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Contribution to the Inverse Dynamics of Flexible Manipulators Guimaraes Bastos Junior, Guaraci Doctoral thesis (2013) This thesis studies innovative, stable but non-causal inverse dynamics algorithms for flexible manipulators. Robust direct optimal control methods are proposed. The nonlinear finite element method is used ... [more ▼] This thesis studies innovative, stable but non-causal inverse dynamics algorithms for flexible manipulators. Robust direct optimal control methods are proposed. The nonlinear finite element method is used to derive the mechanical model of the multibody system and the time discretization is performed using the generalized-alpha method. The sparse gradients of the optimization constraints are computed using a semi-analytical method. The inverse dynamics of both serial and parallel kinematic manipulators with flexible links and joints is successfully studied using the proposed method. Finally, the possible extension of the method for the integrated control/structure optimization of mechatronic systems is investigated. [less ▲] Detailed reference viewed: 129 (30 ULg)Inverse dynamics of serial and parallel underactuated multibody systems using a DAE optimal control approach Guimaraes Bastos Junior, Guaraci ; ; Bruls, Olivier in Multibody System Dynamics (2013) The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum ... [more ▼] The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems with serial and parallel planar topology, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints (servoconstraints) to the equations of motion and applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (preactuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method roposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. This paper proposes an alternative solution strategy which is based on an optimal control approach using a direct transcription method. The method is illustrated for the inverse dynamics of an underactuated serial manipulator with rigid links and four degrees-of-freedom and an underactuated parallel machine. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software. [less ▲] Detailed reference viewed: 86 (18 ULg)Inverse dynamics of parallel kinematic manipulators with flexible links Guimaraes Bastos Junior, Guaraci ; ; Bruls, Olivier Conference (2012, May) Detailed reference viewed: 36 (11 ULg)Two optimal control methods for the inverse dynamics of underactuated multibody systems Guimaraes Bastos Junior, Guaraci ; ; Bruls, Olivier Conference (2011, November) The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This work studies the inverse dynamics of non-minimum ... [more ▼] The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This work studies the inverse dynamics of non-minimum phase underactuated multibody systems, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints to the equations of motion and by applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (pre-actuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method proposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. In this work, an alternative solution strategy is proposed which is based on an optimal control approach. More precisely, the direct collocation method and the multiple shooting are considered to solve the resulting optimization problem. The method is illustrated for the inverse dynamics of rigid and flexible underactuated mechanisms. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software. [less ▲] Detailed reference viewed: 64 (14 ULg)INVERSE DYNAMICS OF UNDERACTUATED MULTIBODY SYSTEMS USING A DAE OPTIMAL CONTROL APPROACH Guimaraes Bastos Junior, Guaraci ; ; Bruls, Olivier in Proceedings of the ECCOMAS Thematic Conference (MULTIBODY DYNAMICS) 2011 (2011, July) The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum ... [more ▼] The inverse dynamics analysis of underactuated multibody systems aims at determining the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints to the equations of motion and by applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control forces and torques should start before the beginning of the trajectory (pre-actuation phase) and continue after the end-point is reached (post-actuation phase). The existing stable inversion method proposed for general nonlinear non-minimum phase systems requires to derive explicitly the equations of the internal dynamics and to solve a boundary value problem. This paper proposes an alternative solution strategy which is based on an optimal control approach. The method is illustrated for the inverse dynamics of a planar underactuated manipulator with rigid links and four degrees-of-freedom. An important advantage of the proposed approach is that it can be applied directly to the standard equations of motion of multibody systems either in ODE or in DAE form. Therefore, it is easier to implement this method in a general purpose simulation software. [less ▲] Detailed reference viewed: 137 (25 ULg)Computation of bounded feed-forward control for underactuated multibody systems using nonlinear optimization ; Guimaraes Bastos Junior, Guaraci ; Bruls, Olivier in Proceedings in Applied Mathematics and Mechanics, Volume 1, Special Issue: 82nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) (2011) Detailed reference viewed: 15 (4 ULg)Trajectory Optimization of Flexible Robots Using an Optimal Control Approach Guimaraes Bastos Junior, Guaraci ; Bruls, Olivier in Proceedings of the First Joint International Conference on Multibody System Dynamics (2010, May) In the context of the mechatronic design of lightweight machines and robots, this paper studies optimal control problems in flexible multibody dynamics. Based on a direct transcription of the initial ... [more ▼] In the context of the mechatronic design of lightweight machines and robots, this paper studies optimal control problems in flexible multibody dynamics. Based on a direct transcription of the initial problem, a direct collocation method is used. This method leads to a large but sparse nonlinear programming problem for which standard solvers are available. The implemention of this method based on a finite element simulation tool for flexible multibody systems is described. The connections between the generalized-alpha time integration scheme, which is commonly used for this kind of applications, and the formulation of the optimization problem are highlighted. The methodology is illustrated for two academic examples of rigid and flexible robotic systems. [less ▲] Detailed reference viewed: 150 (26 ULg) |
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