ADAS & Autonomous Vehicle Engineering - November 2023 - 25

Sensors
rFpro's system can render nine different image generators to generate part of a 180-degree field of view that can represent subtleties well.
tire models into the simulation. They are buying really
safety critical components like camera sensors, lidar
sensors and radar sensors. We have to build very detailed
models of those and put those into the simulation as well. "
This vehicle model is computed at some 1,000Hz,
meaning that the full dynamics of the car and its acceleration
states are being calculated every millisecond.
These also are being fed with a high-definition road
surface. " Underneath each of those tires you have an
independent road input and that's running through
what we call our rFpro terrain server, " says Daley.
This server takes the position of every wheel, and
it calculates a volume, it doesn't just take a single point
sample. It is looking at the tire's volume through the
ground, using a one-centimeter (0.39-inch) grid.
" We're modeling that under each tire and therefore
passing back a very detailed road shape to those tires individually, "
explains Daley, " That's still at 1,000 Hertz, once a
millisecond and that's going back up through the system,
through the suspension, the chassis and the vehicle models
are calculating their accelerations and that fundamentally
is what gets passed over to the simulator driver.
" What is the acceleration of the vehicle? It's vertical,
it's horizontal, it's pitch, it's roll and the other thing that
the simulator driver gets back there is the steering feel,
you feel the torque in the steering. So, you provide
torque and position input yourself and the system reacts
by loading up that wheel to the right level. "
Multiple image generators
For dynamic driver-in-the-loop simulators, the rFpro
system uses nine independent image generators (IGs),
which basically are PCs with a graphics card generating
an image. Each generates a small portion of the
180-degree screen. " The 180-degree screen is divided
by nine. You've got 20 degrees per screen, but because
you need the screens to overlap with each other you
need to render more than 20 degrees and then blend
the two together, so you get a seamless image. So,
each IG is probably giving 30 degrees to allow for five
ADAS & AUTONOMOUS VEHICLE ENGINEERING
ADAS & AUTONOMOUS VEHICLE ENGINEERING
The system accurately represents the blur effect of a fast object overtaking
a stationery object.
degrees of overlap at each edge, " says Daley.
Simulation is not just about a faithful recreation of
what we as humans can see. Simulation systems designers
such as rFpro need to factor in the camera sensors, lidar
sensors and radar sensors and how these devices map
their surroundings. Then the appropriate training data for
those sensors can be generated from machine learning.
Daley likens the training data to how you train
children, using dogs as an example, " You train your
children by showing them a picture of a dog and saying,
'Dog, and here's a different dog.' It's still a dog, but it's a
different dog and I might point at a real dog, or I might
point at a picture of a dog. You're giving your child
training data, which is the input image and the answer. "
The team at rFpro realized a few years ago that in
addition to real-time simulations, for safety- critical situations,
the engineering data needed to be correct. " We
can reuse the vehicle simulations, the traffic control, we
can reuse the locations that we've built, but what we need
to do is allow us to do these lighting calculations. We
started from the ground up with a blank sheet of paper
and we wrote a dedicated ray trace rendering engine
that now sits alongside the real time engine. They are
two independent engines that you swap between. This
is not a hybrid solution, " explains Daley.
November 2023 25
November 2023 25
rFpro
rFpro

ADAS & Autonomous Vehicle Engineering - November 2023

Table of Contents for the Digital Edition of ADAS & Autonomous Vehicle Engineering - November 2023