A Low-Cost System for Remote Access and Control of Automation Equipment （1）

1. Introduction 

The highly dynamic environment of higher education has presented a range of challenges and opportunities. Some of these challenges and opportunities have arisen due to limitations of facilities and resources in educational institutions. Recently, the COVID-19 pandemic has also necessitated physical distancing and remote learning in many countries around the globe. Blended and online delivery of courses has become increasingly relevant during lockdown and physical distancing scenarios. Delivering and managing online and digital learning has been a crucial part of blended/online courses. In this respect, technology has become a powerful tool to develop educational systems. The internet has become a powerful tool for business innovation and positive change in education. 

While many course learning materials and activities are made available online [1–3], executing practical assessments with physical equipment can be challenging. Often it is easier to conduct these practical assessments in the traditional way, requiring the students to be physically present with the equipment. In face-to-face learning, students often require additional time to complete their practical activities outside the scheduled class times. Classroom access and lab/equipment availability are the main challenges faced, especially in shared learning spaces. A solution to this problem is to allow the students to complete their practical work off-campus by providing a remote access to the on-campus lab equipment. The internet plays a crucial role in enabling the remote access. This concept can be used to support distance learning and thus to enable the students to remotely perform and monitor their practical work. A review of contemporary virtual and remote laboratory implementations is presented in [4]. According to the authors, a virtual lab uses programs to simulate laboratory environments where students access and conduct experiments in a virtual space.  （Machines 2021, 9, 138. https://doi.org/10.3390/machines9070138 https://www.mdpi.com/journal/machinesMachines 2021, 9, 138 2 of 18）

Onthe other hand, a remote lab is where experiments are located physically away from the experimenter, and the experiments are conducted in a real physical environment. The authors’ review and analysis confifirm the advantages of virtual and remote laboratories such as 24 × 7 access, flflexibility and freedom of learning pace, and reset/retrial without resource wastage. Several implementations are reviewed, including virtual and remote laboratories for programming robots [5], Virtual Instrument Systems in Reality (VISIR) for engineering [6], and VPLab for virtual programming to develop computer programming knowledge and skills [7]. There were no reviews on remote laboratories for programming PLC controlled devices in real physical environments. Maiti et al. [8] discuss Remote Access Laboratories (RALs) and Remote Laboratory Management Systems (RLMSs) for distributed remote labs. Remote Access Laboratories have been used to establish experimental expertise on practical engineering topics. Distributed remote laboratories aim to share experiment through a distributed architecture between institutions and individuals. Experiments from various fifields are combined as part of a greater system. Remote Laboratory Management Systems (RLMSs) integrate experiments using multiple control strategies. When incorporating an existing experiment into a new distributed RAL system, analysing the experiment with respect to its host or new RLMS is useful in deciding the best methods for inclusion. They propose a framework called SHASS (Software, Hardware, Assessment, Support, and Share-ability) for such evaluation based on experiment properties. The development of a distance learning system using virtual reality and augmented technologies is discussed in [9]. 

Two research directions considered are: use of augmented reality applications in the development of e-labs for undergraduate students, master's students, and researchers; and learning systems and simulation of robotic systems based on movements in a virtual reality environment, respectively. Developing the e-lab programme required the confifiguration of sensors and the development of a communication network. The remotely controlled robot system is a 5-axis Mitsubishi RV-M1 Move master which uses a CCD camera for remote-control observation. A computer determines each object’s position and orientation, and then the human operator sets the order of robot operations. Internet web-based laboratories that enable remote operation of experiments used for training in undergraduate engineering courses have been implemented in [10]. This implementation uses LabVIEW software to perform remote control and monitoring of laboratory equipment. The approach is beneficial for developing countries where resources can be shared through the internet. A disadvantage is the cost associated with purchasing and utilising National Instruments data acquisition (DAQ) boards and LabVIEW software. The experiments described in the paper use LabVIEW virtual instruments as the controllers for electropneumatic and electromechanical systems. This would be an unnecessary additional layer of control and cost for the PLC-controlled devices requiring remote access in this research. The development of a remote lab with two user interfaces for teaching programming and robotics using Arduino boards is presented in [11]. 

One of the interfaces is based on visual programming while the other interface is similar to the original Arduino textual programming language. Access to the Arduino lab can be made via a mobile application or web browsers. The authors claim their implementation is suitable for courses in institutions with limited resources. While the implementation focuses on low-cost, it is primarily developed for teaching Arduino micro-controller programming, not PLC programming. A concept for remote programming, confifiguration, and monitoring for the development and testing of embedded devices is presented in [12]. Basic proof-of-concept functionality has been achieved allowing for easy interaction with remote embedded devices. The authors claim the hardware price of the developed prototype was lower than commercial solutions. However, no numerical values were provided. Another embedded systems design remote laboratory system is presented in [13]. Four experiments are connected via USB to a server PC and a remote user accesses the server via the internet. Each experiment has a separate micro-controller, and a web-interface controls them. (Machines 2021, 9, 138 3 of 18 )

Bellmunt et al. [14] present a remote laboratory for PLC programming based on a flflexible manufacturing cell. The developed system consists of a separate PLC for each station and an IP camera for observation. The PLCs are connected over the local area network for local control. A router and internet connection are used for remote control. In this system, the stations are dependent on each other, and it is an expensive system since it requires multiple PLCs. This type of system is also set up for network (ethernet) PLC programming. Some PLCs, such as the one in this paper, are set up for USB programming. While there are other examples of remote virtual PLC-based labs [15,16], the primary focus of this paper is on remote laboratories for programming PLC-controlled physical devices. Other examples similar to [14] include [17–20]. All these implementations are developed for web-based programming. 

The system presented in [17] uses a computer as a WebAccess web server to remotely monitor and control a PLC based system. Their emphasis is not on remote learning but on developing advanced PLC programming skills of remote monitoring and control. The design of three web-based automated systems using a client-server software system termed Remote Control System Architecture (RCSA) is presented in [18]. The three systems also have their own associated PLCs, unlike the research presented in this paper, which uses a single PLC due to resource and cost limitations. Using web browsers can be simple and effective for the user as mentioned in [20]. 

A drawback is that the system developer needs to be profificient in client-server tools such as JavaScript, PHP, ASP.NET, and databases [19,20]. This paper presents the design of a solution for providing access to multiple automation lab equipment remotely. Initial work on the design is presented in [21]. A modifified fifinal version of the design that was prototyped and tested is described in this paper. The emphasis of the design is on a low-cost solution that enables students to program and operate PLC-based equipment remotely in a way that is similar to being physically present with the equipment. This involves remotely accessing free software to program PLC that is connected to a computer via a USB cable. Additional software and an embedded system were developed to facilitate the selection of hardware connected to the PLC.