Category Archives: Brake testing

Introducing VBOX Test Suite

The versatility of Racelogic’s range of VBOX GPS data loggers, together with the various modules, inertial units, and displays that accompany and enhance them, has led to extensive use within virtually every sector of the automotive testing industry.

The test engineer using high quality hardware can only take full advantage of it if the software being used alongside is of the same standard. It needs to be extremely capable and versatile, like the hardware it supports.

This is difficult to achieve: a supporting program that can be used to analyse just about any kind of test can itself become tiresomely long-winded and complex to set up and use. When pressure is mounting for evaluation to be conducted in as short a time as possible – whether it’s because of limited track time, cost, or production deadlines – having to spend lengthy periods setting up the software, with lots of time needed for post processing and reporting, is counter-productive and undermines the reasons for acquiring top of the range hardware in the first place.

Racelogic have now produced a software package, VBOX Test Suite, that solves the problem of advanced features versus ease of use in one go. They also recognise the fact that, although VBOX units around the world are used in hugely varying test environments, most of them are still purchased by individual departments to do one job. Developed based on extensive feedback from engineers who use a VBOX every day at the sharp end of vehicle development, the ethos behind the new software is to significantly reduce the time it takes to conduct specific tests to exacting modern standards, and therefore caters to specialised applications.

By creating an adaptable working space that allows for multiple sets of data to be compared via separate tabs, the software is as simple to use as it is capable; and it produces reports that present results clearly enough for complex data to be clearly displayed and understood, no matter who is looking at them. The automation of much of the reporting is a key factor in getting results together in a meaningful manner so quickly.

The software also includes video integration for use with Racelogic’s Video VBOX range; customisable graphs; compatibility with satellite imagery so that a positional trace can be overlaid; and live or post-test analysis. Context-sensitive menus means that managing several data sets doesn’t get too complicated.

On first release, VBOX Test Suite allowed for basic performance testing – acceleration and deceleration, triggered by GPS speed or a vehicle CAN input. It has now been updated, however, to include ‘plugins’ for specific types of testing.

One of Racelogic’s core competencies has always been for brake testing, so it made sense that the first additional component to the software should cater for engineers conducting brake stops. Any VBOX 3i user in the world who carries out braking development can get full use out of it, as the software is configured so that it conforms to regulations in all regions. The brake test plugin can carry out auto-calibration of wheel speeds; calculates wheel slip; and produces results based on a speed to speed parameter or via alternative inputs such as a trigger, brake pressure and position values.

Tests can be run within a tightly defined set of criteria, such as between temperature ranges. Centreline deviation is automatically calculated during each run, and thresholds can be applied to ensure that the operative gets immediate feedback on the validity of results. The report it produces includes all the relevant information along with the engineer’s notes.

The most recent additions to VBOX Test Suite are for lateral and longitudinal aquaplane characterisation to allow the tyre test engineer to perform a complete evaluation of a tyre’s performance in aquaplane conditions.

aquaplane-longitudinal

The lateral aquaplane plugin allows the user to specify ‘entry criteria’ to ensure that the vehicle is fully settled and in as steady state as possible before entering the water bath, where the test begins. Then, by closely monitoring the vehicle’s lateral acceleration at varying entry speeds, the software produces a comprehensive report of the maximum acceleration obtained during each run. This then allows the engineer to understand the peak acceleration value that can be achieved by a given tyre, as well as the rate which grip decreases once aquaplane has occurred. This data can be directly compared to other tyre compounds to provide engineers with the information needed to grade tyre performance in wet corner conditions.

The longitudinal aquaplane plugin employs a user-definable threshold slip value for each wheel, providing the user with the opportunity to choose between reaching the aquaplane condition when one, or all of the tyres, exceed this value. Wheel speeds can be automatically calibrated in comparison with GPS speed but this doesn’t need to be done in the actual test area – it can be done anywhere, further reducing pressure on track time. Pre-entry test conditions are also user-definable, in order to ensure the vehicle is in a steady state before the test begins.

Racelogic already have the next set of plugins under development and will soon be releasing updates to allow for coast-down, again configured to differing region’s standards and specifications such as J2263 or the latest WLTP GTR15; Euro NCAP AEB protocol; and R41 Pass By Noise.

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Co-located Antenna and IMU

We sell a significant number of IMUs. The IMU04 came out last year and it’s popular because integration with GPS gives stability to the velocity output when conditions are sub-optimal – like under trees. And we’ve worked really hard on this product so that the pitch and roll accuracies are now down to 0.06 degrees (RMS).

All well and good but there is an element in using one that can be a bit of a pain. You have to measure, very accurately, the distance between the GPS antenna and the IMU. Sounds simple enough but it can be really tricky, especially if there’s a significant curve to the car roof.

