LabVIEW Control Universal Workbench
There has been a significant growth in computerized laboratories for educational purposes, especially for motion control. They represent a growing field in various industrial applications and have become invaluable tools for conducting real-time experiments in a safe manner using often expensive or unique laboratory equipment. The development and continuous improvement of software applications such as NI LabVIEW allows for easy implementation of control algorithms and the creation of user-friendly interfaces using virtual instruments.
Increased internet speeds and reliability of connections facilitate the expansion of remote labs, where users can connect to lab benches from remote locations and conduct engineering experiments. This allows laboratories to be shared between universities, greatly increasing their economic sustainability and practicality. The ability for students to perform tasks in groups of 2 or 3 helps to develop collaboration and cooperation skills between them.
The laboratory provides teaching tools in various courses in the field of power electronics and electromobility. As an integral part of the discipline of engineering and applied science, control theory deals with the complex behavior of dynamical systems. Therefore, it plays an important role in the education of engineering students.
A traditional closed-loop motion control system with a cascaded controller consists of three main components: the motion controller, the controlled device (motor), and a feedback device—for position, speed, and current measurement. Feedback devices also convert the controlled output variable into some other variable (feedback signal), which is compared to the input control signal in the error detection circuit. In this way, the controller determines the deviation of the signal and generates a new control signal by means of a complex algorithm.
In the fields of mechatronics and power electronics, the laboratory has potential for further computerization. Furthermore, these laboratories are always based on test benches with fixed mechanical structures, which leads to increased equipment costs in order to cover many different experiments. Furthermore, few experiments involving major components widely used in industrial machines such as linear stages, linear scales, absolute encoders, resolvers.
The developed general-purpose flexible mechanical platform utilizes smart BLDC motors and drivers, a linear platform and a linear scale, as shown in Figure 1. It represents a wide variety of industrial applications for precise position control: microelectronics, robotics, automotive and laser cutting industries, CNC milling machines, hard disk manufacturing, etc.
While the LabVIEW programming environment provides all the tools needed to build a common graphical interface, organizing and fitting basic controls and indicators into front panel screens is not an easy task. Considering the need for realism when representing laboratory experiments, a virtual moving linear stage has been created.
It visualizes the movement of the moving table in real time and displays its current position relative to the center of the stage. Two indicators show the emergency end limit detected by the inductive proximity switches. Additionally, several other areas can be identified:
status area
Provides real-time information on motor speed, acceleration/deceleration and load utilization, DC bus voltage, hardware temperature, emergency status and alarms.
command area
System functions are provided via buttons. The following events may be triggered:
• Servo drive initialization – upload all parameters to the servo drive and check if it is ready to be activated;
• Servo Drive Diagnostics – Opens the additional diagnostics window discussed above. Allows for a comprehensive analysis of the state of the system to be performed and future adjustments;
• Motor on/off – manual activation/deactivation of the control of the motor; – axis homing procedure – automatic movement of the table to find the index signal of the linear scale and calibrate the current position according to this index; find the coordinates of the emergency end limit switch, and set the software limit to 10mm in front of them;
• Manual Linear Stage Control – Provides basic manual positioning of linear stages;
• Automatic linear stage control – allows programmable motion control depending on the task: data acquisition and graphical representation of important currents and voltages in the system; some preselected step responses for dynamic systems; experimentation with control systems – inverted pendulum, camera detection, etc.
Advanced Multipurpose Graphics Window
New software tools for communication, diagnostics, control, and data acquisition based on LabVIEW virtual instruments. The platform can be used to experiment with various types of flexible mechanical systems, as interfaces to five feedback devices widely used in industrial machines are provided: linear scales, resolvers, incremental encoders, absolute encoders, and Hall sensor commutation. It can be used as an experimental basis to compare and experiment with many control algorithms in the presence of parametric model uncertainties, mechanical disturbances, and noise. As such, the platform can be an invaluable learning tool for undergraduate and postgraduate students as well as industry practitioners.
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