scholarly journals Manipulator End-Effector Position Control

2012 ◽  
Vol 48 ◽  
pp. 684-692 ◽  
Author(s):  
Ivan Virgala ◽  
Alexander Gmiterko ◽  
Róbert Surovec ◽  
Martina Vacková ◽  
Erik Prada ◽  
...  
Keyword(s):  
Position Control ◽  
End Effector

scholarly journals Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3498
Author(s):  
Youqiang Zhang ◽  
Cheol-Su Jeong ◽  
Minhyo Kim ◽  
Sangrok Jin
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Friction Model ◽  
Surgical Instruments ◽  
Control Input ◽  
End Effector ◽  
Motor Current ◽  
Direct Teaching ◽  
End Effectors ◽  
Teaching Operation

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.

scholarly journals Proposal of a Decoupled Structure of Fuzzy-PID Controllers Applied to the Position Control in a Planar CDPR

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 745
Author(s):  
Marco Carpio ◽  
Roque Saltaren ◽  
Julio Viola ◽  
Cristian Calderon ◽  
Juan Guerra
Keyword(s):  
Position Control ◽  
Control Structure ◽  
Parallel Robot ◽  
Pid Controllers ◽  
Fuzzy Pid ◽  
End Effector ◽  
Robot Systems ◽  
Decoupled Control ◽  
The Mathematical Model ◽  
Decoupled Structure

The design of robot systems controlled by cables can be relatively difficult when it is approached from the mathematical model of the mechanism, considering that its approach involves non-linearities associated with different components, such as cables and pulleys. In this work, a simple and practical decoupled control structure proposal that requires practically no mathematical analysis was developed for the position control of a planar cable-driven parallel robot (CDPR). This structure was implemented using non-linear fuzzy PID and classic PID controllers, allowing performance comparisons to be established. For the development of this research, first the structure of the control system was proposed, based on an analysis of the cables involved in the movement of the end-effector (EE) of the robot when they act independently for each axis. Then a tuning of rules was carried out for fuzzy PID controllers, and Ziegler–Nichols tuning was applied to classic PID controllers. Finally, simulations were performed in MATLAB with the Simulink and Simscape tools. The results obtained allowed us to observe the effectiveness of the proposed structure, with noticeably better performance obtained from the fuzzy PID controllers.

A hybrid impedance control scheme for underwater welding robots with a passive foundation in the controller domain

SIMULATION ◽  
2017 ◽  
Vol 93 (7) ◽  
pp. 619-630 ◽  
Author(s):  
Sunil Kumar ◽  
Vikas Rastogi ◽  
Pardeep Gupta
Keyword(s):  
Minimum Distance ◽  
Position Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Graph Model ◽  
Proportional Integral Derivative ◽  
End Effector ◽  
Flexible Arm ◽  
Control Scheme ◽  
Effective Stability

A hybrid impedance control scheme for the force and position control of an end-effector is presented in this paper. The interaction of the end-effector is controlled using a passive foundation with compensation gain. For obtaining the steady state, a proportional–integral–derivative controller is tuned with an impedance controller. The hybrid impedance controller is implemented on a terrestrial (ground) single-arm robot manipulator. The modeling is done by creating a bond graph model and efficacy is substantiated through simulation results. Further, the hybrid impedance control scheme is applied on a two-link flexible arm underwater robot manipulator for welding applications. Underwater conditions, such as hydrodynamic forces, buoyancy forces, and other disturbances, are considered in the modeling. During interaction, the minimum distance from the virtual wall is maintained. A simulation study is carried out, which reveals some effective stability of the system.

Aerial Contact Manipulation With Soft End-Effector Compliance and Inverse Kinematic Compensation

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xinjun Sheng ◽  
Zhao Ma ◽  
Ningbin Zhang ◽  
Wei Dong
Keyword(s):  
Degrees Of Freedom ◽  
Position Control ◽  
Mechanical Design ◽  
Impact Resistance ◽  
High Strength ◽  
Inverse Kinematic ◽  
End Effector ◽  
Precise Position ◽  
Positioning Errors ◽  
Aerial Platform

Abstract This paper presents the development of a six degrees-of-freedom manipulator with soft end-effector and an inverse kinematic compensator for aerial contact manipulation. Realizing the fact that aerial manipulators can hardly achieve precise position control, a compliant manipulator with soft end-effector is first developed to moderate end-effector positioning errors. The manipulator is designed to be rigid-soft combined. The rigid robotic arm employs the lightweight but high-strength materials. The compliance requirement is achieved by the soft end-effector so that the mechanical design for the joints are largely simplified. These two features are beneficial to lighten the arm and to ensure the accuracy. In the meantime, the pneumatic soft end-effector can further moderate the probable insufficient accuracy by endowing the manipulator with compliance for impact resistance and robustness to positioning errors. With the well-designed manipulator, an inverse kinematic compensator is then proposed to eliminate lumped disturbances from the aerial platform. The compensator can ensure the stabilization of the end-effector by using state estimation from the aerial platform, which is robust and portable as the movement of the platform can be reliably obtained. Both the accuracy and compliance have been well demonstrated after being integrated into a hexarotor platform, and a representative scenario aerial task repairing the wind turbine blade-coating was completed successfully, showing the potential to accomplish complex aerial manipulation tasks.