Why does this need to be measured? Well there are a couple of reasons. Firstly, the performance of the Kalman Filter is optimised when the correct distance is known. And secondly, because of Lever Arm Correction: a vehicle’s roof will initially travel faster than its centre of gravity when the brakes are applied. And where’s the antenna? On the roof… so integrating the IMU with the GPS data allows for this overshoot to be adjusted; but you’ve got to know how far away they are from each other and this measurement introduces the potential for human error.

IMU-lever-arm
Lever arm correction in braking

So here’s the solution: co-locate the IMU and antenna. This rather handy little unit allows the IMU to fit snugly inside it, with the antenna mounted on top. With the data sources coming from exactly the same place, the overshoot is eliminated.

“But” you say “with the IMU on the roof, it will pitch forward further than it would do if was mounted inside the car at the COG.” Yes, it will, but this can be translated back to where you’d normally fit it, and that’s much easier than measuring between the antenna and IMU. It also means that you can swap the setup between vehicles far more quickly.

IMU_roof-mount
Co-located GPS antenna and IMU.

Coming to a Test Track Near You…

…Well almost. MIRA and Heyford Park, to be exact.

We have got ourselves a hospitality trailer. Why? Well I detect a bit of a trend with the trade shows we do: they’re still worthwhile but slowly becoming less so, with fewer of the engineers and decision makers that we’re used to seeing. They can’t get out of the office: too much on their plate.

So we thought we’d go to them. We’re parking up at MIRA Proving Ground where a lot of our UK customers are based, on the 12th May; and then to Heyford Park in Oxfordshire two days later.

The best thing about this is that we aren’t limited to what we can show people on an exhibition stand – we can actually demonstrate things. We’ll have a braking setup, a steering robot (courtesy of ABD), and a couple of cars showing vehicle separation/ADAS. And if you’re not in one of those demos, come into the trailer for coffee, cake, and a chat.

Once we’ve completed our UK dates, the trailer heads off to Europe where it will visit the likes of Renault, Goodyear, and Continental. I suspect that in 2016 we’ll look to hire some facilities in Germany and invite a whole load of customers along for the day.

Look out for the splashy BMW on the motorway.

VBOX-roadshow

VBOX Test Suite

If there’s one thing I’ve learned in my travels over the last few years, which has seen me visiting a good variety of customers, it’s that they all want software for specific tasks.

This is not to downplay the role of all those frighteningly intelligent test and calibration engineers out there, who are all perfectly capable of driving VBOX Tools and setting up very complicated test structures. It’s just that they’re under a lot of pressure and it kind of makes sense to be able to send out a less qualified driver to carry out procedures – but that to do this they need software that is really easy to use.

So. Taking this feedback we set about designing the eventual replacement for VBOX Tools. Our next gen analysis software had to be really straightforward to use but equally capable of processing complex data, and cover the whole gamut of testing and dynamics in which we specialise. It was decided that the best way to achieve this is to have a ‘base’ program, and then augment it with plugins. That way each test department will only have to have the level that they need; so those who’re only interested in straight-line performance will have a nice simple setup in comparison to their colleagues in ADAS who require more.

Here it is – VBOX Test Suite. At the moment it’s just a relatively simple performance analysis package, but we’re working on the first range of plugins that will cover all the ADAS stuff as well as aquaplane, coastdown, NVH, and so on. The nice thing about plugins is that they’re customisable – we can make them specifically for any application. Let me know what you want.

I’ll let the video explain how it works.

 

New data analysis software – VBOX Test Suite from Racelogic on Vimeo.

Integrated Inertial Measurements

It is largely accepted that the most accurate and cost effective way to carry out vehicle dynamics testing and development is with the use of GPS equipment. In some situations, however, it pays to also use inertial measurements to either augment the available data, or to overcome problems encountered in certain environments – such as a test track that isn’t in an entirely open area, or one which suffers from an obstructed view to open skies in some areas.

VBox3i_IMU04_RLCAB120

We’ve been supplying IMU integration with the VBOX3i data logger for a few years, but now we’ve got a new Inertial Measurement Unit which has a much higher performance due to tighter GPS synchronisation, better calibration and a higher sample rate.

Integrated Speed Measurements

Firstly, the new IMU04 has improved levels of velocity smoothing to cope with interruptions to the GPS signal, thanks to a new real time Kalman Filter which blends the inertial data with that of the GPS system. Although most test tracks are located in open areas, bridges over the test track and overhanging trees can lead to signal degradation– this is where the integration with the IMU signals ensures that GPS dropouts are eliminated.

KFspeed
In this example you can see that the GPS velocity trace (blue) drops outs underneath a bridge. The IMU integrated data (red trace) gives a much cleaner and un-interrupted signal.

For instance, carrying out manoeuvres such as a coast-down test (the results of which are critical to a manufacturer from a homologation perspective, as they form a significant proportion of their calculations of fuel consumption data released to the public) can be completed on a course that takes the vehicle under a bridge, which would not have been possible using GPS alone. IMU integration ensures a consistent velocity log is maintained during the momentary loss of satellite signal lock.

