scholarly journals Modelling for Contact Stress Control in Automated Polishing

2021 ◽  
Author(s):  
Avery Roswell
Keyword(s):  
Dynamic Model ◽  
Contact Stress ◽  
Tool Path ◽  
Coupling Effect ◽  
Open Loop ◽  
Friction Torque ◽  
Spindle Speed ◽  
Work Piece ◽  
Loop Control ◽  
System A

This research pertains to the initial steps in designing an end-effector for automated polishing, and focuses on: (1) controlling the contact stress on the work-piece surface, and (2) controlling the torque or the spindle speed to overcome the friction torque (hence, preventing the tool from stalling) and maintain a desired polishing rate. By forming a contact stress model, parameter planning is achieved and then augmented to already existing tool path data. A dynamic model for the particular end-of-arm tooling used is derived. The dynamic model clearly shows a coupling effect between the pressure and spindle speed of the system. A closed-loop control scheme, designed to eliminate the coupling is then introduced. The effectiveness of parameter planning is assessed through open loop testing. The parameter planning method allows polishing without significantly changing the part profile, whereas, without the parameter planning, the part profile is changed considerably.

scholarly journals Modelling for Contact Stress Control in Automated Polishing

2021 ◽  
Author(s):  
Avery Roswell
Keyword(s):  
Dynamic Model ◽  
Contact Stress ◽  
Tool Path ◽  
Coupling Effect ◽  
Open Loop ◽  
Friction Torque ◽  
Spindle Speed ◽  
Work Piece ◽  
Loop Control ◽  
System A

This research pertains to the initial steps in designing an end-effector for automated polishing, and focuses on: (1) controlling the contact stress on the work-piece surface, and (2) controlling the torque or the spindle speed to overcome the friction torque (hence, preventing the tool from stalling) and maintain a desired polishing rate. By forming a contact stress model, parameter planning is achieved and then augmented to already existing tool path data. A dynamic model for the particular end-of-arm tooling used is derived. The dynamic model clearly shows a coupling effect between the pressure and spindle speed of the system. A closed-loop control scheme, designed to eliminate the coupling is then introduced. The effectiveness of parameter planning is assessed through open loop testing. The parameter planning method allows polishing without significantly changing the part profile, whereas, without the parameter planning, the part profile is changed considerably.

Design and control of 2-DoF joystick using MR-fluid rotary actuator

2021 ◽  
pp. 1045389X2110639
Author(s):  
Bao Tri Diep ◽  
Quoc Hung Nguyen ◽  
Thanh Danh Le
Keyword(s):  
Pid Controller ◽  
Force Feedback ◽  
Control Method ◽  
Open Loop ◽  
Friction Torque ◽  
Feedback Controls ◽  
Loop Control ◽  
Fuzzy Logic Algorithm ◽  
Experimental Apparatus ◽  
Close Loop Control

The purpose of this paper is to design a control algorithm for a 2-DoF rotary joystick model. Firstly, the structure of the joystick, which composes of two magneto-rheological fluid actuators (shorten MRFA) with optimal configuration coupled perpendicularly by the gimbal mechanism to generate the friction torque for each independent rotary movement, is introduced. The control strategy of the designed joystick is then suggested. Really, because of two independent rotary movements, it is necessary to design two corresponding controllers. Due to hysteresis and nonlinear dynamic characteristics of the MRFA, controllers based an accurate dynamic model are difficult to realize. Hence, to release this issue, the proposed controller (named self-turning fuzzy controllers-STFC) will be built through the fuzzy logic algorithm in which the parameters of controllers are learned and trained online by Levenberg-Marquardt training algorithm. Finally, an experimental apparatus will be constructed to assess the effectiveness of the force feedback controls. Herein, three experimental cases are performed to compare the control performance of open-loop and close-loop control method, where the former is done through relationship between the force at the knob and the current supplied to coil while the latter is realized based on the proposed controller and PID controller. The experimental results provide strongly the ability of the proposed controller, meaning that the STFC is robust and tracks well the desirable force with high accuracy compared with both the PID controller and the open-loop control method.

