【摘要】：目前,小型金屬鑄件的拋磨以人工作業(yè)為主,拋磨環(huán)境非常惡劣,并且人工效率比較低,工件均一性不佳,拋磨質(zhì)量難以得到保證。隨著人工成本的增加以及對工人健康防護的重視,人工拋磨勢必會被機器拋磨甚至自動化拋磨所替代。本文結(jié)合國家863計劃項目子課題“面向精密拋磨的機器人力位混合控制技術(shù)研究與工程實現(xiàn)”,對面向小型金屬鑄件的機器人自動拋磨關(guān)鍵技術(shù),包括機器人自動拋磨工藝分析和系統(tǒng)設(shè)計、拋磨質(zhì)量建模以及機器人力控制策略進行研究。首先,結(jié)合人工拋磨經(jīng)驗,進行了小型金屬鑄件的拋磨工藝分析和離線仿真分析。根據(jù)力控制精度要求,設(shè)計了被動力控砂帶機結(jié)構(gòu)和主動力控機器人末端工具,提出了基于力傳感器的機器人主動力控制和基于氣缸緩沖的砂帶機被動力控制相結(jié)合的機器人自動拋磨系統(tǒng),并搭建了主被動力控制機器人自動拋磨控制系統(tǒng),奠定了本課題的硬件基礎(chǔ)。然后,通過剖析拋磨質(zhì)量的各個影響因素,提出了以砂帶速度、機器人速度、拋磨力和工件表面曲率為模型自變量,表面粗糙度為模型因變量的基于支持向量回歸拋磨質(zhì)量模型。采用遍歷、遺傳和粒子群三種算法對拋磨質(zhì)量模型參數(shù)分別進行尋優(yōu),遴選速度更快、均方誤差更小的算法。之后利用尋優(yōu)參數(shù)進行了拋磨質(zhì)量建模和實驗驗證�；谒兄频臋C器人自動拋磨系統(tǒng),提出了相應的機器人拋磨主被動力控制策略。通過實驗比較中值濾波、均值濾波和卡爾曼濾波三種濾波算法,選出抗干擾能力強且預測性能好的算法,并確定其關(guān)鍵參數(shù)。通過推導工具重力補償公式,解決其位姿變化對傳感器的影響。提出笛卡爾空間機器人拋磨阻抗算法,并探討其阻抗參數(shù)對控制系統(tǒng)的影響。針對拋磨作業(yè)環(huán)境多變問題,提出面向機器人拋磨的模糊阻抗算法,并通過實驗驗證其魯棒性。最后,根據(jù)方案和算法設(shè)計,搭建了機器人自動拋磨系統(tǒng)標定實驗平臺,并設(shè)計了機器人拋磨人機交互軟件,包括系統(tǒng)通訊、運動控制、力監(jiān)控和力控制等模塊。利用激光跟蹤儀進行機器人自動拋磨系統(tǒng)標定實驗,開展機器人拋磨重力補償實驗、恒力控制實驗和機器人自動拋磨實驗驗證。實驗結(jié)果表明,該機器人自動拋磨系統(tǒng)的力控制精度在±5N以內(nèi),恒力拋磨的工件光潔度更高、表面粗糙度更低、拋磨表面連續(xù)均勻性更好。
[Abstract]:At present, the grinding of small metal castings is dominated by manual work. The polishing environment is very bad, and the manual efficiency is low, the uniformity of workpiece is not good, and the quality of polishing is difficult to be guaranteed. With the increase of labor cost and the emphasis on health protection of workers, manual grinding will be replaced by machine polishing or even automatic grinding. In this paper, the key technology of robot automatic grinding for small metal castings is discussed, which is a subproject of the national 863 project, "Research and engineering realization of robot force position hybrid control technology for precision grinding". It includes automatic polishing process analysis and system design, grinding quality modeling and robot force control strategy. Firstly, the grinding process and off-line simulation of small metal castings are analyzed based on manual grinding experience. According to the requirement of force control precision, the structure of dynamic sand belt machine and the end tool of main power control robot are designed. A robot automatic polishing and grinding system based on force sensor and pneumatic cylinder buffer is proposed, and the automatic grinding control system is built. Laid the hardware foundation of this subject. Then, by analyzing the factors that affect the grinding quality, the paper puts forward that the sand belt velocity, robot speed, polishing force and surface curvature of workpiece are the independent variables of the model. Support vector regression based polishing quality model with surface roughness as a dependent variable. The ergodic, genetic and particle swarm optimization algorithms are used to optimize the parameters of the polishing quality model respectively. The selection speed is faster and the mean square error is smaller. After that, the grinding quality modeling and experimental verification are carried out by optimizing parameters. Based on the developed automatic polishing system for robot, a dynamic control strategy for the main body of robot polishing is proposed. Three filtering algorithms, median filter, mean filter and Kalman filter, are compared experimentally. The algorithms with strong anti-interference ability and good prediction performance are selected, and the key parameters are determined. By deducing the formula of gravity compensation, the influence of the position and pose change on the sensor is solved. A grinding impedance algorithm for Cartesian space robot is proposed, and the influence of impedance parameters on the control system is discussed. A fuzzy impedance algorithm for robot polishing is proposed and its robustness is verified by experiments. Finally, according to the scheme and algorithm design, the calibration experiment platform of robot automatic polishing system is built, and the man-machine interactive software of robot polishing is designed, including system communication, motion control, force monitoring and force control, and so on. The laser tracker is used to calibrate the robot automatic polishing system, to carry out the robot polishing gravity compensation experiment, the constant force control experiment and the robot automatic polishing experiment verification. The experimental results show that the force control accuracy of the automatic polishing system is less than 鹵5N, the finish of the workpiece with constant force polishing is higher, the surface roughness is lower, and the continuous uniformity of the polishing surface is better.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP242

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