Biomimetic Design And Adhesion Performance Research Of Soft Gripper With Claws

Being of great value in hazard detection,reconnaissance,agricultural produce picking,and biomimetic soft climbing robot considered to be an important developing direction in robotic community.Furthermore,end-effector is one of the crucial components for executing climbing task.In this paper,a novel biomimetic flexible gripper with claws was developed,then the adhesion mechanism of the gripper was discussed and the performance of it was evaluated qualitatively as well as quantitatively.The development of gripper was inspired by biological structure of Inchworm.After observing and analyzing the gripping mechanism of the claws of Inchworm,an Inchworm-claw-like flexible gripper was developed based on application requirements.To be specific,the adhesion adaptability,adhesion reliability and the influence of clamping parameters on them were considered,and the first generation multi-drive with multi-claw gripper was introduced firstly.Afterwards,scheme verification and structural optimization were conducted,and the second generation of single-driver with triple-jaw flexible gripper was achieved.The SMA(shape memory alloy)coil driven based scheme was applied to these two generation of grippers,while passive adaptive attachment was realized by under-actuated method.Subsequently,structural parameters optimization,components design,material selection and prototype fabrication in the second generation of gripper were introduced in detail.Finally,kinematic model of the gripper was established,which was verified by a series of experiment.The result confirmed the rationality and reliability of the developed biomimetic flexible gripper with claws.The results show that the first-generation multi-drive with multi-claw gripper is able to generate a maximum of 9.1N grasping force,which is 10 times as many as its own weight(68g).While the second-generation single-driver with triple-jaw gripper could generate 3.5N gripping force,which is 20 times as many as its own weight(16.6g).The gripper not could grasp the regular objects(wooden cylinders,cones,round tables,balls,pyramids,etc)as well as irregular objects(cement stone,tuff,coal cinder,variable cross-section plastic bottles,etc).Single-driver with triple-jaw gripper showed better adaptive performance than the first-generation gripper.Moreover,the maximum anti-overturning force of the first-generation Gripper could reach 0.23kg with surface toughness was Ral2.5,the second-generation gripper of that could reach 0.13kg.Both generation of grippers could perform the normal operations of soft module we developed for climbing robots in the status of overturning,vertical inversion,and suspension.On the surface of 60Cw-600Cw sandpaper,both holders can meet the reliable attachment and operation of the soft module climbing robot.Furthermore,the single-driver with triple-jaw gripper was more compact and lighter,with higher self-study ratio,and higher utilization rate of each claw.Besides,one single SMA driver was satisfy the requirements of climbing.All of these made the gripper easier to control and better to reflect concept of bionic design.