This paper is devoted to the impedance control problem of a double-acting hydraulic piston actuator. Thereby, it is the task of the impedance controlsystem to produce a response to an external force which corresponds...
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This paper is devoted to the impedance control problem of a double-acting hydraulic piston actuator. Thereby, it is the task of the impedance controlsystem to produce a response to an external force which corresponds to the response of a predefined mechanical system, with a desired (nonlinear) stiffness and a desired (nonlinear) damping characteristics around a desired operating point of the piston position. The controller design is based on a port-Hamiltonian representation of the mathematical model utilizing the fundamental thermodynamic relations of an isentropic fluid.
This paper deals with the modeling and nonlinear control of an ER (electrorheological) actuator consisting of a double-rod cylinder and four ER valves in a full-bridge configuration. Basically, we have to face two dif...
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This paper deals with the modeling and nonlinear control of an ER (electrorheological) actuator consisting of a double-rod cylinder and four ER valves in a full-bridge configuration. Basically, we have to face two difficulties within the controller design: First of all, the ER effect is inherently nonlinear and secondly, the ER full-bridge provides more control inputs than necessary for solving the primary control task. We will show that these additional degrees-of-freedom can be exploited to circumvent undesirable operation and to optimize the overall closed-loop performance. Furthermore, the nonlinearities of the mathematical model will be systematically included in the controller design. Measurement results performed on an experimental test-stand will demonstrate the feasibility of the proposed strategy.
This paper deals with the modeling and control of a three-degrees-of-freedom helicopter laboratory experiment. The helicopter belongs to the class of mechanical systems underactuated by one control. The mathematical m...
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This paper deals with the modeling and control of a three-degrees-of-freedom helicopter laboratory experiment. The helicopter belongs to the class of mechanical systems underactuated by one control. The mathematical model is derived using the Lagrange formalism in combination with the concept of twists and wrenches. It can be proven that the full system is not configuration flat. Nevertheless, by a slight modification of the generalized forces, which can also be interpreted in terms of a constructive change in the experimental set-up, we are able to design a flatness-based controller. Experimental results demonstrate the effectiveness of the proposed concept.
In this paper a novel approach to the Cartesian impedance control problem for robots with flexible joints is presented. The proposed controller structure is based on simple physical considerations, which are motivatin...
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In this paper a novel approach to the Cartesian impedance control problem for robots with flexible joints is presented. The proposed controller structure is based on simple physical considerations, which are motivating the extension of classical position feedback by an additional feedback of the joint torques. The torque feedback action can be interpreted as a scaling of the apparent motor inertia. Furthermore the problem of gravity compensation is addressed. Finally, it is shown that the closed loop system can be seen as a feedback interconnection of passive systems. Based on this passivity property a proof of asymptotic stability is presented.
The main characteristic of the walking robots is that they are able to move away on not arranged, horizontal and rough terrain. The movement of the walking robots can be divided in two modes: - under condition of the ...
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The main characteristic of the walking robots is that they are able to move away on not arranged, horizontal and rough terrain. The movement of the walking robots can be divided in two modes: - under condition of the static stability, - under condition of the dynamic stability. The loss of static or quasi-static stability may be produced in two cases, namely: - the vertical projection of the gravity center is out of support polygon, - one or more tangential components of reaction forces from support points are greater than the friction forces. The movement of the walking robot under dynamical stability conditions may be realized when the forward average speed is greater than a certain limit. In the work are analyzed the possibilities of determination of the limit conditions for the stable displacement of the quadrupedal walking robots.
This contribution deals with the systematic derivation of an analytical model for a silicon tuning fork gyroscope with piezoelectric drive and piezoresistive read-out. The mathematical model serves as a basis for opti...
The two main goals of this contribution are to demonstrate the integration of hydraulic actuator systems with PCH systems and to discuss a modification of the well known input-output linearization in connection with P...
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The two main goals of this contribution are to demonstrate the integration of hydraulic actuator systems with PCH systems and to discuss a modification of the well known input-output linearization in connection with P...
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The two main goals of this contribution are to demonstrate the integration of hydraulic actuator systems with PCH systems and to discuss a modification of the well known input-output linearization in connection with PCH systems. We will show that this approach is closely related to the existence of so called Casimir functions in the PCH context. Finally, industrial measurements demonstrating the implemented control law will be presented.
This paper addresses the impedance control problem for flexible joint manipulators. An impedance controller structure is proposed, which is based on an exact decoupling of the torque dynamics from the link dynamics. A...
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This paper addresses the impedance control problem for flexible joint manipulators. An impedance controller structure is proposed, which is based on an exact decoupling of the torque dynamics from the link dynamics. A formal stability analysis of the proposed controller is presented for the general tracking case. Preliminary experimental results are given for a single flexible joint.
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