Research On Master-Slave Control System For Hydraulic Excavators

Most construction machines such as excavators, loaders, cranes are operated with single lever mechanical-hydraulic joysticks in the way of speed control. The traditional way of operation is short of intuition and requires higher operation skills of the driver. In this thesis, a more intuitive operation named master-slave control system has been developed based on a multi-lever force feedback joystick PHANTOM Omni and the existing integrated multi-DOF test rig of 2 ton excavator. Experiments showed that the bucket can achieve a fine trajectory tracking with the master-slave control system, proving of this control scheme reasonable and feasible.The thesis is outlined as follows:In chapter 1, the master-slave control and force feedback technology were introduced. The current research progresses of its application in the field of construction machinery were reviewed all over the world. Then, the main research objective, significance and topics of the study in the thesis were pointed out and discussed.In chapter 2, the kinematic mathematical model of the 4-DOF excavator working device including swing was established. And a simulation model was built in Matlab/Simulink. Based on the analysis and simulation of kinematics, the working space diagram of the excavator can be get rapidly and exactly.In chapter 3, the dynamic mathematical model of the 4-DOF excavator working device was established using Lagrangian dynamics method. And then dynamic simulation and analysis were carried out both in MATLAB/Simulink and Solidworks/Cosmosmotion environment. As for the influence of the hydraulic cylinders and other link rods, the dynamic model was further analysised and simplified in order to improve the accuracy.In chapter 4, the structure of the master-slave control system and its main components were explained in details. Using socket programming, UDP/IP communication interface was established to exchange information between the PHANTOM software Visual C++ and the control program in Matlab/xPC Target environment. As for the workspace differences between PHANTOM Omni and the excavator, two kinds of workspace matching methods, which are based on joints and position increments, were proposed. A virtual reality monitoring system was also developped to make the simulation and operation visualized.In chapter 5, an improved PID control algorithm was introduced to test the trajectory tracking performance of the master-slave control system.The experimental results showed that this kind of operation mode is intuitive and simple and the bucket could track the position of PHANTOM Omni well.In chapter 6, some conclusions are given and some new views are put forward in the future.