Cooperative robot applications are characterized by the fact that humans and machines share the same workspace at different times. However, mechanically separating safety devices, where the worker can only reach the robot through a safety door, are often an obstacle to optimal and efficient work processes. This is why such robot scenarios, whose aim is to increase productivity, are designed with an openly accessible workspace - which also becomes a danger zone during operation. Non-contact safety at all times, with situationally-adapted speed adjustment for optimum robot performance, both implemented on the basis of broad application knowledge.

Sick offers such a safety-tested and ready-to-integrate system solution for cooperative robot applications with sBot Speed-UR. The central components are an S300 mini safety laser scanner and a FlexiSoft safety controller. The safety package not only aims to protect people in the working environment of a robot, but also to improve the process efficiency of human-robot interaction. Safety and productivity are therefore two sides of the same coin. Safe and productive cooperation between man and machine is made possible by the adaptive perception capability of the sBot Speed-UR safety system, which automatically adjusts the robot's operating conditions to the position of people in its environment.

Adaptive perception for higher productivity

sBot Speed-UR is a complete, ready-to-integrate solution consisting of the S300 mini safety laser scanner and Flexi Soft safety controller. © Sick

The "eye" of the system is an S300 mini safety laser scanner. It meets the safety requirements of performance level d in accordance with EN ISO 13849 and SIL2 in accordance with IEC 61508 and complies with the requirements for optoelectronic protective devices in accordance with type 3 of IEC 61496. The range of the 270° protective field is up to 3 m. The visual perception capability of the sensor allows different field sets to be monitored within the field of view - each consisting of a warning and a protective field. In the context of the sBot Speed-UR safety system, two field sets are monitored, each of which is dependent on the current robot speed and forms the basis of the adaptive perception capability.

The FlexiSoft safety controller - which also meets all relevant safety requirements - acts as an intelligent link between the laser scanner and the robot controller. In the event of a person approaching, it is responsible for activating the defined safety-monitored speed of the robot - right through to triggering the safety stop or, if necessary, an emergency stop. Once the person has left the protective field again, the safety controller checks whether the conditions for a safe, automatic restart have been met. This also prevents the robot from starting up unexpectedly, for example during set-up or service work.

The S300 mini safety laser scanner monitors the working area of machines. © Sick

The safety system adjusts the operating conditions of robots according to the presence of people in their working area, thus supporting the optimum productivity of robot applications. The robot's workspace is monitored by two field sets: The larger field set 1 is designed for the robot's production speed in terms of movement dynamics, machine overtravel and hazard risk. The geometrically smaller field set 2 takes these factors into account at a safely reduced machine speed, as is the case with persons detected by the larger field set.

Less downtime, gentle robot operation

What does this mean in concrete terms in cooperative robot operation? If a person enters the warning field of field set 1 while the process is running, the robot safely reduces its speed. As the robot now runs more slowly and therefore has a lower dynamic response and shorter stopping time in the event of a safety or emergency stop, the sBot Speed-UR now activates field set 2 with a reduced protective field. The robot only switches to the safety stop when this is entered. If the person leaves the work area again, the robot starts up again automatically - initially at a safely reduced speed and monitored by field set 2. It then resumes its original working speed with protection from field set 1.

The sBot Speed-UR safety system is designed for use in the UR3, UR5 and UR10 robot models from Universal Robots. © Sick

This safely monitored reduction in speed means greater productivity and availability with optimized human-robot interaction compared to a complete stop and process standstill. The safety system also allows the robot to be moved manually during set-up mode, for example to teach in gripping points. New tasks can therefore be set up quickly and flexibly. The gently controlled, two-stage braking and acceleration during automatic restart also prevents unnecessary wear on the robot and its drive components, which can have a positive effect on its service life.

Easy adaptation to different locations

The economic efficiency of robots increases with the possibility of using them for different activities in changing work environments. This is possible with sBot Speed-UR. Different, location and function-related configurations of field sets can be stored in the safety system controller. The correct protective field settings can be activated, for example, when an RFID safety system such as the TR4 from Sick reports its new working position to the robot. Once the working position has been correctly identified, the safety system settings are enabled for the new working environment. The user therefore only needs to move the robot into position to get it ready to start. Without release by the correct ID code, for example at an incorrect or unintended installation location, sBot Speed-UR - and therefore the robot - cannot be started.

In addition to automation and safety functions, sBot Speed offers a complete wiring plan that enables system integration into robot controllers. © Sick

The sBot Speed-UR system variant is the first manufacturer-specific version of the sBot Speed safety system. It is specially adapted in key points for use in the robot models UR3, UR5 and UR10 from the manufacturer Universal Robots. This applies, for example, to the UR-specific wiring diagram and the parameter settings for the selectable operating modes "Active mode" and "Programming mode". The description and connection of additional safety components that are required to meet relevant safety standards, as well as the setting instructions for the UR safety configuration, are also specially designed for the robot models mentioned. The wiring diagram, the safety logic program, the UR-related parameter settings and the SISTEMA file are also included in the documentation. The safety system enables the commissioning engineer or operator to program the robot when setting up the robot or changing functions and to move it safely, for example to teach in gripping points.

The sBot Speed safety system and the sBot Speed-UR variant enable freely accessible robot applications to be individually safeguarded up to performance level d in accordance with ISO 13849. This applies equally to the initial equipping of robots as well as their subsequent safety-related and functional retrofitting. The sBot Speed safety system and the sBot Speed-UR variant are available immediately; further variants with other robot manufacturers are in preparation. Each variant of sBot Speed can be migrated: Additional safety functions can also be implemented in the safety controller at a later date.

Felipe Pino, Product Manager Global Business Center Industrial Safety at Sick / ag