| As an agricultural country, every year our contry produced a large number of agricultural and sideline products, and the current logistics and express industry is developing rapidly,so the sorting work of which is very labor-effective, we want a manipulator which can complete the grasping work of thin-skinned and easy-hurt target objects having all shapes and sizes can be invented to help peple finishe such work. The traditional industrial manipulator has played an important role in the grasping work of high load and single objects, but they are at a loss in grasping and sorting the targets of changing shapes and sizes and easy fragile. In order to solve the problem, this paper propose a kind of an robotic gripper with flexible constraint linkage which is driven by stepping motor, and designed the direction change adjustment mechanism of the finger, transfer motion and force through rigid hinge, which makes the gripper have enough grasping force and a good adaptability to the target objects.At first, this paper designs the overall structure of the manipulator,including finger structure, regulating mechanism of finger direction, and the drive mechanism. The design of the finger structue refers to the human finger,and the finger mechanism has certain characteristics of personification by simulating six bar linkage.At the same time, introduce variable constraint elastic rod to let finger mechanism have flexible structure.The regulating mechanism of finger direction, the design of which refers to a tray gripper,makes the manipulator have a good adaptability to grasp objects of different shape.And adopt stepper motor to drive across four bar linkage directly,and analyse the movement of it.Driving mechanism works by the use of leadscrew nut mechanism and linear bearing guide bar,which is driven by stepper motor, with the advantages of simplness,reliability and convinience of the design of control system. Then use CREO,a 3D design software,to creat overall 3D model of the gripper.The finger mechanism kinematics analysis is the key of the robotic gripper research, Used the skeleton model analysis method of CREO software to verify the validity of the theoretical calculation. Studyed the finger movement characteristics, and the mean root section optimization design was carried out on the driving mechanism. Statics of finger mechanism, this thesis probes into the application of manipulator ADMAS software simulation analysis.Then designed the gripper control system, including hardware circuit and software part. Upper machine adopts industrial computer, the hardware design part mainly for the next bit machine parts, including the AVR control panel, pressure signal disposal circuit. Stepper motor driven by belt encoder closed-loop drive, realize high precision position control, upper and lower position machine communication through USB transfer module to realize the serial port. PC software using Visual C++ integrated development environment and combining MFC source function library to complete. AVR control program uses the CodevisionAVR software debugging.Finally complete contact force feedback control system debugging, kill pressure sensor calibration experiment, position, speed control, using manipulator for fetching the experiment of different grab objects, control system functions to achieve the design requirement, can sense contact to grab objects, and feedback control stepping motor deceleration to downtime, achieve the goal of no damage to grab objects. Because the finger mechanism has flexible degree of freedom and buffer, for does not agree to the size of the object is the maximum, minimum sample, testing through the contact force feedback system, to control the step motor parameters setting, realize to such grab objects without feedback reliable fetching potential. |
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