Vibration Control of Redundant Flexible-Joint Manipulators

1997 ◽  
Vol 119 (1) ◽  
pp. 119-125
Author(s):  
Fengfeng Xi
Keyword(s):  
Numerical Simulations ◽  
Vibration Control ◽  
Control Method ◽  
Optimization Technique ◽  
Main Idea ◽  
The Other ◽  
Control Law ◽  
Flexible Joint ◽  
Flexible Joint Manipulator

Presented in this paper is a method for controlling vibrations of a redundant flexible-joint manipulator. The main idea behind this method is to utilize joint redundancy to minimize the change in the manipulator inertia, so that a simple gain-fixed control law can be used to control joint vibrations. For this purpose, two optimal joint trajectory generators are proposed; one is based on the extended Jacobian method and the other is based on an optimization technique. Numerical simulations are provided to demonstrate the effectiveness of the proposed control method.

Observer-based robust control for flexible-joint robot manipulators: A state-dependent Riccati equation-based approach

2020 ◽  
Vol 42 (16) ◽  
pp. 3135-3155
Author(s):  
Neda Nasiri ◽  
Ahmad Fakharian ◽  
Mohammad Bagher Menhaj
Keyword(s):  
Robust Control ◽  
Control Problem ◽  
Riccati Equation ◽  
Power Transmission ◽  
Control Method ◽  
Main Idea ◽  
Robotic Systems ◽  
Flexible Joint ◽  
State Dependent ◽  
Highly Nonlinear

In this paper, the robust control problem is tackled by employing the state-dependent Riccati equation (SDRE) for uncertain systems with unmeasurable states subject to mismatched time-varying disturbances. The proposed observer-based robust (OBR) controller is applied to two highly nonlinear, coupled and large robotic systems: namely a manipulator presenting joint flexibility due to deformation of the power transmission elements between the actuator and the robot known as flexible-joint robot (FJR) and also an FJR incorporating geared permanent magnet DC motor dynamics in its dynamic model called electrical flexible-joint robot (EFJR). A novel state-dependent coefficient (SDC) form is introduced for uncertain EFJRs. Rather than coping with the OBR control problem for such complex uncertain robotic systems, the main idea is to solve an equivalent nonlinear optimal control problem where the uncertainty and disturbance bounds are incorporated in the performance index. The stability proof is presented. Solving the complicated robust control problem for FJRs and EFJRs subject to uncertainty and disturbances via a simple and flexible nonlinear optimal approach and no need of state measurement are the main advantages of the proposed control method. Finally, simulation results are included to verify the efficiency and superiority of the control scheme.

High Performance Structural Vibration Control by a Preview of the Future Seismic Waveform Generated With a Wave Transmission Network and an AI-Based Estimation System

2019 ◽  
Author(s):  
Kazuhiko Hiramoto ◽  
Taichi Matsuoka ◽  
Katsuaki Sunakoda
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Small Scale ◽  
Control Law ◽  
Time Interval ◽  
Transmission Network ◽  
Control Performance ◽  
Seismic Waveform ◽  
The Future ◽  
Estimation System

Abstract We propose a new active vibration control strategy based on the future seismic waveform information obtained in remote observation sites. The waveform information in the remote site is transmitted by a waveform transmission network to the structure under control. The waveform transmission network is realized by interconnecting multiple controlled structures and observation sites. By using the future waveform information obtained through the network, we propose a control law realizing fairly higher control performance over the conventional structural control methodologies. A preview control law consisting of the state-feedback and feedforward control (preview action) is adopted. For the preview action, future values of the disturbance in some time interval are necessary. However, because the future value of the earthquake waveform is unknown, the preview action contributing the performance improvement is generally impossible. To get over this difficulty, an AI-based wave estimation system to estimate the future earthquake waveform is proposed. The wave estimation system is a multi-layered artificial neural network (ANN). Through a small scale simulation study with a recorded earthquake event in Japan, we show that the proposed control method achieves much higher control performance over the conventional LQ-based active control.

scholarly journals Sliding mode controller design for second-order unstable processes with dead-time

2020 ◽  
Vol 71 (4) ◽  
pp. 237-245
Author(s):  
Mohammad Atif Siddiqui ◽  
Md Nishat Anwar ◽  
Shahedul Haque Laskar
Keyword(s):  
Performance Index ◽  
Dead Time ◽  
Sliding Mode ◽  
Search Algorithm ◽  
Optimization Technique ◽  
Second Order ◽  
The Other ◽  
Control Law ◽  
Continuous Control ◽  
Discontinuous Control

