SPEEDBOX
GPS Based non-contact speed sensor.
Product Details
The SPEEDBOX is a state of the art GPS based “non contact” speed sensor with a typical accuracy of 0.1mph. This level of performance is far, far better than is possible with even carefully calibrated wheel speed sensors. The SPEEDBOX has several outputs and is designed to be connected to a data logging or display system.
Introducing the SPEEDBOX
What is the SPEEDBOX?
In most auto sport and industrial test applications, speed is the most important parameter; unfortunately it is often the least accurate. The SPEEDBOX is a state of the art GPS based “non contact” speed sensor. The SPEEDBOX measures speed very accurately 200 times every second with no interpolation, and with a typical accuracy of 0.1mph. This level of performance is far, far better than is possible with even carefully calibrated wheel speed sensors. The SPEEDBOX has several outputs and is designed to be connected to a data logging or display system.
Who is the SPEEDBOX designed for?
The SPEEDBOX can be used in any automotive, motorcycle or boating application where a very accurate measure of speed is required. The sensor is ideal for sports and professional applications.
What does the SPEEDBOX do?
The SPEEDBOX takes measurements from a high accuracy GPS receiver and digital accelerometers and combines them to calculate a single, very high accuracy measurement of speed. The GPS speeds are calculated from the frequency shift of the signals from the satellites and are very accurate, but are slow to update. In contrast the speeds from the accelerometer update very quickly but tend to drift off over a period of a few minutes. The SPEEDBOX uses a highly advanced self-optimising filter to combine them to get the best properties of both the GPS and accelerometer measurements.
What are the key competitor advantages of the SPEEDBOX?
The SPEEDBOX is an exceptional product. It’s high accuracy, high output update rate, low latency, small size and economical cost are a unique and exciting combination. The sealed aluminium and compact size make it ideal for any auto sport application, as well as motorbikes and boats.
Description and Features:
There are many problems with using wheel speed sensors that limit their accuracy even when they have been carefully calibrated. Even assuming that there is no slip between the tyre and the road (which there is during acceleration and braking) the tyres rolling circumference changes with tyre temperature, tyre wear, tyre pressure and speed. Typically +/-2% calibration error is about as good as you can practically achieve even at steady speeds. Speed accuracy when you are braking and accelerating is of course far, far worse, so speeds braking into and accelerating out of corners are always particularly inaccurate. The situation is even worse on a motorbike, as when the bike leans for the corners the rolling radius changes. Finally boats have up to now largely relied on readings from a pitot tube which have there own set of problems which cause very large errors.
In contrast the accuracy of the SPEEDBOX is typically within 0.1mph at low rates of acceleration, and 0.2mph at high rates of acceleration or breaking almost irrespective of the situation. In practice the speed error from the SPEEDBOX is so low, it’s not easy to validate it against anything else as there is no straightforward reference which is known to be much more accurate. Crucially, the SPEEDBOXs output latency is also very low at about 5mS, so for practical applications it can be ignored completely. The SPEEDBOX is so accurate because of the intelligent way in which the accelerometer and GPS data is combined in real time. This is achieved using a specially designed self-optimising Kalman filter, the results of a great deal of testing in conjunction with the very best reference GPS receivers and optical sensors available. In practice 0.1mph is a nominal accuracy and is dependant on GPS coverage, most of the time it is far better.
The SPEEDBOX is housed in a purpose designed CNC machined aluminium housing sealed to IP65. Internally the most sensitive components are built onto a vibration isolated sub assembly. Installation simply requires that the SPEEDBOX is mounted flat and inline with the vehicle fore-aft axis. The GPS antenna should be placed on the highest point of the vehicle pointing directly upwards.
Outputs
There are 3 analogue outputs, one each for longitudinal acceleration, lateral acceleration and speed. There is a pulse per meter digital output, often used in applications where a wheel speed input is expected and a serial data output, which is compatible with our dashboard, video overlay and CAN products. All outputs are updated 200 times per second.
Outputs
There are 3 analogue outputs, one each for longitudinal acceleration, lateral acceleration and speed. There is a pulse per meter digital output, often used in applications where a wheel speed input is expected and a serial data output, which is compatible with our dashboard, video overlay and CAN products. All outputs are updated 200 times per second.
There are 3 analogue outputs, one each for longitudinal acceleration, lateral acceleration and speed. There is a pulse per meter digital output, often used in applications where a wheel speed input is expected and a serial data output, which is compatible with our dashboard, video overlay and CAN products. All outputs are updated 200 times per second.
Construction and Installation
The SPEEDBOX is housed in a purpose designed CNC machined aluminium housing sealed to IP65. Internally the most sensitive components are built onto a vibration isolated sub assembly, for mounting in high vibration environments. Installation requires that the SPEEDBOX is mounted flat and inline with the vehicle fore-aft axis. The GPS antenna should be placed on the highest point of the vehicle pointing directly upwards.
The SPEEDBOX is housed in a purpose designed CNC machined aluminium housing sealed to IP65. Internally the most sensitive components are built onto a vibration isolated sub assembly, for mounting in high vibration environments. Installation requires that the SPEEDBOX is mounted flat and inline with the vehicle fore-aft axis. The GPS antenna should be placed on the highest point of the vehicle pointing directly upwards.