High Bandwidth Motion Control for Multi-Axis Servohydraulic Mechanisms

2007 ◽  
Author(s):  
A. R. Plummer
Keyword(s):  
Motion Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Earthquake Simulation ◽  
Control Approach ◽  
Six Degrees Of Freedom ◽  
Modes Of Vibration ◽  
High Bandwidth ◽  
Rigid Mass ◽  
Acceleration Tracking

A practical motion control method is presented for multiaxis parallel servohydraulic mechanisms in which the payload behaves as a rigid mass. The ability of this method to decouple the control axes is demonstrated. A modal control approach is used – i.e. the modes of vibration of the system are controlled individually. These modes are dependent on the inertial properties of the payload and the compliance of the actuators due to oil compressibility. For each mode, a partial non-linear dynamic inversion is performed in the control loop. To avoid the need to differentiate the position feedback signals, accelerometers are also used, and three-element motion state vectors are estimated using composite filtering. Command feedforward is used to increase the tracking bandwidth, and the closed-loop part of the controller can be conceived as a model-based disturbance observer. Simulation results are presented based on a detailed validated model of a large vibration table used for earthquake simulation. Just three of the six degrees-of-freedom of the table are considered, and the results for horizontal acceleration tracking response are presented, along with the ability of the controller to reject the ‘overturning moment’.

Theory and Experiments on the Compliance Control of Redundant Robot Manipulators

1990 ◽  
Vol 112 (4) ◽  
pp. 653-660 ◽  
Author(s):  
H. Kazerooni ◽  
K. G. Bouklas ◽  
J. Guo
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Robot Manipulators ◽  
Industrial Robot ◽  
Redundant Robot ◽  
Control Approach ◽  
Six Degrees Of Freedom ◽  
The Stability ◽  
Control Methodology ◽  
Theory And Experiments

This work presents a control methodology for compliant motion in redundant robot manipulators. This control approach takes advantage of the redundancy in the robot’s degrees of freedom: while a maximum six degrees of freedom of the robot control the robot’s endpoint position, the remaining degrees of freedom impose an appropriate force on the environment. To verify the applicability of this control method, an active end-effector is mounted on an industrial robot to generate redundancy in the degrees of freedom. A set of experiments are described to demonstrate the use of this control method in constrained maneuvers. The stability of the robot and the environment is analyzed.

DUTY-CYCLED SPINNING BASED 3D MOTION CONTROL APPROACH FOR BEVEL-TIPPED FLEXIBLE NEEDLE INSERTION

2018 ◽  
Vol 18 (07) ◽  
pp. 1840017 ◽  
Author(s):  
QIN YAO ◽  
XUMING ZHANG
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Tracking Error ◽  
Open Loop ◽  
Loop Control ◽  
3D Motion ◽  
Control Approach ◽  
Target Error ◽  
The Mean ◽  
Simulation Results

Flexible needle has been widely used in the therapy delivery because it can advance along the curved lines to avoid the obstacles like important organs and bones. However, most control algorithms for the flexible needle are still limited to address its motion along a set of arcs in the two-dimensional (2D) plane. To resolve this problem, this paper has proposed an improved duty-cycled spinning based three-dimensional (3D) motion control approach to ensure that the beveled-tip flexible needle can track a desired trajectory to reach the target within the tissue. Compared with the existing open-loop duty-cycled spinning method which is limited to tracking 2D trajectory comprised of few arcs, the proposed closed-loop control method can be used for tracking any 3D trajectory comprised of numerous arcs. Distinctively, the proposed method is independent of the tissue parameters and robust to such disturbances as tissue deformation. In the trajectory tracking simulation, the designed controller is tested on the helical trajectory, the trajectory generated by rapidly-exploring random tree (RRT) algorithm and the helical trajectory. The simulation results show that the mean tracking error and the target error are less than 0.02[Formula: see text]mm for the former two kinds of trajectories. In the case of tracking the helical trajectory, the mean tracking error target error is less than 0.5[Formula: see text]mm and 1.5[Formula: see text]mm, respectively. The simulation results prove the effectiveness of the proposed method.

Balancing Control of a Mobile Manipulator with Two Wheels by an Acceleration-Based Disturbance Observer

2018 ◽  
Vol 15 (03) ◽  
pp. 1850005 ◽  
Author(s):  
Yeong-Geol Bae ◽  
Seul Jung
Keyword(s):  
Disturbance Observer ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Experimental Studies ◽  
Service Robot ◽  
Mobile Manipulator ◽  
Control Performance ◽  
Six Degrees Of Freedom ◽  
Inertia Model ◽  
Balancing Control

This paper presents the balancing control performance of a mobile manipulator built in the laboratory as a service robot called Korean robot worker (KOBOKER). The robot is designed and implemented with two wheels as a mobile base and two arms with six degrees-of-freedom each. Kinematics and dynamics of the robot are analyzed. For the balancing control performance, two wheels are controlled independently by the time-delayed control method based on the inertia model of the robot. The acceleration information obtained directly from the sensor is used for the modified disturbance observer structure called an acceleration-based disturbance observer (AbDOB). Experimental studies of the balancing control of the robot are conducted to compare the control performances by both a PID control method and an AbDOB.

