Design And Implementation Of Zero Calibration System For Servo Motor Absolute Encoder

Servo drive system is widely applied in the automatic motion control fields.The zero-calibration of the absolute encoder is one of the key technologies for precise and efficient motion control.But,the existing zero-calibration systems can only be used for specific encoder type without guaranteed efficiency and accuracy.To realize the integrated automation calibration of multi-type encoder and improve the precision and efficiency,a servo motor absolute encoder zero-calibration system is designed containing software,firmware program and experimental verification.The main contents are as follows:The error sources of the zero-calibration system are analyzed.Based on servo motor zero calibration flow and demand tapping,the overall scheme of the absolute encoder zero-calibration system is determined with the combination of the PC software and servo drive.And,its principle and steps are introduced in detail.A zero-calibration software is developed using the modular programming design scheme so that the requirements can be satisfied,including high cohesion,low coupling and easy to expand.The developed software can accomplish functions of parameters read and write,data acquisition,drawing observation and one-touch zero-calibration.The overall architecture,the implementation of the communication module,zero-calibration module and data graphical interface module are elaborated emphatically.For the servo drive firmware program development,the idea of finite state machine is adopted to design the overall program,realizing the communication protocol of absolute encoder so as to control and calibrate multi-protocol type absolute encoder.Moreover,to ensure reliable communication between the software and servo drive,RS232-based serial interface circuit and communication protocol are presented to realize the high-speed stable data interaction between various modules.A zero-calibration system platform is built for experimental validation.The functional test is carried out to verify the feasibility and practicality.Furthermore,the speed profiles-tracking test is performed.The results demonstrate the improved motion control performance,applicability and the superiority of the developed zero-calibration system.