直接示教机器人的位姿优化算法研究与实现
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摘要
直接示教型机器人具有示教方便、操作简单等特点,在喷涂、弧焊、抛光等任务轨迹复杂的机器人加工领域具有较高的应用价值。但由于人手在直接示教时存在抖动,若直接采用示教轨迹点进行再现,机器人在运动过程中往往会产生振动,从而影响加工质量,甚至缩短机器人的使用寿命。针对上述问题,提出了一种基于曲线拟合的机器人位姿优化算法,可对机器人的位姿轨迹进行平滑处理。首先对直接示教轨迹进行均匀重采样,分别利用B样条曲线和四元数曲线对采样点位置数据和姿态信息进行拟合,然后采用泰勒展开法对曲线进行插补,最后通过实验验证了该算法的有效性,并将该算法应用于自行研制的六关节直接示教喷涂机器人,实验结果表明有效减小了机器人再现时的振动。
Direct teaching robots,due to its feature of simplified programming procedure,is highly valuable in the applications of industrial processing such as spraying,arc welding and polishing. Nevertheless,due to the shaking of human hands in direct teaching,robots will often vibrate in the playback phase,thus affecting the machining quality and even shorten its service life. A pose optimization algorithm based on curve fitting is presented,which can smooth the trajectory of pose. Firstly,the teaching trajectory is uniformly resampled,the position data and the orientation data are fitted with B-spline curves and quaternion curves,respectively. After that,a method based on Taylor expansion is used to interpolate the curves. The algorithm proposed was verified and evaluated by an experiment in a self-developed six-joint direct teaching spray painting robot. The results of the experiment show that the vibration of the robot during the playback phase is evidently reduced.
Direct teaching robots,due to its feature of simplified programming procedure,is highly valuable in the applications of industrial processing such as spraying,arc welding and polishing. Nevertheless,due to the shaking of human hands in direct teaching,robots will often vibrate in the playback phase,thus affecting the machining quality and even shorten its service life. A pose optimization algorithm based on curve fitting is presented,which can smooth the trajectory of pose. Firstly,the teaching trajectory is uniformly resampled,the position data and the orientation data are fitted with B-spline curves and quaternion curves,respectively. After that,a method based on Taylor expansion is used to interpolate the curves. The algorithm proposed was verified and evaluated by an experiment in a self-developed six-joint direct teaching spray painting robot. The results of the experiment show that the vibration of the robot during the playback phase is evidently reduced.
引文
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[2]Bang H C,Choi B S,Lee J M.Time-optimaltrajectory planning for a robot system under torque and impulse constraints[J].International Journal of Control Automation&System,2006,4(1):10-16.
[3]马睿,胡晓兵,殷国富,等.六关节工业机器人最短时间轨迹优化[J].机械设计与制造,2014(4):30-32.
[4]Zhang Q G,Greenway R B.Development and implementation of a NURBS curve motion interpolator[J].Robotics and ComputerIntegrated Manufacturing,1998,14(1):27-36.
[5]任秉银,梁兆东,孔民秀.机械手空间圆弧位姿轨迹规划算法的实现[J].哈尔滨工业大学学报,2012,44(7):27-31.
[6]季晨.工业机器人姿态规划及轨迹优化研究[D].哈尔滨:哈尔滨工业大学,2013.
[7]虞铭财,杨勋年,汪国昭.高阶连续的单位四元数插值曲线[J].计算机辅助设计与图形学学报,2005,17(3):437-441.
[8]Piegl L,Tiller W.The NURBS book[M].New York:Springer,1997:364-376.
[9]许小勇,钟太勇.三次样条插值函数的构造与Matlab实现[J].兵工自动化,2006,25(11):76-78.
[10]Kim M,Kim M,Shin S Y.Acompact differential formula for the first derivative of a unit quaternion curve[J].Computer Animation&Virtual Worlds,2015,7(1):43-57.