Indeed, there are some facilities that are not ideal places in which to conduct other procedures such as high-dynamic brake stops – they may be tree-lined, but are still used because they’re conveniently located. Integrated Inertial and GPS measurements allow for this convenience to be fully exploited because it can provide the same level of accuracy normally only possible from testing in an entirely open arena.

KFGoogleEarth
Interrupted GPS signal. The blue trace is GPS Position only; the red trace is the corrected position data obtained via integration of the accelerometer data from the IMU and GPS signals.

This is an extract from an article originally featured in Automotive Testing Technology – for the full content click here.

Mira Goes Live

Mira Proving Ground have recently introduced a resource which has the potential to be of great assistance to VBOX customers.

I was over there recently to test whether the signal they output from a permanently installed base station is compatible with our kit. Indeed it is – and they now transmit an RTK correction signal to just about every part of the facility. This is a seriously useful feature they’re offering: it means that if you’ve got a VBOX3i RTK and our latest radio modems, you can just rock up and start testing with 2cm positional accuracy.

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If you’re carrying out tests that require a high level of positional accuracy – so ADAS validation or development, for instance – you’ll be able to get on with it pretty much immediately without having to first set up a base station.

One of the happy by-products to this is consistency in brake testing. Although positional accuracy to 2cm isn’t necessary to measure stopping distance, it does allow for comparison of results taken from differing areas of the track, which wears in the same way that any road surface does and can lead to sometimes puzzling results. The enhancement of knowing precisely at which point of the road surface the tests are carried out can iron out these anomalous results.

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Braking Down

Been getting around a lot recently, visiting customers at a variety of test facilities. It’s a really useful exercise because I get to see VBOXs being put through their paces in the environment for which they were designed, rather than on my desk, connected to a LabSat and a roof-borne antenna.

It’s also an ideal opportunity to, shall we say, dispel some misconceptions. I touched on this briefly a few months back. Some things just get stuck in people’s heads and it takes a physical demonstration or an authoritative intervention to change their mind.

This time, it’s brake stops. A ‘core competency’ (as my colleagues in the Marketing Department would have me put it) of VBOX products. At a certain European test track engineers carry out brake stop manoeuvres over a distance-marked tarmac area. Whilst I was there I witnessed a couple of these and was then called over by one of the drivers. He complained that the brake distance results were very inconsistent.

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I checked his test procedure. I asked how he initiates the start of the test. His response was, in my world at least, very surprising: “We hit the brakes at the first marker.”

The reason they conduct these stops on a marked out apron is so that they can get definitive results based not just on the GPS data, but also on where the car actually stops. They were seeing VBOX results that differed to those based on the painted track markers.

You can’t do it this way. I explained that, no matter how good a driver you are, it isn’t possible to brake at exactly the same point each time. Once I’d set them up with a light-barrier, so that the test start point was always the same, the results spoke for themselves.

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Getting the High Five from NCAP

Just got back from the Automotive Testing Expo in Stuttgart, where we had a pretty busy three days. As I expected, our increasing focus on ADAS probably took up 50% or more of the conversations we had on the stand. It’s got me thinking about just how the manufacturers market their new models these days.

ATE_Stuttgart
It wasn’t too long ago that just about every advert you saw for a new car – TV or print – concentrated on speed and handling. Excitement. Sportiness. But that’s all changed, partially through legislation and political correctness, but also because the sheer volume of regulations – each generating a new acronym – that must be adhered to when developing a new car. Given that we sell equipment for developing the systems that keep people alive, either by accident avoidance or crash protection, we need to be ahead of the curve. Or at least on it.

Stuttgart was full of the current buzz acronym: AEB. Autonomous Emergency Braking. It’s not all that new in terms of concept or even practical application, but the reason so many test engineers mentioned it to me is because of the forthcoming NCAP star rating itinerary. For 2014 there’s going to be a new generation of cars being launched, all with AEB, because Euro NCAP won’t hand out five stars unless they have it. Next year AEB is only necessary for collision mitigation, but for 2016 it will also be for pedestrian protection.

The full NCAP ratings report can be found here.

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Not Your Normal Truckstop

I’ve been in Sweden, training some Volvo Truck development engineers. They use our ADAS testing packages to develop collision mitigation systems, and they showed me some recent footage of their new FH truck, fitted with not only a collision warning system but an emergency brake.

It’s absolutely superb. Watch the video to see what I mean – the truck, on approaching the slow moving car, first warns the driver who doesn’t respond. It then takes things into its own hands and brakes independently. It looks like a truly remarkable driver aid, not to mention a fairly dramatic moment.

The engineers that I met are justifiably proud of what they’ve developed, and rightly so. An advanced driver assistance system with this level of precision is something to be proud of.

But I think the best thing about this footage is something I was told just as we wrapped up the training course: the car in the video, the one that appears to be imminently smashed into by a large Volvo truck, is the test engineer’s personal vehicle. They clearly have an immense confidence in their product. Nice to know that VBOX played a large part in this.

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