Position Control of Flexible Robot Arms Using Mechanical Waves

1998 ◽  
Vol 120 (3) ◽  
pp. 334-339 ◽  
Author(s):  
William O’Connor ◽  
Donogh Lang
Keyword(s):  
Position Control ◽  
Flexible Robot ◽  
Reflected Waves ◽  
Robot Arms ◽  
Lumped Parameter ◽  
Mechanical Waves ◽  
Time Optimal ◽  
Active Vibration Damping ◽  
Active Vibration ◽  
Spring System

A novel position control strategy for flexible robot arms based on wave propagation and absorption techniques is presented. The arm is modeled by a lumped-parameter mass-spring system with an actuator at one end and a load mass at the other. The actuator is required to position the remote load and, simultaneously, to provide active vibration damping. It does so by propagating mechanical waves through the system and absorbing reflected waves. Only the first two masses and springs need to be characterized and observed to determine the required actuator movement. The control algorithm is robust and compares very favorably with the time-optimal performance of bang-bang control. It is also inherently adaptive.

scholarly journals Wave-based planar motion and vibration control of under-actuated mass-spring arrays

2018 ◽  
Vol 37 (2) ◽  
pp. 269-278
Author(s):  
Hossein Habibi ◽  
William O’Connor
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Control Technique ◽  
Effective Control ◽  
Entire System ◽  
Flexible System ◽  
Planar Array ◽  
Active Vibration Damping ◽  
Active Vibration ◽  
Angular Displacements

This paper considers the problem of position control and active vibration damping of a planar, array (or grid) of masses and springs, by a single actuator, attached to one corner of the array, which is required to translate and rotate the entire system from rest to rest, through target linear and angular displacements, simultaneously. An obvious challenge is that the system has many degrees of freedom, with many undamped vibration modes, and is clearly highly under-actuated. The control technique is a development of “wave-based control,” whereby rapid and effective control of the entire system is achieved, robustly, using measurements made only at the actuator, of the actuator’s own motion and of the forces between the actuator and the attached flexible system. No detailed system model or system identification is needed. The actuator need not be ideal. The array does not have to be uniform, in its geometry or in the mass and spring values. The control strategy is simple to implement. The 2D array is of interest in itself as a benchmark control challenge, but it can also be considered a model of various lumped structures, or a discretisation of distributed systems.

On tracking control of flexible robot arms

2000 ◽  
Vol 45 (3) ◽  
pp. 520-527 ◽  
Author(s):  
M.A. Arteaga ◽  
B. Siciliano
Keyword(s):  
Tracking Control ◽  
Flexible Robot ◽  
Robot Arms

Modale Regelung von Werkzeugmaschinen*/Modal control for machine tools

2019 ◽  
Vol 109 (05) ◽  
pp. 358-364
Author(s):  
C. Peukert ◽  
P. Pöhlmann ◽  
S. Ihlenfeldt ◽  
J. Müller ◽  
M. Merx
Keyword(s):  
Machine Tools ◽  
Vibration Damping ◽  
Modal Control ◽  
Modal Approach ◽  
Active Vibration Damping ◽  
Active Vibration

Vorschubachsen von Werkzeugmaschinen werden oft mit mehreren, parallel wirkenden Antrieben ausgestattet. Auch zusätzliche Aktoren für die aktive Schwingungsdämpfung kommen zunehmend zum Einsatz. Im Beitrag wird die modale Regelung für Werkzeugmaschinen vorgestellt. Sie ermöglicht es, die Eigenformen individuell zu regeln und die angeregten Schwingungen mit allen verfügbaren Aktoren gezielt zu bedämpfen. Es werden Ergebnisse zur modalen Regelung am Beispiel einer Gantry-Anordnung vorgestellt.   Feed axes of machine tools are often equipped with several parallel acting drives. Additional actuators for active vibration damping are also increasingly used. This article introduces the modal control for machine tools. The modal approach enables the eigenmodes to be controlled independently and the excited vibrations to be damped specifically with all available actuators. The results for the modal control of a gantry arrangement are presented as an example.

Time-Optimal Coordination Control for the Gear-Shifting Process in Electric-Driven Mechanical Transmission (Dog Clutch) without Impacts

2020 ◽  
Vol 9 (2) ◽  
pp. 155-168
Author(s):  
Ziwang Lu ◽  
◽  
Guangyu Tian ◽  
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Control Method ◽  
Synchronization Control ◽  
Mechanical Transmission ◽  
Coordination Control ◽  
Optimal Position ◽  
Drive Motor ◽  
Time Optimal ◽  
Optimal Coordination

Torque interruption and shift jerk are the two main issues that occur during the gear-shifting process of electric-driven mechanical transmission. Herein, a time-optimal coordination control strategy between the the drive motor and the shift motor is proposed to eliminate the impacts between the sleeve and the gear ring. To determine the optimal control law, first, a gear-shifting dynamic model is constructed to capture the drive motor and shift motor dynamics. Next, the time-optimal dual synchronization control for the drive motor and the time-optimal position control for the shift motor are designed. Moreover, a switched control for the shift motor between a bang-off-bang control and a receding horizon control (RHC) law is derived to match the time-optimal dual synchronization control strategy of the drive motor. Finally, two case studies are conducted to validate the bang-off-bang control and RHC. In addition, the method to obtain the appropriate parameters of the drive motor and shift motor is analyzed according to the coordination control method.

Design, Kinematics and Prototype of a Flexible Robot Arm With Planar Springs

2015 ◽  
Author(s):  
Peng Qi ◽  
Hongbin Liu ◽  
Lakmal Seneviratne ◽  
Kaspar Althoefer
Keyword(s):  
Preliminary Test ◽  
Industrial Applications ◽  
Robot Arm ◽  
Kinematic Modeling ◽  
Flexible Robot ◽  
Element Analysis ◽  
Robot Arms ◽  
Environmental Interactions ◽  
In Series ◽  
Fea Simulation

Flexible robot arms have been developed for various medical and industrial applications because of their compliant structures enabling safe environmental interactions. This paper introduces a novel flexible robot arm comprising a number of elastically deformable planar spring elements arranged in series. The effects of flexure design variations on their layer compliance properties are investigated. Numerical studies of the different layer configurations are presented and finite Element Analysis (FEA) simulation is conducted. Based on the suspended platform’s motion of each planar spring, this paper then provides a new method for kinematic modeling of the proposed robot arm. The approach is based on the concept of simultaneous rotation and the use of Rodrigues’ rotation formula and is applicable to a wide class of continuum-style robot arms. At last, the flexible robot arms respectively integrated with two different types of compliance layers are prototyped. Preliminary test results are reported.

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