Research of Multi-Movement Parameters Iterative Control of Multi-Degrees-of-Freedom Earthquake Simulation

2013 ◽  
Vol 353-356 ◽  
pp. 2008-2014
Author(s):  
Pan Tian ◽  
Zhang Wei Chen
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Synthesis Method ◽  
Low Frequency ◽  
Control Area ◽  
Synthetic Control ◽  
Earthquake Simulation ◽  
Simulation Test ◽  
Movement Parameters ◽  
Iterative Control

Acceleration iterative control is generally used in multi-degrees-of-freedom earthquake simulation test. To overcome the shortcoming of poor displacement amplitude accuracy in this control, a multi-degrees-of-freedom earthquake simulation control strategy based on multi-movement parameters iterative control is proposed. This control divide the frequency range of earthquake simulation test into displacement control area, the synthetic control area and acceleration control area from the low frequency to the high frequency, and correct the acceleration errors spectrum and displacement error spectrum by iterative control method, and produce shaker driver signal by synthesis method, and realize the displacement replication and acceleration replication at the same time. The experimental results which are got in multi-degrees-of-freedom earthquake simulation facility indicate that this control can achieve high accuracy multi-degrees-of-freedom earthquake simulation test after several times iterative.

Design of Robust Nonlinear Optimal Controller for Underwater Vehicle to Move in Depth Channel Using Gradient Descent Method with Systematic Step Selection

2014 ◽  
Vol 704 ◽  
pp. 320-324
Author(s):  
Marzieh Ahmadi ◽  
Abolfazl Halvaei Niasar ◽  
Alireza Faraji ◽  
Hassan Moghbeli
Keyword(s):  
Gradient Descent ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Parametric Uncertainty ◽  
Underwater Vehicle ◽  
Descent Method ◽  
Optimal Controller ◽  
Gradient Descent Method ◽  
Six Degrees Of Freedom ◽  
Step Selection

This paper proposes the design of a robust nonlinear optimal controller to move the underwater vehicle in the depth channel using gradient descent method. A nonlinear model with six degrees of freedom (6-DOF) has been extracted for the underwater vehicle. To selection of the model and design of controller, conventional assumptions used for other controllers have not been considered and the developed controller can be implemented via at least assumptions. In presented control method, systematic step selection for solving of the algorithm has increased the rate of convergence significantly. The performances of the proposed robust controller for moving in depth channel with considering of parametric uncertainty for the model have been confirmed via some simulations. The results show the desirable performance of developed controller.

Man-machine interaction-based motion control of a robotic walker

2020 ◽  
pp. 1-21
Author(s):  
Chengjie Zhang ◽  
Shuai Guo ◽  
Fengfeng (Jeff) Xi
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Fuzzy Controller ◽  
Gait Training ◽  
Recognition Algorithm ◽  
Simulated Patients ◽  
Acceptable Error ◽  
Control Approach ◽  
Robotic Walker ◽  
Force Signal

BACKGROUND: The aging population brings the problem of healthcare and dyskinesia. The lack of mobility extremely affects stroke patient’s activities of daily living (ADL) and decreases their quality of life. To assist these mobility-limited people, a robotic walker is designed to facilitate gait rehabilitation training. OBJECTIVE: The aim of this paper is to present the implementation of a novel motion control method to assist disabled people based on their motion intention. METHODS: The kinematic framework of the robotic walker is outlined. We propose an intention recognition algorithm based on the interactive force signal. A novel motion control method combined with T-S fuzzy controller and PD controller is proposed. The motion controller can recognize the intention of the user through the interactive force, which allows the user to move or turn around as usual, instead of using their hands to control the walker. RESULTS: Preliminary experiments with healthy individuals and simulated patients are carried out to verify the effectiveness of the algorithm. The results show that the proposed motion control approach can recognize the user’s intention, is easy to control and has a higher precision than the traditional proportional–integral–derivative controller. CONCLUSION: The results show that users could achieve the task with acceptable error, which indicates the potential of the proposed control method for gait training.

scholarly journals A compliant control method for robust trot motion of hydraulic actuated quadruped robot

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881323 ◽  
Author(s):  
Teng Chen ◽  
Xuewen Rong ◽  
Yibin Li ◽  
Chao Ding ◽  
Hui Chai ◽  
...  
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Middle Layer ◽  
Bottom Layer ◽  
Hydraulic Cylinder ◽  
Simulation Software ◽  
Lateral Impact ◽  
Software Environment ◽  
Control Approach ◽  
Active Compliance

A motion control approach is proposed for hydraulic actuated quadruped robots, aiming to achieve active compliance and robust motion control. The approach is designed with a structure of three layers. Servo valve-controlled asymmetric hydraulic cylinder model is established to obtain the relationship between the desired torque and the control current signal, which is the bottom layer. The middle layer is based on the virtual model of the leg for active compliance. The upper layer considers the torso posture and velocity into planning the foot trajectories based on the spring loaded inverted pendulum model. Trotting gait simulations are conducted based on the proposed framework in the simulation software environment Webots. The motion control approach has been implemented on a robot prototype SCalf-II (SDU calf), where experiments have been conducted including omnidirectional trotting gait, lateral impact recovery and climbing slopes. The experiments demonstrate that the proposed approach can effectively control the hydraulic actuated robots.

