Transparency performance improvement for multi-master multi-slave teleoperation systems with external force estimation

2017 ◽  
Vol 40 (13) ◽  
pp. 3851-3859 ◽  
Author(s):  
Farhad Azimifar ◽  
Saman Ahmadkhosravi Rozi ◽  
Ahmad Saleh ◽  
Iman Afyouni
Keyword(s):  
Control Strategy ◽  
Closed Loop ◽  
Estimation Algorithm ◽  
Lyapunov Theory ◽  
Shared Environment ◽  
Force Estimation ◽  
Teleoperation System ◽  
Common Control ◽  
Control Scheme ◽  
External Forces

Cooperative teleoperation combines two traditional areas of robotics, that is, teleoperation and collaborative manipulation. Cooperative telerobotic systems consist of multiple pairs of master and slave robotic manipulators operating in a shared environment. The most common control frameworks for nonlinear systems, that is, Proportional Derivative (PD) controllers, possess considerable deficiency in contact motion. In this paper, a novel control scheme is proposed for a nonlinear bilateral cooperative teleoperation system with time delay. In addition to position and velocity signals, force signals are employed in the control strategy. This modification significantly enhances the poor transparency when the slave robots are in collision with the environment. To cope with external forces measurement, a modified force estimation algorithm is proposed to estimate human and environment forces. The closed loop stability of the nonlinear cooperative teleoperation system with the proposed control scheme is investigated using the Lyapunov theory. The main achievement of this research is the stability of the closed loop cooperative teleoperation system in the presence of estimated operator and environmental forces. In addition, it is theoretically and experimentally proved that force reflection occurs and transparency is improved at the same time. Experimental results demonstrate the efficiency of the presented control strategy in free motion as well as when the slave robots are in contact with the environment.

Performance analysis in delayed nonlinear bilateral teleoperation systems by force estimation algorithm

2017 ◽  
Vol 40 (5) ◽  
pp. 1637-1644
Author(s):  
Farhad Azimifar ◽  
Kamran Hassani ◽  
Amir Hossein Saveh ◽  
Farhad Tabatabai Ghomshe
Keyword(s):  
Closed Loop ◽  
Force Measurement ◽  
Estimation Algorithm ◽  
Lyapunov Theory ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Teleoperation Systems ◽  
System With Time Delay

This paper establishes a novel control strategy for a nonlinear bilateral teleoperation system with time delay. Besides position and velocity signals, force signals are additionally utilized in the control scheme. This modification significantly improves the poor transparency during contact with the environment. To eliminate the external force measurement, a force estimation algorithm is proposed for the master and slave robots. The closed loop stability of the nonlinear teleoperation system with the proposed control scheme is investigated through the Lyapunov theory. Furthermore, it is theoretically and experimentally proved that force reflection occurs and transparency is enhanced simultaneously. Consequently, experimental results verify the efficiency of the new control scheme in free motion and during collision of the slave robot with the environment.

Transparency Improvement by External Force Estimation in a Time-Delayed Nonlinear Bilateral Teleoperation System

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
H. Amini ◽  
S. M. Rezaei ◽  
Ahmed A. D. Sarhan ◽  
J. Akbari ◽  
N. A. Mardi
Keyword(s):  
Control Algorithm ◽  
Force Measurement ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Environmental Force ◽  
The Stability ◽  
External Forces ◽  
Teleoperation Systems

Teleoperation systems have been developed in order to manipulate objects in environments where the presence of humans is impossible, dangerous or less effective. One of the most attractive applications is micro telemanipulation with micropositioning actuators. Due to the sensitivity of this operation, task performance should be accurately considered. The presence of force signals in the control scheme could effectively improve transparency. However, the main restriction is force measurement in micromanipulation scales. A new modified strategy for estimating the external forces acting on the master and slave robots is the major contribution of this paper. The main advantage of this strategy is that the necessity for force sensors is eliminated, leading to lower cost and further applicability. A novel control algorithm with estimated force signals is proposed for a general nonlinear macro–micro bilateral teleoperation system with time delay. The stability condition in the macro–micro teleoperation system with the new control algorithm is verified by means of Lyapunov stability analysis. The designed control algorithm guarantees stability of the macro–micro teleoperation system in the presence of an estimated operator and environmental force. Experimental results confirm the efficiency of the novel control algorithm in position tracking and force reflection.

A novel nonsingular integral terminal sliding mode control scheme in epilepsy treatment

2021 ◽  
pp. 014233122110507
Author(s):  
Moshu Qian ◽  
Zhen Zhang ◽  
Guanghua Zhong ◽  
Cuimei Bo
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Sliding Mode ◽  
Tracking Error ◽  
Lyapunov Theory ◽  
Terminal Sliding Mode ◽  
Loop Control ◽  
Control Approach ◽  
Control Scheme ◽  
Loop Control System

