Automation, Robotics and Intelligent Manufacturing
This domain tests whether you can specify a robot or automated cell that meets rate and accuracy targets, prove the safety functions are adequate, and integrate the control layers without opening an OT security hole.
Robot fundamentals
- Six-axis articulated arms give six degrees of freedom; SCARA suits planar pick-and-place, delta robots suit high-speed sorting.
- Accuracy is hitting the commanded point; repeatability is returning to a taught point. Repeatability is typically an order of magnitude better - ISO 9283 governs the test.
- Payload includes the end-effector, workpiece and inertia; reach envelope, cycle time and mounting must all be checked against ISO 10218-1 for the robot and -2 for the system.
Safety engineering
- Risk assessment per ISO 12100 drives the protective measures; PPE and signage are last, guarding and safe design are first.
- Safety functions are then rated: ISO 13849-1 performance level a to e, or IEC 62061/61508 SIL. An emergency stop is normally required at PL d, category 3.
- Collaborative operation per ISO/TS 15066 has four modes: safety-rated monitored stop, hand guiding, speed and separation monitoring, and power and force limiting, the last with body-region force and pressure limits.
Control and integration
- A PLC executes a scan cycle: read inputs, run the program, update outputs. Long scan times delay safety and interlock responses.
- ISA-95 levels 0 to 4 separate field devices from enterprise systems; OPC UA carries vertical integration securely, MQTT suits telemetry, MTConnect exposes machine data.
- IEC 62443 zones and conduits segment OT networks; OT patching lags IT and availability outranks confidentiality.
Worked example
A cell runs a 480-minute shift with 30 minutes planned breaks, 45 minutes of breakdown, 720 units produced, of which 20 are scrapped, at an ideal cycle time of 0.5 minutes. Planned production time = 450 minutes; run time = 405; availability = 405/450 = 90.0%; performance = (0.5 × 720)/405 = 88.9%; quality = 700/720 = 97.2%; OEE = 77.8%. The biggest loss is performance, so the fix is cycle-time related, not maintenance.
Traps that cost marks
- Using calendar time in the availability denominator, which should be planned production time.
- Claiming collaborative status without an ISO/TS 15066 force and pressure assessment.
- Confusing accuracy with repeatability when specifying the robot.
- Omitting the end-effector from the payload calculation.