Fail Safe Over EtherCAT: Advantages in Practice

Summary

Autonomous Mobile Robots (AMR), Automated Guided Vehicles (AGVs) or Automatic Guided Vehicles (AGV) are increasingly being used in complex production lines and large warehouses of goods and materials. However, autonomous self-driving systems could also provide valuable services in other environments and, for example, significantly increase the efficiency of workflows.

However, conventional AGVs, i.e. first-generation systems, are usually packed with a wide variety of components and cables, plus the space required for the battery. As a result, there is often a blatant lack of space inside or the systems are correspondingly large. The numerous different components also require a lot of coordination work in energy management, control and design. As a result, maintenance is also time-consuming, so that the cost-effectiveness for use away from large production and logistics facilities is not given. The size and complexity of the systems complicates application scenarios with smaller space conditions or less financially strong companies. So technology needs to become leaner. However, an essential aspect and a major challenge so far has been the indispensable integration of safety functions.

Next-generation AGVs are compact and efficient thanks to Integrated Motion and FSoE

Next-generation AGVs could now expand their capabilities. The decisive innovation lies in the simple connection of all components via a single cable and protocol: Fail Safe over EtherCAT . In the compact and energy-efficient systems, gearbox, motor, encoder, servo controller, laser scanner, control hardware and software are coordinated and connected in such a way that intelligent and safe motion control is possible with significantly less resources and space requirements.
 
The next-generation AGV requires significantly fewer components and significantly less cabling inside – a significant difference to conventional solutions. This significantly simplifies development, makes production leaner and maintenance easier. The volume saved can either be used to design the AGVs smaller overall or to install more powerful batteries. Thus, such a system scores with a longer range and requires less downtime.

Safety in AGV and robotics

Safety remains a crucial issue. Robotic systems are getting closer and closer to humans. This applies in particular to cobots, but also to classic industrial robots. Especially in environments where the paths of mobile robots and human specialists cross, functional safety is indispensable. FSoE technology allows easy integration of reliable safety functions such as Safely Limited Speed (SLS), Safe Limited Position (SLP), Safe Stop 1 (SS1) and Safe Stop 2 (SS2).
 
FSoE is thus advancing from the digital side to the most important enabler for efficient safety, this is referred to as fieldbus safety. Without FSoE, integrating safety functions requires an immense number of cables and I/Os. In conventional AGVs, in addition to the standard encoder, there is a safety encoder on each axis, each with a cable, and a safety brake, also with a corresponding cable. In addition, cobots also have force/torque sensors with high cable use as well as input keys for teaching.
 
With FSoE, all functions can be integrated with much less effort. Until now, however, there has been no one-size-fits-all solution where this has been implemented, although some manufacturers of AGVs and cobots have developed proprietary solutions. The embedded systems specialist Synapticon recently implemented this approach as a standard product suitable for mass production, as one of the first providers in the field of Integrated Motion. FSoE is now available in the embedded controller class, which is suitable for cobots and AGVs.

FSoE is a relatively new, less complex architecture for all robotics, especially for mobile robots with manipulators. This makes it possible to build hybrid systems consisting of cobot and AGV, i.e. a robot arm on a moving platform with only one controller. The previous alternatives to FSoE were, for example, PROFIsafe (Safety Controller) or CAN bus as a serial bus system in safety-critical systems. However, EtherCAT has established itself as the standard for robot control in the robotics sector. FSoE now makes EtherCAT safety-capable, not only in theory, but also in practice. Unlike CAN, EtherCAT supports high bandwidth and data rate with low latency, which is essential for the use of robot systems close to or with humans.
 
EtherCAT and FSoE are not only standardized, they are also market leaders in terms of product diversity. The international EtherCAT community is constantly growing and the number of EtherCAT products with safety functions and FSoE is constantly increasing. This year's trade fairs, such as the Hannover Messe or Automatica, have impressively demonstrated this.
 
Due to the wide range of products, the user can choose between different providers and is not limited to one manufacturer. The user becomes more independent, a great advantage in today's market situation, where it is strategically important to be able to replace components.
 
"I learn from many conversations that numerous current and innovative product developments rely on EtherCAT and FSoE right from the start," reports Peter Brinkmann, CEO of Brinkmann Electronic.

How to save cables, components, space and weight

Synapticon now has a comprehensive portfolio of highly compact servo drives whose safety is certified by TÜV SÜD. The latest certificate now also confirms the functional safety with regard to STO (Safe Torque Off) and SBC (Safe Brake Control) of the new Somanet Circulo series. FSoE ensures higher efficiency and safety, no matter for which purpose, such as temperature, humidity, force, speed, a sensor is to be integrated. Special control and regulation technology ensures that as little heat as possible is generated even during operation on the smallest of surfaces. This benefits the level of performance and energy efficiency, which is important for manufacturers of robots and automation components, but also for machine builders who rely on certified safety technology.

Synapticon drives are mechanically integrated into motor and gear units. This is another step that saves space, weight, cables and installation. The production process is optimized by fewer work steps. By reducing the number of components, complexity in purchasing and warehousing is reduced.

How drives and sensors can be securely linked together

Brinkmann Electronic is a service developer with a lot of experience in motion and safety. With the product bel.guard, Brinkmann Electronic offers a platform for safe motion control. Bel.guard has an FSoE master and can therefore safely evaluate and control a large number of sensors and drives. Integrated safety functions for monitoring, stop functions and simple logic can be optimally adapted to multi-axis systems. This forms, for example, the basis for the safety architecture of the entire robot or AGV.
 
The technologies of Synapticon and Brinkmann Electronic are well coordinated and can work together optimally. Furthermore, bel.guard is also able to integrate advanced third-party sensors and EtherCAT technologies.

Demo system as a practical example

A demo system set up for the SPS 2021 shows how these components work in conjunction with hardware and software. Here, the servo drives and encoders from Synapticon are used together with the safety software from Brinkmann Electronic. The system is completed by safety sensors, industrial PC and motor / transmission units. The basic Integrated Motion technology from Synapticon and the evaluation platform bel.guard from Brinkmann Electronic Berlin, which play a central role here, prove to be particularly flexible in this context. Numerous combinations with complete axles with or without gearbox from other renowned manufacturers are also possible.

"Through joint effort and use of the open interfaces, this demo demonstrated a new solution quality that enables completely new thinking," explained Peter Brinkmann.
 

Certified functional safety now also with FSoE

In the low-voltage environment, solutions that combine certified STO and SBC safety functions will be in demand in the future. Therefore, it is the right step to extend the certified functional safety from safe motion functions such as SLS (Safely Limited Speed), SP (Safe Position), SLT (Safely Limited Torque) to fieldbus safety using FSoE. Some manufacturers are already developing products that build massively on this next level of safety.
 
Ultra-compact, high-performance servo drives are intended for integrated axis designs in robotics and motion components in demanding mechanical engineering. They are used in robot arms, service robots, more and more machines and also in automated logistics solutions. FSoE now delivers a decisive advantage in terms of safety. The advent of FSoE in robotics means that there is no longer a need for proprietary systems. The possibilities offered by FSoE, especially in the safety area, are now actually available as standard. This reduces costs at the system level, with greater scalability and flexibility. These are the factors that ultimately matter in practice.