The purpose of my work is to examine the operation of a wire-based robotics application over a wireless network.
As a first step I became familiar with the new components of robotic applications. Programming PLC for controlling the application and programming the robot arm UR5.
Then I compiled an own application that contained a PLC controller with an UR5 robot arm and an I / O module. The components are connected using a ProfiNet protocol, an Ethernet-based industry protocol. In the application, the switches connected to the I / O module could be used to control the movement of the robot arm. In this task, the challenge was to understand the logic of PLC programming because it is far from the current high-level programming methods.
Then I transplanted the wired network connecting the PLC, UR5 robot arm and I / O module to various wireless technologies. In WiFi I used VxLan Tunneling to solve the Ethernet connection between PLC and ProfiNet devices. For LTE, I used OpenVPN Tunnel because devices on the public LTE network do not have public IPs so the devices cannot see each other directly. SDR cards, which are the prototype of Ericsson's internal 5G radio. Grant Ethernet base connection, so I plugged it directly into the robot application.
Each wireless technology has supported other application settings. I have performed measurements on wireless network properties such as delay and jitter and application cycle time. I've extended the PLC code to be able to compare wireless networks and determine the KPIs for networks. I fitted a model of the data from the measurement. Using this model, I simulated wireless networks and obtained almost the same measurement results as in real networks.
Realistic measurements and simulations also show that the best performance was given by SDR cards as they could meet the delay characteristics required for ProfiNet protocol operation with little latency and reliability. The ProfiNet protocol can tolerate a fixed delay and, to a certain extent, jitter if the jitter value does not exceed three times the cycle time. The LTE also performed quite well with its relatively stable delay and small jitter. However, the WiFi network is not as deterministic as the other networks and has much higher latency and jitter values, so it can only support a large cycling application.
All in all, it is suitable for ProfiNet to operate on a wireless network with the appropriate delay characteristics.