Angular Positioning and Vibration Control of a Slewing Flexible Control by Applying Smart Materials and Sliding Modes Control

Author(s):  
Frederic C. Janzen ◽  
Jose M. Balthazar ◽  
Angelo M. Tusset ◽  
Rodrigo T. Rocha ◽  
Jeferson Jose de Lima

Flexible links undergoing a slewing motion are widely found in aerospace structures such as satellites and robotic manipulators. In this kind of systems, the lighter the structure the better is its performance and more cost effective is the system. However, the positioning control of flexible structures is challenging because the flexibility may lead the system to vibrate in larger amplitudes, which makes the need of using actuators to control and reduce vibrations. An alternative for those actuators is the use of smart materials, as SMA (Shape Memory Alloys) to control vibrations of such structures. This work will present the angular positioning and vibration control of a flexible link. The angular position control is a torque driven by a DC motor controlled through a sliding modes control method. The system is considered as non-ideal, it means that the vibration of the flexible link accomplishes to the DC motor shaft. SMA actuators are coupled to the flexible link with the objective to reduce the vibration amplitudes and reducing so the settling time of the system. The SMA actuators are controlled through an electric voltage applied to its terminals by applying the Sliding modes control method. The dynamical equations of motion for the system are developed considering a dead zone nonlinearity of the DC motor and a phenomenological model for the SMA. The flexible link is modeled as a continuous structure and just the first vibration mode is analyzed. Numerical simulations results are presented to demonstrate the effectiveness of the sliding modes strategy for the positioning control of the DC motor and for the vibration suppression of the flexible link by using SMA actuators.

Author(s):  
Frederic Conrad Janzen ◽  
Angelo Marcelo Tusset ◽  
Jose Manoel Balthazar

This work presents the angular positioning control of a flexible beam like structure connected to the shaft of a DC (Direct Current) motor. The coupling between the flexible structure and the DC motor is considered as not ideal being that the structure model considers three vibration modes. A non-linearity known as death zone is included in the DC motor model. To control the angular position a Sliding mode controller is proposed and the influence of the control gains is analyzed numerically. Numerical simulations will be presented to demonstrate the application of the sliding modes technic in order to control the positioning of the flexible link by controlling the DC motor armor current.


Author(s):  
Byeongil Kim ◽  
Gregory N. Washington

This paper investigates a novel nonlinear positioning control methodology for piezoelectric stack actuators. Piezoelectric devices become very common recently for precise positioning, primarily due to the fact that they are solid state and can be accurately controlled by a voltage or current input. However, hysteresis decreases positioning accuracy and could lead to instability. The ultimate goal is to reduce it so that the piezoelectric device has a nearly linear relationship between the input field and output strain. The main purpose of this research is the reduction of the hysteresis utilizing a hysteresis model and a nonlinear model-based controller. A novel control method called model predictive sliding mode control (MPSMC) will be utilized on an actuator using a nonlinear energy-based hysteresis model. The idea of MPSMC is to implement model predictive control techniques to improve sliding mode control by forcing the system to reach the sliding surface in an optimal manner. Simulations and experiments were conducted to verify the technique.


2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Barış Can Yalçın ◽  
Haluk Erol

A semiactive vibration control method is developed to cope with the dynamic stability problem of a horizontal axis washing machine. This method is based on adjusting the maximum force values produced by the semiactive suspension elements considering a washing machine’s vibration data (three axis angular position and three axis angular acceleration values in time). Before actuation signals are received by the step motors of the friction dampers, vibration data are evaluated, and then, the step motors start to narrow or expand the radius of bracelets located on the dampers. This changes the damping properties of the damper in the suspension system, and thus, the semiactive suspension system absorbs unwanted vibrations and contributes to the dynamic stability of the washing machine. To evaluate the vibration data, the angular position and angular acceleration values in three axes are defined in a function, and the maximum forces produced by semiactive suspension elements are calculated according to the gradient of this function. The relation between the dynamic stability and the walking stability is also investigated. A motion (gyroscope and accelerometer) sensor is installed on the top-front panel of the washing machine because a mathematical model of a horizontal axis washing machine suggests that the walking behavior starts around this location under some assumptions, and therefore, calculating the vibrations occurring there is crucial. Semiactive damping elements are located under the left and right sides of the tub. The proposed method is tested during the spinning cycle of washing machine operation, increasing gradually from 200 rpm to 900 rpm, which produces the most challenging vibration patterns for dynamic stability. Moreover, the sound power levels produced by the washing machine are measured to evaluate the noise performance of the washing machine while the semiactive suspension system is controlled. The effectiveness of the proposed control method is shown through experimental results.


Author(s):  
Diego Rolim Porto ◽  
Gabriel da Silva Lima ◽  
Wallace Moreira Bessa

2009 ◽  
Vol 419-420 ◽  
pp. 617-620
Author(s):  
Wei Chen ◽  
Yue Qing Yu ◽  
Xin Hua Zhao ◽  
Lian Yu Zhao

Underactuated flexible manipulator with redundant degrees of freedoms is investigated. Position control method of a single active joint driving the passive joint is given. According to the characteristics of nonholonomiclly redundant flexible manipulators, the optimal control strategy of multiple active joints driving the passive joints is proposed. As the elastic vibration of flexible links can not be eliminated only through position control, the vibration control schemes are presented again. The simulation results show that the elastic vibration is suppressed effectively. Therefore, for nonholonomically redundant flexible manipulator, both position control and vibration control are implemented successfully, which verifies the validity of the control schemes.


Author(s):  
Debargha Chakraborty ◽  
Binanda Kishore Mondal ◽  
Souvik Chatterjee ◽  
Sudipta Ghosh

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 67
Author(s):  
Laixi Zhang ◽  
Chenming Zhao ◽  
Feng Qian ◽  
Jaspreet Singh Dhupia ◽  
Mingliang Wu

Vibrations in the aircraft assembly building will affect the precision of the robotic drilling system. A variable stiffness and damping semiactive vibration control mechanism with quasi-zero stiffness characteristics is developed. The quasi-zero stiffness of the mechanism is realized by the parallel connection of four vertically arranged bearing springs and two symmetrical horizontally arranged negative stiffness elements. Firstly, the quasi-zero stiffness parameters of the mechanism at the static equilibrium position are obtained through analysis. Secondly, the harmonic balance method is used to deal with the differential equations of motion. The effects of every parameter on the displacement transmissibility are analyzed, and the variable parameter control strategies are proposed. Finally, the system responses of the passive and semiactive vibration isolation mechanisms to the segmental variable frequency excitations are compared through virtual prototype experiments. The results show that the frequency range of vibration isolation is widened, and the stability of the vibration control system is effectively improved without resonance through the semiactive vibration control method. It is of innovative significance for ambient vibration control in robotic drilling systems.


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