A new scheme for hybrid force-position control

Robotica ◽  
1993 ◽  
Vol 11 (5) ◽  
pp. 453-464 ◽  
Author(s):  
Véronique Perdereau ◽  
Michel Drouin
Keyword(s):  
Position Control ◽  
External Environment ◽  
Contact Forces ◽  
End Effector ◽  
Complex Tasks ◽  
To Come ◽  
Tip Position ◽  
Robotic Tasks

SUMMARYMany robotic tasks require the end-effector to come into contact with the external environment. In such complex tasks, the manipulator is constrained by the environment, and certain DOFs are lost for motion. The contact forces must be controlled in constraint directions, while the tip position is simultaneously controlled in the free directions.

scholarly journals Position control for haptic device based on discrete-time proportional integral derivative controller

2022 ◽  
Vol 12 (1) ◽  
pp. 269
Author(s):  
Nguyen Van Tan ◽  
Khoa Nguyen Dang ◽  
Pham Duc Dai ◽  
Long Vu Van
Keyword(s):  
Discrete Time ◽  
Pid Controller ◽  
Position Control ◽  
Haptic Device ◽  
Advanced Technology ◽  
Proportional Integral Derivative ◽  
Force Output ◽  
Kinematic Equation ◽  
End Effector ◽  
Proportional Integral

Haptic devices had known as advanced technology with the goal is creating the experiences of touch by applying forces and motions to the operator based on force feedback. Especially in unmanned aerial vehicle (UAV) applications, the position of the end-effector Falcon haptic sets the velocity command for the UAV. And the operator can feel the experience vibration of the vehicle as to the acceleration or collision with other objects through a forces feedback to the haptic device. In some emergency cases, the haptic can report to the user the dangerous situation of the UAV by changing the position of the end-effector which is be obtained by changing the angle of the motor using the inverse kinematic equation. But this solution may not accurate due to the disturbance of the system. Therefore, we proposed a position controller for the haptic based on a discrete-time proportional integral derivative (PID) controller. A Novint Falcon haptic is used to demonstrate our proposal. From hardware parameters, a Jacobian matrix is calculated, which combines with the force output from the PID controller to make the torque for the motors of the haptic. The experiment was shown that the PID has high accuracy and a small error position.

Experimental Research on Force/Position Control of a Wire-Driven Parallel Rehabilitative Robot

2011 ◽  
Vol 138-139 ◽  
pp. 68-73 ◽  
Author(s):  
Ke Yi Wang ◽  
Fang Chao Ma ◽  
Meng Hao ◽  
Li Xun Zhang ◽  
Pan Liu
Keyword(s):  
Position Control ◽  
Parallel Robot ◽  
Force Balance ◽  
Robot System ◽  
End Effector ◽  
Wire Tension ◽  
Parallel Control ◽  
The Wire ◽  
And Control ◽  
Force Balance Equation

During rehabilitative training, a 3-DOF wire-driven parallel robot driven was designed to coordinate and control the trainer pelvis movement. Based on the force balance equation of the end-effector, the stiffness problem about the robot system was analyzed and one kind of force/position parallel control strategy was proposed that the position loop would realize the end-effector motion trajectory, and the force loop would control the wire tension. The experimental results have shown that the robot systematic stiffness is related with the wire tension and can be changed to realize the compliance control of the robot system by adjusting the wire tension.

Comparing model-based control methods for simultaneous stiffness and position control of inflatable soft robots

2020 ◽  
pp. 027836492091196
Author(s):  
Charles M. Best ◽  
Levi Rupert ◽  
Marc D. Killpack
Keyword(s):  
Dynamic Models ◽  
Position Control ◽  
Sliding Mode ◽  
Joint Stiffness ◽  
Variable Stiffness ◽  
Soft Robots ◽  
End Effector ◽  
Simultaneous Control ◽  
Stiffness Model ◽  
Stiffness Control

Inflatable robots are naturally lightweight and compliant, which may make them well suited for operating in unstructured environments or in close proximity to people. The inflatable joints used in this article consist of a strong fabric exterior that constrains two opposing compliant air bladders that generate torque (unlike McKibben actuators where pressure changes cause translation). This antagonistic structure allows the simultaneous control of position and stiffness. However, dynamic models of soft robots that allow variable stiffness control have not been well developed. In this work, a model that includes stiffness as a state variable is developed and validated. Using the stiffness model, a sliding mode controller and model predictive controller are developed to control stiffness and position simultaneously. For sliding mode control (SMC), the joint stiffness was controlled to within 0.07 Nm/rad of a 45 Nm/rad command. For model predictive control (MPC) the joint stiffness was controlled to within 0.045 Nm/rad of the same stiffness command. Both SMC and MPC were able to control to within 0.5° of a desired position at steady state. Stiffness control was extended to a multiple-degree-of-freedom soft robot using MPC. Controlling stiffness of a 4-DOF arm reduced the end-effector deflection by approximately 50% (from 17.9 to 12.2cm) with a 4 lb (1.8 kg) step input applied at the end effector when higher joint stiffness (40 Nm/rad) was used compared with low stiffness (30 Nm/rad). This work shows that the derived stiffness model can enable effective position and stiffness control.

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