End-users of electric vehicles expect in-vehicle navigation to provide up-to-date, contextual, and relevant information. As faultless validation requires a monitored car to run through millions of kilometers, EV navigation testing is no piece of cake. Automakers have to process significant amounts of data to deliver compatible and safe vehicles as well as reach intended market efficiency.
Reaching destinations: when EV is ready to take next steps
Everybody loves the idea of an electric vehicle but doesn’t consider it as a real rival for usual cars. It’s quite reasonable for now, as the technology is not yet commercially viable at a large scale. In this blog post, we won’t discuss the cost of electricity or battery shortage. We’ll focus on the end-user perspective.
If you are on the cutting edge of technology, already sitting in your electric car, you expect the same level of user experience. You want to be sure that you will arrive at the destination point and preferably in the most convenient and fastest way. The advanced technology is no longer that advanced when you have to call the tow truck in the middle of nowhere. Or when you have to spend half a day somewhere in a no-name town waiting for the battery to charge enough to hit the highway.
What’s en-route for automakers?
Making drivers completely satisfied with the vehicle they’ve bought is the primary task of automakers. For this purpose, the intelligent assistant of the driver comes in handy.
It’s not all about the simple navigation with its core meaning, but let’s name it the “advanced navigation.” Modern navigation systems for EVs should not only show drivers the correct and most optimized route but prompt the nearest charging stations and predict mileage covered based on battery load.
Today, even usual cars have more than hundred of electronic control units (ECU) for various subsystems. The electronic hardware components in infotainment systems interconnect with specific standardized communication protocols such as the controller area network (CAN). CAN or any other network protocol support allows microcontrollers and devices to communicate with each other in applications without the host computer. These modules help in establishing the human machine interface (HMI) services like navigation, internet connectivity, and smartphone integration with the infotainment system. Then what to say about EVs?
Thorough testing is the priority
Producing high-quality software demands a significant effort in testing, which is probably one of the most expensive and intensive parts of the automotive software development process. For this reason, each navigation assembly elapses early testing of the basic functionality on the test bench. However, only testing on a real car gives a full picture of the quality of the software.
EV range anxiety is the main issue that should be solved with the intelligent assistant. The first thing is to be sure that the trip requested by the driver is feasible by ensuring that:
- there are charging stations along the way for the vehicle to recharge to continue the journey;
- the vehicle charge at the destination will be over a minimum threshold.
Otherwise, the system must notify the driver to prevent a no-return scenario where the vehicle has not enough charge to reach the next charging point. Navigation unburdens drivers from having to find charging stations and plan stops over long trips manually. Instead, it examines the current vehicle charge, its consumption model, and the predicted charge consumption along the route to determine when the recharge is required.
The main algorithm aims at the online and offline search for nearby charging stations. The assistant helps to pick up a charging station to select it as a stopover and arrange a route for destinations beyond the current driving range. As a result, drivers will see the ETA, including the estimated charging time. The route calculated respects a minimal arrival state of charge for charging stops and end destination. The algorithm finds the area of low battery status along the way.
Charging stations calculations should take the following into account:
- сurrent charging level;
- minimum arrival charging level;
- search radius;
- charging stations type.
If a charging station is en-route and a driver gets to the destination point with the acceptable percent of charge, the assistant will consider this way as reachable.
DCS DC/AC stations are preferred and selected in case the charging time is less than a predefined value. If no charging stations fall into a calculated radius — the route is considered unreachable.
Charging time is one more thing to take into account and test. It is calculated based on the charging curve and charging station power. This algorithm makes more precise predictions. It also chooses charging stations based on their location – closer ones to the initial route would be preferred.
Plus, it might help with planning routes on mountain roads. As they tend to be winding, simple predictions without geometry consideration might be too primitive.
EV navigation testing requires adjusting and modification of different external and internal data which comes from the ECUs — the current battery charge of the vehicle or real-time traffic condition, for instance. Additional parameters can be set in the engineering menu inside the car. On the other hand, you should make sure your software works correctly from a user’s perspective, not just from a technical side. Exploratory testing is a manual testing approach that emphasizes the tester’s freedom and creativity to spot quality issues in a running system. For this reason, we take one- or two-day long test drives to emulate intensive real car usage on the highway with active navigation. During such testing, you will spot problems that slipped through your build pipeline unnoticed.
In-vehicle display systems — particularly the instrument cluster — are increasingly becoming a popular service partner for the driver. Aside from the instrument cluster, the head-up display is rapidly gaining importance as a source of information. As the main output, these systems make it possible to read and verify the critical indicators of EV. But field testing could not be complete without an analysis tool – CAN bus monitor. During each test drive, the data traffic between ECUs is recorded by loggers from the bus systems and could be even accessed and configured already on the route. There could be different interfaces (channels) selected: Analog-in, Flex-Ray, CAN-HS, LIN, CAN-LS, Digital-in, or even Ethernet. Afterward, recorded and downloaded data can be converted into the needed format and on the exact log level. It is crucial for function validation, load tests, quality control, or simple debugging of the software.
Heading for the destination
The higher you move up in your test pyramid, the more likely you enter the realms of testing when the features you build work correctly from a user’s perspective. The field testing of the EV navigation solutions is a must. But due to high maintenance costs, you should aim to reduce the number of end-to-end tests to a bare minimum.
Testing the HMI became very demanding and time-consuming. Because of the multiplicity of HMI variants, a better approach and test coverage is a goal for the testing process. The current trend to platform-based products allows unifying the process of end-to-end testing with the tight set up of individual configurations.
Next-gen vehicles required appropriate navigation that will make journeys safer and more reliable by intuitively alerting drivers of driving range, upcoming events like slippery roads, or providing general understanding of the road beyond what the eye can see.
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