PDC sensor for machine safety
An ultrasonic sensor for machine safety is a non-contact device designed to detect obstacles, people, or objects in the path of industrial machinery, robots, and automated equipment to prevent collisions. These sensors provide real-time detection with high accuracy, enabling automatic slowdowns or emergency stops to protect personnel and equipment. This guide covers the operating principles, safety certifications, and applications of ultrasonic sensors for machine safety.
An ultrasonic sensor for machine safety is a non-contact device specifically designed to detect obstacles, people, or objects in the path of industrial machinery, robots, and automated equipment to prevent collisions and protect personnel. These sensors are an essential component of modern industrial safety systems, providing real-time detection that enables automatic slowdowns, emergency stops, or other protective actions when a potential collision is detected. The sensors use sound waves to detect objects regardless of material or surface. They are insensitive to weather conditions, visual irritation, and dirt. Safety-rated ultrasonic sensor systems, such as the USi-safety from Pepperl+Fuchs, are certified according to EN ISO 13849 category 3 PL d. These systems protect people and objects from potential dangers and collisions, taking their place in the range of electro-sensitive protective devices. The sensors can be used to safeguard hazard areas on mobile machines such as robots, industrial trucks, machines, and plants.
PDC Sensor
The operating principle of an ultrasonic machine safety sensor is based on the time-of-flight measurement of sound waves. The sensor emits high-frequency ultrasonic pulses toward the monitored area. When an object or person enters the detection zone, the sound waves reflect off the target and return to the sensor. The sensor measures the time taken for the echo to return and calculates the distance to the object. Safety-rated systems feature redundant monitoring and fail-safe design to ensure reliable operation. The USi-safety system, for example, provides safety functions with only one sensor unit, without requiring redundancy, and reliably detects moving and stationary objects with any shape, color, or surface in an elliptical, three-dimensional sound field of up to two and a half meters. Dirt, temperature, air flow, and humidity have no impact on the function of the sensor. The sensor's reaction time is typically 99 ms.
Ultrasonic machine safety sensors offer significant advantages over optical safety systems. Unlike laser scanners, ultrasonic sensors can detect obstacles that hang from above into the lane or are raised off the ground. They are not affected by dust, dirt, air currents, humidity, or similar factors. The sensors detect objects made of different materials reliably. The sensor units are extremely small and can be freely positioned, making them suitable for installation in confined spaces. The elliptical sound field has an opening angle of ±17° and ±5°, optimized for monitoring a 3-D range. The sensors feature a teach-in function for teaching in the complete detection area as a standard environment, which suppresses vehicle contours that could cause disturbances. This flexibility and robustness make ultrasonic sensors an excellent choice for almost all safety applications in industry and outdoors.
The applications of ultrasonic machine safety sensors are extensive across industrial automation. In human-robot collaboration (HRC), flexible ultrasonic sensor systems provide proximity sensing to enhance safety controls and prevent collisions between robots and environmental objects. These sensors can achieve accuracy of 3 mm over a detection range of 510 mm. In automated guided vehicles (AGVs) and autonomous mobile robots (AMRs), ultrasonic sensors provide reliable collision protection in all directions of travel. The USi-safety system can protect AGVs in automatic reverse travel, even when the vehicle is loaded. On reach stackers and other material handling equipment, ultrasonic sensors ensure precise distance measurement between the picker and the container, automatically reducing speed to avoid collisions. In industrial trucks and machines, the sensors provide collision protection in safety applications up to PL c/SIL 1 or PL d/SIL 2, even for retrofits. The sensors are also used in aviation for collision protection between aircraft and ground equipment.
The safety certifications and standards for ultrasonic machine safety sensors ensure reliable protection. The USi-safety system is the only safe ultrasonic sensor system according to EN ISO 13849 category 3 PL d. This safety approval means the benefits of ultrasonic technology can now be utilized for safety applications. The sensors feature two short-circuit and cross-circuit-monitored OSSD safety outputs per channel for the adjustable protection field, and one PNP switching output for the warning field. The control interface offers two safe OSSD outputs, ensuring fail-safe operation. The sensor units comply with IP69K protection, and the control interface complies with IP65. The sensors have an operating temperature range of -30°C to +50°C. If multiple USi-safety systems are installed on several independent AGVs that cross each other's paths, mutual interference suppression prevents them from interfering with each other's function. This comprehensive safety design ensures that ultrasonic machine safety sensors provide reliable protection in the most demanding industrial environments.
