New Data: A Look At The Davis Technologies Vehicle Position Sensor

In drag racing, performance can be measured in horsepower, top speed, or elapsed time, and there are numerous ways to improve each of these measurements. Before you can begin the cultivation process for killer numbers at the track, you need to grow a solid database of information to allow the adjustments to have more of an impact. Racers and tuners now have a new way to gain valuable data through the Davis Technologies Vehicle Position Sensor (VPS), a device with expanded capabilities over a traditional G-meter, which simply measures lateral acceleration forces.

Shannon Davis, the proprietor of Davis Technologies, has helped shape the performance landscape of modern drag racing with many of his high-tech products. When racers are able to combine data from their onboard acquisition methods with the Davis Technologies Profiler or Traction Control module, they can conquer the toughest track conditions and put the maximum amount of power down to the track surface. Now the VPS will provide an advanced tool for racers to use, so they can see—with a high degree of accuracy—exactly what their car is doing at different points throughout a run.

The VPS provides extremely accurate data which will assist in tuning an entire racecar, from the engine to the chassis.

The Birth Of VPS

Davis Technologies has developed these products over the last several years, and the need to complement each innovation with other devices has become apparent. The VPS came from the need for a G-meter that could maximize what the Profiler does for a racecar. The G-meters that are currently on the market just don’t provide the level of accuracy needed for drag racing—their operation speed just isn’t quick enough to measure the near-instantaneous changes in vehicle performance. These units also have a high level of signal filtration that will mask sudden drops in G-forces on a pass.

Being able to see the instantaneous drops in G-forces can make the difference in a run, if the Profiler is able to catch tire slippage quickly enough, so Shannon set out to build a better mousetrap to maximize the capability of the Profiler.

“We really needed a higher resolution G-meter for the Profiler so we could see if the car lost G-forces before it hit the Profiler curve, or if the car is losing G-forces after it hit the Profiler curve. If you’re losing G-forces before you hit the Profiler, then the car is spinning the tires. That’s when you would hit the Profiler curve. It would adjust the timing, and the G-forces would come back. Having an accurate G-force reading can be the difference if you hit the curve on the Profiler too soon and lose performance, or too late and lose time on the track due to tire spin,” Shannon explains.

The VPS can be used with the touch-screen that's included with the Profiler or via a handheld if there is no Profiler in use.

The VPS may be the perfect tool to help a Profiler work to its maximum potential, but it doesn’t require the Profiler to function. Shannon designed the VPS to be a full stand-alone unit that can function with the rest of a racecar’s electronics to assist with data acquisition and management.

Since wheelstands are exciting but don’t help you win races, Shannon wanted to include a wheelie control protocol with the VPS. To make that happen, a gyro would need to be used inside the unit — but why just stop at one? Inside the VPS, Shannon included several gyros, multiple Accelerometers, a three-axis Magnetometer, and an Inertial Motion Unit (IMU). All of these sensors work together to provide the VPS with the data it needs to control wheelstands and much more.

The VPS is totally a stand-alone unit within the electronics of a racecar. People have thought you needed a Profiler to make it work and you don’t, it will work with what’s already in your car. – Shannon Davis

According to Shannon, the development process of the VPS has been worthwhile, but had its trials and tribulations along the way.

“A lot of aggravation has come from this process, that’s for sure. We thought ‘this shouldn’t be that hard.’ Three years later, we now have a working product that’s very reliable. This is the fifth or sixth version of the hardware at this point, and now I know a lot of ways on how to not make a G-meter. We really wanted to pick this unit apart and make it work in such a way that racers could rely on it before it was ever released, so that’s why the development took so long.”

As one of the last steps in the development process, Shannon conducted an experiment with the VPS to test its data accuracy. The idea was to create a “virtual timeslip” off just the data generated from the unit and compare it to an actual time slip. This type of feature could be useful for teams where they might not get a timeslip due to jumping the tree, running at a no-time event, or if there is an error in the timing system and a slip isn’t generated.

Once mounted, the VPS can work with any ECU after it has been plugged into the correct ports.

“We were a little off on the sixty-foot, but that could be due to how the car was staged or some other variables, but everything else was spot-on as we created a virtual timeslip. They matched out to the hundredth, and that tells us that our accelerometer is accurate. This was an exercise to see if our G-meter was working correctly and it showed it was,” Shannon explains.

How The VPS Works

Davis Technologies packed all the different sensors into the VPS so it could be a robust piece of data-gathering technology. It’s a situation where just one sensor won’t do that job, so all of them are combined to be used at different times to bring in all the information needed. Currently, the VPS uses five general analog outputs that provide all of the information it produces to the ECU or fuel injection system inside the racecar.

The next step is for the VPS to use its built-in CANbus technology to interface with ECUs so all the information can come across just two wires. This is still being finalized to work with all ECUs on the market and will require just a simple firmware upgrade along with the correct wiring, once the capability is available.

