| During the robot operation, the robot end-effector of the fingers grasping mechanism contacts with the job object directly. Whether grabbing the target object is stable or not relates to the success or failure of operation task. So grab stability study for the target is the focus in the field of robot. In recent years, the development of the computer vision technology and multi-sensor information fusion technology has made great progress. The robot working environment and the geometrical characteristics of the object can be known by the computer visual. So through the information fusion technology of the multi-sensor to research grab stability of the object has become an effective way to solve the current problems. The research in the thesis are as followings:1. The design of the manipulator. Firstly, the configuration of mechanical arm and the overall manipulator were designed. It included the determination of the arm’s length and the calculation selection of joint motor and bending strength check of the arm.Secondly, the end-effector was made. It included the design principles, finger-driven forms and calculation analysis. It also included the design of the fingers gripping mechanism motion control and the design of the entire grab experimental platform of power supply system. At last, we used the TOF camera to obtain visual information,2. Analysis and simulation of the manipulator kinematics. Using the D-H method to establish kinematics mathematical model of the manipulator. Then, the positive and reverse solutions were carried on. Using Pro/e to establish the three-dimensional model of the manipulator. The ADAMS software was imported to create virtual prototype of the manipulator. With the powerful simulation function of ADAMS, kinematics simulation analysis was made. The angular velocity of each joint, the torque curve of each joint, the displacement and velocity of the manipulator end point were measured to analyze the dynamic motion characteristics of the manipulator. It also verified the rationality for selection calculation of the joint motor and the correctness for the kinematics equations. The basis for the design optimization and motion control of manipulator provides was provided.3. Summary of stable grasping theory of two parallel fingers of manipulator.Mechanical analysis of contact point type of fingers and rigid ellipsoid was made. Thenecessary conditions of space grab stability were obtained through force closure of two fingers of the friction point contact grab object. Then, condition of contact grab stability was derived. Finally, the condition of two parallel finger grasping object bounded stability was given. The Stable grasping theory of two parallel fingers provides the theoretical basis for the further experimental analysis.4. Stable grasping experiment on two parallel fingers of manipulator. Firstly, the grabbling experimental platform of the manipulator of two-finger parallel was set up.Then the cooked eggs as the exception of the rigid ellipsoid was chose. Through visual information, cross-section and different longitudinal of geometry characteristic information of the ellipsoid were got. Use grab stability theory of the inductive to predict whether the intersection of the maximum lateral surface contour and different longitudinal surface contour of the object meeting the condition of the stability grabbling. Finally, the point set was verified by stable grasping experimental. And the reasons of not consistent of the prediction result and the experimental results were analyzed. The success rate of experiment was 66.67%. And this experiment validated grasping stability theory for rigid ellipsoid initially. |
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