Organizational Unit:

Institute for Robotics and Intelligent Machines (IRIM)

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https://hdl.handle.net/1853/70657

Includes Organization(s)

Organizational Unit

Biorobotics and Human Modeling Lab

Organizational Unit

Humanoid Robotics Laboratory

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Now showing 1 - 10 of 10

Symbolic Modeling and Dynamic Simulation of Robotic Manipulators with Compliant Links and Joints

(Georgia Institute of Technology, 1989) Cetinkunt, Sabri ; Book, Wayne J.

The explicit, non-recursive symbolic form of the dynamic model of robotic manipulators with compliant links and joints are developed based on a Lagrangian-assumed mode of formulation. This form of dynamic model is suitable for controller synthesis, as well as accurate simulations of robotic applications. The final form of the equations is organized in a form similar to rigid manipulator equations. This allows one to identify the differences between rigid and flexible manipulator dynamics explicitly. Therefore, current knowledge on control of rigid manipulators is likely to be utilized in a maximum way in developing new control algorithms for flexible manipulators. Computer automated symbolic expansion of the dynamic model equations for any desired manipulator is accomplished with programs written based on commercial symbolic manipulation programs (SMP, MACSYMA, REDUCE). A two-link manipulator is used as an example. Computational complexity involved in real-time control, using the explicit, non-recursive form of equations, is studied on single CPU and multi-CPU parallel computation processors.
Performance of Lightweight Manipulators Under Joint Variable Feedback Control: Analytical Study of Limitations

(Georgia Institute of Technology, 1988-06) Cetinkunt, Sabri ; Book, Wayne J.

The performance limitations of joint variable feedback controlled manipulators due to manipulator flexibility are studied in fine and gross motions. A finite dimensional time-domain manipulator model is used in the study. Fine motion analysis results agree very well with the previously reported results based on infinite dimensional frequency domain models. The limitations of a class of adaptive controllers in high speed gross motion control are studied. Manipulation speeds are quantified as low, medium, or high with reference to the arm flexibility and dynamic nonlinearities.
Symbolic Modeling and Dynamic Simulation of Robotic Manipulators with Compliant Links and Joints

(Georgia Institute of Technology, 1988-05) Cetinkunt, Sabri ; Book, Wayne J.

The explicit, non-recursive symbolic form of the dynamic model of robotic manipulators with compliant links and joints are developed based on Lagrangian-assumed modes formulation. This form of dynamic model is suitable for controller synthesis, as well as accurate simulations of robotic applications. The final form of the equations are organized in a form similar to rigid manipulator equations. This allows one to identify the differences between rigid and flexible manipulator dynamics explicitly. Therefore, current knowledge on control of rigid manipulators is likely to be utilized in a maximum way in developing new control algorithms for flexible manipulators. Computer automated symbolic expansion of the dynamic model equations for any desired manipulator is accomplished with programs written based on commercial symbolic manipulation programs (SMP, MACSYMA, REDUCE). A two-link manipulator is used as an example. Computational complexity involved in real-time control, using the explicit, non-recusive form of equations, is studied on a single CPU and multi- CPU parallel computation processors.
Symbolic Modeling of Flexible Manipulators

(Georgia Institute of Technology, 1987-04) Cetinkunt, Sabri ; Book, Wayne J.

This paper presents a new systematic algorithm to symbolically derive the full nonlinear dynamic equations of motion of multi-link flexible manipulators. Lagrange's-Assumed modes method is the basis of the new algorithm and adapted in a way suitable for symbolic manipulation by digital computers. It is applied to model a two-link flexible arm via a commercially available symbolic manipulation program. The advantages of the algorithm and simulation results are discussed.
Symbolic Modeling of Flexible Robotic Manipulators

(Georgia Institute of Technology, 1987-04) Book, Wayne J. ; Cetinkunt, Sabri

This paper presents a new systematic algorithm to symbolically derive the full nonlinear dynamic equations of motion of multi-link flexible manipulators. Lagrange's-assumed modes method is the basis of the new algorithm and adapted in a way suitable for symbolic manipulation by digital computers. The advantages of obtaining dynamic equations in symbolic form and of the presented algorithm are discussed. Application of the algorithm to a two-link flexible arm example via a commercially available symbolic manipulation program is presented. Simulation results are given and discussed.
Symbolic modelling and dynamic analysis of flexible manipulators

(Georgia Institute of Technology, 1986-10) Cetinkunt, Sabri ; Siciliano, Bruno ; Book, Wayne J.

