scholarly journals System integration and control design of a maglev platform for space vibration isolation

2019 ◽  
Vol 25 (11) ◽  
pp. 1720-1736 ◽  
Author(s):  
Zhaopei Gong ◽  
Liang Ding ◽  
Honghao Yue ◽  
Haibo Gao ◽  
Rongqiang Liu ◽  
...  
Keyword(s):  
System Integration ◽  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Minimum Energy ◽  
Optimization Method ◽  
Dominant Factor ◽  
Loop Control ◽  
Scientific Experiments ◽  
Micro Vibration ◽  
Close Loop Control

Micro-vibration has been a dominant factor impairing the performance of scientific experiments which are expected to be deployed in a micro-gravity environment such as a space laboratory. The micro-vibration has serious impact on the scientific experiments requiring a quasi-static environment. Therefore, we proposed a maglev vibration isolation platform operating in six degrees of freedom (DOF) to fulfill the environmental requirements. In view of the noncontact and large stroke requirement for micro-vibration isolation, an optimization method was utilized to design the actuator. Mathematical models of the actuator's remarkable nonlinearity were established, so that its output can be compensated according to a floater's varying position and a system's performance may be satisfied. Furthermore, aiming to adapt to an energy-limited environment such as space laboratory, an optimum allocation scheme was put forward, considering that the actuator's nonlinearity, accuracy, and minimum energy-consumption can be obtained simultaneously. In view of operating in 6-DOF, methods for nonlinear compensation and system decoupling were discussed, and the necessary controller was also presented. Simulation and experiments validate the system's performance. With a movement range of 10 × 10 × 8 mm and rotations of 200 mrad, the decay ratio of −40 dB/Dec between 1 and 10 Hz was obtained under close-loop control.

Study on Practical FBG Acceleration System

2011 ◽  
Vol 346 ◽  
pp. 546-550
Author(s):  
Wei Guang Zhang ◽  
Jian Zhang
Keyword(s):  
System Application ◽  
High Frequency ◽  
High Sensitivity ◽  
Acceleration Measurement ◽  
Cross Sensitivity ◽  
Loop Control ◽  
Sensitivity Problem ◽  
Micro Vibration ◽  
Low Sensitivity ◽  
Close Loop Control

A micro vibration, high sensitivity FBG demodulation system with close loop control is presented. By introducing a close loop control, the difficulty in matched FBG making process is overcame. Further more, the FBG strain-temperature cross sensitivity problem is settled. And low sensitivity in high frequency of cantilever FBG accelerator is overcame either. An example of the system application in acceleration measurement is introduced.

Study on a 4-DOF multi-dimensional vibration isolation platform based on 4-UPU parallel mechanism

2021 ◽  
Author(s):  
Ying Zhang ◽  
Xiaodong Guo ◽  
Shijia Yu
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Kinematic Model ◽  
Experimental Studies ◽  
Optimization Method ◽  
Response Analysis ◽  
Vibration Model ◽  
Fixed Base ◽  
Physical Prototype

A novel 4-DOF (degrees of freedom) multi-dimensional vibration isolation platform (MDVIP) based on 4-UPU (U denotes universal joint, P denotes prismatic joint) parallel mechanism is put forward for vibration isolation of the sensitive devices. It consists of 4 limbs and each limb has two universal joints and a module of spring damper. The kinematic model and vibration model of the proposed MDVIP are established and analyzed. The main dimensions of the MDVIP and the parameters of the spring damper module are designed by optimization method to meet various design requirements and constraints. Both the virtual prototype and physical prototype of the MDVIP are built to testify the vibration isolation performance. The results of numerical calculation, simulation and experimental studies based on vibration response analysis show that the proposed MDVIP can isolate at least 78% vibration from the fixed base in three axial directions and 64% vibration in the direction around the Z-axis, and thus may attenuate the disturbances to the items on the moving platform to a large extent.

