On the road, pedestrians are particularly at risk, a fact reflected in the high proportion of deaths. In most accidents, the pedestrian collides with the front of the vehicle. Serious injuries can occur if the pedestrian’s head hits the engine hood or other hard structures in the area around the windshield.
The pressure tube sensor from Bosch provides a pressure-based sensor system designed to detect collisions with pedestrians. Bosch has already been using a pedestrian-protection system based on acceleration sensors for many years.
The pressure tube sensor, integrated into the front spoiler of the vehicle, consists of an elastic silicone tube filled with air. Two peripheral pressure sensors are located at each end of the tube. The sensor was developed in accordance with ISO standard 26262 for safety-relevant electronic systems in vehicles.
If the system detects a collision with a pedestrian, it triggers protective mechanisms, such as an active engine hood device or windshield airbag within 10 to 15 milliseconds of the impact. These can absorb the kinetic energy produced by the pedestrian’s head, thereby minimizing the severity of the injuries sustained. The evaluation electronics of the sensor system are integrated into the airbag control unit.
The pressure tube sensor is connected to the airbag control unit via a PSI5 interface (peripheral sensor interface) that controls the power supply as well as the transfer of data.
The tube in the sensor system is fitted along the length of the cross-member in the energy-absorbing foam on the bumper. The pressure sensors at the end of the tube are either screwed directly into the crossbeam, inserted into the energy-absorbing foam, or attached to the bumper overlay.