PDC Sensor for Collision Protection - Ultrasonic Safety-Rated Sensing for AGV and Mobile Robot Collision Avoidance
This in-depth technical article examines the application of PDC sensors for collision protection, covering the ultrasonic safety-rated sensing for automated guided vehicles (AGVs) and mobile robots, the EN ISO 13849 category 3 PL d certification, the three-dimensional monitoring for comprehensive vehicle protection, and the integration with AGV control systems for reliable collision avoidance.
Ultrasonic collision protection sensors provide safety-rated obstacle detection for automated guided vehicles (AGVs) and mobile robots, preventing collisions with personnel, objects, and infrastructure. The USi-safety ultrasonic sensor system is the only safe ultrasonic sensor system according to EN ISO 13849 category 3 PL d, enabling reliable monitoring of three-dimensional spaces, making it ideal for use on materials handling equipment. When moving materials using AGVs, all directions of travel must be reliably protected to keep personnel and objects in the lane safe from collisions. At least one protection measure to PL d in the main direction of travel (forward) and at least one to PL c in the secondary directions (sideways and reverse) are required. With load transfers, a protection measure to PL d is needed for automatic reverse travel if loaded pallets are picked up or placed on the ground. The sensor used for collision protection must not only reliably detect obstacles but also output the corresponding signal quickly enough that the self-driving robot can brake or change direction in time.
PDC Sensor
The three-dimensional monitoring capability provides comprehensive protection around the AGV or mobile robot. The sensor's elliptical sound field has an opening angle of ±17° and ±5°, optimized for monitoring a 3-D range and detecting obstacles that hang from above into the lane or are raised off the ground. Unlike laser scanners, the ultrasonic sensor can detect obstacles that hang from above or are raised off the ground, providing more comprehensive protection in complex environments. The sensor units are extremely small and can be freely positioned, meaning they can be detached from the control interface for flexible positioning in the extremely narrow space of the fork arms. The sensor reliably detects moving and stationary objects with any shape, color, or surface, ensuring that all potential collision hazards are detected. Dirt, temperature, air flow, and humidity have no impact on the function of the sensor, ensuring reliable operation in demanding industrial and outdoor environments.
The EN ISO 13849 category 3 PL d certification ensures the sensor meets the highest safety standards for AGV collision protection. The safety approval means the benefits of ultrasonic technology over optical systems can now be utilized for safety applications. The control interface offers two safe OSSD outputs per channel for the adjustable protection field and one PNP switching output for the warning field. The reaction time is typically 99 ms, ensuring rapid response to detected obstacles. The sensing range is up to 2,500 mm, providing adequate coverage for AGV collision protection. The sensor units comply with IP69K degree of protection, while the control interface complies with IP65. The operating temperature range of -30°C to +50°C ensures reliable operation in a wide range of environmental conditions.
The integration with AGV control systems uses the sensor's safety outputs to stop or slow the vehicle when an obstacle is detected. The sensor provides two short-circuit and cross-circuit-monitored OSSD safety outputs for the adjustable protection field, ensuring fail-safe operation. When an obstacle enters the protection field, the OSSD outputs switch to the safe state, triggering an emergency stop of the AGV. The PNP switching output for the warning field can be used to slow the vehicle or activate warning lights before the obstacle enters the protection field. The teach-in function for teaching in the complete detection area as a standard environment increases operational safety, with the function suppressing vehicle contours that could cause disturbance. If the USi-safety system is installed on several independent AGVs that happen to cross each other's paths, the mutual interference suppression prevents them from interfering with their function, and a physical connection between the systems is therefore unnecessary.
The future of ultrasonic collision protection is moving toward enhanced accuracy and integration with autonomous vehicle systems. The development of 3D ultrasonic sensors, such as the Toposens ECHO ONE, inspired by the sophisticated echolocation abilities of bats, represents a significant leap forward in mobile robotics collision avoidance. The use of sensor fusion, combining ultrasonic with radar and vision sensors, is improving the robustness of collision detection in complex environments. The ongoing advancement in ultrasonic transducer technology and signal processing is improving the range, accuracy, and reliability of collision protection sensors. The ultrasonic collision protection sensor continues to evolve, providing the safety-rated obstacle detection required for AGV and mobile robot collision avoidance in modern logistics and manufacturing.