Visual-Servo Autonomous Robotic Manipulators for Capturing Non-Cooperative Target

2014 ◽  
Author(s):  
Gangqi Dong ◽  
Z. H. Zhu
Keyword(s):  
Degrees Of Freedom ◽  
Robotic Manipulators ◽  
Robotic Manipulator ◽  
Loop Control ◽  
Six Degrees Of Freedom ◽  
Transformation Matrices ◽  
Control Scheme ◽  
And Control ◽  
Close Loop Control ◽  
Real State

This paper presents a methodology of vision-based pose and motion estimation of non-cooperative targets as well as a control scheme for robotic manipulators to perform autonomous capture of non-cooperative targets. A combination of photogrammetry and extended Kalman filter is proposed for real time state estimation of the non-cooperative target. Once the vision-based estimation is obtained, a real state of the target regarding to the global frame is calculated based on the transformation matrices of coordinate frames. So as to make a capture, a desired state of the end effector is defined in accordance with the real state of the target aforementioned, and further a corresponding desired state of the robotic manipulator is derived by inverse kinematics. Then a close-loop control scheme is adopted to drive the robot to the desired state previously obtained. Experiments have been designed and implemented on a custom built six degrees of freedom robotic manipulator with an eye-in-hand configuration. The experimental results demonstrated the feasibility and effectiveness of the proposed methodology and control scheme.

Simulation of Multi-Closed Loop Control With Feed Forward Control of Micro-Vibration Isolation Platform

2014 ◽  
Author(s):  
Qianqian Wu ◽  
Honghao Yue ◽  
Rongqiang Liu ◽  
Liang Ding ◽  
Zongquan Deng
Keyword(s):  
Vibration Isolation ◽  
Closed Loop ◽  
Control Method ◽  
Magnetic Levitation ◽  
Low Frequency ◽  
Closed Loop Control ◽  
Vibration Source ◽  
Feed Forward ◽  
Loop Control ◽  
Micro Vibration

Micro vibration in the ideal-zero gravity environments has complicated science experiment results. A magnetic levitation vibration isolation platform is needed to isolate the vibration source to provide acceptable acceleration level in low frequency range. The configuration of the Lorentz actuators is discussed in the paper. And the modeling of the transformation matrix from the force to the current is deduced. In order to generate desired force, the current is needed to predict precisely. To study the characteristics of the system, the single degree of freedom system is analyzed. A multi-closed loop control scheme is put forward to achieve vibration isolation control. To evaluate the effect of each control parameter, frequency domain analysis of the transfer function is simulated. In order to further increase the control effectiveness, a feed forward compensation control algorithm is added to control the vibration of cables that connect the upper platform and the base. By regulating these control parameters, bode curves can be obtained. Comparing the two methods, it can be concluded that the control method with feed forward compensation is better than the one without that.

A 6-DOF micro-vibration isolation platform based on the quasi-zero-stiffness isolator

2021 ◽  
pp. 095440622110108
Author(s):  
Jie Tang ◽  
Yang Yang ◽  
Yinghui Li ◽  
Dengqing Cao
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Lagrange Equation ◽  
Great Influence ◽  
Excitation Amplitude ◽  
Regulation Mechanism ◽  
Structure Parameters ◽  
Dynamical Equations ◽  
Micro Vibration ◽  
Isolation Performance

Micro-vibrations generated by rotating machinery could influence the working performance of the precise instruments equipped in industrial facilities, aircraft, ships, etc. Isolation systems are thus essential for preventing the high-sensitive instruments from being disturbed. In this work, a 6 degrees-of-freedom (DOF) micro-vibration isolation platform is proposed based on the quasi-zero-stiffness (QZS) isolator. The structure of the isolation platform is a conventional Stewart mechanism equipped with the QZS isolators in each leg. To analyze the stiffness of the leg, the static analysis is carried out. Afterwards, the stiffness of the platform in six directions are also discussed. Moreover, the dynamical equations of the isolation platform are formulated by the Lagrange Equation. Finally, the dynamic response of the proposed model is investigated and compared with the linear case whose stiffness of the leg is linear. The results show that the newly designed QZS platform in this work has a good isolation performance, which can attenuate the external vibrations significantly within a broad frequency band. Parametric analysis shows that the structure parameters, damping and excitation amplitude have a great influence on the isolation performance of the QZS platform. Delightfully, the result of indicates that, (a) the newly designed QZS platform is able to provide an excellent isolation performance in all the six DOFs, which advances the dynamic study of multi-dimensional QZS vibration isolation; (b) The multi-dimensional vibration isolation platform is innovatively designed using geometric nonlinear technology, there is no influence of the magnetic sources to the precision instruments when compared with the previous designs; (c) the regulation mechanism of the structure parameters of the QZS isolation platform on the dynamic transmission characteristics of the system is revealed, which indicates that the platform is particularly suitable for micro-vibration isolation whose vibration magnitude and frequency are quite low.

