A stability proof is presented for a nonlinear PD (NPD) controller and third order systems. Nonlinear-stiffness control has been described previously in the literature and experimentally demonstrated;but to date, no s...
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A stability proof is presented for a nonlinear PD (NPD) controller and third order systems. Nonlinear-stiffness control has been described previously in the literature and experimentally demonstrated;but to date, no stability proof has been given for systems of degree greater than 2 and the case where the stiff gain exceeds the limit established by the circle criterion. The limitation is important because, for this case, the circle is quite conservative and much of the benefit of NPD control comes with gains greater than could previously be proven to be stable. The stability of 3rd order systems with nonlinear-stiffness PD control and gains exceeding the circle-criterion limit is established by demonstrating a Lyapunov function. The damping achieved by high-gain NPD control is demonstrated by simulation.
The proceedings contains 42 papers. Topics discussed include robotics and manipulators, dynamics and control of flexible structures, deployment dynamics, impact dynamics, microgravity, multi-body dynamics, friction of...
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The proceedings contains 42 papers. Topics discussed include robotics and manipulators, dynamics and control of flexible structures, deployment dynamics, impact dynamics, microgravity, multi-body dynamics, friction of harmonic drive actuators, piezo-damping of light structures, laser communications.
We present two new effects related to intelligent fluids. The first one is the control of the transmission of a laser beam by using the change of turbidity of an electrorheological fluid in the presence of an electric...
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ISBN:
(纸本)0819421650
We present two new effects related to intelligent fluids. The first one is the control of the transmission of a laser beam by using the change of turbidity of an electrorheological fluid in the presence of an electric field. The second one is the control of the aggregation of non magnetic particles by a magnetic field in order to change the viscosity of the fluid. This fluid is made of non magnetic particles in suspension in a high magnetization ferrofluid.
An old-rooted endeavour of man, i.e. fabrication of material and structures taking inspiration from nature, is again actively pursued under a renewed name: biomimesis. This approach, once belonging to the realm of bio...
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ISBN:
(纸本)0819421650
An old-rooted endeavour of man, i.e. fabrication of material and structures taking inspiration from nature, is again actively pursued under a renewed name: biomimesis. This approach, once belonging to the realm of biological sciences, is based on the observation that, when one tries to embody our recognition criteria for biological organisms in an explicit list, nothing can be found on that list that cannot be mimicked by some inorganic system. Hence, a large variety of artifacts can be made, all possessing, to some extent, life-like features. Biomimetic arguments are today common reasoning in experimental studies about `origin-of-life' and in `advanced robotics'; a relatively new entry pertains to the area of `material science'.
control approaches for a two-link flexible manipulator are studied in the context of robust synthesis for Linear Parameter-Varying systems. Different treatments of the inertia matrix variations in the manipulator syst...
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ISBN:
(纸本)185312415X
control approaches for a two-link flexible manipulator are studied in the context of robust synthesis for Linear Parameter-Varying systems. Different treatments of the inertia matrix variations in the manipulator system are examined in three control law design formulations. The first two designs are based upon scaled H∞ or structured singular value synthesis. The third design makes use of a new approach for robust gain-scheduled synthesis. Results show that this gain-scheduling technique maximizes both performance and robustness over the entire range of manipulator configurations.
Chemomechanical transformations are used to produce a mechanical force from a reversible chemical reaction in order to generate artificial muscular contraction, on the model of the biological muscle. The design and ex...
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ISBN:
(纸本)0819421650
Chemomechanical transformations are used to produce a mechanical force from a reversible chemical reaction in order to generate artificial muscular contraction, on the model of the biological muscle. The design and experimentation of an original artificial muscle using an ion-exchange polymer which reacts inside a soft envelope, derived from research on pneumatic artificial McKibben muscle, is presented. Then a chemomechanical actuator constituted of two artificial muscles has been conceived: first results are shown on position control in open-loop mode.
This paper presents results from an ongoing collaboration between Wilkes University and the University of Wisconsin - La Crosse in using the Internet for undergraduate education in robotics. An interface has been deve...
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ISBN:
(纸本)0819423033
This paper presents results from an ongoing collaboration between Wilkes University and the University of Wisconsin - La Crosse in using the Internet for undergraduate education in robotics. An interface has been developed which allows computer science students at UW - La Crosse to control a robotic manipulator on the Wilkes University campus using images transmitted from Wilkes. The focus of this paper is the interface which monitors the image transmission and the control which the student user has over that transmission. An option in the interface allows the user to crop the image to a desired size in order to focus on a specific feature. Results of experiments performed by the joint undergraduate research groups at both institutions in using this component, as well as the associated educational outcomes, are presented here.
The control of rigid and flexible robots is performed using models for predicting the behaviour of their structure. It needs to characterize mechanical parameters. We first present the friction phenomenon in the actua...
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ISBN:
(纸本)185312415X
The control of rigid and flexible robots is performed using models for predicting the behaviour of their structure. It needs to characterize mechanical parameters. We first present the friction phenomenon in the actuators. The usual Coulomb's model of friction combined with viscosity is no more adapted to robot reducers. We have to identify the friction parameters to reduce the control perturbations. We distinguish the static and the quasi-static friction. We verify that the dry friction torque depends on the applied load and on the angular position. In a second time, we describe the stiffness study. The stiffness of each actuator involves an inaccuracy. It is important to know and correct the angular deflection shift. After a theoretical approach, we will present the experimental results and propose a general model.
The problem of impact dynamics of space robotic systems that consist of a rigid manipulator supported by a flexible deployable structure is addressed. Due to joint back-drivability and the dynamic coupling between the...
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ISBN:
(纸本)185312415X
The problem of impact dynamics of space robotic systems that consist of a rigid manipulator supported by a flexible deployable structure is addressed. Due to joint back-drivability and the dynamic coupling between the manipulator and its supporting structure, unknown motion of the system occurs after it makes impulsive contact with the environment. A method that uses the system's dynamic model is proposed to estimate the motion of the system after impact. The method which uses an idea of virtual inertia increment due to frictions and servo control torques, is verified experimentally using the MIT Vehicle Emulation System (VES II). The experimental results show that the impact force and the system motion after impact can be reduced if the manipulator configuration prior to impact and the controller gains are properly selected.
It is envisioned that in the future long-arm manipulators such as the Space Shuttle RMS and the ETS-VII Remote Manipulator Arm will be required to perform various types of constrained motion tasks, such as work-surfac...
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ISBN:
(纸本)185312415X
It is envisioned that in the future long-arm manipulators such as the Space Shuttle RMS and the ETS-VII Remote Manipulator Arm will be required to perform various types of constrained motion tasks, such as work-surface inspection, assembly, and cleanup. In the presence of contact point disturbances, due to either unknown contour profiles or movement of the work surface relative to the robot, the robot must ensure a minimum amount of contact force error while at the same time maintaining the desired constraint. This paper discusses the disturbance rejection properties of several commonly-used explicit force control strategies and highlights the control issues particular to force control of kinematically constrained mechanisms. A general disturbance-based model for constrained manipulators which is based on previous work on the simultaneous position/force control of constrained robots is also presented. Simulation results of this model elucidate the problems and issues relevant to the force control task of kinematically constrained manipulators.
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