| 1. |
- Björkman, Mattias, et al.
(författare)
-
A New Concept for Motion Control of Industrial Robots
- 2008
-
Ingår i: Proceedings of the 17th IFAC World Congress. - Linköping : Linköping University Electronic Press. - 9783902661005
-
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.
|
|
| 2. |
- Moberg, Stig, 1962-, et al.
(författare)
-
A Benchmark Problem for Robust Control of a Multivariable Nonlinear Flexible Manipulator
- 2008
-
Ingår i: Proceedings of the 17th IFAC World Congress. - Linköping : Linköping University Electronic Press. - 9783902661005 ; , s. 1206-1211
-
Konferensbidrag (refereegranskat)abstract
- A benchmark problem for robust feedback control of a manipulator is presented. The system to be controlled is an uncertain nonlinear two link manipulator with elastic gear transmissions. The gear transmission is described by nonlinear friction and elasticity. The system is uncertain according to a parametric uncertainty description and due to uncertain disturbances affecting both the motors and the tool. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only disturbance rejection. The proposed model is validated by experiments on a real industrial manipulator.
|
|
| 3. |
|
|
| 4. |
- Moberg, Stig, et al.
(författare)
-
A New Approach to Modelling and Control of Flexible Manipulators
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This work investigates feedforward control of elastic robot structures. A general serial link elastic robot model which can describe a modern industrial robot in a realistic way is presented. The feedforward control problem is discussed and a solution method for the inverse dynamics problem is proposed. This method involves solving a differential algebraic equation (DAE). A simulation example for an elastic two axis planar robot is also included and shows promising results.
|
|
| 5. |
- Moberg, Stig, 1962-, et al.
(författare)
-
On Feedback Linearization for Robust Tracking Control of Flexible Joint Robots
- 2008
-
Ingår i: Proceedings of the 17th IFAC World Congress. - Linköping : Linköping University Electronic Press. - 9783902661005 ; , s. 12218-12223
-
Konferensbidrag (refereegranskat)abstract
- Feedback linearization is one of the major academic approaches for controlling flexible joint robots. This contribution investigates the discrete-time implementation of the feedback linearization approach for a realistic three-axis robot model. A simulation study of high speed tracking with model uncertainty is performed. It is assumed that full state measurements of the linearizing states are available. The feedback linearization approach is compared to a feedforward approach.
|
|
| 6. |
- Moberg, Stig, et al.
(författare)
-
Robust Control Of A Flexible Manipulator Arm : A Benchmark Problem
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A control engineering benchmark problem with industrial relevance is presented. The process is a simulation model of a nonlinear four-mass system, which should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only the so-called regulator problem.
|
|
| 7. |
- Norrlöf, Mikael, et al.
(författare)
-
Experimental Comparison of Observers for Tool Position Estimation of Industrial Robots
- 2009
-
Ingår i: Proceedings of the 48th IEEE Conference on Decision and Control. - Linköping : Linköping University Electronic Press. - 9781424438723 - 9781424438716 ; , s. 8065-8070
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates methods for tool position estimation of industrial robots. It is assumed that the motor angular position and the tool acceleration are measured. The considered observers are different versions of the extended Kalman filter as well as a deterministic observer. A method for tuning the observers is suggested and the robustness of the methods is investigated. The observers are evaluated experimentally on a commercial industrial robot.
|
|
| 8. |
- Wallén, Johanna, et al.
(författare)
-
ILC Applied to a Flexible Two-Link Robot Model using Sensor-Fusion-Based Estimates
- 2009
-
Ingår i: Proceedings of 48th IEEE Conference on Decision and Control. - Linköping : IEEE. - 9781424438723 - 9781424438716 ; , s. 458-463
-
Konferensbidrag (refereegranskat)abstract
- Estimates from an extended Kalman filter (EKF) is used in an Iterative Learning Control (ILC) algorithm applied to a realistic two-link robot model with flexible joints. The angles seen from the arm side of the joints (arm angles) are estimated by an EKF in two ways: 1) using measurements of angles seen from the motor side of the joints (motor angles), which normally are the only measurements available in commercial industrial robot systems, 2) using both motor- angle and tool-acceleration measurements. The estimates are then used in an ILC algorithm. The results show that the actual arm angles are clearly improved compared to when only motor angles are used in the ILC update, even though model errors are introduced.
|
|
| 9. |
- Wernholt, Erik, et al.
(författare)
-
Experimental Comparison of Methods for Multivariable Frequency Response Function Estimation
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nonparametric estimation methods for the multivariable frequency response function are experimentally evaluated using closed-loop data from an industrial robot. Three classical estimators (H1, joint input-output, arithmetic mean) and two estimators based on nonlinear averaging techniques (harmonic mean, geometric/logarithmic mean) are considered. The estimators based on nonlinear averaging give the best results, followed by the arithmetic mean estimator, which gives a slightly larger bias. The joint input-output estimator, which is asymptotically unbiased in theory, turns out to give large bias errors for low frequencies. Finally, the H1 estimator gives the largest bias for all frequencies.
|
|
| 10. |
- Wernholt, Erik, et al.
(författare)
-
Frequency-Domain Gray-Box Identification of Industrial Robots
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper considers identification of unknown parameters in elastic dynamic models of industrial robots. Identifying such models is a challenging task since an industrial robot is a multivariable, nonlinear, resonant, and unstable system. Unknown parameters (mainly spring-damper pairs) in a physically parameterized nonlinear dynamic model are identified in the frequency domain, using estimates of the nonparametric frequency response function (FRF) in different robot configurations/positions. The nonlinear parametric robot model is linearized in the same positions and the optimal parameters are obtained by minimizing the discrepancy between the nonparametric FRFs and the parametric FRFs (the FRFs of the linearized parametric robot model). In order to accurately estimate the nonparametric FRFs, the experiments must be carefully designed. The selection of optimal robot configurations for the experiments is also part of the design. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest.
|
|
