Feedback control of a planar manipulator with an unactuated elastically mounted end effector

2003 ◽  
Author(s):  
M. Reyhanoglu ◽  
S. Cho ◽  
N.H. McClamroch
Keyword(s):  
Feedback Control ◽  
End Effector

Task-Space Control Design and Performance Evaluation for a 6DOF Stewart Nanoscale Platform

2008 ◽  
Author(s):  
Chun-Chung Li ◽  
Yung Ting ◽  
Yi-Hung Liu ◽  
Yi-Da Lee ◽  
Chun-Wei Chiu
Keyword(s):  
Feedback Control ◽  
Hybrid Control ◽  
Feedforward Control ◽  
Feedback Controller ◽  
Test Method ◽  
Computation Method ◽  
Task Space ◽  
Force Output ◽  
End Effector ◽  
Control Scheme

A 6DOF Stewart platform using piezoelectric actuators for nanoscale positioning objective is designed. A measurement method that can directly measure the pose (position and orientation) of the end-effector is developed so that task-space on-line control is practicable. The design of a sensor holder for sensor employment, a cuboid with referenced measure points, and the computation method for obtaining the end-effector parameters is introduced. A control scheme combining feedforward and feedback is proposed. The inverse model of a hysteresis model derived by using a dynamic Preisach method is used for the feedforward control. Hybrid control to maintain both the positioning and force output for nano-cutting and nano-assembly applications is designed for the feedback controller. The optimal gain of the feedback controller is searched by using relay feedback test method and genetic algorithm. In experiment, conditions with/without external load employed with feedforward, feedback, and feedforward with feedback control schemes respectively are carried out. Performance of each control scheme verifies the capability of achieving nanoscale precision. The combined feedforward and feedback control scheme is superior to the others for gaining better precision.

Combining Motion Primitives and Image-Based Visual Servo Control

2020 ◽  
Author(s):  
Ghananeel Rotithor ◽  
Ashwin P. Dani
Keyword(s):  
Feedback Control ◽  
Open Loop ◽  
Servo Control ◽  
Visual Servo ◽  
Motion Generation ◽  
End Effector ◽  
Visual Servo Control ◽  
Dynamic Movement ◽  
Motion Primitive ◽  
Dynamic Movement Primitives

Abstract Combining perception feedback control with learning-based open-loop motion generation for the robot’s end-effector control is an attractive solution for many robotic manufacturing tasks. For instance, while performing a peg-in-the-hole or an insertion task when the hole or the recipient part is not visible in the eye-in-the-hand camera, an open-loop learning-based motion primitive method can be used to generate end-effector path. Once the recipient part is in the field of view (FOV), visual servo control can be used to control the motion of the robot. Inspired by such applications, this paper presents a control scheme that switches between Dynamic Movement Primitives (DMPs) and Image-based Visual Servo (IBVS) control combining end-effector control with perception-based feedback control. A simulation result is performed that switches the controller between DMP and IBVS to verify the performance of the proposed control methodology.

scholarly journals Control Performance Evaluation of Serial Urology Manipulator by Virtual Prototyping

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Hu Shi ◽  
Jiajie Li ◽  
Lianjie Guo ◽  
Xuesong Mei
Keyword(s):  
Fixed Point ◽  
Feedback Control ◽  
Feedforward Control ◽  
Tracking Error ◽  
Dynamics Simulation ◽  
Average Error ◽  
Bottom Surface ◽  
End Effector ◽  
Manipulator Design ◽  
Control Implementation

AbstractProstatic hyperplasia and tumor are common diseases, and the minimally invasive surgery inserting the instruments through the urethra into the prostate is commonly conducted. Taking the robotic manipulator for such surgery into consideration, this paper analyses the workspace of the end effector, and proposes the distribution error of the fixed point and the tracking error of manipulator end effector on the cone bottom surface of the workspace as the basis for control implementation of the manipulator. The D-H coordinate system of the manipulator is established and the trajectory planning of the end effector in the Cartesian space is carried out. The digital model was established, and dynamics simulation was performed in Solidworks and Matlab/Simulink environment to guide the manipulator design. Trajectory mapping and synchronization control between virtual model and the actual manipulator are realized based on digital twin technique. The virtual manipulator can reflect the real-time state of the manipulator with data interaction by comparing the dynamics simulation results with the motor current values obtained by experiment. Experiment was carried out with PD feedback control and Newton–Euler dynamics based feedforward control to get the trajectory tracking characteristic of each motor, errors of the fixed point and tracking performance of the end effector of the manipulator. The results show that compared with PD feedback control, feed forward control implementation can achieve a reduction of 30.0% in the average error of the fixed point of the manipulator and a reduction of 33.3% in the maximum error.

Design of force/position control laws for constrained robots, including effects of joint flexibility and actuator dynamics

Robotica ◽  
1999 ◽  
Vol 17 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Hariharan Krishnan
Keyword(s):  
Feedback Control ◽  
Position Control ◽  
Mathematical Representation ◽  
Control Law ◽  
Differential Algebraic Equation ◽  
Force Output ◽  
End Effector ◽  
Joint Flexibility ◽  
Actuator Dynamics ◽  
Constrained Robot

In this paper, a mathematical representation of constrained robot systems in the form of a differential-algebraic equation model is first considered. This model in modified further to include the joint flexibility between the linkages of the robot, and the actuator dynamics. The objective is to design a feedback control law for the system so that the position output variables (typically the end-effector position) and the force output variables (typically the contact force between the robot's end-effector and the contact surface) of the robot follows the desired position and the desired force trajectories, respectively, despite the presence of joint flexibility and actuator dynamics. A systematic procedure is developed for designing a feedback control law which ensures that the position variables track the desired position trajectories exponentially, and the force variables track the desired force trajectories exponentially. Since the development of the control law is based on the model of a constrained robot system which includes the effects of actuator dynamics and joint flexibility, it is possible to achieve better tracking performance using the force/position control law developed in this paper in cases where such effects are significant.

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