For the validation of complex systems, it is necessary to set up an appropriate test environment that effectively stimulates the sensors to verify the behavior of the vehicle under real-world conditions.
Altran Italia has integrated an innovative radar object simulator based on NI technologies and a 3D virtual road scenario simulator into an HIL set up to produce a scenario-based tester that fully synchronizes camera and radar data to validate sensor fusion algorithms.
Figure 2. ALTRAN-NI ADAS HIL Test Solution
The 3D scenario is based on the Unity 3D Graphic Engine, a cross platform game engine by Unity Technologies, and is fully configurable allowing customization of parameters such as number of lanes, lighting conditions, and track type. A variety of other graphic model environments also exist on the market and could be used similarly such as IPG Carmaker and TASS PreScan.
The graphic engine reproduces the scene from the viewpoint of a camera placed on the windshield of a vehicle. The scene can be modified based on the height from the ground and the camera’s field of view. It is also possible to show an obstacle (for example, a vehicle) at a set distance from the camera at a defined speed.
Figure 3. Unity Graphic Engine Scenario
For the vehicle control, the graphic engine receives the position of the brake pedals and throttle in addition to the steering angle. A PXI System acquires this data in addition to signals from the steering wheel and pedals (Logitech G29). The dynamic vehicle model is integrated within the graphics engine and is highly configurable.
Figure 4. Standard Maneuvers
Per the selected obstacle scenario (with some examples above as a starting point), the graphic engine outputs the vehicle speed as well as information needed by the VRTS to produce an RF signal. All input/output information is exchanged with the PXI through a proprietary protocol and can be changed as needed.
A CAN communication with PXI-8512/2 was used in this setup to retrieve information from the scenario generator about radar targets (distance, radar cross sections, angle of arrival, and speed). The PXI-8512/2 is a two-port high-speed CAN/CAN-FD interface for PXI Systems used for transmitting and receiving CAN bus frames at 1 Mbit/s. The information is sent to the Obstacle Generator only if the information about the targets changes between consecutive readings.
In addition to sending the data to the Obstacle Simulator and acquiring pedal and steering signals, PXI also emulates the CAN messages sent to and from the radar and camera over a private vehicle network.
CAN messages are synchronized with the 3D virtual scenario and RF Target Generator to produce the correct environment for validating modern camera and radar data.