An Approach to Motion and Force Control of Coordinated Robot Arms in the Presence of Joint Flexibility

1994 ◽  
Vol 116 (3) ◽  
pp. 326-335 ◽  
Author(s):  
Yan-Ru Hu ◽  
Andrew A. Goldenberg
Keyword(s):  
Contact Force ◽  
Force Control ◽  
Lyapunov Stability Theory ◽  
Internal Force ◽  
System Stability ◽  
Motion Controller ◽  
Flexible Joint ◽  
Robot Arms ◽  
Simulation Results ◽  
And Control

A system consisting of several flexible joint robot arms is studied in this paper. The paper addresses the motion and force control problem of such systems. A coordinating controller, consisting of a motion controller, contact force controller, and internal force controller, is designed to distribute the load between the coordinated flexible joint robot arms, and control the motion of the object, the internal force and contact force between the object and the environment, as well generate the desired joint elastic force. The system stability is analyzed based on Lyapunov stability theory. It is shown that with the proposed controller the motion and force control variables can be regulated to track asymptotically their desired trajectories. Simulation results are given to illustrate the performance of the proposed controller.

An Adaptive Approach to Motion and Force Control of Multiple Coordinated Robots

1993 ◽  
Vol 115 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Yan-Ru Hu ◽  
A. A. Goldenberg
Keyword(s):  
Contact Force ◽  
Force Control ◽  
Lyapunov Stability Theory ◽  
Internal Force ◽  
Object Motion ◽  
Tracking Accuracy ◽  
Unknown Parameters ◽  
Adaptive Law ◽  
Control Scheme ◽  
Force Tracking

In this paper an approach to motion and force control of multiple coordinated robots, based on an adaptive scheme, is developed. The approach can be used to control the motion of an object held by the robots, the contact force between the object and the environment, and the internal force which do not contribute to the object motion and contact force. Three subsystem error equations are generated, i.e., position error subsystem, contact force error subsystem, and internal force error subsystem. The adaptive law is derived to estimate the unknown parameters of the multiple coordinated robots, the object, and the environment in terms of the three error subsystem equations. The convergence of the position, contact, internal force errors, and parameter errors is analyzed based on the Lyapunov stability theory. The paper shows that the adaptive control scheme improves the position, and the internal and contact force tracking accuracy for a class of robotic systems with uncertain knowledge of the dynamic model.

Catastrophe Analysis of Planar Three-Spring Systems

1998 ◽  
Author(s):  
J. P. Yin ◽  
D. Marsh ◽  
J. Duffy
Keyword(s):  
Contact Force ◽  
Force Control ◽  
Energy Function ◽  
System A ◽  
Spring System ◽  
Spring Mechanism ◽  
And Control ◽  
Control Tool ◽  
Contact Force Control

Abstract A special planar three-spring mechanism is proposed for contact force control. An energy function is defined to describe the behavior of this kind of mechanism. It can be used to perform the catastrophe analysis of this mechanism. The analysis result can be used as a design and control tool. By comparing the three-spring system and a two-spring system, we found the three-spring mechanism has better stability than the two-spring system. A three-spring mechanism which can be used to control a general contact force in a plane is also analyzed.

The Model of Transfer Robot in Chemical Mechanical Polishing

2013 ◽  
Vol 647 ◽  
pp. 867-874
Author(s):  
Jian Wei Zhao ◽  
Xin Chun Lu ◽  
Yong Yong He
Keyword(s):  
Material Processing ◽  
Chemical Mechanical Polishing ◽  
Lagrange Equation ◽  
Mechanical Polishing ◽  
System Stability ◽  
Dynamics Model ◽  
Strongly Coupled ◽  
Simulation Results ◽  
And Control ◽  
Important Kind

Transfer robot of chemical mechanical polishing (TRCMP) has some joints. For an important kind of special transfer robot, it is used as automatic material processing equipment in the semiconductor manufacture. The TRCMP has nonlinear, strongly coupled, multi-joints and under actuated, and these characteristics brought some difficulties to model and control. A dynamic model of the TRCMP was based on Lagrange equation and Newton dynamics theory. Then linearization of the dynamics model was done and its state-space equations were established. This structure of the model established is very simple, and it can control the TRCMP effectively and easy. Simulation results proved the system stability, and experiment results analyzed verified that the model of TRCMP is valid and rational.

