基于三维点云的运输车粮箱动态均匀装载方法研究

Dynamic Uniform Loading Method of Grain Box of Transport Vehicle Based on Three-dimensional Point Cloud

为了解决联合收获机运输车协同作业时,运输车粮箱装载不均匀,导致粮箱装载利用率低的问题,提出了一种基于三维点云的动态均匀装载方法。该方法利用相机获取运输车粮箱内装载物的三维点云作为状态反馈信息,建立装载均匀性评估方式,以最均匀装载状态为目标,通过实时调整卸料装载点位置,使粮箱保持在均匀的装载状态。针对装载物相互遮挡对相机形成视觉盲区的问题,通过建立装载物的堆体模型和相机的遮挡模型,以最小期望误差为目标对盲区内装载物高度进行估计,并据此进行点云填充,从而得到能完整反映粮箱装载状态的三维点云。在搭建平台进行的实验中,对粮箱装载过程中可能出现的轻载、中载和重载3种装载状态进行测量,并对盲区点云位置进行估计,其盲区估计的平均误差低于5 cm。仿真结果表明,动态均匀装载方法能在有限装载周期内,将粮箱从任意的初始装载状态装载为均匀状态。单次装载量的平均高度增量为2 cm、粮箱的初始装载状态为空载时,装载物的最大高度方差为1 cm^(2)。单因素仿真结果表明,稳定状态下的装载物高度方差与单次装载量正相关。

In order to solve the low loading efficiency caused by uneven loading during the cooperative operation of combine-harvester and transport vehicle,a three-dimensional point cloud based dynamic uniform loading method was proposed.The three-dimensional point cloud of the stowage in the grain box obtained by the camera was used as a state feedback to build up the uniformity evaluation method.With the purpose of accomplishment of the most uniform loading state,the position of unloading and loading point was adjusted in real time to keep the granary in the uniform loading state.According to the established grain pile model and camera occlusion model,the height of grain bulks within camera blind area was estimated with the minimum expected error to complete the defective point cloud which caused by mutual occlusion between heaps.Three loading states of light load,medium load and heavy load which may occur during loading were measured based on the constructed experiment platform.The average error of the blind area height estimation was less than 5 cm.The simulation results showed that the proposed method can load the granary from arbitrary initial loading state to uniform loading state in a finite loading cycle.The maximum height variance of the load was 1 cm2 under the condition that the initial loading state of the grain box was empty and loading with average height increment of 2 cm.The height variance of loading in stable state was positively correlated with the single loading amount according to single factor analysis.Compared with the traditional fixed points loading method,the loading capacity of dynamic uniform loading method was twice higher when they both stopped the loading process at the maximum loading height of 0.35 m.