Flexible Manipulator For Nondestructive Grasping And Sensing Of Fruits And Vegetables

Soft manipulator is a new type of manipulator that combines bionics,materials science,engineering,and so on.At present,the soft manipulator has been introduced into the picking and sorting of agricultural products in the field of agriculture due to its high adaptability,which means,it can be highly adapted to the objects,to achieve soft and stable grasping.Owing to the vulnerable surface of agricultural products,how to avoid the damage of agricultural products in the process of grasping has attracted extensive attention from researchers.In summary,the method of embedding the flexible sensor into the soft manipulator is adopted in this paper to control the grasping characteristics of the soft manipulator by detecting the contact force between the claw fingers and the object to avoid damage.Therefore,a flexible stretchable polymer optical fiber sensor has been designed and fabricated in this thesis,and its structural parameters are characterized,and its stretchability,sensitivity,and position resolution are investigated in detail.In this thesis,a flexible stretchable polymer optical fiber sensor was prepared by a template method using a polymer with a low elastic modulus.Secondly,this thesis explores two methods to improve the sensitivity.The first one is to introduce an air column structure into the fiber,and the pressure detection sensitivity can reach 2.133 N^-1.The second method is to design a double helix structure,and the tensile detection sensitivity can reach 1.050.Besides,the double helix optical fiber designed in this paper can distinguish the pressing position,which demands a small light source,with light equipment.Finally,this thesis designed and manufactured a soft manipulator based on fluid variable-pressure drive,in which a flexible optical fiber sensor is embedded.At the same time,the software application program is designed and developed to realize the real-time control of the soft manipulator and the real-time display of the contact force,to achieve smooth,stable,and non-destructive grasping of fruits and vegetables.