| 1. |
- Axelsson, Patrik, 1985-, et al.
(författare)
-
H∞-Controller Design Methods Applied to One Joint of a Flexible Industrial Manipulator
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Control of a flexible joint of an industrial manipulator using H∞ design methods is presented. The considered design methods are i) mixed-H∞ design, and ii) H∞ loop shaping design. Two different controller configurations are examined: one uses only the actuator position, while the other uses the actuator position and the acceleration of end-effector. The four resulting controllers are compared to a standard PID controller where only the actuator position is measured. The choices of the weighting functions are discussed in details. For the loop shaping design method, the acceleration measurement is required to improve the performance compared to the PID controller. For the mixed-H∞ method it is enough to have only the actuator position to get an improved performance. Model order reduction of the controllers is briefly discussed, which is important for implementation of the controllers in the robot control system.
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| 2. |
- Axelsson, Patrik, 1985-, et al.
(författare)
-
H∞-Controller Design Methods Applied to One Joint of a Flexible Industrial Manipulator
- 2014
-
Ingår i: Proceedings of the 19th IFAC World Congress, 2014. - : International Federation of Automatic Control. - 9783902823625 ; , s. 210-216
-
Konferensbidrag (refereegranskat)abstract
- Control of a flexible joint of an industrial manipulator using H∞ design methods is presented. The considered design methods are i) mixed-H∞ design, and ii) H∞ loop shaping design. Two different controller configurations are examined: one uses only the actuator position, while the other uses the actuator position and the acceleration of end-effector. The four resulting controllers are compared to a standard PID controller where only the actuator position is measured. The choices of the weighting functions are discussed in details. For the loop shaping design method, the acceleration measurement is required to improve the performance compared to the PID controller. For the mixed-H∞ method it is enough to have only the actuator position to get an improved performance. Model order reduction of the controllers is briefly discussed, which is important for implementation of the controllers in the robot control system.
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| 3. |
- Axelsson, Patrik, 1985-, et al.
(författare)
-
H∞ Synthesis Method for Control of Non-linear Flexible Joint Models
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An H∞ synthesis method for control of a flexible joint, with non-linear spring characteristic, is proposed. The first step of the synthesis method is to extend the joint model with an uncertainty description of the stiffness parameter. In the second step, a non-linear optimisation problem, based on nominal performance and robust stability requirements, has to be solved. Using the Lyapunov shaping paradigm and a change of variables, the non-linear optimisation problem can be rewritten as a convex, yet conservative, LMI problem. The method is motivated by the assumption that the joint operates in a specific stiffness region of the non-linear spring most of the time, hence the performance requirements are only valid in that region. However, the controller must stabilise the system in all stiffness regions. The method is validated in simulations on a non-linear flexible joint model originating from an industrial robot.
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| 4. |
- Axelsson, Patrik, 1985-, et al.
(författare)
-
H∞ Synthesis Method for Control of Non-linear Flexible Joint Models
- 2014
-
Ingår i: Proceedings of the 19th IFAC World Congress, 2014. - : International Federation of Automatic Control. - 9783902823625 ; , s. 8372-8377
-
Konferensbidrag (refereegranskat)abstract
- An H∞ synthesis method for control of a flexible joint, with non-linear spring characteristic, is proposed. The first step of the synthesis method is to extend the joint model with an uncertainty description of the stiffness parameter. In the second step, a non-linear optimisation problem, based on nominal performance and robust stability requirements, has to be solved. Using the Lyapunov shaping paradigm and a change of variables, the non-linear optimisation problem can be rewritten as a convex, yet conservative, LMI problem. The method is motivated by the assumption that the joint operates in a specific stiffness region of the non-linear spring most of the time, hence the performance requirements are only valid in that region. However, the controller must stabilise the system in all stiffness regions. The method is validated in simulations on a non-linear flexible joint model originating from an industrial robot.
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| 5. |
- Axelsson, Patrik, 1985-, et al.
(författare)
-
Single Joint Control of a Flexible Industrial Manipulator using H∞ Loop Shaping
- 2012
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Control of a flexible joint of an industrial manipulator using H∞ loop shaping design is presented. Two controllers are proposed; 1) H∞ loop shaping using the actuator position, and 2) H∞ loop shaping using the actuator position and the acceleration of end-effector. The two controllers are compared to a standard PID controller where only the actuator position is measured. Using the acceleration of the end-effector improves the nominal performance. The performance of the proposed controllers is not significantly decreased in the case of model error consisting of an increased time delay or a gain error.
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