PSI - Issue 32

A.V. Churkin et al. / Procedia Structural Integrity 32 (2021) 277–283 Author name / StructuralIntegrity Procedia 00 (2019) 000 – 000

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6. Discussion Depending on the purpose of using a drive with a stepper motor, there are two main strategies for building control algorithms: by position and by speed. Thus, when building precise positioning systems, it is necessary to determine the basic(starting) position of the control body before starting the movement, from which the movement coordinates will be counted, which is typical for systems with incremental position counters. And in the speed control mode, the actual position of the working body is not so important, but it is necessary to maintain the set speed and acceleration. When using the ZET 7160-s module in the above design of the stepper motor control, to implement the speed control strategy, the parameter "Number of pulses to stop" must be set to "0", and to implement the exact movements of the drive, you must set the numerical value of the number of pulses to stop. The actual movement of the control body will be determined not only by the parameters of the engine, but also by the parameters of the mechanical transmission between the stepper motor and the control body, so it is most appropriate to conduct an experimental calibration of the developed positioning system to assess the actual movements. Some difficulties are caused by the implementation of the control algorithm associated with the need to introduce a data recording cycle in the control module (input contact " Save changes to the sensor”) after the engine movement parameters are set. This feature is characteristic of the implementation of the control system over the CAN bus and the visual programming component "Configuration ZET 7xxx_1", interacting with the firmware of the hardware module ZET 7160-s. The firmware of the latter is made by the developers of the equipment and has the possibility of software updates over the Ethernet network by means of the ZETLAB complex. When implementing the above example of building a control system for the SD, the firmware firmware No. 7.736 was used. In the process of working on the SU project, a firmware limitation was revealed that is not described either in the operating manual of the hardware module or in the ZETView software manual. For example, you need to implement an algorithm for moving the control from two logical steps. The first for 800 pulse-steps, and the second again for 800 pulses. For the first step, the operator must enter the parameters of the stepper motor movement ( Fig. 5 B) in the digital information input selectors (speed, acceleration, number of pulses to stop), select the desired direction of rotation with the button and activate the stepper motor driver by pressing the button to the "stepper motor on"position. After that, you need to transfer the entered data by clicking the "Apply" button associated with the “Save changes to Sensor "contact of the “ZET7xxx_1 Configura tion" element (Fig.3) to the ZET 7160-s hardware module, which will generate control pulses DIR, ENA and PUL on the HBS 57 module and start the process of moving the stepper motor. When performing the second step of the algorithm, the operator does not need to enter the motion parameters, since they remain the same. Logic suggests that the only action of the operator should be to click the "Apply" button in the window interface of the control program. However, there will be no reaction of the stepper motor control program to the operator's action, because the firmware firmware of the hardware module "considers" that if no changes in the motion parameters were made, then no movement should occur, despite the incoming pulse "Save changes to the sensor “of the "Configuration ZET7xxx_1" element. Therefore, we can not make two steps of movement with the same movement parameters, when implementing the position control algorithm. An additional difficulty is the implementation of the task of stopping the motion drive in the event of an emergency with the control object, since the ZET 7160-s module does not have the input physical contacts “Accident” and/or”Limit switch". For example, the HBS 57 driver module has an output pin “ALM", which is responsible for its own em ergency failure, which occurs when the incoming control pulses PUL+ and the actual movements of the HSE 57 motor mismatch. Therefore, for its processing, it will be necessary to implement an alternative method of registration, which in turn leads to the need to introduce new modules into the control system, which can reduce the speed of the SU reaction and lead to the complexity of the system as a whole. The latter imposes additional requirements for the qualification of the operator and programmer developing the control programs of the SD in the visual programming environment of the SCADA system ZETView.