| 1. |
- Markusson, Ola, 1971-, et al.
(författare)
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Iterative Learning Control of Nonlinear Non-Minimum Phase Systems and its Application to System and Model Inversion
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this contribution we place ILC in the realm of numerical optimization. This clarifies the role played by the design variables and how they affect e.g. convergence properties. We give a model based interpretation of these design variables and also a sufficient condition for convergence of ILC which is similar in spirit to the sufficient and necessary condition previously derived for linear systems. This condition shows that the desired performance has to be traded against modelling accuracy. Finally, one of the main benefits of ILC when non-minimum phase systems are concerned, the possibility of non-causal control, is given a comprehensive coverage.
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| 2. |
- Andersson, Magnus, et al.
(författare)
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A Simulation and Animation Tool for Studying Multivariable Control
- 2002
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Ingår i: Proceedings of the 15th IFAC World Congress. - 9783902661746 ; , s. 1432-1432
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Konferensbidrag (refereegranskat)abstract
- A simulation and animation tool for education in multivariable control is presented. The purpose of the tool is to support studies of various aspects of multivariable dynamical systems and design of multivariable feedback control systems. Different ways to use this kind of tool in control education are also presented and discussed.
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| 3. |
- Ardeshiri, Tohid, 1980-, et al.
(författare)
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Convex Optimization Approach for Time-Optimal Path Tracking of Robots with Speed Dependent Constraints
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The task of generating time optimal trajectories for a six degrees of freedom industrial robot is discussed and an existing convex optimization formulation of the problem is extended to include new types of constraints. The new constraints are speed dependent and can be motivated from physical modeling of the motors and the drive system. It is shown how the speed dependent constraints should be added in order to keep the convexity of the overall problem. A method to, conservatively, approximate the linear speed dependent constraints by a convex constraint is also proposed. A numerical example proves versatility of the extension proposed in this paper.
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| 4. |
- Ardeshiri, Tohid, 1980-, et al.
(författare)
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Convex Optimization Approach for Time-Optimal Path Tracking of Robots with Speed Dependent Constraints
- 2011
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Ingår i: Proceedings of the 18th IFAC World Congress. - : IFAC. - 9783902661937 ; , s. 14648-14653
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Konferensbidrag (refereegranskat)abstract
- The task of generating time optimal trajectories for a six degrees of freedom industrial robot is discussed and an existing convex optimization formulation of the problem is extended to include new types of constraints. The new constraints are speed dependent and can be motivated from physical modeling of the motors and the drive system. It is shown how the speed dependent constraints should be added in order to keep the convexity of the overall problem. A method to, conservatively, approximate the linear speed dependent constraints by a convex constraint is also proposed. A numerical example proves versatility of the extension proposed in this paper.
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| 5. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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Bayesian Methods for Estimating Tool Position of an Industrial Manipulator
- 2012
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Ingår i: Proceedings of Reglermöte 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- State estimation of a flexible industrial manipulator is presented using experimental data. The problem is formulated in a Bayesian framework where the extended Kalman filter and particle filter are used. The filters use the joint positions on the motor side of the gearboxes as well as the acceleration at the end-effector as measurements and estimates the corresponding joint angles on the arm side of the gearboxes. The techniques are verified on a state of the art industrial robot, and it is shown that the use of the acceleration at the end-effector improves the estimates significantly.
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| 6. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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Bayesian State Estimation of a Flexible Industrial Robot
- 2012
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Ingår i: Control Engineering Practice. - : Elsevier. - 0967-0661 .- 1873-6939. ; 20:11, s. 1220-1228
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Tidskriftsartikel (refereegranskat)abstract
- A sensor fusion method for state estimation of a flexible industrial robot is developed. By measuring the acceleration at the end-effector, the accuracy of the arm angular position, as well as the estimated position of the end-effector are improved. The problem is formulated in a Bayesian estimation framework and two solutions are proposed; the extended Kalman filter and the particle filter. In a simulation study on a realistic flexible industrial robot, the angular position performance is shown to be close to the fundamental Cramér-Rao lower bound. The technique is also verified in experiments on an ABB robot, where the dynamic performance of the position for the end-effector is significantly improved.
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| 7. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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Extended Kalman Filter Applied to Industrial Manipulators
- 2010
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Ingår i: Proceedings of Reglermöte 2010.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper summarizes previous work on tool position estimation on industrial manipulators, and emphasize the problems that must be taken care of in order to get a satisfied result. The acceleration of the robot tool, measured by an accelerometer, together with measurements of motor angles are used. The states are estimated with an extended Kalman filter. A method for tuning the covariance matrices for the noise, used in the observer, is suggested. The work has been focused on a robot with two degrees of freedom.
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| 8. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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Method to Estimate the Position and Orientation of a Triaxial Accelerometer Mounted to an Industrial Manipulator
- 2012
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Ingår i: Proceedings of the 10th IFAC Symposium on Robot Control. - 9783902823113 ; , s. 283-288
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Konferensbidrag (refereegranskat)abstract
- A novel method to find the orientation and position of a triaxial accelerometer mounted on a six degrees-of-freedom industrial robot is proposed and evaluated on experimental data. The method consists of two consecutive steps, where the first is to estimate the orientation of the accelerometer from static experiments. In the second step the accelerometer position relative to the robot base is identified using accelerometer readings when the accelerometer moves in a circular path and where the accelerometer orientation is kept constant in a path fixed coordinate system. Once the accelerometer position and orientation are identified it is possible to use the accelerometer in robot model parameter identification and in advanced control solutions. Compared to previous methods, the accelerometer position estimation is completely new, whereas the orientation is found using an analytical solution to the optimisation problem. Previous methods use a parameterisation where the optimisation uses an iterative solver.
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| 9. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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Tool Position Estimation of a Flexible Industrial Robot using Recursive Bayesian Methods
- 2012
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Ingår i: Proceedings of the 2012 IEEE International Conference on Robotics and Automation. - 9781467314039 - 9781467314046 ; , s. 5234-5239
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Konferensbidrag (refereegranskat)abstract
- A sensor fusion method for state estimation of a flexible industrial robot is presented. By measuring the acceleration at the end-effector, the accuracy of the arm angular position is improved significantly when these measurements are fused with motor angle observation. The problem is formulated in a Bayesian estimation framework and two solutions are proposed; one using the extended Kalman filter (EKF) and one using the particle filter (PF). The technique is verified on experiments on the ABB IRB4600 robot, where the accelerometer method is showing a significant better dynamic performance, even when model errors are present.
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| 10. |
- Björkman, Mattias, et al.
(författare)
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A New Concept for Motion Control of Industrial Robots
- 2008
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Ingår i: Proceedings of the 17th IFAC World Congress. - Linköping : Linköping University Electronic Press. - 9783902661005
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Konferensbidrag (refereegranskat)abstract
- This paper gives a short summary of an industrial development work on model-based motion control. This development has resultet in high robot motion performance simultaneously with an efficient use of the installed drive system of the robot.
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