Maglev Linear Actuator for Nanopositioning

2002 ◽  
Author(s):  
Won-jong Kim ◽  
Himanshu Maheshwari ◽  
Jie Gu
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Force Feedback ◽  
Linear Actuator ◽  
Test Results ◽  
Loop Control ◽  
Nanoscale Structures ◽  
Six Degrees Of Freedom ◽  
Positioning Device ◽  
Disturbance Analysis

Manufacture of nanoscale structures and atomic-level manipulation is an emerging technology field in the 21st century [1,2]. This paper presents a novel magnetically levitated instrument capable of six-degrees-of-freedom (6-DOF) motion with a single moving part. The applications, where this generic positioning device can be used, are manufacturing of nanoscale structures, assembly and packaging of microparts, vibration isolation for delicate instrumentation and motion/force feedback in telepresence surgery. The key element of this stage is a linear actuator capable of providing forces in both suspension and translation without contact. The total range of motion for the linear actuator is ±250 μm. In this paper, we present the closed-loop control test results and stochastic noise/disturbance analysis and prediction for the linear actuator.

An Efficient Approach for Modeling and Control of a Quadrotor

2016 ◽  
Vol 4 (2) ◽  
pp. 1-16
Author(s):  
Ahmed S. Khusheef
Keyword(s):  
Pid Control ◽  
Control Method ◽  
Mechanical Design ◽  
Loop Control ◽  
Modeling And Control ◽  
Loop Control System ◽  
And Control ◽  
Close Loop Control ◽  
Close Loop Control System ◽  
Made In

 A quadrotor is a four-rotor aircraft capable of vertical take-off and landing, hovering, forward flight, and having great maneuverability. Its platform can be made in a small size make it convenient for indoor applications as well as for outdoor uses. In model there are four input forces that are essentially the thrust provided by each propeller attached to each motor with a fixed angle. The quadrotor is basically considered an unstable system because of the aerodynamic effects; consequently, a close-loop control system is required to achieve stability and autonomy. Such system must enable the quadrotor to reach the desired attitude as fast as possible without any steady state error. In this paper, an optimal controller is designed based on a Proportional Integral Derivative (PID) control method to obtain stability in flying the quadrotor. The dynamic model of this vehicle will be also explained by using Euler-Newton method. The mechanical design was performed along with the design of the controlling algorithm. Matlab Simulink was used to test and analyze the performance of the proposed control strategy. The experimental results on the quadrotor demonstrated the effectiveness of the methodology used.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

Acoustic radiation simulation and pre-stress effect on compact acoustic levitation platform

2019 ◽  
Vol 33 (07) ◽  
pp. 1950080 ◽  
Author(s):  
Bin Wei ◽  
Yongyong He ◽  
Wei Wang
Keyword(s):  
Pressure Distribution ◽  
Acoustic Radiation ◽  
Near Field ◽  
Parameters Optimization ◽  
Squeeze Film ◽  
Acoustic Levitation ◽  
Stress Effect ◽  
Biological Engineering ◽  
Loop Control ◽  
Close Loop Control

In order to satisfy the requirements of precise components with tidiness, low power and high stability in the field of biological engineering, medical equipment and semiconductors etc. a pre-stress acoustic transport prototype without horn was proposed in this paper. The mechanism of levitation and transport which is driven by orthogonal waves was revealed by the analysis of waveform and squeeze film characteristics in high-frequency exciting condition; also, the electric, solid and acoustic coupled finite element method (FEM) was established to investigate the effect of pre-stress and acoustic pressure distribution in the near field. The levitation and driving capacity of near field acoustic levitation (NFAL) transport platform without horns can be proved in this experiment and further to achieve the goal of parameters optimization. The theoretical and experimental results indicate that the pre-stress has a significant effect on resonant frequency and levitating stability, the pre-stress are determined by the DC voltage offset which is related to the system working point so that we cannot increase the offset and exciting voltage unlimitedly to improve the stability. At the same time, the calculated pressure distribution of acoustic radiation can generally reflect the regional bearing capacity in near and far field for levitation. These achievements can partly solve the problem of accuracy design of prototype and thickness of gas film, supporting for accuracy close loop control of levitating height.

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