Study On Key Techniques Of Pipe Laying Manipulator Based On Simulation And Experiment

As the urbanization speed becomes faster and faster in China, all kinds of pipe laying projects increase continuously. At present, the technology of pipe laying stays in the mixing state of workers and machines, the crane and excavator are used to help workers laying and jointing the pipe. Because the trench to lay the pipe is deep, trench cave-ins happens easily, which causes fatal injuries to workers often, so how to reduce the injuries, how to increase the efficiency of pipe laying,and how to combine the scientific technology with pipe laying are the problems to eager to solve in pipe laying projects.The pipe laying manipulator in the paper is an automatic machine which is used in pipe laying projects in municipal construction; it can increase the pipe laying efficiency and safety. The paper mainly studies the following questions, the working principle of manipulator, the control algorithm, the dynamics analysis based on virtual prototype and experiment analysis. The main study work and specific contents as follows:1. The Study on Manipulator's Mechanical PrincipleFor suiting the pipe laying site in municipal construction, the pipe laying manipulator is designed with self-locked function. The manipulator is mounted to excavator, it has four degrees, and consists of turning-connecting mechanism, crossing guide and fork lifting mechanism. The manipulator mounted to the excavator can adjust the pipe pose in the space. The fork lifting mechanism uses the pipe gravity to lock the pipe, then the pipe and manipulator are fixed together. After the pipe being laid, the spring on the fork will make the fork replace. For avoiding squashing the pipe, the clamping force which the fork exerts on the pipe is analyzed, the formula to calculate the clamping force and factors to affect the clamping force are obtained, which supplies the basis for manipulator working normally. The kinematic model and dynamic model of manipulator are built by D-H ways, which makes the basis for control system.2. The Virtual Prototype Modeling of Manipulator and Dynamic Simulation and ExperimentIn order to simulate the manipulator'work correctly, and supply parameters for design, the virtual prototype of manipulator is built by Solidworks and Adams soft. The following methods of the virtual prototype are used:considering the deformation of some components will affect the dynamic characteristics of manipulator, the virtual prototype is rigid-flexible coupling, stress and strain analysis of flexible component is done; for avoiding redundant constraints appearing, and making force between the wheel and guide closer to actual condition, a shaft without quality is placed between wheels; for simulating friction force in working conditions, and in accordance with traditional ways to add friction force can't track change of friction force in real time, the equivalent external force is used to replace the friction force in the manipulator. The experimental prototype is made based on the parameters obtained from the simulation, and experiment on the prototype is done. By comparing the results of simulation and experiment, the virtual prototype is built correctly, and is similar with the experimental prototype highly.3. The Study on Location Technology of ManipulatorIn accordance with the actual working condition s of manipulator, the location technology of the manipulator laying the pipe is studied, and the photoelectric location system is designed. By using the theory on inverse transformation of coordinate, the mathematical model of photoelectric location system is built, and the mathematical model offers the basic parameters for the control system to make the manipulator moving, which can realize the pipe laying and jointing. The experiment on the photoelectric location system is done, the capability of data acquisition and wireless transmission is tested, and the experimental results are analyzed. From the experiment, the factors that affect the work capability of photoelectric location system is known. The test on the photoelectric location system shows that the location system can satisfy the needs for manipulator laying pipe.4. The Study on Manipulator's Control AlgorithmThe pipe laying manipulator is a multiple input-output, non-linear, strong coupling mechanical system, when the manipulator lays the pipe, change of manipulator's pose and pipe's pose will affect the mechanical system seriously, so the traditional control way of tracking control and anti-interference control can't satisfy the manipulator's needs of stability and anti-interference. Based on the analysis of manipulator's kinematics and dynamics, one fuzzy neural network controller based on RBF is designed, the controller has 10 input signals and 5 output signals, and an improved genetic algorithm is used to optimize the fuzzy rules and membership functions, then the controller is simulated. The simulation results shows that every joint can follow the output trajectory correctly under the control of controller, which can satisfy the precision requirement of laying pipe.