H ∞ Closed-Loop Control for Uncertain Discrete Input-Shaped Systems

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
John Stergiopoulos ◽  
Anthony Tzes
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Controller Synthesis ◽  
Linear Quadratic ◽  
Robust Controller ◽  
Loop Control ◽  
System A ◽  
Input Shaper ◽  
Uncertain Input ◽  
Plant Simulation

The article addresses the problem of stabilization for uncertain discrete input-shaped systems. The uncertainty affects the autoregressive portion of the transfer function of the system. A discrete input shaper compensator is designed in order to reduce the oscillations of the plant’s response. The input-shaped system’s dynamics are appropriately reformulated for robust controller synthesis, and a robust H∞-controller is used in an outer-loop, in order to guarantee stability of the uncertain input-shaped plant. Simulation results confirm the efficacy of the proposed combined scheme in comparison with open-loop input shaping and closed-loop linear quadratic control.

scholarly journals Pick-and-Place Task Implementation Using Visual Open-Loop Control

2019 ◽  
Vol 13 (3) ◽  
pp. 211-216
Author(s):  
Paweł Kołosowski ◽  
Adam Wolniakowski ◽  
Mariusz Bogdan
Keyword(s):  
Visual Processing ◽  
Template Matching ◽  
Visual Recognition ◽  
Open Loop ◽  
Work Piece ◽  
Loop Control ◽  
Pick And Place ◽  
Place Task ◽  
Sorting System ◽  
And Control

Abstract In the ever increasing number of robotic system applications in the industry, the robust and fast visual recognition and pose estimation of workpieces are of utmost importance. One of the ubiquitous tasks in industrial settings is the pick-and-place task where the object recognition is often important. In this paper, we present a new implementation of a work-piece sorting system using a template matching method for recognizing and estimating the position of planar workpieces with sparse visual features. The proposed framework is able to distinguish between the types of objects presented by the user and control a serial manipulator equipped with parallel finger gripper to grasp and sort them automatically. The system is furthermore enhanced with a feature that optimizes the visual processing time by automatically adjusting the template scales. We test the proposed system in a real-world setup equipped with a UR5 manipulator and provide experimental results documenting the performance of our approach.

FLEXIBLE DYNAMIC MODEL OF ATTITUDE MANEUVERING OF RAZAKSAT® SATELLITE

2015 ◽  
Vol 76 (12) ◽  
Author(s):  
Teoh Vil Cherd ◽  
Shahriman Abu Bakar ◽  
Sazali Yaacob ◽  
Nor Hazadura Hamzah
Keyword(s):  
Dynamic Model ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Solar Panels ◽  
Assumed Mode Method ◽  
System A ◽  
Mode Method ◽  
Multi Body ◽  
Euler Bernoulli Beam ◽  
Coupling Deformation

In this paper, a dynamic model equation of the RazakSAT® class satellite three flexible solar panels for three-dimensional dynamic studies is developed based on the coupling deformation field. In the model, each solar panel is flexible and attached to the satellite body via a fixed joint where the assumption of Euler-Bernoulli beam is applied for the solar panels. Lagrange and assumed mode method are used to develop the dynamic model of the RazakSAT® multi-body system. A comprehensive model of flexible satellite has been provided in ANSYS environment as a reference when simulating the theoretical response generated by MATLAB to show that the coupling effect on the characteristics of the flexible sub system while undergoing rigid-body rotational motion.

