Research On The Characteristics Of Large Flexible Dexterous Finger

As final executing manipulator for robot to interact with outside environment, the terminal actuators have been paid much attention. Simulating the structure and function of human hand, robot multi-fingered dexterous hand which has better dexterity and adaptability greatly improves the intelligent level of robot. Therefore robot multi-fingered dexterous hand has both great research significance and application value.In recent years, the application of robots has been extending to medical, agricultural and service areas, and its grasping targets are always soft and crisp objects. So the multi-fingered dexterous hand is required to have great flexibility. As a kind of actuator and manipulator, the new type flexible pneumatic actuator FPA, developed by our researching group, has quite a few characteristics such as simple structure, flexible and high power/weight ratio, especially applicable to the areas with high demand of security and flexibility, but will produce twisting deformation when grasping objects. Improved FPA, a new type of air-driven finger, named large flexible dexterous finger, is proposed in this paper. Large flexible dexterous finger not only maintains the flexibility, but also takes into account the stiffness. The main work and achievements in this paper is as follows:(1) The static model and basical properties of large flexible dexterous finger are profoundly studied. Through the principle of torque balance, the static model is established. The effects of different parameters on the bending angle are analyzed. Based on the theory of pneumatic hydrodynamic and thermodynamics, the dynamic models of inflating and deflating for large flexible dexterous finger are obtained. Produced large flexible dexterous finger and built the experimental platform. Experiments are carried out to verify the static model.(2) The prediction model of large flexible dexterous finger’s bending angle is proposed. The basic theory, structure and training process of BP neural network are introduced to establish the network model for predicting. The sample data obtained through the experiment of finger static characteristics were used to train and verify the prediction model.(3) The kinematic model of large flexible dexterous finger is proposed. Analyzed the form of finger movement, the description equation of fingertip’s position and orientation is deduced. Unloaded kinematic model is obtained based on the modified D-H method and the jacobian matrix is calculated. Discussed the geometry constraints for the finger contact with object, the multi-point contact kinematic model is established. The experimental platform is built to verify the kinematic model.(4) The structure design of a large flexible3-fingered hand and a large flexible soft hand is proposed. The condition for selecting the number of joints and fingers as well as the cross-sectional structure in dexterous hand is studied. The working principle of large flexible3-fingered hand is introduced. The kinematic model of finger tips is deduced and the simulation for motion and grasping is studied. Designed a large flexible soft hand, the kinematic model and envelop grasping model are established. The simulation for motion is carried out.Large flexible dexterous finger proposed in this paper has characteristics of better flexibility, easy produced, easy control and the stiffness which pure flexible pneumatic finger lacks of. It has a broad application situation such as medical, agricultural, service, military and so on.