| The material bag transferring system can reduce the low quality manual labor of workers and improve the operation efficiency of factories,warehouses and wharfs.At present,the material bag transferring system is under developing,especially in unstacking operation prone to errors.The main reason is that the packaging material of the material bag is easy to be damaged and deformed,which brings many difficulties to the design of the material bag transferring manipulator.In addition,an automated material bag transferring system needs to be complemented by visual devices.Therefore,this paper focuses on the material bag transferring manipulator and material bag visual identification technology.1、A new type of cable-driven push-back mechanism is proposed and the overall design of the underactuated material bag transferring manipulator is carried out.First of all,on the basis of demand analysis,the material bag transferring manipulator design index is determined.Secondly,a new underactuated transmission mechanism is designed by combining the advantages of link mechanism and cable pulley mechanism,which not only has the large transmission ratio of link mechanism but also has the long-distance transmission ability of cable pulley mechanism.Finally,the overall design of the manipulator is carried,the finger adopts the design of independent disassembly,the internal skeleton adopts the laminated structure and the metacarpal joint is installed with a braking mechanism.2、The kinematics and mechanics of the underactuated material bag transferring manipulator are analyzed.The DH parameter method is used to describe the complete grasping position and posture of the manipulator under the fixed coordinates of the grasping section,the relationship between the length of the cable and the angle of the joint is analyzed and established.Then,the moving process of the mobile grabbing mode is simulated numerically,and the characteristics of the change speed of the driving cable length in this grabbing mode are obtained.Taking the instantaneous velocity of cable as the equation condition,the statics analysis method based on the principle of virtual power is improved,and then the statics calculation formula of the three-joint manipulator paper is derived.3、The grasping stability of the manipulator is analyzed and the parameters are optimized.Firstly,the relationship between the negative value of the contact force calculation and the failure of the stable grab is established.Then the material bag stable grasping model is quantified,and the stable pose ratio of the three-joint manipulator is taken as the initial optimization condition to analyze the optimization direction of the design parameters of the manipulator.Secondly,the stable pose ratio is improved from 10.2%to 29.55%by further optimization through genetic algorithm.Finally,the holding bag position and metacarpal joint brake device are introduced to further optimize the two distal phalanxes.the proportion of stable position in holding position is improved and then the ability of holding material bag stably is enhanced.4、The manipulator designed in this paper is simulated and analyzed.The co-simulation platform of ADAMS and MATLAB/Simulink is built.The accuracy of the contact force calculation formula and the superiority of the new mechanism in the contact force conversion ability is verified by kinematic simulation,as well as the adaptability of the grasping process of the manipulator and the accuracy of the calculation formula between cable length and joint angle is also verified.Then the static contact grasping simulation is carried out to verify that the optimized manipulator could reach a stable grasping state under the position and posture of holding the material bag.5、The technology of material bag position and posture recognition is studied and the related software is developed.Firstly,a pose description method is designed,which included the angle of the long side of the material bag,the center coordinates and the coordinates of the gripper points.Then based on the traditional image processing algorithm,a set of position and pose recognition algorithm of bag image is designed.Finally,a software based on the algorithm is developed on the MATLAB App Designer platform,and the feasibility of the algorithm is verified through the pose recognition experiments of a variety of material bag images. |
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