Jonathan Newell visits National Instruments to discover how Veristand can help automotive developers unravel complex system architectures for test and validation.
It’s already been a very long time since there was anything remotely simple about the cars we drive or the ability to recognise problems, self diagnose or even attempt to repair them without detailed knowledge or specialist equipment. Now, with electrification, different powertrain options, driver assist systems, high levels of connectivity and ultimately autonomy, private transport is certainly not going to become any simpler.
With this rise in complexity comes a degree of consumer anxiety about reliability, repair costs and long term resale value as noted in a recent AA motorist survey, which revealed that this anxiety along with purchase price are the root cause of a reluctance to purchase electric vehicles in as many as 3 out of 10 drivers.
Whilst the additional functions, features and safety benefits of partially autonomous, ADAS equipped vehicles are all very welcome, there is a significant cost penalty that is ultimately borne by the consumer and which needs to be factored into the total cost of ownership when purchasing decisions are made.
One case study of a US automotive manufacturer showed that the Bill-of-Materials cost of a brake light system had grown from $67 to a staggering $450 due to the addition of sensors, detection systems and cameras for ADAS features. Whilst some of this cost is for the extra hardware installed, there is also a significant cost burden resulting from development, prototyping and testing the system. Taking large chunks out of this cost whilst still maintaining the additional new functions is the conundrum of complexity facing the automotive industry.
To understand what tools are available to the industry to unravel this problem, I travelled to National Instruments’ (NI) UK headquarters in Newbury to speak to Jeremy Twaits, a Senior Field Marketing Engineer at the company.
Taking cost out of the design, development, test and validation loop is something that Twaits is certain can be achieved by using the correct design optimisation tools as well as performing validation exercises at each stage of the process.
“By using such tools at every stage of the development cycle, rectification costs can be avoided. These can be significant and tend to escalate by an order of magnitude, the further along the design cycle you go,” he says.
He went on to explain that design optimisation using software tools such as LabVIEW can help to detect bugs and errors early enough to avoid functional redundancies and inefficiencies.
As product complexity increases, the subject of reliability becomes more focused. For a consumer product, the perception of reliability can be a crucial factor in making purchasing decisions, especially for emerging technology.
With few electric or autonomous vehicles being in existence that have been through a full life cycle, there is understandable consumer anxiety about full lifecycle costs and about maintenance costs if maintainability hasn’t been correctly modelled. I asked Twaits whether this was something that can be built into the design model.
He explained that the software is very flexible and so such things as maintainability and part replacement costs can be put into the workflow to give a picture of field service requirements.
Twaits went on to say that there were other factors in serviceability that need to be taken into account as well such as continued test capability in the field. “It’s expected within a 15-20 year lifespan of a new vehicle that the test programs will change many times but a capability to test at all versions and iterations will remain a necessity,” he says.
Reactive verification platform
NI’s renowned test and measurement platform, TestStand, has been extended and re-engineered to produce the VeriStand verification and Hardware-in-th-Loop (HIL) simulation platform.
Whereas TestStand is designed for developing test and measurement sequences, VeriStand is designed around the need for model integration and the verification of functions with highly variable multiple sensor inputs. It can therefore be used for simulating embedded software or engine control units (ECUs).
“VeriStand provides the ability to go outside the constraints of sequenced inputs to more real time based reactive environments,” says Twaits.
This flexibility is important for unravelling the complexity conundrum because with so many variables creating a cloud of inputs from various sources, the ability to perform tests using sequences from an enormous matrix of valid variable ranges is both impractical and ineffective in terms of both cost and time.
A further advantage of the VeriStand platform is that it’s possible to pull in code and models that have been created in other environments. Such environments can include standard automotive industry software models of terrain, GPS, aerodynamics and engine performance or they can include standard mathematical models or input from NI’s LabVIEW NXG.
LabVIEW has the advantage that it can be programmed for controlling hardware such as actuators or taking inputs from sensors or DAQ systems.
Simulating RF environments at WMG
A Connected Autonomous Vehicle (CAV) simulation facility at the Warwick Manufacturing Group (WMG) in the University of Warwick is being used for research, test and validation of new automotive technology, including virtual verification and validation.
WMG’s 3xD Simulator aims to provide an innovative platform to bridge the gap between traditional hardware-in-the-loop (HIL) and road-based field tests. The simulator provides a drive-in, driver-in-the-loop and multiaxis driving experience.
The simulator is housed in a Faraday cage so that it can be integrated with the RF environment, including satellite information. Being fully immersive, the simulator can test how the driver reacts when noise is added to the car stereo or how the vehicle reacts when satellite signals are lost in an urban environment.
Sensor and communications include LiDAR, RADAR and scenery generation as well as Bluetooth, 4G, V2X and location information using GNSS.
Emulating satellite constellations that provide position information (GNSS) requires distinguishing between different environments. Driving on urban roads, intra-urban roads, and motorways inhibits different signal characteristics, such as signal strength, reflections and the number of satellites that are visible.
NI’s PXI platform was used to emulate the RF environment because of the versatility and flexibility of the equipment. By combining it with LabVIEW, vector signal transceivers can be used to dynamically change the signal type and strength of the satellites depending on the vehicle’s simulated position.
The RF emulator uses three NI PXIe-1085 chassis with two vector signal generators (6.6 GHz) and two vector signal transceivers (6.6 GHz) that can generate GNSS, AM/FM/DAB, and 4G/LTE channels simultaneously.
A typical test on the simulator uses generated GNSS signals, depending on the simulated location and scene. The location data is converted into the actual satellite positions to construct a satellite constellation signal, which is transmitted to the vehicle navigation system. When the vehicle drives through an urban environment, the software automatically decreases the signal strength and the number of visible satellites. These adjustments can also be implemented manually through a user interface.