Research On Compliant Control Of Loading Robots For Fast Moving Consumer Goods Logistic

With the development of logistics and technology,the huge trade volume of goods such as express delivery and FMCG(fast-moving consumer goods)has also continuously driven the development of logistics transportation tools to high-end smart devices.As a result,many domestic and overseas loading systems continue to emerge when the demand for large 3-D warehouses from FMCG increases.Existing specialized mechanisms are designed for certain specific cargoes,and such mechanisms can only be limited to a particular cargo and its specific loading scenario,such as truss loading systems or special loading and unloading machines and other equipment;In addition,there are commonly used industrial robots combined with mobile platforms to implement loading tasks,but their loading efficiency and space utilization rate of the actual compartments do not meet the needs of enterprises.In this context,a large-scale load-bearing robotic system for multi-specification heavy-duty FMCG buildings has been developed.The subject of this paper is a heavy-duty load-carrying robot with a long telescopic arm,which is used in large consumer production enterprises such as condiments and beverages.It belongs to the loading mechanism of the loading system.As the loading robot can handle multiple heavy FMCG products in practice,it can be applied to trucks or containers of different sizes,so the loading robot has two characteristics of "long telescopic" and "heavy".At the same time,due to these two characteristics,the end effector suffers from chattering,poor flexibility,and poor dynamic performance.Therefore,based on this class of specially loaded robots,in this paper,we design a compliant control strategy to improve the control performance and robustness of the robot control system under heavy-duty work.The main points of the paper are as follows.(1)Firstly,the long-telescopic and heavy-load robot mechanism is analyzed and the mechanism model is established.The forward and inverse kinematics of the loading robot are modeled using the modified D-H method,and the Jacobian of the loading robot is modeled using the vector product method.Matlab was used to validate and simulate the motion planning for the loading motion.(2)The rigid body dynamic model of the long-telescopic heavy-load robot is established according to the Lagrange dynamic modeling method,and the trajectory tracking control is designed.Finally,the rigid-body kinetic model was validated by Adams.(3)In the case of force feedforward and PI control by force control,the position control of important joints is carried out to realize force/position hybrid control.The sliding mode control law is designed for position control,and the hyperbolic tangent function is introduced into the power reaching law to improve the convergence rate of the system and reduce the chatter.Force-based impedance control was added to improve end compliance.(4)Due to the deformation of the telescopic arm in the movement of the extended arm,it needs to be flexible.Based on the corresponding FMCG loading at the large arm and end,the centralized load was added accordingly,and both simulations and experiments were conducted.Through the analysis of sliding mode control,impedance control and field experiments,it is proved that the designed compliant control reduces the chattering and frequency of the loading robot under heavy load,improves the dynamic performance of the control system,and meets the control performance requirements of the actual long and flexible heavy load.