Vibration Control of a Space Flexible Robot Manipulator Using PZT Actuators

2011 ◽  
Vol 66-68 ◽  
pp. 1142-1148 ◽  
Author(s):  
Jun Qiang Lou ◽  
Yan Ding Wei
Keyword(s):  
Control Strategy ◽  
Vibration Suppression ◽  
Robot Manipulator ◽  
Equations Of Motion ◽  
System Stability ◽  
Flexible Manipulator ◽  
Flexible Robot ◽  
Simulation Results ◽  
And Control ◽  
And Robotics

The dynamic analysis and control of flexible robot manipulators have been the main concerns of many recent studies in aeronautics and robotics. Moreover, the complexity of this problem increases when a flexible manipulator carries a payload. In this paper, we proposed a space two-link flexible manipulator with tip payload featuring surface-bonded piezoelectric torsional actuator and shear actuator. The equations of motion for the system are obtained using Hamilton’s principle. A Lyapunov-based controller is proposed to suppress the vibration of the system. Stability of the system is also investigated. The simulation results demonstrate the proposed control strategy is well suited for active control of vibration suppression on flexible manipulators.

scholarly journals Development of a Virtual Force Sensor for a Low-Cost Collaborative Robot and Applications to Safety Control

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2603 ◽  
Author(s):  
Shih-Hsiang Yen ◽  
Pei-Chong Tang ◽  
Yuan-Chiu Lin ◽  
Chyi-Yeu Lin
Keyword(s):  
Contact Force ◽  
External Force ◽  
Force Control ◽  
Low Cost ◽  
Force Sensor ◽  
Production Costs ◽  
Robot Arm ◽  
Robot Arms ◽  
Virtual Force ◽  
Collaborative Robot

To protect operators and conform to safety standards for human–machine interactions, the design of collaborative robot arms often incorporates flexible mechanisms and force sensors to detect and absorb external impact forces. However, this approach increases production costs, making the introduction of such robot arms into low-cost service applications difficult. This study proposes a low-cost, sensorless rigid robot arm design that employs a virtual force sensor and stiffness control to enable the safety collision detection and low-precision force control of robot arms. In this design, when a robot arm is subjected to an external force while in motion, the contact force observer estimates the external torques on each joint according to the motor electric current and calculation errors of the system model, which are then used to estimate the external contact force exerted on the robot arm’s end-effector. Additionally, a torque saturation limiter is added to the servo drive for each axis to enable the real-time adjustment of joint torque output according to the estimated external force, regulation of system stiffness, and achievement of impedance control that can be applied in safety measures and force control. The design this study developed is a departure from the conventional multisensor flexible mechanism approach. Moreover, it is a low-cost and sensorless design that relies on model-based control for stiffness regulation, thereby improving the safety and force control in robot arm applications.

scholarly journals Complex dynamical behaviors of a novel exponential hyper–chaotic system and its application in fast synchronization and color image encryption

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042110033
Author(s):  
Javad Mostafaee ◽  
Saleh Mobayen ◽  
Behrouz Vaseghi ◽  
Mohammad Vahedi ◽  
Afef Fekih
Keyword(s):  
Image Encryption ◽  
Chaotic System ◽  
Sliding Mode ◽  
Color Image ◽  
Equilibrium Points ◽  
Lyapunov Stability Theory ◽  
System Stability ◽  
Color Image Encryption ◽  
Terminal Sliding Mode ◽  
Finite Time Stability

This paper proposes a novel exponential hyper–chaotic system with complex dynamic behaviors. It also analyzes the chaotic attractor, bifurcation diagram, equilibrium points, Poincare map, Kaplan–Yorke dimension, and Lyapunov exponent behaviors. A fast terminal sliding mode control scheme is then designed to ensure the fast synchronization and stability of the new exponential hyper–chaotic system. Stability analysis was performed using the Lyapunov stability theory. One of the main features of the proposed controller is the finite time stability of the terminal sliding surface designed with high–order power function of error and derivative of error. The approach was implemented for image cryptosystem. Color image encryption was carried out to confirm the performance of the new hyper–chaotic system. For image encryption, the DNA encryption-based RGB algorithm was used. Performance assessment of the proposed approach confirmed the ability of the proposed hyper–chaotic system to increase the security of image encryption.

