基于转动惯量的采后甘蓝自动定向方法研究

Automatic Orientation Method for Postharvest Cabbage Based on Moment of Inertia

针对采后甘蓝人工连续定向效率低、劳动强度大等问题,以“中甘15号”甘蓝为研究对象,提出了一种基于转动惯量的采后甘蓝自动定向方法。首先,建立了采后甘蓝的简化几何模型,对3个惯量主轴的转动惯量及其定向运动稳定性进行了理论分析;其次,建立了定向仿真模型,基于ADAMS软件分析了26种初始姿态的采后甘蓝在定向过程中的位移差值和采后甘蓝中心轴与辊轮轴线的夹角随时间的变化规律;最后,搭建自动定向试验平台,以辊轮直径、轴向间隙、径向间隙和角速度为试验因素,以采后甘蓝中心轴与辊轮轴线的夹角和定向成功率为试验指标,进行了单因素和正交试验。理论分析和仿真结果表明,采后甘蓝在定向运动过程中,逐渐趋向绕转动惯量最小且唯一的中心轴转动,且该运动状态动态稳定,即实现了采后甘蓝的自动定向。试验结果表明,试验因素对采后甘蓝中心轴与辊轮轴线的夹角影响的显著性主次顺序为辊轮直径、角速度、轴向间隙、径向间隙,试验因素对定向成功率影响的显著性主次顺序为角速度、辊轮直径、轴向间隙、径向间隙;最优参数组合为辊轮直径80 mm、轴向间隙80 mm、径向间隙70 mm、角速度6 rad/s。在最优参数组合下进行了验证试验,结果表明,采后甘蓝中心轴与辊轮轴线的夹角平均值为(6.72±1.23)°,定向所需时间为6.8 s,定向成功率为96%,满足采后甘蓝自动定向及后续高通量处理的需求。

The orientation of postharvest cabbage is the key to the automatic operation of the postharvest processing system,which provides the position and posture conditions for the subsequent root trimming,detection and grading,etc.Aiming at the problems of low efficiency and high labor intensity of artificial continuous orientation of postharvest cabbage,an automatic orientation method based on the moment of inertia for postharvest cabbage was proposed,and the“Zhonggan 15”cabbage was taken as the research object.Firstly,the simplified geometric model of postharvest cabbage was established,and the moment of inertia in the three principal axes of inertia and the motion stability of postharvest cabbage during orientation were analyzed.Secondly,the orientation simulation model was established,and the variations both of displacement difference and included angle with time of 26 initial attitudes of postharvest cabbage during orientation were simulated and analyzed based on ADAMS software,to verify the feasibility of the method.Finally,automatic orientation test platform was built,and single factor test and orthogonal test were carried out with the roller diameter,axial clearance,radial clearance and angular velocity as test factors,and the included angle between the central axis of postharvest cabbage and the roller axis and the orientation success rate as test indexes.It can be seen from the theoretical analysis and simulation results,postharvest cabbage gradually tended to rotate around the central axis with the smallest and only moment of inertia during the orientation,and the movement state was stable.That was to say,the automatic orientation of postharvest cabbage by this method can be realized.The experimental results showed that the primary and secondary influence order of test factors on the included angle between the central axis of postharvest cabbage and the roller axis was roller diameter,angular velocity,axial clearance and radial clearance.And the primary and secondary influence order of test factors on the orientation success rate was angular velocity,roller diameter,axial clearance and radial clearance.The optimal parameters of roller diameter,axial clearance,radial clearance and angular velocity were 80 mm,80 mm,70 mm and 6 rad/s,respectively.On the condition of the optimal parameter combination,the validation test was carried out.The average included angle between the central axis of postharvest cabbage and the roller axis was(6.72±1.23)°,the time needed for orientation was 6.8 s,and the orientation success rate was 96%,which met the requirements of automatic orientation and subsequent high-throughput processing for postharvest cabbage,and also provided theoretical basis and technical support for orientation operation of postharvest processing that can be applied in other irregular spherical fruits and vegetables.