【摘要】：本文針對(duì)提高柔性多體系統(tǒng)軌跡跟蹤精度的要求,將一種含有柔性桿件的3-RRRU空間并聯(lián)機(jī)器人作為研究對(duì)象,系統(tǒng)地分析了該剛?cè)峄旌舷到y(tǒng)的非線性正動(dòng)力學(xué)模型和逆動(dòng)力學(xué)模型,提出了一種適用于閉鏈機(jī)構(gòu)的柔性動(dòng)力學(xué)方程的求解方法,并根據(jù)系統(tǒng)的逆動(dòng)力學(xué)模型對(duì)控制策略進(jìn)行了研究,所取得的研究成果如下:(1)基于向量環(huán)法建立了剛性3-RRRU并聯(lián)機(jī)器人的逆運(yùn)動(dòng)學(xué)模型,然后利用牛頓-歐拉法求出了各個(gè)運(yùn)動(dòng)關(guān)節(jié)的約束反力和約束力矩�；谧匀蛔鴺�(biāo)法構(gòu)建了剛性空間梁?jiǎn)卧蛣傂詣?dòng)平臺(tái)的質(zhì)量矩陣,并根據(jù)拉格朗日法求出了剛性機(jī)構(gòu)的動(dòng)力學(xué)模型,同時(shí)驗(yàn)證了該方法與參考坐標(biāo)法建立的動(dòng)力學(xué)模型具有等效性。并聯(lián)機(jī)構(gòu)的剛性模型為其柔性動(dòng)力學(xué)模型的構(gòu)建和求解提供了重要的理論依據(jù)。(2)針對(duì)剛性3-RRRU并聯(lián)機(jī)器人,在考慮所有關(guān)節(jié)摩擦力矩的情況下,基于運(yùn)動(dòng)學(xué)模型和動(dòng)力學(xué)模型提出了一種新型的近似時(shí)間最優(yōu)的平滑軌跡規(guī)劃方法,通過引入相平面上的零值偽加速度曲線,能夠有效地確定軌跡的加減速過程,并通過理論和實(shí)驗(yàn)論證了規(guī)劃方法的可行性和有效性,總結(jié)出并聯(lián)機(jī)器人和串聯(lián)機(jī)器人在規(guī)劃過程中體現(xiàn)出的不同特性,該方法可用于柔性并聯(lián)機(jī)器人的軌跡規(guī)劃。(3)利用自然坐標(biāo)法和絕對(duì)節(jié)點(diǎn)坐標(biāo)法構(gòu)建了剛?cè)峄旌?-RRRU并聯(lián)機(jī)器人的非線性動(dòng)力學(xué)模型。與傳統(tǒng)的線彈性動(dòng)力學(xué)方法相比,該模型不僅未做任何線性化處理,而且考慮了柔性空間梁?jiǎn)卧募羟行?yīng),同時(shí)可描述柔性構(gòu)件的大范圍彈性變形。(4)為了避免連續(xù)介質(zhì)力學(xué)中泊松閉鎖現(xiàn)象的發(fā)生,對(duì)彈性矩陣和應(yīng)變能進(jìn)行了合理分割,同時(shí)針對(duì)并聯(lián)機(jī)構(gòu)的特性,給出了計(jì)算彈性力及其雅克比矩陣的新方法,從而提高了求解的計(jì)算效率。根據(jù)柔性并聯(lián)機(jī)器人動(dòng)力學(xué)方程的特性,對(duì)其求解原則、求解方法和求解性能進(jìn)行了詳細(xì)的分析和說明。(5)針對(duì)柔性并聯(lián)機(jī)器人動(dòng)力學(xué)模型在求解過程中出現(xiàn)的破壞剛性約束的問題,提出了一種瞬態(tài)剛體校正法,從而保證了數(shù)值迭代方法在求解動(dòng)力學(xué)模型正解和逆解過程中的正確性。然后,根據(jù)所獲得的逆動(dòng)力學(xué)解構(gòu)建了系統(tǒng)的控制策略,并通過動(dòng)態(tài)軌跡跟蹤實(shí)驗(yàn)驗(yàn)證了控制策略的可行性,說明了仿真分析結(jié)論與實(shí)驗(yàn)結(jié)果具有良好的一致性。
[Abstract]:In order to improve the trajectory tracking accuracy of flexible multi-body system, a kind of 3-RRRU spatial parallel robot with flexible member is taken as the research object in this paper. The nonlinear positive dynamic model and the inverse dynamic model of the rigid-flexible hybrid system are systematically analyzed, and a method for solving the flexible dynamic equations suitable for closed-chain mechanisms is proposed. According to the inverse dynamic model of the system, the control strategy is studied. The results are as follows: (1) the inverse kinematics model of the rigid 3-RRRU parallel robot is established based on the vector loop method. Then the constraint reaction and binding moment of each motion joint are obtained by Newton-Euler method. Based on the natural coordinate method, the mass matrix of rigid spatial beam element and rigid dynamic platform is constructed, and the dynamic model of rigid mechanism is obtained according to Lagrangian method. At the same time, the equivalence of the dynamic model established by this method and the reference coordinate method is verified. The rigid model of the parallel mechanism provides an important theoretical basis for the construction and solution of the flexible dynamic model. (2) for the rigid 3-RRRU parallel robot, the friction torque of all joints is considered. Based on kinematics model and dynamics model, a new approximate time optimal smoothing trajectory planning method is proposed. By introducing zero-valued pseudo-acceleration curve on the phase plane, the acceleration and deceleration process of trajectory can be effectively determined, and the path acceleration and deceleration process can be effectively determined by introducing zero-valued pseudo-acceleration curve on the phase plane. The feasibility and effectiveness of the planning method are proved by theory and experiment, and the different characteristics of parallel robot and series robot in the planning process are summarized. This method can be used in trajectory planning of flexible parallel robot. (3) the nonlinear dynamic model of rigid-flexible hybrid 3-RRRU parallel robot is constructed by using natural coordinate method and absolute node coordinate method. Compared with the traditional linear elastic dynamics method, the model not only does not do any linearization, but also takes into account the shear effect of the flexible spatial beam element. At the same time, the large-scale elastic deformation of flexible components can be described. (4) in order to avoid the occurrence of Poisson locking in continuum mechanics, the elastic matrix and strain energy are segmented reasonably, and the characteristics of parallel mechanism are pointed out. A new method for calculating elastic force and Jacobian matrix is presented, and the computational efficiency is improved. According to the characteristics of dynamic equations of flexible parallel manipulators, the principle of solving the equations is given. The solution method and performance are analyzed and explained in detail. (5) A transient rigid body correction method is proposed to solve the problem of rigid constraint failure in the dynamic model of flexible parallel robot. Thus, the correctness of the numerical iterative method in solving the positive and inverse solutions of the dynamic model is guaranteed. Then, according to the obtained inverse dynamic solution, the control strategy of the system is constructed, and the feasibility of the control strategy is verified by the dynamic trajectory tracking experiment, which shows that the simulation results are in good agreement with the experimental results.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TP242
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本文編號(hào)：2465391