This paper presents a systematic method to symbolically derive the full nonlinear dynamic equations of motion of Multi-link flexible manipulators. Lagrange's-Assumed Modes method is used for the dynamic modelling and implemented via a commercially available symbolic manipulation program. Adaptation of the method suitable for symbolic manipulation and advantages are discussed. Simulation results for a two-link planar flexible arm presented.
Symbolic Modelling and Dynamic Analysis of Flexible Manipulators

(Georgia Institute of Technology, 1986) Cetinkunt, Sabri ; Siciliano, Bruno ; Book, Wayne J.

This paper presents a systematic method to symbolically derive the full nonlinear dynamic equations of motion of Multi-link flexible manipulators. Lagrange's-Assumed Modes method is used for the dynamic modelling and implemented via a commercially available symbolic manipulation program. Adaptation of the method suitable for symbolic manipulation and advantages are discussed. Simulation results for a two-link planar flexible arm presented.
Near Optimum Control of Flexible Robot Arms on Fixed Paths

(Georgia Institute of Technology, 1985-12) Book, Wayne J. ; Cetinkunt, Sabri

This paper presents the analysis and modification of near optimum trajectories for robotic manipulators moving along pre-defined paths. Modifications of trajectories are done such that the vibrations due to flexibility of arms and other components of the manipulator are minimized. Ultimately, the productivity of robotic manipulators depends on the speed of the task execution. Higher productivity requires higher speed of operation and in turn better control and trajectory generation algorithms. Today trajectory generation algorithms do not consider the dynamic characteristics of the manipulators. In order to utilize the available capability in the optimum manner the trajectory generation algorithms need to consider the dynamics of the manipulator, actuator constraints, nature of the task, and flexibility of arms and compliance of the joint connections. In the search for an optimal trajectory that will meet all of the above requirements while optimizing some criterion, some simplifying assumptions have to be made and/or some of the requirements have to be kept out of the formulation so that the defined problem can be solved or some feasible solutions obtained. Once the simplified problem is solved, one may consider modifying the original solution in such a way that the excluded requirements are also satisfied to some extent. In this paper the minimum time control solution of a two link flexible arm with actuator constraints is presented. We solved the minimum time problem with no constraints on the flexible modes and show the time improvement due to the use of light-weight arms. The objective is to modify the trajectory, such that flexible vibrations are bounded while changing the solution from the previous one as little as possible. Practical ways of trajectory modifications for flexible arms are discussed.
Combined approaches to lightweight arm utilization

(Georgia Institute of Technology, 1985-11) Book, Wayne J. ; Dickerson, Stephen L. ; Hastings, Gordon Greene ; Cetinkunt, Sabri ; Alberts, Thomas Edward

In order to use lightweight arms the combination of a number of new approaches in arm design and control may be necessary. This paper describes four complimentary research efforts and how their results will work together. The bracing strategy is proposed first as one scenario of arm usage. It braces the arm against a passive structure to increase rigidity during fine motions of the end effector. Large motions of the arm require path and trajectory planning. Research on minimum time motions that avoid unnecessarily exciting vibrations is described next. The damping of those vibrations that are excited can be accomplished through a combination of active modal feedback control and passive damping. The enhancement of the damping characteristics of arm structures is described. This is important for stable feedback control with actuators and controllers with limited bandwidth. Analytical and experimental results for constrained layer damping are described. in the context of the control problem. An active modal control has been implimented on a simple one link beam. As higher bandwidth is sought from this physical system deviations from the predicted results were observed. A refinement of the model to include anti-aliasing filter, sample-data, and amplifier effects explains the behavior as explained.
Optimum control of flexible robot arms on fixed paths

(Georgia Institute of Technology, 1985-05) Cetinkunt, Sabri ; Book, Wayne J.

Productivity of the industrial robots are directly related to the speed of the task execution. The speed of the robots can be drastically improved by using better control algorithms and reducing the weight of the manipulator. The speed of a robotic manipulator is constrained by manipulator dynamics and actuator capabilities. Increasing the size of the actuators is not a solution since that will increase the weight of the the overall system leading ·to a relatively heavier system. The more realistic approach to the problem is to find the optimum control solution for a manipulator to follow a pre-defined path in minimum time, with limited actuator capabilities. In terms of the dynamic constraints, the weight of the arms may be the most important factor. If a light-weight arm structure is used, actuators will be able to afford higher speeds during the task execution than they would for rigid arm structure. On the other hand using flexible-arms has a major draw-back which is the flexible vibrations, while increasing the speed. This paper presents the minimum time control solution of a two link flexible arm with actuator constraints. We solved the minimum time problem with no constraints on the flexible modes and show· the time improvement due to the use of light-weight arms. The objective is to modify the trajectory, such that flexible vibrations are bounded while changing the solution from the previous one as little as possible. Practical ways of trajectory modifications for flexible arms are discussed.