Autonomous Mobile Robot Safety, Standards, and Considerations

Introduction: Why robot safety is important ?

With an increasing number of AMRs being deployed and customers’ limited experience with this relatively new technology, the topic of mobile robot safety is more important than ever.

Section 1: AMR safety standards

At the time of this blog post, there are several standards out there and it is important to know which ones are relevant and useful to the end customer. Hence, the SESTO AMR system has been designed in accordance with CE standards. The following standards have been certified:

The most important standard in this list is the CE Mark, which was attained by SESTO Robotics. Having the CE Mark means that SESTO Robotics affirms the product’s conformity with European health, safety, and environmental protection standards.

Section 1.1: EMI and EMC testing

Our team invests time and resources in both electromagnetic immunity and emissions testing.

The former measures how our AMR will react when it is exposed to electromagnetic noise and the latter measures the amount of electromagnetic noise generated by our device during normal operations.

The testing is done to comply with safety standards, ensuring our AMRs operate reliably in real-world conditions without being affected by interference from external sources or causing harmful interference to other devices in the operating vicinity.

Check out our LinkedIn post for what the team has set up and prepared prior to official compliance testing.

Section 2: SESTO AMR safety technology and how they ensure operational safety

To adhere to ISO 13849-1 standard, a separate Safety PLC that monitors the individual wheel speed of the AMR’s drive wheels was incorporated. This Safety PLC deduces whether the actual velocity of the AMR is within the safety-rated wheel speed through a safety-rated encoder. Based on feedback from the encoders and safety PLC, the AMR’s safety lasers projects the correlating protective field zone. This enables the AMR to come to a safe stop before contacting the obstacle when an obstacle is detected in the safety laser protective field.

Example of Magnus AMR Functionalities

Section 3: How to ensure workplace safety when deploying AMRs

1.Emergency planning and evacuation

In an emergency situation, the primary goal is to get everyone out of the hazardous situation as quickly as possible. In this scenario, the AMRs should allow a clear path for humans to reach exit doors. Ensure that your facility’s external alarm system is integrated with the internal messaging system of each AMR.

2. Obstacle detection, stopping, and navigation

A fully loaded AMR may need more time to stop from a given speed. LIDAR sensors and 3D cameras help SESTO AMRs notice obstacles in their path so there is plenty of time to stop smoothly. LED lights, visual and audio indicators provide a visual warning of navigation, approach, and status. Safety bumpers serve as a secondary safety function to stop when it comes into contact with an object. It also acts as a safety feature during free/manual navigation and during docking / undocking manoeuvres where the safety laser protective fields are temporarily disabled.

Within a facility, zones can be set up allowing different speeds for different situations. Also known as Protective Field Zone (refer to the above table), the Safety PLC will select a safety laser protective field zone for the safety laser to project, based on the AMR’s movement speed. When the safety laser protective field is breached, the emergency stop sequence will be carried out. For SESTO AMRs, zones are pre-configured or automatically assigned when the Safety PLC automatically detects the zone based on the AMR’s speed.

3. Payload capacity and stability

Payload stability should not exceed the unit’s capacity. The weight should be positioned as close as possible to the robot’s centre. This ensures that a fully loaded AMR will have a higher centre of stability. SESTO Robotics assesses facility requirements to ensure that the correct payload is chosen to fit the client’s needs.

4. The nature of the surrounding environment

Surface irregularities eg. potholes may be hazards. The surface on which AMR travels will impact its balance and ability to stop safely. Be sure to scan the surfaces for anything that may lead to an AMR losing track of its location or tipping over and spilling its load. The angle of incline and decline is defined for all SESTO AMRs – meaning that the AMR has a specification for the angle of the slope it can travel on. Brakes are engaged whenever SESTO AMR stops so that the AMR will not slide or roll down a slope. SESTO AMRs are equipped with a bogie that helps keep wheels to the ground as it travels through different terrains.

5. Interaction with other machines

A Fleet Management System serves as the master planner of the entire fleet of robots and controls robot-to-robot communication. For instance, in parts loading and unloading, a machine may send a signal to the enterprise system indicating that an AMR is needed to pick up a part. The AMR will have to reduce its approach speed when approaching the machine, in case a person stops in the way. The Safety PLC ensures that each robot is communicating correctly with the Fleet Management System, avoiding collisions or wrong task allocations.

For network security, The AMR System supports a secure connection. For secured authenticity, each connected device shall be assigned an IP address in the network. The devices will then each be installed with an SSL certificate and Key.

Section 4: Safety questions to ask when considering an AMR deployment

Question: Does the AMR stops when it sees people?

Answer: Yes. In addition to the Safety Controller as the overarching system, key safety features like LIDARs, 3D camera, protective field zones, front and rear Emergency Stops, and safety bumpers are all fully functioning on a SESTO AMR, enabling it to effectively detect people.

Question: Can AMR reverse and do they have sensors to see behind them?

Answer: Yes. Unlike other vendors, SESTO AMRs have two 3D cameras on the front and back respectively. This gives a full 360-degree view of the surroundings enabling AMRs to reverse easily if required.

Check out this video which shows how the SESTO AMR reacts to obstacles.