Kinematics and cooperative control of a robotic spinal surgery system

Robotica ◽  
2014 ◽  
Vol 34 (1) ◽  
pp. 226-242 ◽  
Author(s):  
Haiyang Jin ◽  
Ying Hu ◽  
Wei Tian ◽  
Peng Zhang ◽  
Zhangjun Song ◽  
...  
Keyword(s):  
Spinal Surgery ◽  
Cooperative Control ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Control Mode ◽  
Assessment Index ◽  
Control Approach ◽  
Screw Insertion ◽  
Six Degrees Of Freedom ◽  
Speed Mode

SUMMARYSpinal surgery is considered a high-risk surgery. To improve the accuracy, stability, and safety of such operations, we report the development of a novel six-degrees-of-freedom Robotic Spinal Surgical System that can assist surgeons in performing transpedicular surgery, one of the most common spinal surgeries. After optimization performed using Response Surface Methodology, the largest available workspace of the robot is determined and is found to easily cover the entire operation area. Cooperative control and navigation-based active control are implemented for different processes of the operation. We propose a hybrid control approach based on the speed and torque interface at the joint level. In this mode, the robot is compliant in Cartesian space, benefitting both the accuracy and efficiency of the operation. A comprehensive assessment index, combining the subjective and objective criteria in terms of positioning and operation efficiency, is proposed to compare the performance of cooperative control in speed mode, torque mode, and hybrid control mode. Active fine adjustment experiments are carried out to verify the positioning accuracy, and the results are found to satisfy the requirements of operation. As an application example, a pedicle screw insertion experiment is performed on a pig vertebral bone, demonstrating the effectiveness of our system.

scholarly journals Design and development of anchoring positioning control system for riprap leveling ship

2021 ◽  
Vol 233 ◽  
pp. 04007
Author(s):  
Xiaotao Hua ◽  
Yan Liu ◽  
Haiyang Sun ◽  
Jianru Chen
Keyword(s):  
Control System ◽  
Equilibrium State ◽  
Degrees Of Freedom ◽  
Wind Wave ◽  
Control Method ◽  
Positioning Control ◽  
Six Degrees Of Freedom ◽  
Hydrodynamic Parameters ◽  
Convergence Control ◽  
Heading Angle

It is very important to level foundation bed by riprap in water and soil engineering. In this paper, a real-time feedback convergence control method is proposed to control the position and heading angle of the riprap leveling ship. The wind, wave, current and hydrodynamic parameters are obtained by empirical formula; the tension of four cables is calculated according to the balance equation of six degrees of freedom, and then the cable deformation is obtained. According to the deformation of the cable, the length of the cable in a certain equilibrium state can be obtained. The length of four cables can be lengthened or shortened by comparing the length of cables at two balanced positions. The length of cables can be controlled by winch to complete the anchoring and positioning control of leveling ship.

scholarly journals A Manipulator Control Method Based on Deep Deterministic Policy Gradient with Parameter Noise

2021 ◽  
Author(s):  
Haifei Zhang ◽  
Xu Jian ◽  
Liting Lei ◽  
Fang Wu ◽  
Lanmei Qian ◽  
...  
Keyword(s):  
Motion Control ◽  
Control Method ◽  
State Variables ◽  
Control Approach ◽  
Environment Model ◽  
Policy Gradient ◽  
The Stability ◽  
Reinforcement Learning Models ◽  
Policy Optimization ◽  
Manipulator Control

Abstract Focusing on the motion control problem of two link manipulator, a manipulator control approach based on deep deterministic policy gradient with parameter noise is proposed. Firstly, the manipulator simulation environment is built. And then the three deep reinforcement learning models named the deep deterministic policy gradient (DDPG), asynchronous advantage actor-critical (A3C) and distributed proximal policy optimization (DPPO) are established for training according to the target setting, state variables and reward & punishment mechanism of the environment model. Finally the motion control of two link manipulator is realized. After comparing and analyzing the three models, the DDPG approach based on parameter noise is proposed for further research to improve its applicability, so as to cut down the debugging time of the manipulator model and reach the goal smoothly. The experimental results indicate that the DDPG approach based on parameter noise can control the motion of two link manipulator effectively. The convergence speed of the control model is significantly promoted and the stability after convergence is improved. In comparison with the traditional control approach, the DDPG control approach based on parameter noise has higher efficiency and stronger applicability.

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