Vibration Stabilization of a Flexible Beam Under Fluid Loading by Utilizing Piezoceramics

OBJECTIVE: The accuracy of stroke volume variation (SVV) obtained by the FloTrac™/Vigileo™ system in otherwise healthy patients undergoing brain surgery was assessed. METHODS: Anaesthesia was induced in 48 patients with minimal fluid infusion. Before surgery, fluid volume loading was performed by infusion with Ringer's lactate solution in 200 ml steps over 3 min, repeated successively if the patient responded with an increase in stroke volume of ≥ 10%, until the increase was < 10% (nonresponsive). RESULTS: A total of 157 volume loading steps were performed in the 48 patients. Responsive and nonresponsive steps differed significantly in baseline values of blood pressure, heart rate and SVV. Significant correlations were found between the change in stroke volume after fluid loading and values of blood pressure, heart rate and SVV before fluid loading, with SVV the most sensitive variable. CONCLUSION: Stroke volume variation obtained using the FloTrac™/Vigileo™ system is a sensitive predictor of fluid responsiveness in healthy patients before brain surgery.

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The Study of Dynamic Modeling and Multivariable Feedback Control for Flexible Manipulators with Friction Effect and Terminal Load

Sensors ◽

10.3390/s21041522 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1522

Author(s):

Fuli Zhang ◽

Zhaohui Yuan

Keyword(s):

Dynamic Model ◽

Vibration Suppression ◽

Control Method ◽

Coupling Effect ◽

Flexible Manipulator ◽

Flexible Beam ◽

Robot Dynamics ◽

Joint Friction ◽

Balance Principle ◽

Multivariable Feedback

The flexible manipulato is widely used in the aerospace industry and various other special fields. Control accuracy is affected by the flexibility, joint friction, and terminal load. Therefore, this paper establishes a robot dynamics model under the coupling effect of flexibility, friction, and terminal load, and analyzes and studies its control. First of all, taking the structure of the central rigid body, the flexible beam, and load as the research object, the dynamic model of a flexible manipulator with terminal load is established by using the hypothesis mode and the Lagrange method. Based on the balance principle of the force and moment, the friction under the influence of flexibility and load is recalculated, and the dynamic model of the manipulator is further improved. Secondly, the coupled dynamic system is decomposed and the controller is designed by the multivariable feedback controller. Finally, using MATLAB as the simulation platform, the feasibility of dynamic simulation is verified through simulation comparison. The results show that the vibration amplitude can be reduced with the increase of friction coefficient. As the load increases, the vibration can increase further. The trajectory tracking and vibration suppression of the manipulator are effective under the control method of multi-feedback moment calculation. The research is of great significance to the control of flexible robots under the influence of multiple factors.

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Improving the Detection of the Contact Point in Active Sensing Antennae by Processing Combined Static and Dynamic Information

Sensors ◽

10.3390/s21051808 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1808

Author(s):

Luis Mérida-Calvo ◽

Daniel Feliu-Talegón ◽

Vicente Feliu-Batlle

Keyword(s):

Contact Point ◽

Load Cell ◽

Robotic Systems ◽

Accurate Estimation ◽

Flexible Beam ◽

Dynamic Information ◽

New Developments ◽

Static Information ◽

Insect Antennae ◽

Flexible Antenna

The design and application of sensing antenna devices that mimic insect antennae or mammal whiskers is an active field of research. However, these devices still require new developments if they are to become efficient and reliable components of robotic systems. We, therefore, develop and build a prototype composed of a flexible beam, two servomotors that drive the beam and a load cell sensor that measures the forces and torques at the base of the flexible beam. This work reports new results in the area of the signal processing of these devices. These results will make it possible to estimate the point at which the flexible antenna comes into contact with an object (or obstacle) more accurately than has occurred with previous algorithms. Previous research reported that the estimation of the fundamental natural frequency of vibration of the antenna using dynamic information is not sufficient as regards determining the contact point and that the estimation of the contact point using static information provided by the forces and torques measured by the load cell sensor is not very accurate. We consequently propose an algorithm based on the fusion of the information provided by the two aforementioned strategies that enhances the separate benefits of each one. We demonstrate that the adequate combination of these two pieces of information yields an accurate estimation of the contacted point of the antenna link. This will enhance the precision of the estimation of points on the surface of the object that is being recognized by the antenna. Thorough experimentation is carried out in order to show the features of the proposed algorithm and establish its range of application.

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A Nonlinear Magnetic Stabilization Control Design for an Externally Manipulated DC Motor: An Academic Low-Cost Experimental Platform

Machines ◽

10.3390/machines9050101 ◽

2021 ◽

Vol 9 (5) ◽

pp. 101

Author(s):

Leonardo Acho

Keyword(s):

Hall Effect ◽

Position Control ◽

Low Cost ◽

Time Derivative ◽

Control Design ◽

Dc Motor ◽

Flexible Beam ◽

Experimental Platform ◽

Hall Effect Sensor ◽

Vibrational Control

The main objective of this paper is to present a position control design to a DC-motor, where the set-point is externally supplied. The controller is conceived by using vibrational control theory and implemented by just processing the time derivative of a Hall-effect sensor signal. Vibrational control is robust against model uncertainties. Hence, for control design, a simple mathematical model of a DC-Motor is invoked. Then, this controller is realized by utilizing analog electronics via operational amplifiers. In the experimental set-up, one extreme of a flexible beam attached to the motor shaft, and with a permanent magnet fixed on the other end, is constructed. Therefore, the control action consists of externally manipulating the flexible beam rotational position by driving a moveable Hall-effect sensor that is located facing the magnet. The experimental platform results in a low-priced device and is useful for teaching control and electronic topics. Experimental results are evidenced to support the main paper contribution.

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