On-line Measurement And Control Compensation Technologies For Robot Flexible Manufacturing System

Major equipment is the backbone of the national economy, which best represents the level and ability of manufacturing. Due to the presence of many problems with major equipment such as bulky, complex structure, high precision and large assembly adjustment, there are a lot of basic scientific problems, key application technology and engineering practice need to overcome. Among them the measurement and control problems in the process of manufacturing are the key to improve the level of equipment manufacturing. In this paper, the process of complex drilling of a large spherical surface is investigated, and the critical technologies of on-line measurement and compensation control are studied. The automated processing level of large manufacturing equipment and the system accuracy of measurement and control are improved on the basis of exiting manufacturing technology. The real-time positioning accuracy and the machining precision are raised, via introducing the combined dynamic measurement system in the design and employing a series of techniques, e.g. system calibration, environmental factors model construction, dynamic error compensation, feedback control strategy optimization choice.The robot measurement and control system is constructed of multi-source dynamic measurement platform, robot motion control module, and data integration and fusion module. Considering the precision requirements of the object in large equipment manufacturing and the complexity of the robot motion paths, the visual system consists of four infrared cameras and three-dimensional spherical targets, ensuring the robot is visible at any position in the processing area. Meanwhile, the inertial measuring instrument was introduced into the system to improve the measurement accuracy of robot end actuator’s attitude. The above-mentioned visual system and inertial measuring instrument constitute a combined measurement platform for dynamic posture capture and analysis of robot end actuator. Thus it can improve the angle measuring accuracy of using a single vision system and avoid the difficulty of dynamic tracing of traditional large size measuring equipment such as laser tracker.On the basis of studying on the calibration model of minimum error of distance and of minimum error of position, it proposed the improved method of the step-by-step calibration. Thus it accomplished the unity of the two coordinate systems of measuring system and control system, finished the robot kinematics parameter calibration and improved the precision of robot end position and posture after calibration. Meanwhile, the robot kinematics parameter calibration uncertainty was analyzed and the robot positioning error distribution in the whole movement space was studied, it will has a great help to evaluate and improve the precision of positioning and machining accuracy in the whole space. In addition, it compared and analyzed the precision and applicability of different calibration method.It analyzed the influence of joint angle error, temperature and loads on the positioning of robot and built the error model of kinematics parameter. In view of the above various affecting factors, it carried out the specific study work of theory and analysis. The causes for the angle error of robot are studied, and the influence factors of each error component are determined through the experimental analysis. It also studied the thermal deformation model of robot caused by the external environment temperature change, robot friction and motor rotation fever, designed the temperature compensation method for field application and built the load error model and the compensation method is put forward.The precision control method of robot motion was proposed respectively for the two modes of motion of PTP and CP. It designed a step compensation method to improve the control precision of PTP. And, it built a feedback control loop and researched the design approach of system delay and control cycle.