Research On Adaptive Flexible Multi-fingered Hand With Alterable Palm Of Robot

Automation technology has also been used increasingly in the field of food processing with the rapid development of robotics.However,it is difficult for the existing robotic endholder to achieve good grasps at the action object of food automation industry that is soft,brittle,vulnerable,and have different sizes and shapes.In addition,grasping planning has also become a hot issue with the development of robotic multi-fingered hands.Various methods of grasping planning have been proposed by domestic and foreign scholars,but these methods have certain limitations on the practical application,and have complicated calculations.Therefore,an adaptive flexible multi-fingered hand with alterable palm of robot was designed based on bionics principle,and the FAPH algorithm based on the flexible multifingered hand with alterable palm was proposed by this paper.The multi-fingered hand can adapt the objects with different shape and size by the configuration transformation of the alterable palm mechanism.It can adapt the objects that are soft,brittle and vulnerable by controlling the pressure of entering the soft fingers.the optimal grasping point number and position based on the flexible multi-fingered with alterable palm can be calculated by the FAPH algorithm,which not only improved the grasping quality and adaptability of the robotic multifingered hand,but also reduced the difficulty of grasping planning and controlling.The main works of this paper are as follows:(1)The flexible multi-fingered hand with alterable palm was divided into two parts: the alterable palm mechanism and the soft fingers by means of “decoupling”.The alterable palm with six degrees of freedom was designed based on the analysis of the bionic principle of human hands,which changed the working space and the grasping point position by the configuration transformation;the existing structural solution and manufacturing method were selected to make the soft fingers based on the analysis of human fingers.(2)The kinematic analysis of the alterable palm mechanism was carried out,and the mathematical model was established to analyze how to transform the configuration of the mechanism when grasp the object by using two,three or four fingers.The trajectory of a single soft finger and the working space when grasping by multiple fingers was analyzed by Matlab.It shows that the alterable palm mechanism greatly increases the working space of the soft fingers,and makes the soft fingers reach most of the positions of the space through the analysis and comparison,which obviously improves the adaptability of multi-fingered hands.(3)The evaluation indexes of the stability for grasping by two,three,four fingers were proposed through the analysis of the actual grasping requirements,and based on the evaluation indexes,the FAPH algorithm was proposed for the multi-fingered hand,and the number and position coordinates of the optimal grasping points can be calculated.The specific process of the algorithm was further explained through the example calculation.(4)The control system of the multi-fingered hand was designed,including pneumatic control and mechanism control.The main hardware modules of the control system were selected,and the software of the control system was developed,including the human-computer interface based on PC and Raspberry Pi and the test system interface that can test the performance of the soft fingers.(5)The prototype experiment of the flexible multi-fingered hand with alterable palm was carried out,including the construction of the experimental platform,the experiment of the configuration transformation of the alterable palm mechanism,the experiment of the FAPH grasping planning algorithm and the grasping experiment that selected 23 different objects with different shapes,sizes,quality and so on.The validity and reliability of the configuration planning of the alterable palm mechanism and the algorithm of FAPH grasping planning were verified,and the adaptability of the flexible multi-fingered hand with alterable palm for different objects and the stability of grasping were tested.The results show that the control system,grasping ability and adaptability of the flexible multi-fingered hand with alterable palm meet the expected design requirements.