Gap control for a proportional floating vacuum pad

2008 ◽  
Vol 222 (11) ◽  
pp. 2069-2076
Author(s):  
J-C Renn ◽  
C-Y Chen ◽  
C-H Lu
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Control Mode ◽  
Work Piece ◽  
Force Output ◽  
Suction Force ◽  
Loop Control ◽  
Control Approach ◽  
Control Schemes ◽  
Gap Control

In this article, a new proportional pneumatic floating vacuum pad is developed and constructed. There are two features concerning this new vacuum pad. The first is the inclusion of a proportional solenoid, which enables the continuously variable control of the suction force output. The floating mechanism design between the vacuum pad and the work-piece is the second feature, which is more preferable in real industries because it can protect the surface of the work-piece from scratches or other damage. Moreover, in addition to the open-loop gap control mode, two closed-loop gap control schemes are proposed in this paper. The first is the constant gap control. A preset gap is input to the controller as the command input that further drives the proportional solenoid to maintain a steady-state gap between the vacuum pad and the work-piece. In the second control approach, the gap between the vacuum pad and the work-piece is kept as large as possible to minimize the energy consumption. Both closed-loop control schemes are successfully implemented in this study.

Open-loop control of compensation for optical propagation through a turbulent shear flow

1998 ◽  
Author(s):  
C. Truman ◽  
Lenore McMackin ◽  
Robert Pierson ◽  
Kenneth Bishop ◽  
Ellen Chen
Keyword(s):  
Shear Flow ◽  
Open Loop ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Open Loop Control ◽  
Loop Control ◽  
Optical Propagation

scholarly journals Sensuator: A Hybrid Sensor–Actuator Approach to Soft Robotic Proprioception Using Recurrent Neural Networks

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Pornthep Preechayasomboon ◽  
Eric Rombokas
Keyword(s):  
Neural Networks ◽  
Recurrent Neural Networks ◽  
Linear Models ◽  
Open Loop ◽  
Proof Of Concept ◽  
State Estimator ◽  
Loop Control ◽  
Practical Applications ◽  
Soft Actuator ◽  
The Cost

Soft robotic actuators are now being used in practical applications; however, they are often limited to open-loop control that relies on the inherent compliance of the actuator. Achieving human-like manipulation and grasping with soft robotic actuators requires at least some form of sensing, which often comes at the cost of complex fabrication and purposefully built sensor structures. In this paper, we utilize the actuating fluid itself as a sensing medium to achieve high-fidelity proprioception in a soft actuator. As our sensors are somewhat unstructured, their readings are difficult to interpret using linear models. We therefore present a proof of concept of a method for deriving the pose of the soft actuator using recurrent neural networks. We present the experimental setup and our learned state estimator to show that our method is viable for achieving proprioception and is also robust to common sensor failures.

scholarly journals The Study of Dynamic Modeling and Multivariable Feedback Control for Flexible Manipulators with Friction Effect and Terminal Load

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1522
Author(s):  
Fuli Zhang ◽  
Zhaohui Yuan
Keyword(s):  
Dynamic Model ◽  
Vibration Suppression ◽  
Control Method ◽  
Coupling Effect ◽  
Flexible Manipulator ◽  
Flexible Beam ◽  
Robot Dynamics ◽  
Joint Friction ◽  
Balance Principle ◽  
Multivariable Feedback

The flexible manipulato is widely used in the aerospace industry and various other special fields. Control accuracy is affected by the flexibility, joint friction, and terminal load. Therefore, this paper establishes a robot dynamics model under the coupling effect of flexibility, friction, and terminal load, and analyzes and studies its control. First of all, taking the structure of the central rigid body, the flexible beam, and load as the research object, the dynamic model of a flexible manipulator with terminal load is established by using the hypothesis mode and the Lagrange method. Based on the balance principle of the force and moment, the friction under the influence of flexibility and load is recalculated, and the dynamic model of the manipulator is further improved. Secondly, the coupled dynamic system is decomposed and the controller is designed by the multivariable feedback controller. Finally, using MATLAB as the simulation platform, the feasibility of dynamic simulation is verified through simulation comparison. The results show that the vibration amplitude can be reduced with the increase of friction coefficient. As the load increases, the vibration can increase further. The trajectory tracking and vibration suppression of the manipulator are effective under the control method of multi-feedback moment calculation. The research is of great significance to the control of flexible robots under the influence of multiple factors.

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