A Solution to Study Different Homing Methods （研究不同的导航方法的解决方案）.pdf

ANALELE UNIVERSITĂŢII “EFTIMIE MURGU” REŞIŢA ANUL XXI, NR. 2, 2014, ISSN 1453 - 7397 Mihai Raă, Adrian Graur, Leon Mandici, Gabriela Raă A Solution to Study Different Homing Methods Using a PLC In a positioning control with stepper motors it is very important to know zero location. For this purpose it is necessary a homing command. This paper presents a solution that allows the study of different methods implemented to find a home position (also called: zero point) and to observe the differences between these methods. Keywords: position control, stepper motors, educational technology, automation 1. Introduction The basic purpose of control systems is to keep system behavior on the desired value [1]. In industry are used two common classes of control systems:  open loop control systems (the output is generated based on inputs)  closed loop control systems (the output is maintained at a level so that there is no difference between the process variable and the setpoint). In low-cost open-loop industrial applications for positioning control systems in many cases are used stepper motors. Usually stepper motors were designed to provide precise positioning control within an integer number of steps. They have stable open loop operation to any step position and consequently no feedback is needed to control them. In positioning control systems with or without feedback it is necessary to identifier what is the zero position (home position), which is a unique location somewhere over the course of travel. The stage will accurately go to this position when commanded to “home.”