Drives & Controls March 2023

27 www.drivesncontrols.com March 2023 MOBILE ROBOTS n protocols and interfaces. Safety standards provide guidelines on implementing safety-related components, preparing the environment, and maintaining machines or equipment. While compliance with various safety standards – ISO, DIN, IEC, ANSI and so on – is mostly voluntary, machine-builders in the EU are legally required to follow the safety standards in the Machinery Directives. Directive 2006/42/EC applies to mobile robot manufacturers. In some applications, Directive 2014/30/EU (which regulates the electromagnetic compatibility of equipment) might also be relevant. Directive 2006/42/EC describes the requirements for the design and construction of safe machines introduced into the European market. Mobile robot manufacturers can only affix CE labels and deliver their machines to customers if they can prove in the declaration of conformity that they have fulfilled the Directive’s requirements. Although other safety standards are not mandatory, manufacturers should still follow them as they help to fulfil the requirements of the Machinery Directive 2006/42/EC. For example, manufacturers can follow the guidance in ISO 12100 to reduce risks to an acceptable residual level. They can use ISO 13849 or IEC 62061 to find the required safety level for each risk and ensure that the corresponding safety-related function meets the defined requirements. Mobile robot manufacturers decide how they will achieve a certain safety level. For example, they can decrease the speed of their robots to lower the risk of collisions and severity of injuries to an acceptable level. Or they can ensure that the robots operate only in separated zones where human access is prohibited. Ensuring reliable CAN communications CAN communications – a reliable and easy-to- implement standard since the 1980s – is still growing in popularity, mainly due to its use in booming applications, such as e-mobility and battery energy storage systems. CAN is simple, energy and cost-efficient. All of the devices on a network can access all the information, and it’s an open standard, so users can adapt and extend the messages to suit their needs. For mobile robot manufacturers, CAN connections are becoming vital because it allows them to monitor the lithium-ion batteries widely used in robot drive systems, either as retrofits or in new installations. It is essential to: n establish reliable connections to CAN or CANopen to perform checks such as monitoring battery status and performance; and n protect systems from electromagnetic interference (EMI), because EMI can destroy a system’s electronics. The risk of EMI is significant in retrofits because adding new components, such as batteries next to communication cables, can introduce high- frequency electromagnetic disturbances. Accessing mobile robots remotely The ability to access a mobile robot’s control system remotely allows engineers to troubleshoot and resolve many problems without needing to travel to the site. The challenge is to balance the needs of the IT department with those of engineers. IT departments will want to ensure that their networks remain secure, reliable, and retain integrity. As a result, remote access systems should include the following security measures: n use outbound connections rather than inbound connections to minimise the impact on the firewall; n separate the relevant traffic from the rest of the network; n encrypt and protect all traffic to ensure its confidentiality and integrity; n ensure that vendors work in line with, or are certified to, relevant security standards such as ISO 27001; and n ensure that suppliers complete regular security audits. It should be easy for remote users to connect to mobile robots and access the required information. If an installation changes, it should be easy to scale the number of robots as required. As we’ve seen, mobile robots pose many communication and safety challenges. You need to be able to establish wireless connections, send data over different networks, ensure safety, connect to CAN systems, and securely access the robots remotely. To complicate matters, each installation must be re-assessed and adapted to meet the on-site requirements. Modern communication systems have modular designs, allowing a networking product designed for one standard or protocol to be replaced by another designed for a different protocol, without impacting other parts of the machine. For example, Bluetooth may be the most suitable wireless standard in one installation, whileWi-Fi may provide better coverage in another. Similarly, one site may use the Profinet and PROFIsafe protocols, while another may use different protocols. In both scenarios, communications products can be used to change the networking technology in mobile robots to meet the local requirements, without changing the hardware design. n