【摘要】：由于柔性機械臂具有質(zhì)量輕、負(fù)載自重比高和靈活性好等優(yōu)點，從而在航天等領(lǐng)域得到了越來越廣泛的應(yīng)用。但是柔性臂的彈性振動問題，嚴(yán)重影響其快速性和準(zhǔn)確性，這對振動抑制研究提出了挑戰(zhàn)。在實際應(yīng)用中，柔性臂的負(fù)載往往不能確定，而是在一定范圍內(nèi)變化，從而導(dǎo)致在非標(biāo)稱模型條件下振動抑制效果降低。為了能夠在變負(fù)載情況下快速地消除柔性臂的殘余振動，本課題采用Euler-Bernoulli梁作為柔性臂模型，研究了基于振動主動控制的抑振策略，，并且能夠根據(jù)其末端負(fù)載的變化調(diào)整控制參數(shù)。 首先，以懸臂梁為基本模型，分析了在負(fù)載自重比分別為0(即空載)、10%和20%三種情況下的振型，并利用MATLAB和ANSYS計算出前四階固有頻率值。同時，選用壓電陶瓷作為致動器，建立了致動器作用下懸臂梁振動的模態(tài)運動方程。根據(jù)這一數(shù)學(xué)模型，提出了致動器位置優(yōu)化配置的準(zhǔn)則，并利用遺傳算法計算出了最優(yōu)位置。 其次，為了使控制器中的參數(shù)能夠跟隨由負(fù)載改變引起的固有頻率參數(shù)變化，實現(xiàn)自適應(yīng)控制，需要根據(jù)控制器的輸入和輸出對懸臂梁的固有頻率參數(shù)進行辨識。本文采用遞推最小二乘法(RLS)設(shè)計了固有頻率辨識算法，闡述了該算法辨識系統(tǒng)固有頻率的基本原理，并推導(dǎo)得出了計算公式。 然后，根據(jù)致動器作用下懸臂梁振動的數(shù)學(xué)模型，設(shè)計了積分振動控制器(IRC)，建立了閉環(huán)控制系統(tǒng)模型，優(yōu)化了控制參數(shù)，并從理論上說明了該控制策略能夠增大系統(tǒng)阻尼。通過對整個閉環(huán)系統(tǒng)的魯棒性分析，說明了進行自適應(yīng)控制的必要性，并建立了整個閉環(huán)系統(tǒng)現(xiàn)實自適應(yīng)控制的框圖。 最后，搭建了基于MATLAB/Simulink和dSPACE的實時仿真控制系統(tǒng)，對固有頻率辨識算法的準(zhǔn)確性和IRC控制模型的有效性以及控制參數(shù)的相對最優(yōu)性進行了驗證。實驗結(jié)果表明，固有頻率辨識算法具有較高的精度，與理論分析值的誤差可控制在5%以內(nèi)；IRC控制模型能夠比較有效地抑制三種負(fù)載自重比情況下懸臂梁的振動，使振動系統(tǒng)的阻尼比至少增大一倍，而且所優(yōu)化的控制器參數(shù)相對最優(yōu)。
[Abstract]:Due to the advantages of light weight, high load-to-weight ratio and good flexibility, flexible manipulator has been more and more widely used in aerospace and other fields. However, the elastic vibration of the flexible arm seriously affects its rapidity and accuracy, which poses a challenge to the study of vibration suppression. In practical applications, the load of the flexible arm can not be determined, but it changes within a certain range, which results in the reduction of the vibration suppression effect under the condition of non-nominal model. In order to eliminate the residual vibration of flexible arm rapidly under variable load, Euler-Bernoulli beam is used as the model of flexible arm, and the vibration suppression strategy based on active vibration control is studied in this paper. And the control parameters can be adjusted according to the change of the end load. Firstly, taking the cantilever beam as the basic model, the mode shapes of the first four order natural frequencies are calculated by using MATLAB and ANSYS when the load gravity ratio is 0 (i.e., no load), 10% and 20%, respectively. At the same time, using piezoelectric ceramics as actuators, the modal motion equations of cantilever beam vibration under actuators are established. According to this mathematical model, a criterion for optimal placement of actuators is proposed, and the optimal position is calculated by genetic algorithm. Secondly, it is necessary to identify the natural frequency parameters of the cantilever beam according to the input and output of the controller in order to make the parameters in the controller change with the natural frequency parameters caused by the load change and realize the adaptive control. In this paper, the recursive least square method (RLS) is used to design the natural frequency identification algorithm, and the basic principle of the algorithm to identify the natural frequency of the system is expounded, and the calculation formula is derived. Then, according to the mathematical model of cantilever beam vibration under the action of actuator, the integral vibration controller (IRC), is designed and the closed-loop control system model is established, and the control parameters are optimized. It is shown theoretically that the control strategy can increase the damping of the system. Through the robustness analysis of the whole closed-loop system, the necessity of the adaptive control is explained, and the block diagram of the real adaptive control of the whole closed-loop system is established. Finally, a real-time simulation control system based on MATLAB/Simulink and dSPACE is built to verify the accuracy of the natural frequency identification algorithm, the effectiveness of the IRC control model and the relative optimality of the control parameters. The experimental results show that the natural frequency identification algorithm has high accuracy, and the error between the natural frequency identification algorithm and the theoretical analysis value can be controlled less than 5%. The IRC control model can effectively suppress the vibration of the cantilever beam under three load-weight ratios, and increase the damping ratio of the vibration system by at least one time, and the optimal parameters of the controller are relatively optimal.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TP241;TB535

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