Test simulates pedestrians' safety

A testing company is helping automakers and their suppliers pass new European regulations to improve pedestrian safety in accidents.

VIA-Systems Inc. has designed a Free Motion Headform test system and a Pedestrian Impact system that will help automakers judge whether their vehicle designs will soften the impact on pedestrians. Both use three basic test probes: a headform, an upper legform, and a lower legform.

"The two systems are used for component-level testing of door inner panels and structures to simulate the interaction of the driver or passenger with the doors," explains John Cheyne, vice president, VIA-Systems and VIA Test Laboratories. In their basic forms, both include a pneumatic actuator, a guide system, door fixtures, pressure control systems, and high-speed data acquisition system. The tests use the VIA 201 Free Motion Headform Test system base unit and control system.

Cheyne says the company uses Pro/ENGINEER, a 3D solid modeling tool, to design the test systems. "We hold brainstorming sessions with our staff here and are given a fair degree of latitude in picking functionality for the test systems," he adds. "Once we agree on a basic direction, we spend a couple of weeks working with a smaller group of controls integrators and fabricators."

Their goal is to evaluate the performance of a door system-at a component level-for a fraction of the cost of actual testing. "Design cycle times are being compressed every year, so this methodology of testing allows automotive manufacturers to send in prototype parts and panels before they go to hard tooling and then to production levels," continues Cheyne. "This testing slashes costs from several hundred thousand dollars for prototype vehicles down to less than $30,000, at a nominal cost of $1,000 to $2,000 per test."

The Pedestrian Impact test simulates a person hit by a car, and determines where the contact points would be on the vehicle. It incorporates several parameters: lower legform to bumper tests, upper legform to bumper tests, upper legform to bonnet leading edge tests, child headform to bonnet top tests, adult headform to windscreen tests, and child and adult headform to bonnet top tests.

"The basic method we use is a hydraulic/ pneumatic system," explains Cheyne. Major components of the system include a propulsion system, interface fixtures, the actual test probes, high-speed video and data acquisition systems, and a motion control system, all mounted on a motion control base unit.

The Head Impactor control and measurement system includes a portable rackcart, which contains all the required electronics-PC, laser printer, PLCs, and measurement signal conditioning. Eight high-speed data acquisition systems collect test data. Other components include: remote pendant controls with motor selection, motor direction, and motor speed, incremental linear measurement sensors with 0.1 mm accuracy, angular/rotational position measurement made with encoders and tilt sensors, and pressure measurements made through pressure transducers with 0.01% accuracy.

The test systems encompass propulsion-type, pneumatic/hydraulic systems with test velocities of 35 to 40 kmh (22 to 25 mph), and probe weight ranges from 3.5 kg to 13.4 kg (7.75 to 29.5 lbs). The control system measures pneumatic pressure and propulsion system position, and also operates the pressure control valves, launch valves, and emergency pressure dump valves via PLC control.