In this paper, a closed-loop brain stimulation control problem is investigated using the nonsingular integral terminal sliding mode (NITSM) control approach. First, the thalamocortical model of epilepsy seizure is given, which is composed of the cortical PY-IN subnetwork and the subcortical RE-TC subsystem. Then, a nonsingular integral terminal sliding mode surface is designed utilizing the derived output tracking error, and the stability of the sliding mode dynamics is proved by Lyapunov approach. Furthermore, a disturbance observer (DOB) based NITSM controller design approach is proposed for the established thalamocortical model, and the reachability of the closed-loop control system under the designed controller is analyzed using Lyapunov theory. Finally, simulation results are given to illustrate the effectiveness and superiority of the designed control scheme.

scholarly journals Hybrid Force and Position Control Strategy of Robonaut Performing Object Transfer Task

2018 ◽  
Vol 160 ◽  
pp. 05003
Author(s):  
Gang Chen ◽  
Yu-Qi Wang ◽  
Qing-Xuan Jia ◽  
Pei-Lin Cai
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Control Method ◽  
Transfer Task ◽  
Internal Force ◽  
Matlab Simulation ◽  
Constraint Force ◽  
Common Control ◽  
Transfer Operation ◽  
External Forces

This paper proposes a coordinated hybrid force/position control strategy of robonaut performing object transfer operation. Firstly, the constraint relationships between robonaut and object are presented. Base on them, the unified dynamic model of the robonaut and object is established to design the hybrid force/position control method. The movement, the internal force and the external constraint force of the object are considered as the control targets of the control system. Finally, a MATLAB simulation of the robonaut performing object transfer task verifies the correctness and effectiveness of the proposed method. The results show that all the targets can be control accurately by using the method proposed in this paper. The presented control method can control both internal and external forces while maintaining control accuracy, which is a common control strategy.

Blood Glucose Regulation for Diabetic Mellitus Using a Hybrid Intelligent Techniques

2005 ◽  
Author(s):  
Vidya Nandikolla ◽  
Desineni Naidu
Keyword(s):  
Optimal Control ◽  
Blood Glucose ◽  
Control Strategy ◽  
Closed Loop ◽  
Glucose Regulation ◽  
Regulation System ◽  
Blood Glucose Regulation ◽  
Control Scheme ◽  
Optimal Control Scheme ◽  
Soft Control

In this paper, we use a mathematical model for the interaction between the blood glucose and insulin concentration and investigates the on-line control schemes necessary to accomplish an external blood glucose regulation. The dynamic model is described in terms of blood glucose level, and net insulin level in blood as two state variables and external rate of blood glucose concentration as control variable. Using optimal regulation results, an objective is chosen to minimize the deviation of blood glucose from a preset level. The closed-loop optimal control scheme is developed for the biosystem in which a blood glucose sensor feeds information to a pump to release computed amount of insulin into the circulation system. The performance of the proposed optimal control scheme is compared with experimental results. Further to improve the closed-loop optimal performance, a soft control strategy based on adaptive neuro-fuzzy inference system (ANFIS) is devised leading to synergy of hard (optimal) and soft (artificial intelligent) control. ANFIS is a simple learning technique which is implemented in the framework of adaptive neural networks that provides the best optimization tool to find parameters that best fits the data. The application of this synergetic (hard and soft) control strategy to the diabetic regulation system shows good agreement between the experimental data and the theoretical/simulated results.

scholarly journals Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yuling Li
Keyword(s):  
Time Delays ◽  
Closed Loop ◽  
Internal Model Control ◽  
Bilateral Teleoperation ◽  
Closed Loop System ◽  
Teleoperation System ◽  
Model Control ◽  
The Stability ◽  
External Forces ◽  
Teleoperation Systems

The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC) design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

scholarly journals Adaptive Nonlinear Tire-Road Friction Force Estimation for Vehicular Systems Based on a Novel Differentiable Friction Model

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zhi-Jun Fu ◽  
Wei-Dong Xie ◽  
Xiao-Bin Ning
Keyword(s):  
Friction Force ◽  
Estimation Algorithm ◽  
Friction Model ◽  
Lyapunov Theory ◽  
Nonlinear Observer ◽  
Estimation Methods ◽  
Vehicle Speed ◽  
Force Estimation ◽  
Observer Error ◽  
Road Friction

A novel adaptive nonlinear observer-based parameter estimation scheme using a newly continuously differentiable friction model has been developed to estimate the tire-road friction force. The differentiable friction model is more flexible and suitable for online adaptive identification and control with the advantage of more explicit parameterizable form. Different from conventional estimation methods, the filtered regression estimation parameter is introduced in the novel adaptive laws, which can guarantee that both the observer error and parameter error exponentially converge to zero. Lyapunov theory has been used to prove the stability of the proposed methods. The effectiveness of the estimation algorithm is illustrated via a bus simulation model in the Trucksim software and simulation environment. The relatively accurate tire-road friction force was estimated just by the easily existing sensors signals wheel rotational speed and vehicle speed and the proposed method also displays strong robustness against bounded disturbances.

