Data Driven Vibration Control:A Review

With the ongoing advancements in sensor networks and data acquisition technologies across various systems like manufacturing,aviation,and healthcare,the data driven vibration control(DDVC)has attracted broad interests from both the industrial and academic communities.Input shaping(IS),as a simple and effective feedforward method,is greatly demanded in DDVC methods.It convolves the desired input command with impulse sequence without requiring parametric dynamics and the closed-loop system structure,thereby suppressing the residual vibration separately.Based on a thorough investigation into the state-of-the-art DDVC methods,this survey has made the following efforts:1)Introducing the IS theory and typical input shapers;2)Categorizing recent progress of DDVC methods;3)Summarizing commonly adopted metrics for DDVC;and 4)Discussing the engineering applications and future trends of DDVC.By doing so,this study provides a systematic and comprehensive overview of existing DDVC methods from designing to optimizing perspectives,aiming at promoting future research regarding this emerging and vital issue.

A rotary pneumatic actuator for the actuation of the exoskeleton knee joint

Rotary pneumatic actuators that are made out of linear one are always best suited for exoskeleton joint actuation due to its inherent power to weight ratio. This work is a modified version of knee actuation system that has already been developed and major modifications are made in order to make it more suitable for human wearing and also to reduce its bulkiness and complexity. The considered actuator system is a rotary actuator where a pulley converts the linear motion of the standard pneumatic piston into the rotary motion. To prove the capability of the actuator, its performance characteristics such as torque and power produced are compared to the required torque and power at the knee joint of the exoskeleton in swing phase and are found to be excellent. The two-way analysis of variance（ANOVA）is performed to find the effect of the throat area valve on knee angle. The ANOVA shows the significant effect of the throat area variation on the knee angle flexion made by the proposed actuator. A relationship between the throat area of flow control valve, that is connected to the exit port of the direction control valve, and angular displacement of the knee joint has been formulated. This relationship can be used to design a control system to regulate the mass flow rate of air at the exit and hence the angular velocity of the knee joint can be controlled.

A Maximum Principle for Fully Coupled Forward-Backward Stochastic Control System Driven by Lvy Process with Terminal State Constraints

This paper is concerned with a fully coupled forward-backward stochastic optimal control problem where the controlled system is driven by Levy process, while the forward state is constrained in a convex set at the terminal time. The authors use an equivalent backward formulation to deal with the terminal state constraint, and then obtain a stochastic maximum principle by Ekeland＇s variational principle. Finally, the result is applied to the utility optimization problem in a financial market.

Modeling and Robust Discrete LQ Repetitive Control of Electrically Driven Robots

Discrete linear quadratic control has been efciently applied to linear systems as an optimal control.However,a robotic system is highly nonlinear,heavily coupled and uncertain.To overcome the problem,the robotic system can be modeled as a linear discrete-time time-varying system in performing repetitive tasks.This modeling motivates us to develop an optimal repetitive control.The contribution of this paper is twofold.For the frst time,it presents discrete linear quadratic repetitive control for electrically driven robots using the mentioned model.The proposed control approach is based on the voltage control strategy.Second,uncertainty is efectively compensated by employing a robust time-delay controller.The uncertainty can include parametric uncertainty,unmodeled dynamics and external disturbances.To highlight its ability in overcoming the uncertainty,the dynamic equation of an articulated robot is introduced and used for the simulation,modeling and control purposes.Stability analysis verifes the proposed control approach and simulation results show its efectiveness.

Data Driven Model-Free Adaptive Control Method for Quadrotor Trajectory Tracking Based on Improved Sliding Mode Algorithm

In order to solve the problems of dynamic modeling and complicated parameters identification of trajectory tracking control of the quadrotor,a data driven model-free adaptive control method based on the improved sliding mode control(ISMC)algorithm is designed,which does not depend on the precise dynamic model of the quadrotor.The design of the general sliding mode control(SMC)algorithm depends on the mathematical model of the quadrotor and has chattering problems.In this paper,according to the dynamic characteristics of the quadrotor,an adaptive update law is introduced and a saturation function is used to improve the SMC.The proposed control strategy has an inner and an outer loop control structures.The outer loop position control provides the required reference attitude angle for the inner loop.The inner loop attitude control ensures rapid convergence of the attitude angle.The effectiveness and feasibility of the algorithm are verified by mathematical simulation.The mathematical simulation results show that the designed model-free adaptive control method of the quadrotor is effective,and it can effectively realize the trajectory tracking control of the quadrotor.The design of the controller does not depend on the kinematic and dynamic models of the unmanned aerial vehicle(UAV),and has high control accuracy,stability,and robustness.

Spintronic terahertz emitter with integrated electromagnetic control

Spintronic thin films are considered as one of the promising terahertz(THz)source candidates,owing to their high performance and low cost.Much effort has been made to achieve spintronic THz sources with broadband and high conversion efficiency.However,the development of spintronic THz emitters with good compatibility,low cost,and miniaturized technology still faces many challenges.Therefore,it is urgent to extend commercial and portable spintronic THz emitters to satisfy many practical applications.Herein,we design a new generation of spintronic THz emitters composed of an alter-nating electromagnet and a miniaturized electronic controller.Not only can this new type of spintronic THz emitter largely simplify the ancillary equipment for spintronic sources,it also has a twice larger THz signal compared to the traditional THz time-domain spectroscopy systems with a mechanical chopper.Experimental results and theoretical calculations for electromagnetic coils show that our design can stably generate THz signals that are independent of the frequency and magnetic field of alternating signals.As the spin thin film is optimized,a magnetic field as low as 75 G satisfies the require-ment for high performance THz emission.Hence,not only is the efficiency of the pump power enhanced,but also the driving current in the electromagnet is decreased.We believe that it has a wide range of applications and profound implications in THz technology based on spintronic emitters in the future.