time varying fault behavior by feed forward path. Firstly, a fault diagnosis scheme is presented for detecting and estimating the fault behavior from...
When robots leave industrial settings, they have to be designed allowing intuitive communication with the humans they interact with. The current paper focuses on collaboration in kinesthetic tasks. Herein, we investigate decision situations. This way, the need of communication between partners can be addressed. The current paper introduces for the first time an experimental paradigm which allows studying...
Typical industrial assembly tasks require an accuracy that cannot be realized by only feedback control if a minimum speed is given by a conveyor. Feed-forward has proven to be advantageous, using predictions of the desired trajectory which will be computed from sensor values. These predictions are improved by a model based classification of the sensor data to typical scenarios. In contrast to linear...
This paper presents motion control concepts on parallel robots with explicit focus on anti-windup-design and trajectory-tracking. Starting from modeling and exact feedback linearization, a cascade control is designed. Improvements to control laws with respect to input-saturations are derived by using concepts of anti-windup compensation. A multiple-axis anti-windup-control is presented, guaranteeing...
This paper presents the manipulator with the new joint which can passively switch free state to drive state and vice versa. The manipulator with the free-state joint is categorized as a system subjected to a nonholonomic constraint; hence, its smooth feedback control cannot be implemented. In this paper, the issues on its control are clarified through the test with the experimental setup of the manipulator...
This paper discusses how mobile manipulators with an under-actuated vertical arm can be designed to be differentially flat. The property of differential flatness is achieved by appropriate inertia redistribution of the vertical arm and a wide range of under-actuation becomes possible. As a result of having the flatness property, the under-actuated mobile manipulators are capable of executing point-to-point...
A simple, under-actuated robotic winch, called the “Winch-Bot,” is developed for surface inspection of a large object. The Winch-Bot, placed over an object surface, has only one actuator for tracing a free geometric path in a vertical plane. The cable length is controlled in relation to the direction of the cable so that the inspection end-effecter hanging at the tip of the cable can follow the path...
We present a novel approach to legged locomotion over rough terrain that is thoroughly rooted in optimization. This approach relies on a hierarchy of fast, anytime algorithms to plan a set of footholds, along with the dynamic body motions required to execute them. Components within the planning framework coordinate to exchange plans, cost-to-go estimates, and “certificates” that ensure the output...
This paper brings forward two kinds of PD control schemes of adaptive neural-variable structure for uncertain robot trajectory tracking. The first scheme consists of a PD feedback and a dynamic compensator which is composed of RBF neural network and variable structure. The adaptive laws of Network weights are based on Lyapunov function method. This controller can guarantee stability of closed-loop...
This paper is concerned with the design of robust active queue management (AQM) controllers for a class of TCP networks. In TCP/IP networks, the packet-dropping probability function is limited between 0 and 1. Therefore, a TCP network with AQM controller was modeled as a rate-based non-linear system with a saturated input. The nonlinear output feedback AQM controller is proposed for achieving the...
This paper proposes a novel feedrate interpolation strategy depending on the error feedback information. The proposed strategy incorporates the real-time non-uniform rational B-spline (NURBS) algorithm and is applied in a biaxial contouring stage system. The objective of the strategy is to improve the contouring accuracy to cope with the high-precision standard nowadays. The proposed method does achieve...
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