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| 2. |
- Alcocer, Alex, et al.
(author)
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Force Estimation and Control in Robot Manipulators
- 2004
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In: Robot control 2003 : A proceeding volume from the 7th IFAC Symposium Wroclaw, Poland, 1-3 September 2003 - A proceeding volume from the 7th IFAC Symposium Wroclaw, Poland, 1-3 September 2003. - 0080440096 ; 1, s. 31-36
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Conference paper (peer-reviewed)abstract
- In this paper we present some results on model based force estimationand how these estimates can be integrated in a common robot force controlscheme. A generalization of the force estimation method proposed inHacksel and Salcudean (1994) is done and a force observerable to follow ramp environmental forces is introduced. Anextension of this method for robotic manipulators is also experimentallyverified for an industrial robot with an open control systemarchitecture during a force control task.
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| 3. |
- Alcocer, Alex, et al.
(author)
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Force Estimation and Control in Robot Manipulators
- 2003
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In: IFAC Proceedings Volumes. ; 36, s. 55-60
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Conference paper (peer-reviewed)abstract
- In this paper we present some results on model based force estimation and how these estimates can be integrated in a common robot force control scheme. A generalization of the force estimation method proposed in [Hacksel and Salcudean, 1994] is done and a force observer able to follow ramp environmental forces is introduced. An extension of this method for robotic manipulators is also experimentally verified using an industrial robot with an open control system architecture during a force control task.
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| 4. |
- Andersson, Alina, et al.
(author)
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Analytic Parameterization of Stabilizing Controllers for the Surge Subsystem of the Moore-Greitzer Compressor Model
- 2013
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In: Proc. 2013 American Control Conference (ACC2013). - 0743-1619. - 9781479901777 ; , s. 5257-5262
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Conference paper (peer-reviewed)abstract
- This paper is based on a new procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. The new procedure is motivated by the challenges of output feedback control design for the 3-state Moore-Greitzer compressor model. First, we use conditions for stability of a transformed system and the associated matching conditions to find the data of the stabilizing controllers for the surge subsystem. Second, using the set of stabilizing controllers satisfying the given constraints for the closed-loop system with the dynamic output feedback controller we made optimization over the parameter set. We present the data of the stabilizing controllers and the new constraints for the corresponding parameters. The contributions in this paper are simplified conditions for the synthesis and optimization over the control parameter set.
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| 5. |
- Andersson, Alina, et al.
(author)
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Robustness of the Moore-Greitzer Compressor Model's Surge Subsystem with New Dynamic Output Feedback Controllers
- 2014. - 3
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In: 19th IFAC World Congress. - : Elsevier. - 2405-8963. - 9783902823625 ; 47, s. 3690-3695
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Conference paper (peer-reviewed)abstract
- This work presents an extension of a design procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. In this work we used an axial gas compressor model described by the 3-state Moore-Greitzer compressor model (MG) that has some challenges for output feedback control design (Planovsky and Nikolaev 1990), (Rubanova 2013). The more general constraints for the investigation of the robustness with respect to parametric uncertainties and measurement noise are shown.
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| 6. |
- Andersson, Alina, et al.
(author)
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Sufficient Conditions for Dynamic Stabilization of 3-State Moore-Greitzer Compressor Model
- 2015
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In: 2015 IEEE 54th Annual Conference on Decision and Control (CDC). - 9781479978861 - 9781479978847 ; , s. 4394-4399
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Conference paper (peer-reviewed)abstract
- We consider the classical 3-state Moore-Greitzer model, which is commonly used for approximating dynamics of deviations of flow and pressure variables in an axial compressor from their nominal steady-state values. The linearization of the nonlinear system is not controllable and, therefore, even local asymptotic stability cannot be achieved using methods of linear control theory. We propose a family of parametrized partialstate feedback control laws and derive sufficient conditions to guarantee global asymptotic stability of the closed-loop system. The stability analysis uses the integral quadratic constraints technique for the case of non-strict frequency condition and novel arguments for characterization of omega-limit sets.
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| 7. |
- Bagge Carlson, Fredrik, et al.
(author)
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Identification of LTV Dynamical Models with Smooth or Discontinuous Time Evolution by means of Convex Optimization
- 2018
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In: 2018 IEEE 14th International Conference on Control and Automation (ICCA). - 9781538660898
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Conference paper (peer-reviewed)abstract
- We establish a connection between trend filtering and system identification which results in a family of new identification methods for linear, time-varying (LTV) dynamical models based on convex optimization. We demonstrate how the design of the cost function promotes a model with either a continuous change in dynamics over time, or causes discontinuous changes in model coefficients occurring at a finite (sparse) set of time instances. We further discuss the introduction of priors on the model parameters for situations where excitation is insufficient for identification. The identification problems are cast as convex optimization problems and are applicable to, e.g., ARX models and state-space models with time-varying parameters. We illustrate usage of the methods in simulations of jump-linear systems, a nonlinear robot arm with non-smooth friction and stiff contacts as well as in model-based, trajectory centric reinforcement learning on a smooth nonlinear system.
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| 8. |
- Bagge Carlson, Fredrik, et al.
(author)
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Linear Parameter-Varying Spectral Decomposition
- 2017
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In: American Control Conference (ACC), 2017. ; , s. 146-151
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Conference paper (peer-reviewed)abstract
- A linear parameter-varying (LPV) spectral decomposition method, based on least-squares estimation and kernel expansions, is developed. Statistical properties of the estimator are analyzed and verified in simulations. The method is linear in the parameters, applicable to both the analysis and modeling problems and is demonstrated on both simulated signals as well as measurements of the torque in an electrical motor.
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| 9. |
- Bagge Carlson, Fredrik, et al.
(author)
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Modeling and Identification of Position and Temperature Dependent Friction Phenomena without Temperature Sensing
- 2015
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In: 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). ; , s. 3045-3051
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Conference paper (peer-reviewed)abstract
- This paper investigates both positional dependence in systems with friction and the influence an increase in temperature has on the friction behavior. The positional dependence is modeled with a Radial Basis Function network and the temperature dependence is modeled as a first order system with the power loss due to friction as input, eliminating the need for temperature sensing. The proposed methods are evaluated in both simulations and experiments on two industrial robots with strong positional and temperature friction dependence.
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| 10. |
- Bagge Carlson, Fredrik, et al.
(author)
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Particle Filter Framework for 6D Seam Tracking Under Large External Forces Using 2D Laser Sensors
- 2016
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In: 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems. - 9781509037629 ; , s. 3728-3734
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Conference paper (peer-reviewed)abstract
- We provide a framework for 6 DOF pose estimation in seam-tracking applications using particle filtering. The particle filter algorithm developed incorporates measurements from both a 2 DOF laser seam tracker and the robot forward kinematics under an assumed external force. Special attention is paid to modeling of disturbances in the respective measurements, and methods are developed to assist the selection of sensor configurations for optimal estimation performance. The developed estimation algorithm and simulation environment are provided as an open-source, extendable package, written with an intended balance between readability and performance.
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