Nonlinear Vibration Control Experimental System Design of a Flexible Arm Using Interactive Actuations from Shape Memory Alloy

Abstract

The flexible arm easily vibrates due to its thin structural characteristics, which affect the operation accuracy, so reducing the vibration of the flexible arm is a significant issue. Smart materials are very widely used in the research topic of vibration suppression. Considering the hysteresis characteristic of the smart materials, based on previous simulation research, this paper proposes an experimental system design of nonlinear vibration control by using the interactive actuation from shape memory alloy (SMA) for a flexible arm. The experiment system was an interactive actuator–sensor–controller combination. The vibration suppression strategy was integrated with an operator-based vibration controller, a designed integral compensator and the designed n-times feedback loop. In detail, a nonlinear vibration controller based on operator theory was designed to guarantee the robust stability of the flexible arm. An integral compensator based on an estimation mechanism was designed to optimally reduce the displacement of the flexible arm. Obtaining the desired tracking performance of the flexible arm was a further step, by increasing the n-times feedback loop. From the three experimental cases, when the vibration controller was integrated with the designed integral compensator, the vibration displacement of the flexible arm was much reduced compared to that without the integral compensator. Increasing the number of n-times feedback loops improves the tracking performance. The desired vibration control performance can be satisfied when n tends to infinity. The conventional PD controller stabilizes the vibration displacement after the 7th vibration waveform, while the vibration displacement approaches zero after the 4th vibration waveform using the proposed vibration control method, which is proved to be faster and more effective in controlling the flexible arm’s vibration. The experimental cases verify the effectiveness of the proposed interactive actuation vibration control approach. It is observed from the experimental results that the vibration displacement of the flexible arm becomes almost zero within less time and with lower input power, compared with a traditional controller.

Advanced Vibration-Based Fault Diagnosis and Vibration Control Methods

“…This Special Issue on “Advanced Vibration-Based Fault Diagnosis and Vibration Control Methods” includes twelve papers ranging across different methods used in the electrical and mechanical industries’ systems. The papers include a good literature review of the current new works on the verification of mechanical properties identification based on the impulse excitation technique and mobile device measurements [ 4 ], the method for bearing fault diagnosis under variable speeds based on envelope spectrum fault characteristic frequency band identification [ 5 ], the interface design of head-worn display applications for condition monitoring in aviation [ 6 ], color recurrence plots for bearing fault diagnoses [ 7 ], the failure mode detection and validation of a shaft-bearing system with common sensors [ 8 ], the strain response and buckling behavior of composite cylindrical shells subjected to external pressure with one end fixed and the other free of boundary conditions [ 9 ], the smartphone-based and data-driven superstructure state prediction method for highway bridges in service [ 10 ], the optimal control algorithm for stochastic systems with parameter drift [ 11 ], the nonlinear vibration control experimental system design of a flexible arm using interactive actuations from shape memory alloy [ 12 ], the design of an active vibration isolation controller with a disturbance observer-based linear quadratic regulator for optical reference cavities [ 13 ], the applicability of touchscreens in manned/unmanned aerial vehicle cooperative missions [ 14 ], and the engineering frequency domain analysis and vibration suppression of flexible aircraft based on an active disturbance rejection controller [ 15 ].…”

“…To reduce the flexible arm, smart materials are widely applied. Li et al [ 12 ] conducted a test system using smart materials with hysteresis characteristics for nonlinear vibration control, which was an interactive actuator–sensor–controller combination. They designed an integral compensator using an estimation mechanism to reduce the displacements of the flexible arms.…”