| 1. |
- Aguilar, Luis T., et al.
(författare)
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Generating oscillations in inertia wheel pendulum via two-relay controller
- 2012
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Ingår i: International Journal of Robust and Nonlinear Control. - Malden : Wiley-Blackwell. - 1049-8923 .- 1099-1239. ; 22:3, s. 318-330
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Tidskriftsartikel (refereegranskat)abstract
- The problem of generating oscillations of the inertia wheel pendulum is considered. We combine exact feedback linearization with two-relay controller, tuned using frequency-domain tools, such as computing the locus of a perturbed relay system. Explicit expressions for the parameters of the controller in terms of the desired frequency and amplitude are derived. Sufficient conditions for orbital asymptotic stability of the closed-loop system are obtained with the help of the Poincare map. Performance is validated via experiments. The approach can be easily applied for a minimum phase system, provided the behavior of the states of the zero dynamics is of no concern. Copyright (C) 2011 John Wiley & Sons, Ltd.
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| 2. |
- Aguilar, Luis T., et al.
(författare)
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Inducing oscillations in an Inertia wheel pendulum via Two-relays controller : theory and experiments
- 2009
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Ingår i: American control conference, 2009. ACC 09. - Piscataway, NJ : IEEE, Institute of Electrical and Electronics Engineers. - 9781424445233 ; , s. 65-70
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Konferensbidrag (refereegranskat)abstract
- A tool for generating a self-excited oscillations for an inertia wheel pendulum by means of a variable structure controller is proposed. The original system is transformed into the normal form for exact linearization. The design procedure, based on Describing Function (DF) method, allows for finding the explicit expressions of the two-relays controller gain parameters in terms of the desired frequency and amplitude. Necessary condition for orbital asymptotic stability of the output of the exactly linearized system is derived. Performance issues of the system with self-excited oscillations are validated with experiments.
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| 3. |
- Gusev, Sergey, et al.
(författare)
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Modification of a PD+ controller for the orbital stabilization of the motions of an all-wheel drive mechanical system
- 2016
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Ingår i: Journal of Applied Mathematics and Mechanics. - : Elsevier BV. - 0021-8928. ; 79:6, s. 546-555
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Tidskriftsartikel (refereegranskat)abstract
- The problem of the orbital stabilization of the forced periodic motions of a non-linear all-wheel drive mechanical system is considered within the framework of a model that is widely used in problems of the planning of the motions and feedback design for industrial robotic manipulators. The basic result is the explicit indication of one of the possible redundant sets of coordinates tranverse to the nominal motion and the derivation of the linearization of their behaviour in an explicit form. The latter enabledus to validate the original approach in the controller design problem and to analyse the behaviour of the closed system in the neighbourhood of the nominal motion. The analytical results are illustrated by solving the problem of stabilizing the motion of the working tool of an industrial ABB IRB140 robotic manipulator that is suboptimal with respect to its high-speed response taking account of the known constraints imposed on the limiting values of the angular velocities of the individual robot components.
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| 4. |
- Pchelkin, Stepan, et al.
(författare)
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A dynamic human motion : coordination analysis
- 2015
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Ingår i: Biological Cybernetics. - : Springer Science and Business Media LLC. - 0340-1200 .- 1432-0770. ; 109:1, s. 47-62
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Tidskriftsartikel (refereegranskat)abstract
- This article is concerned with the generic structure of the motion coordination system resulting from the application of the method of virtual holonomic constraints (VHCs) to the problem of the generation and robust execution of a dynamic humanlike motion by a humanoid robot. The motion coordination developed using VHCs is based on a motion generator equation, which is a scalar nonlinear differential equation of second order. It can be considered equivalent in function to a central pattern generator in living organisms. The relative time evolution of the degrees of freedom of a humanoid robot during a typical motion are specified by a set of coordination functions that uniquely define the overall pattern of the motion. This is comparable to a hypothesis on the existence of motion patterns in biomechanics. A robust control is derived based on a transverse linearization along the configuration manifold defined by the coordination functions. It is shown that the derived coordination and control architecture possesses excellent robustness properties. The analysis is performed on an example of a real human motion recorded in test experiments.
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| 5. |
- Pchelkin, Stepan S., et al.
(författare)
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Algorithms for finding gaits of locomotive mechanisms : case studies for Gorilla robot brachiation
- 2016
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Ingår i: Autonomous Robots. - : Springer Science and Business Media LLC. - 0929-5593 .- 1573-7527. ; 40:5, s. 849-865
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Tidskriftsartikel (refereegranskat)abstract
- We consider a model of a 24-degree-of-freedom monkey robot that is supposed to perform a brachiation locomotion, i.e. to swing from one row of a horizontal ladder to the next one using the arms. The robot hand is constructed as a planar hook so that the contact point, about which the robot swings, is a passive hinge. We identify the 10 most relevant degrees of freedom for this underactuated mechanical system and formulate a tractable search procedure consisting on the following steps: (a) to introduce a parametrized family of coordination patterns to be enforced on the dynamics with respect to a path coordinate; (b) to formulate geometric equality constraints that are necessary to achieve a periodic locomotion; (c) to generate trajectories from integrable reduced dynamics associated with the passive hinge; (d) to evaluate the energetic cost of transport. Moreover, we observe that a linear approximation of the reduced dynamics can be used for trajectory generation, which allows us to incorporate computation of an approximate gradient of the cost function into the search algorithm significantly improving the computational efficiency.
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| 6. |
- Pchelkin, Stepan S., et al.
