Test-system specialist AB Dynamics has developed new drive-by-wire technology that enables test vehicles – including autonomous vehicles (AV) – to be driven entirely via a CAN or ethernet connection, without the need for a human driver or robot actuators. Positioned as a cost- and hardware-saving alternative, the Flex-0 system complements existing driving-robot systems and is already in use by Volvo for a range of advanced test applications.
According to Andrew Pick, business director at Track Test Systems, widespread use of electronic vehicles systems permitted AB Dynamics an opportunity to control the vehicle directly through its CAN network, using a path-following approach but eliminating much of the test hardware that is normally required.
“Conventionally, the hardware installed for an objective vehicle test would include a steering robot, pedal robots, control system, data logger and a motion pack,” Pick explained. “But a Flex-0 installation requires only the motion pack and a much more compact control system, which simplifies and speeds up installation and intrudes less into the cabin space.”
Flex-0 drive-by-wire setup shares the same software interface as the company’s driving robots and ADAS targets, allowing users to copy existing test profiles between the two systems. The GPS motion pack installed in the vehicle provides feedback on position, enabling Flex-0 to be used for a wide range of tests. Volvo has investigated using Flex-0 in the Euro NCAP AEB test, ISO 3888 double lane change, steady-state cornering, and off-road testing.
Regarding complex test scenarios, such as those that arise during AV and ADAS development, Pick noted that Flex-0 creates new possibilities. “Testing autonomous vehicles requires complex traffic scenarios involving multiple vehicles,” he said. For these tests, Guided Soft Targets (GSTs) can be used where there is potential for a collision, but other “background” traffic away from the risk of collision can be populated by regular cars using Flex-0 as a method of synchronized control.
Fiercely protective OEMs
There are situations where robot control is more appropriate than Flex-0, which is why AB Dynamics considers the two technologies to be complementary. For example, Pick explained, individual OEMs are “fiercely protective” of their CAN command formats. This confidentiality means robot actuators are still required where access to the CAN network is denied, such as during competitor-vehicle benchmarking, or testing undertaken by third party agencies.
Robots will also remain for dynamic tests involving extreme steering inputs, where the force required for the maneuver exceeds the vehicle’s steering system capability when commanded by-wire. “For those, our established systems can position a vehicle repeatedly to within 20mm thanks to path-following and speed control using GPS feedback,” Pick said, “eliminating driver fatigue during arduous off-road and durability testing by enabling control from outside the vehicle.”
To minimize constraints imposed by CAN confidentiality requirements, AB Dynamics has configured Flex-0 to output in a standardized format, allowing manufacturers to implement their own conversion to suit the vehicle. OEMs can enable access to their vehicles by providing an interface between the Flex-0 CAN output and the data format required by the vehicle. “This typically requires only a small real-time processor to run the interface,” Pick stated, “such as a dSpace Micro Autobox, and means that the customer does not need to disclose details of its by-wire interface to third parties.”
To support the use of production vehicles as synchronized traffic in test scenarios for AV and ADAS applications, the company is also working to deliver fully interfaced drive-by-wire solutions for a number of representative vehicles, including models from Kia (see video, below) and Ford. Many modern cars have the capability to be controlled by-wire, allowing Flex-0 to drive them as though they had robots fitted.
“This opens up opportunities to use our established Path Following and Synchro technology to perform many types of tests that otherwise would need robots,” Pick said. “As the industry learns more about the testing and validation requirements for autonomous systems, there will be a need to conduct extensive tests that safely replicate real-world road situations.”
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