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Robotics Safety Standards

Overview​

The increasing deployment of robots in industrial and, more recently, collaborative environments necessitates robust safety measures. Robotics safety standards provide guidelines and requirements to mitigate risks associated with human-robot interaction and ensure the safe operation of robotic systems. This section introduces key international standards, focusing on those applicable to industrial and collaborative robots, and outlines general principles of risk assessment and mitigation.

Detailed Explanation​

The Importance of Robotics Safety Standards​

Robots, by their very nature, are powerful machines capable of rapid and forceful movements. Without proper safety considerations, they can pose significant hazards to human workers and the environment. Robotics safety standards are developed by international and national organizations to:

  • Protect personnel: Prevent injuries, fatalities, and health issues.
  • Prevent property damage: Avoid damage to the robot itself, other equipment, and products.
  • Ensure compliance: Meet legal and regulatory requirements.
  • Build trust: Foster confidence in robot technology among users and the public.

Key International Standards​

1. ISO 10218: Industrial Robots Safety Requirements​

The ISO 10218 standard, split into two parts (Part 1 for robots, Part 2 for robot systems and integration), specifies requirements for the safe design and construction of industrial robots and robot systems.

  • ISO 10218-1:2011 (Robots): Focuses on the robot itself (the manipulator and its controller). It covers topics such as safety-related control system performance, emergency stop functions, and requirements for external device interfaces. Its primary goal is to ensure the robot can perform its functions safely in a controlled environment.
  • Traditional Industrial Robot Operation: These robots typically operate in fenced-off areas, separating them completely from human workers to eliminate collision risks. Safety sensors (e.g., light curtains, safety mats) are used to detect human entry into the hazardous area, immediately stopping the robot.

2. ISO/TS 15066: Collaborative Robots​

As robots moved out of cages and into shared workspaces with humans, new safety challenges emerged. ISO/TS 15066 (Technical Specification) provides guidelines for the safe design and application of collaborative robot systems (cobots). This standard introduces new concepts for human-robot collaboration, which include:

  • Safety-rated monitored stop: The robot stops when a human enters the collaborative workspace, and restarts automatically when the human leaves.
  • Hand guiding: The operator can move the robot by hand, allowing for intuitive programming and teaching.
  • Speed and separation monitoring: The robot's speed is reduced as a human approaches, and it stops if the separation distance becomes too small.
  • Power and force limiting (PFL): This is the most complex and critical collaborative operation. The robot is designed and controlled so that contact with a human does not result in pain or injury, by limiting the force and power it can exert. This requires careful consideration of potential contact situations and biomechanical limits of the human body.

Risk Assessment and Mitigation Strategies​

A fundamental principle of robotics safety is risk assessment. Before deploying any robotic system, a thorough risk assessment must be performed to:

  1. Identify hazards: Recognize potential sources of harm (e.g., crushing, trapping, impact, burns, electrical shock).
  2. Estimate risks: Evaluate the likelihood and severity of harm.
  3. Evaluate risks: Determine if the risks are acceptable according to relevant standards.
  4. Implement risk reduction measures: If risks are unacceptable, implement measures following a hierarchy of controls:
    • Eliminate the hazard: Redesign the system to remove the hazard entirely.
    • Substitute: Replace hazardous components with safer ones.
    • Engineering controls: Implement physical safeguards (e.g., fences, light curtains, safety interlocks).
    • Administrative controls: Implement safe work procedures, training, and warning signs.
    • Personal Protective Equipment (PPE): Provide safety glasses, gloves, etc., as a last resort.

For collaborative robots, safety measures often focus on ensuring that contact with a human is either avoided or limited to safe levels, requiring advanced sensing, control, and sometimes specially designed compliant robot structures.

Hands-on Exercise: Basic Risk Assessment for a Robotic Workstation​

This exercise will guide you through a simplified risk assessment process for a common robotic application.

The Scenario​

Imagine an industrial workstation where a collaborative robot (cobot) is used to assist a human worker in assembling small electronic components. The human and robot share the same workspace, but the robot is programmed to slow down or stop if the human approaches too closely.

Your Task​

  1. Identify Hazards: Brainstorm and list at least 5 potential hazards associated with this collaborative robotic workstation. Consider mechanical hazards, electrical hazards, and ergonomic hazards.
  2. Estimate Risks: For each identified hazard, make a qualitative estimation of its risk level (e.g., Low, Medium, High) based on the likelihood of occurrence and the severity of potential harm. Justify your estimation.
  3. Propose Mitigation Strategies: For each hazard, propose at least one mitigation strategy that aligns with the hierarchy of controls (Elimination > Substitution > Engineering Controls > Administrative Controls > PPE).

Example Hazard and Mitigation​

  • Hazard: Crushing injury to the human worker's hand if caught between the cobot arm and the jig.
  • Risk Estimation: Medium (Likelihood: Moderate due to shared workspace; Severity: High due to potential for serious injury).
  • Mitigation Strategy (Engineering Control): Implement a power and force limiting (PFL) function in the cobot's control system, ensuring that any contact forces exerted by the robot are below safe limits defined by ISO/TS 15066. Additionally, use proximity sensors to detect human presence and trigger a safety-rated monitored stop.