(författare)
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On Orbital Stabilization for Industrial Manipulators : Case Study in Evaluating Performances of Modified PD plus and Inverse Dynamics Controllers
- 2017
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Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 25:1, s. 101-117
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Tidskriftsartikel (refereegranskat)abstract
- Orbital stabilization is one of the available alternatives to the classical asymptotic stabilization, known as the reference tracking control, which is typically considered and implemented for controlling motions of industrial robot manipulators. Since asymptotic orbital stability means convergence of solutions of a closed-loop system to an orbit of a reference trajectory, instead of tracking it as a function of time, new feedback designs can potentially improve performance with respect to several key criteria for industrial manipulators such as absolute path accuracy for tool's motions and robustness to uncertainties in the model. The main outcomes of this paper are a new class of controllers that achieve asymptotic orbital stabilization of motions and a novel analytical method for analysis and redesign of system's dynamics using an excessive set of easy-to-compute transverse coordinates. The contributions have been validated in a series of experimental studies performed on a standard industrial robot ABB IRB 140 with the IRC5-system extended with an open control interface. The outcomes of the tests show that the proposed redesign allows achieving significantly reduced deviations of the actual trajectories from the desired ones at different ranges of speeds and for several different paths, often outperforming the state-of-the-art commercial implementations. A comprehensive discussion of one of such experiments is given.
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| 7. |
- Sætre, Christian Fredrik, et al.
(författare)
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Robust orbital stabilization : A Floquet theory-based approach
- 2021
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Ingår i: International Journal of Robust and Nonlinear Control. - : John Wiley & Sons. - 1049-8923 .- 1099-1239. ; 31:16, s. 8075-8108
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Tidskriftsartikel (refereegranskat)abstract
- The design of robust orbitally stabilizing feedback is considered. From a known orbitally stabilizing controller for a nominal, disturbance-free system, a robustifying feedback extension is designed utilizing the sliding-mode control (SMC) methodology. The main contribution of the article is to provide a constructive procedure for designing the time-invariant switching function used in the SMC synthesis. More specifically, its zero-level set (the sliding manifold) is designed using a real Floquet–Lyapunov transformation to locally correspond to an invariant subspace of the Monodromy matrix of a transverse linearization. This ensures asymptotic stability of the periodic orbit when the system is confined to the sliding manifold, despite any system uncertainties and external disturbances satisfying a matching condition. The challenging task of oscillation control of the underactuated cart–pendulum system subject to both matched- and unmatched disturbances/uncertainties demonstrates the efficacy of the proposed scheme.
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| 8. |
- Surov, Maksim, et al.
(författare)
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Case study in non-prehensile manipulation : planning and orbital stabilization of one-directional rollings for the "Butterfly" robot
- 2015
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Ingår i: 2015 IEEE International Conference on Robotics and Automation (ICRA). - Los Alamitos : IEEE Computer Society. - 9781479969234 ; , s. 1484-1489
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Konferensbidrag (refereegranskat)abstract
- We approach a problem of motion planning and stabilization for a benchmark example, known as the "Butterfly" robot. It was proposed as a benchmark challenge for developing systematic techniques for nonprehensile rolling manipulation. A dynamical model of the underactuated system with a non-unilateral contact is derived. The recently proposed methodologies, known as virtual-holonomic-constraints-based motion planning and transverse-linearization-based orbital stabilization, are appropriately extended to suit the task. Finally, the feasibility is demonstrated through a hardware implementation and an experimental validation of the concept.
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| 9. |
- Vazquez, Carlos, et al.
(författare)
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Second Order Sliding Mode Control of a Mobile Hydraulic Crane
- 2014
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Ingår i: 2014 IEEE 53RD ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC). - 9781467360906 ; , s. 5530-5535
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Konferensbidrag (refereegranskat)abstract
- A second order sliding mode control design for a mobile hydraulic system, including bounded model uncertainties and external disturbances, is the subject of study. The proposed algorithm provides a continuous control signal, achieving good performance and chattering attenuation in comparison to other sliding-mode-based techniques. The design includes the formulation of a partial stability problem and we provide the required Lyapunov-function-based analysis. Experimental results are performed over an industrial setup and confirm the effectiveness of the methodology. Moreover, promising results of a comparison with the Super-Twisting and PID controllers are presented.
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| 10. |
- Vazquez, Carlos, et al.
(författare)
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Time-Varying Gain Differentiator : A Mobile Hydraulic System Case Study
- 2016
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Ingår i: IEEE Transactions on Control Systems Technology. - : IEEE. - 1063-6536 .- 1558-0865. ; 24:5, s. 1740-1750
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Tidskriftsartikel (refereegranskat)abstract
- In mobile hydraulic systems, velocities are typically not measured. However, using their reliable estimates for feedback is known to allow designing better control laws. We are going to present a specialized technique to compute such estimates using measurements of positions and pressures in the chambers of hydraulic cylinders. With a rough estimate for an upper bound of the second derivative, computed online from pressures, the goal is to find the first derivative of the position signal in the presence of noise. We propose a differentiator with a continuous time-varying gain, constructed from pressure measurements, achieving chattering attenuation without compromising the performance of estimation. The gain is constructively tuned using analysis based on a time-varying Lyapunov function. In addition, the obtained ultimate bounds on differentiation errors provide a criterion for the enhancement of the precision of the proposed algorithm with a constructive design of its parameters. The experimental results over a forestry-standard mobile hydraulic crane confirm the advantages of the methodology.
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