The VPS Package

The VPS comes complete with a 12-foot-long pre-terminated wiring harness. Also included is the mounting system ready for you to adapt to the car. Everything needed to use the VPS will retail for around $1,499 and that includes the built-in wheelie control.

According to Shannon, the VPS provides some very interesting data to racers and tuners that can be used in different ways.

“The VPS is mounted in the car and it can give you highly accurate, consistent and repeatable data on pitch, roll, and yaw. Everybody wants to know what yaw is. Well, yaw is ‘yaw about to hit the wall,’ and it’s also the axis twisting from the roof to the floor. Pitch is wheelie motion, and roll is the body rolling left and right. All of this is being sampled at a few hundred hertz, and the device puts it out unfiltered. So when you get it into your data system or the Profiler, you can see what really happened by not smoothing the data out,” Shannon explains.

What all of this translates to in a real-world application is a new way to look at data from a pass. During a run, it might look like the car went straight and did exactly what you wanted, but the data from the VPS and the run log might tell a different story. Now, a racer can see more accurately the car might be moving around more than what they thought, and doing it on a consistent basis. Finding small nuggets of information like this will allow a racer to improve the performance of their car in new ways that might not have been possible before.

“Currently, the G-meter might tell you the car is moving around, but the VPS presents the data in a whole new and detailed way that’s in your face. A phrase that we have been getting from the tuners with this is ‘I’m not sure what to do with this data, but it’s really interesting.’ To some extent, we might have answered a question that hasn’t been asked yet, and people are going to start finding new ways to make cars perform better throughout a pass,” Davis explains.

The VPS is mounted in the car and it can give you highly accurate, consistent and repeatable data on pitch, roll, and yaw. – Shannon Davis

The wheelie control option is also designed to do one thing—keep racers safe on the track.

“The VPS has its own wheelie control strategy built into it, and it can output an analog signal to trigger some retard — it can go to a Profiler to command retard to stop a wheelie and pull timing, or it can talk to the ECU to pull timing, as well. Within the ECU, you can do some of its own generic 2D and 3D tables to help with wheelie control. Those tables can command if X-amount of pitch is registered during a run. I want to pull so much timing to create your own wheelie control with it,” Davis says.

Various installations of the VPS show its mounting versatility.

Benefits And Advantages Of The VPS For Racers

Making the tuning call on a racecar requires a lot of data, and the more accurate that data is, the more educated the tuner is with respect to vehicle operating conditions during the decision-making process. The Profiler is a great tool, but having the data that comes from the VPS makes it an even better tool that will assist a racer in making the best choices possible behind their keyboard in the pits.

“The data coming out of the VPS is not pretty and smooth like most racers are used to. It’s giving you the raw numbers, but that’s what you need to have this level of accuracy to see what the car really did. You start looking at things that go on through the run that you might not have seen where there’s a drop in G-forces due to a boost issue or nitrous kit not coming on right away. You would have missed that before because the G-meter wasn’t giving you enough data to see it, so you could look at that point in the run to see a mechanical problem,” Shannon says.

Racers like Manny Buginga and the Bruder brothers, along with tuners like Pete Harrell, have all been assisting Davis Technologies with the development of the VPS.

The VPS can see things like the nose of the car dropping and the G-forces dropping on a pass as the car goes down the track. When you lay that information out with the tire speed and engine speed going up, it will show how much the car was spinning the tire. Having that kind of data makes tuning the Profiler easier since you’re trying to set your Profiler curve to be as accurate as possible to keep those G-forces up. The G-meter is so accurate with the VPS you can keep it off the Profiler curve easier, so it doesn’t pull timing when it doesn’t need to.

The VPS is the type of device that any racer can use to improve their program. You don’t need a Profiler to use it on your car. Bracket and index racers can use the data provided to see a clearer picture of what exactly their car does on a pass at any point on the track, and find ways to improve consistency.

The VPS is a compact device; it mounts easily to a rollbar with the included clamps.

As the VPS goes through its final testing, the benefits it can provide are already starting to show teams new ways they can make changes to their cars.

“So far it’s providing a lot of data and information for people to learn from and figure out. They don’t know if it’s good or bad, but they are looking at the data to see what they can learn. This can be used to figure out solutions to problems you might not know even exist yet. This device really makes it easier to see lots of data and sums it up well,” Davis explains.

The VPS is showing some serious promise as a robust option to gather accurate data inside a racecar. Teams will be able to find new ways to tune their cars throughout an entire pass, and it’s only a matter of time before this device becomes a key tool in every racer’s tuning toolbox.

Article Sources

About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. When Brian is not writing, you can find him at the track as a crew chief, doing freelance photography, or beating on his nitrous-fed 2000 Trans Am.
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