Safety in the world of collaborative robotics

Safety in the world of collaborative robotics

Designed to share space and work with humans, i Collaborative Robots they can certainly boast a higher level of safety than machines on traditional robotic lines.

But what are the standards to respect and the functions that make Cobots like this reliable?
Before seeing it in detail, a clarification is necessary.

Those who work in collaborative robotics know that there are no "collaborative" machines by nature. This is because a robot may be designed for a collaborative task, but it is the application that does all the work. It is the application that makes the robot “collaborative”.

The design of Cobots, therefore, requires attention risk assessments to ensure the safety of human operators throughout their use.

It is crucial that manufacturers consider all possible risks, such as so-called transient or quasi-static contacts, as well as what can happen when the robot is involved in an emergency stop. 

Safety standards

The issue of safety in relation to collaborative robots is therefore complex.

The reference standards are essentially of three types, but to these is added a "technical specification" which is not mandatory, but acts as a guideline.

There are therefore:

  • Type A rules: this is the case of ISO 12100, which generally concerns risk analysis;
  • Type B rules: like the ISO 13849-1, which details the behavior of individual parts of the application;
  • Type C standards: which specifically concern robots and give instructions to manufacturers (ISO 10218-1) and supplements (ISO 10218-2).

There ISO/TS 15066 finally, it is a specific technique that provides some indications on parameters such as force and pressure.

The definition of fixed parameters to evaluate the security of an application is not contemplated. The cases must instead be evaluated individually by conducting, as we anticipated, an analysis not so much on the Cobot but rather on the robotic application as a whole.

Cobot safety features

In order for a robot to be considered suitable for collaborative applications, it must possess four important functions: 

  1. Safety monitored shutdown
    It involves pausing the robot when a worker approaches it. It aims to prevent dangerous movements. The function, in the new edition of ISO 10218-1, is defined as "monitored shutdown";
  2. The manual guide
    It consists of allowing the operator to move the robot using a manual device to transmit movement commands. In the new standard it is defined as "manual driving equipment", and must have an emergency stop button;
  3. Speed and distance monitoring
    This feature increases safety by specifying the minimum protective distance between a robot and an operator in the collaborative workspace. It can be implemented using different methods, such as external sensors, capable of providing operator position and speed data, for the internal calculation of a movement plan to maintain distance.
  4. The limitation of power and strength
    This feature allows contact between the operator and a robot, but protects the human from possible injury or pain. The so-called functions PFL (Power and Force Limiting) can occur through pre-established, non-adjustable or configurable safety designs, or through safety features that can be adjusted or configured. For robots with adjustable or configurable PFL safety functions, exceeding any limit parameter must cause a “protective stop”.

Cobots and Human Work

The possibility of setting stop areas and regulating the speed of movement of the robotic arm are some of the most frequently adopted solutions to secure the area occupied by the operator.

One of the advantages of collaborative robots is that of being able to manage these parameters directly from the control panel, without having to install external control units.

An advantage that significantly reduces commissioning times and increases productivity.
The ability of collaborative robots to share tasks with humans, after all, it guarantees many advantages across a wide range of industrial operations, and therefore ensures a return on the investment made to robotize the industrial line.

The safety functions integrated into the Cobots, first of all, allow you to work together or close to people, contributing to the streamlining, efficiency and speeding up of many repetitive activities.

Despite the numerous safety features, which include lightweight frames, collision detection technology and minimized pinch points, the application of Cobots must however still take additional safety measures into consideration.

Collaborative robots are designed to work alongside human operators thanks to technologies such as force feedback, low inertia servo motors, elastic actuators and collision detection technology that limit its power and speed to levels suitable for contact.

Force and speed monitoring are the hallmark capabilities of collaborative robots.

By detecting the presence of a person within the collaborative workspace, they can operate at slower or faster speeds based on the condition.

This helps them maximize productivity when people are not present within the danger zone.

Finally, many collaborative robots use mechanisms of manual guidance intuitive that allow operators to teach the robot new tasks without the need to explicitly program the movements of the robotic arm. The manual driving mode controls the force and speed to ensure that the teaching process complies with safety standards.

Industrial applications

Based on their tasks, collaborative robots can generally be divided into automated machine tools, machines for handling materials and goods and machines for assembly operations.

They therefore perform automated tasks around other equipment to which they could potentially cause damage.

That's why designers must consider not only all the ways the robot interacts with an operator, but also what aspects of the surrounding environment could be dangerous.

A risk assessment, performed comprehensively, therefore ensures the success of an application's efficiency and will increase performance and benefits for industrial operations.

Material handling applications that benefit from the integration of collaborative robots, for example, include picking, packing, palletizing, sorting and more.

The now widespread use of Cobots for these specific operations demonstrates the great potential of these machines and their consolidated safety.

A concrete example is todrobot TR1 home TOD System.
A revolutionary mobot/Cobot capable of automating logistics and intralogistics processes allowing agility, efficiency and safety in logistics operations picking and placing.

All thanks to an innovative mechanical arm and the patented 3D viewer with AI On Board with which it is equipped, through which it is able to detect the position of the targets and to move in complete autonomy and safety in the workspace.

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