An online estimation algorithm to predict external forces acting on a front-end loader

2021 ◽  
pp. 095965182110055
Author(s):  
Riccardo Madau ◽  
Daniele Colombara ◽  
Addison Alexander ◽  
Andrea Vacca ◽  
Luigi Mazza
Keyword(s):  
Kinematic Model ◽  
Estimation Algorithm ◽  
Average Error ◽  
Specific Reference ◽  
Vehicle Speed ◽  
Force Estimation ◽  
Dynamic Features ◽  
Online Estimation ◽  
Wheel Loaders ◽  
External Forces

One of the most significant goals of earthmoving equipment is to maximize productivity during loading cycles. A real-time knowledge of the forces exchanged between the machine implement and the surrounding, that is, while digging, can be used in different ways to increase productivity. It can be used to determine the amount of material moved by the machine; or to find the optimal bucket trajectory; moreover, as input to traction control systems. This article presents an online force estimation algorithm able to predict vertical and horizontal forces exchanged between the front-loader and the surrounding environment, as well as the reaction forces through the implement itself. Taking the case of a 14-ton wheel loader as reference, this article illustrates the development of a simulation model for the analysis of the machine digging system, along with the instrumentation and testing of the proposed estimation algorithm. The model is divided into two sections describing, respectively, system kinematic and system dynamics. The kinematic model of the front-loader is compared against measurements, and results show an average error lower than 1%. The dynamic model predicts both hydraulic and dynamic features of the machine implement, achieving an accuracy on the payload mass within 2%–3%, even during dynamic conditions. The estimated pushing force reflects the expected behavior when tested for various pushing efforts and in different ground conditions. Eventually, the algorithm was tested on a complete loading cycle and the results show good consistency considering the measured front-loader trajectory and vehicle speed. The proposed model overcomes some drawbacks of the currently used technologies. For example, it allows for an online estimation of the bucket forces for any position of the implement. Although the results discussed in this article pertain to a specific reference machine, the proposed method can be extended to most wheel loaders equipped with standard digging equipment.

scholarly journals Double Closed-Loop Compound Control Strategy for Magnetic Liquid Double Suspension Bearing

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1195
Author(s):  
Jianhua Zhao ◽  
Yongqiang Wang ◽  
Xuchao Ma ◽  
Sheng Li ◽  
Dianrong Gao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Electromagnetic Force ◽  
Closed Loop ◽  
Static Characteristic ◽  
Magnetic Liquid ◽  
Initial Current ◽  
Electromagnetic System ◽  
Initial Flow ◽  
Hydrostatic Force ◽  
Position Feedback

As a new type of suspension bearing, the magnetic liquid double suspension bearing (MLDSB) is mainly supported by electromagnetic suspension and supplemented by hydrostatic support. At present, the MLDSB adopts the regulation strategy of “electromagnetic-position feedback closed-loop, hydrostatic constant-flow supply” (referred to as CFC mode). In the equilibrium position, the external load is carried by the electromagnetic system, and the hydrostatic system produces no supporting force. Thus, the carrying capacity and supporting stiffness of the MLDSB can be reduced. To solve this problem, the double closed-loop control strategy of “electromagnetic system-force feedback inner loop and hydrostatic-position feedback outer loop” (referred to as DCL mode) was proposed to improve the bearing performance and operation stability of the MLDSB. First, the mathematical models of CFC mode and DCL mode of the single DOF supporting system were established. Second, the real-time variation laws of rotor displacement, flow/hydrostatic force, and regulating current/electromagnetic force in the two control modes were plotted, compared, and analyzed. Finally, the influence law of initial current, flow, and controller parameters on the dynamic and static characteristic index were analyzed in detail. The results show that compared with that in CFC mode, the displacement in DCL mode is smaller, and the adjustment time is shorter. The hydrostatic force is equal to the electromagnetic force in DCL mode when the rotor returns to the balance position. Moreover, the system in DCL mode has better robustness, and the initial flow has a more obvious influence on the dynamic and static characteristic indexes. This study provides a theoretical basis for stable suspension control and the safe and reliable operation of the MLDSB.

scholarly journals Robust Quadrotor Control through Reinforcement Learning with Disturbance Compensation

2021 ◽  
Vol 11 (7) ◽  
pp. 3257
Author(s):  
Chen-Huan Pi ◽  
Wei-Yuan Ye ◽  
Stone Cheng
Keyword(s):  
Neural Network ◽  
Reinforcement Learning ◽  
Control Strategy ◽  
External Disturbance ◽  
Control Agent ◽  
Network Control ◽  
Outdoor Environment ◽  
Disturbance Compensation ◽  
Tracking Accuracy ◽  
Control Scheme

In this paper, a novel control strategy is presented for reinforcement learning with disturbance compensation to solve the problem of quadrotor positioning under external disturbance. The proposed control scheme applies a trained neural-network-based reinforcement learning agent to control the quadrotor, and its output is directly mapped to four actuators in an end-to-end manner. The proposed control scheme constructs a disturbance observer to estimate the external forces exerted on the three axes of the quadrotor, such as wind gusts in an outdoor environment. By introducing an interference compensator into the neural network control agent, the tracking accuracy and robustness were significantly increased in indoor and outdoor experiments. The experimental results indicate that the proposed control strategy is highly robust to external disturbances. In the experiments, compensation improved control accuracy and reduced positioning error by 75%. To the best of our knowledge, this study is the first to achieve quadrotor positioning control through low-level reinforcement learning by using a global positioning system in an outdoor environment.

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