中国农业机械化科学研究院集团有限公司 主管

北京卓众出版有限公司 主办

基于CNN和视觉图像特征的农业采摘机器人机械臂抓取末端轨迹跟踪控制方法

End effector trajectory tracking control method for agricultural harvesting robot robotic arm grasping based on CNN and visual image features

  • 摘要: 由于农业采摘机器人的操作环境复杂、不稳定,机械臂会受到外界干扰,如风、振动或作物变形等,导致末端执行器摇晃或机构变形,无法有效动态捕捉机械臂抓取末端轨迹的不确定拐点,进而影响轨迹跟踪精度。因此,提出基于CNN和视觉图像特征的农业采摘机器人机械臂抓取末端轨迹跟踪控制方法。基于时间序列和空间序列提取农业采摘机器人机械臂轨迹信息,设定目标强迫函数,提取机械臂抓取末端运动轨迹时空变化特征;采用CNN计算弹簧非线性干扰和环境力学非线性干扰下的采摘机器人机械臂动力参数非线性误差变化。计算初始点与末端点的运动学定向关系,计算视觉图像特征校准误差,将其输入至控制执行器中,采用视觉校准补偿反馈收敛函数调整目标点与实际点之间的差距,实现轨迹控制。试验表明,该方法对农业采摘机器人机械臂抓取末端轨迹动力参数误差计算精准,在视觉方向校准补偿下针对多点波浪曲线和多点矩形曲线均能有效动态捕捉轨迹的不确定拐点。在内部弹簧非线性干扰和外部环境力学非线性干扰下,该方法的机械臂抓取轨迹跟踪控制效果都表现较好,具有较好的鲁棒性。

     

    Abstract: Due to complex and unstable operating environment of agricultural harvesting robot, robotic arm may be subject to external disturbances such as wind, vibration, or crop deformation, resulting in end effector shaking or mechanism deformation, which cannot effectively capture uncertain turning points of robotic arm's grasping end trajectory dynamically, thereby affecting accuracy of trajectory tracking.Therefore, a end effector trajectory tracking control method for agricultural harvesting robot robotic arm grasping based on CNN and visual image features was proposed.Trajectory information of agricultural harvesting robot robotic arm was extracted based on time series and spatial series, setting target forcing function, and spatiotemporal variation characteristics of robotic arm grasping end effector motion trajectory was extracted.CNN algorithm was used to calculate nonlinear error variation of dynamic parameters of harvesting robot robotic arm under nonlinear spring disturbance and environmental mechanical nonlinear disturbance.Kinematic orientation relationship between initial and end points was calculated, calibration error of visual image features was calculated, inputting calibration error into control actuator, visual calibration compensation feedback convergence function was used to adjust gap between target point and actual point, and to achieve trajectory control.Experimental results showed that proposed method accurately calculated dynamic parameter error of end effector trajectory of agricultural harvesting robot robotic arm grasping.Under visual direction calibration compensation for multi-point wave curves and multi-point rectangular curves, uncertain inflection points of trajectory could be captured dynamically and efficiently.Under nonlinear disturbance of internal springs and external environmental mechanics, proposed method performed well in tracking control grasping trajectory of robotic arm with good robustness.

     

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