scholarly journals Neural Network Based Contact Force Control Algorithm for Walking Robots

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 287
Author(s):  
Byeongjin Kim ◽  
Soohyun Kim
Keyword(s):  
Neural Network ◽  
Contact Force ◽  
Force Control ◽  
Control Algorithm ◽  
Position Control ◽  
Linear Quadratic Regulator ◽  
Walking Robots ◽  
Test Model ◽  
Linear Quadratic ◽  
Contact Force Control

Walking algorithms using push-off improve moving efficiency and disturbance rejection performance. However, the algorithm based on classical contact force control requires an exact model or a Force/Torque sensor. This paper proposes a novel contact force control algorithm based on neural networks. The proposed model is adapted to a linear quadratic regulator for position control and balance. The results demonstrate that this neural network-based model can accurately generate force and effectively reduce errors without requiring a sensor. The effectiveness of the algorithm is assessed with the realistic test model. Compared to the Jacobian-based calculation, our algorithm significantly improves the accuracy of the force control. One step simulation was used to analyze the robustness of the algorithm. In summary, this walking control algorithm generates a push-off force with precision and enables it to reject disturbance rapidly.

Model development and control of an auto-refrigerated polystyrene polymerization reactor

2021 ◽  
pp. 014233122110251
Author(s):  
Reyhane Mokhtarname ◽  
Ali Akbar Safavi ◽  
Leonhard Urbas ◽  
Fabienne Salimi ◽  
Mohammad M Zerafat ◽  
...  
Keyword(s):  
Temperature Control ◽  
Model Development ◽  
Heat Removal ◽  
Superior Performance ◽  
Polymerization Process ◽  
Vacuum System ◽  
Control Scheme ◽  
Simulation Results ◽  
And Control ◽  
Operating Plant

Dynamic model development and control of an existing operating industrial continuous bulk free radical styrene polymerization process are carried out to evaluate the performance of auto-refrigerated CSTRs (continuous stirred tank reactors). One of the most difficult tasks in polymerization processes is to control the high viscosity reactor contents and heat removal. In this study, temperature control of an auto-refrigerated CSTR is carried out using an alternative control scheme which makes use of a vacuum system connected to the condenser and has not been addressed in the literature (i.e. to the best of our knowledge). The developed model is then verified using some experimental data of the real operating plant. To show the heat removal potential of this control scheme, a common control strategy used in some previous studies is also simulated. Simulation results show a faster dynamics and superior performance of the first control scheme which is already implemented in our operating plant. Besides, a nonlinear model predictive control (NMPC) is developed for the polymerization process under study to provide a better temperature control while satisfying the input/output and the heat exchanger capacity constraints on the heat removal. Then, a comparison has been also made with the conventional proportional-integral (PI) controller utilizing some common tuning rules. Some robustness and stability analyses of the control schemes investigated are also provided through some simulations. Simulation results clearly show the superiority of the NMPC strategy from all aspects.

scholarly journals Suppress Vibration on Robotic Polishing with Impedance Matching

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 59
Author(s):  
Junjie Dai ◽  
Chin-Yin Chen ◽  
Renfeng Zhu ◽  
Guilin Yang ◽  
Chongchong Wang ◽  
...  
Keyword(s):  
Contact Force ◽  
Force Control ◽  
Impedance Control ◽  
Impedance Matching ◽  
Industrial Robots ◽  
Contact Phase ◽  
Dynamic Tracking ◽  
Force Tracking ◽  
The Difference ◽  
End Effectors

Installing force-controlled end-effectors on the end of industrial robots has become the mainstream method for robot force control. Additionally, during the polishing process, contact force stability has an important impact on polishing quality. However, due to the difference between the robot structure and the force-controlled end-effector, in the polishing operation, direct force control will have impact during the transition from noncontact to contact between the tool and the workpiece. Although impedance control can solve this problem, industrial robots still produce vibrations with high inertia and low stiffness. Therefore, this research proposes an impedance matching control strategy based on traditional direct force control and impedance control methods to improve this problem. This method’s primary purpose is to avoid force vibration in the contact phase and maintain force–tracking performance during the dynamic tracking phase. Simulation and experimental results show that this method can smoothly track the contact force and reduce vibration compared with traditional force control and impedance control.

Sign in / Sign up

Export Citation Format

Share Document