Test solutions supplier AB Dynamics has unveiled a next-generation pedestrian ADAS target, the Soft Pedestrian 360, developed in collaboration with sister company Dynamic Research. This solution will support the testing of sensor perception and categorization, and reduce the time and cost of testing through its improved robustness and design.
For an enhanced level of realism, the Soft Pedestrian 360 benefits from sophisticated articulation of the knee, hip, shoulder and neck. The solution’s actively articulated knees enable the hip and knee to move independently of each other, controlling the gait and enabling a more varied range of movement to be reproduced compared to passive systems. Realistic movement is crucial when it comes to ensuring that vehicle sensor systems can correctly categorize a pedestrian.
“Properly representing the stance phase of the gait, when the foot is stationary relative to the ground, can be a critical factor in an AEB system’s categorization of the target as a pedestrian,” said Joseph Kelly, chief engineer, Dynamic Research. “Without this attribute, an AEB system could miscategorize the target as something other than a pedestrian and react differently. The team at DRI researched gait characteristics to identify and recreate the correct knee and hip articulation angles as functions of percent of gait cycle.”
Gait is automatically synchronized with the position, speed and acceleration of the target relative to a starting point using the platform’s inertial measurement unit (IMU). Using this method prevents a phenomenon that the team has called Flintstoning, where the foot in the stance portion of the gait is not stationary relative to the ground and results in better characterization.
“Damage to the vehicle under test caused by targets can be a substantial contributor to the total cost of testing ADAS technologies,” commented Kelly. “It isn’t just the damage to the test vehicle but also lost track and engineering time waiting for repairs that substantially increase the cost of testing. For example, if a windshield is damaged, camera systems located behind it often require recalibration, which is time-consuming and costly. We have specifically designed the Soft Pedestrian 360 to minimize the risk of damage to the test vehicle.”
To reduce the chance of the test vehicle sustaining damage, the testing solution must have a minimal amount of external hardpoints and a design which uses a reduced number of heavy components. The Soft Pedestrian 360’s head, limbs and mounting pole attach to the dummies torso via foam blocks which engage corresponding sockets in the torso. When components separate during a simulated accident, the design ensures that no hard points are exposed which could cause expensive damage to the test car. Additionally, each of the servos which operate the testing solution’s limbs and head are encased in foam inside each component for additional vehicle protection during impact.
A novel slipper clutch has been installed to stop the servos from being back driven when hit to prevent damage, increasing durability. A hard-wearing fabric on the exterior of the target covers the foam core to prevent wear and to ensure a consistent shape.
“Efficient use of track time is critical to keeping costs down and maximizing the uptime of both the test vehicle and the test equipment is a critical part of this,” said Kelly. “Before we developed our own pedestrian target, we were regularly changing and repairing servos as a result of damage, and this significantly impacted the test schedule. Our solution aims to make ADAS testing as efficient as possible.”
For increased testing capabilities, the solution’s articulating arms and head can be swapped for static units – when conducting Euro NCAP tests – where articulation isn’t needed. This provides a flexible and cost-effective solution for a range of tests. The Soft Pedestrian 360’s prescriptive head – which is used for NCAP and NHTSA tests – can be changed for an active unit to enable teams to carry out development work. Alternatively, the arms can be changed to represent a pedestrian using a cellphone.
“DRI’s experience working with the world’s leading safety organizations and OEMs has been critical in the development of the Soft Pedestrian 360,” explained Kelly. “Everything we have learned from the hundreds of tests conducted annually has gone into the design and development of the product to reduce test vehicle damage and improve the efficiency of testing. As with all of our products, it has been designed by test engineers, for test engineers.”