AbstractA new approach is proposed to design the sliding mode (SM) controller for the unstable second-order plus dead-time (SOPDT) processes. The sliding mode control consists of two control laws ie continuous control law and discontinuous control law. The continuous control law parameters have been derived in terms of unstable SOPDT process parameters using the root locus technique. On the other hand, the parameters of discontinuous control law are tuned by optimizing a performance index using a recently developed metaheuristic search algorithm, namely the grasshopper optimization technique. The performance index is framed to achieve a good trade-off between performance and control efforts. Finally, simulations are conducted to validate the effectiveness of the proposed approach over the other existing techniques. It is observed that the proposed approach is able to deliver better disturbance rejection, minimal control efforts and good setpoint tracking.

scholarly journals A Transmission Power Self-Optimization Technique for Wireless Sensor Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
F. Lavratti ◽  
A. Ceratti ◽  
D. Prestes ◽  
A. R. Pinto ◽  
L. Bolzani ◽  
...  
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Electromagnetic Interference ◽  
Optimization Technique ◽  
Data Communication ◽  
Main Idea ◽  
The Other ◽  
Wireless Sensor ◽  
Transmission Power

Wireless sensor networks (WSNs) are generally used to monitor hazardous events in inaccessible areas. Thus, on one hand, it is preferable to assure the adoption of the minimum transmission power in order to extend as much as possible the WSNs lifetime. On the other hand, it is crucial to guarantee that the transmitted data is correctly received by the other nodes. Thus, trading off power optimization and reliability insurance has become one of the most important concerns when dealing with modern systems based on WSN. In this context, we present a transmission power self-optimization (TPSO) technique for WSNs. The TPSO technique consists of an algorithm able to guarantee the connectivity as well as an equally high quality of service (QoS), concentrating on the WSNs efficiency (Ef), while optimizing the transmission power necessary for data communication. Thus, the main idea behind the proposed approach is to trade off WSNs Ef against energy consumption in an environment with inherent noise. Experimental results with different types of noise and electromagnetic interference (EMI) have been explored in order to demonstrate the effectiveness of the TPSO technique.

A model-based PID-like motion control method for flexible-joint manipulator with harmonic drives

2021 ◽  
pp. 095440622110369
Author(s):  
Guocai Yang ◽  
Yechao Liu ◽  
Junhong Ji ◽  
Minghe Jin ◽  
Songhao Piao
Keyword(s):  
Position Control ◽  
Control Method ◽  
Joint Torque ◽  
Dynamics Model ◽  
Motion Error ◽  
Flexible Joint ◽  
Speed Range ◽  
Position Controller ◽  
Flexible Joint Manipulator ◽  
Better Than

A novel control method is proposed to achieve high trajectory tracking precision, for flexible-joint manipulators. The method consists of three major parts: joint torque generator, joint torque tracker and motor position controller. The expected torque is generated by a PID controller based on the manipulator’s rigid dynamics model. In the torque tracker, motor position is corrected in both feedback and feedforward ways. Finally, the motor position controller is responsible to track the corrected motor trajectory to achieve the torque and position control. To suppress nonlinear friction, a disturbance observer is also implemented. The method is verified with a seven-DOFs manipulator. Simulation and experimental results show that, the proposed method is efficient and practical to suppress vibration caused by flexible transmission and disturbance due to friction. As result, high positioning accuracy is achieved in a certain wide working speed range. The no-load motion accuracy is better than 0.6 mm with a manipulator whose length is 1.8 meter, and the motion error is less than 3 mm with loading of four kilograms.

A new control method of flexible-joint manipulator with harmonic drive

2020 ◽  
Vol 234 (9) ◽  
pp. 1868-1883
Author(s):  
Guocai Yang ◽  
Yechao Liu ◽  
Minghe Jin
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Joint Stiffness ◽  
Adaptive Controller ◽  
Harmonic Drive ◽  
Flexible Joint ◽  
Assignment Method ◽  
Uncertain Dynamics ◽  
Tracking Controller ◽  
Flexible Joint Manipulator

Considerable elasticity and nonlinear friction caused by harmonic transmission challenge the performance of flexible-joint manipulators. The uncertain dynamics of manipulator and the inadequate measurable states also limit the controller design. A new control method is proposed to address these problems, achieving the precise motion control of the flexible-joint manipulator. The method consists of three cascaded controllers: an adaptive controller, a torque-tracking controller, and a motor controller. The adaptive controller was adopted to generate the desired torque ensuring the robustness for uncertain dynamics. The torque-tracking controller derived the position compensation for motor control according to the torque error. As the elastic torque is under control, the vibration caused by harmonic drive can be eliminated. The motor was controlled based on poles-assignment method and friction compensation. The Kalman observer based on the Brownian motion model observed both velocity and the high-order derivatives of torque sensing. The stability of the control method was strictly proved. Calibration was performed on each joint to obtain the required joint stiffness and motor friction parameters. The control method was verified on a single joint and the frequency response of the system was obtained. The results show that the controller has good performance. The controller was realized on the self-developed seven-degree-of-freedom manipulator. The results reveal that the controller has high-precision tracking performance.

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