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Mounting

RT Strut

The RT-Strut is a fast car mounting system for the RT2000, RT3000 and RT4000 families of Inertial and GPS Navigation Systems. Using the RT-Strut the RT systems can be mounted securely in most cars in minutes.

The RT-Strut wedges between the floor and the roof of the car, normally in front of the back seat and across the transmission tunnel. A built-in spring provides the necessary force required to keep the RT-Strut in place. A lever is used to release and engage the spring. Wide feet at the bottom of the RT-Strut ensure excellent yaw rigidity.

The RT-Strut uses a carbon fibre Pole for an extremely stiff yet lightweight design.

       Components for the RT-Strut  RT mount

Base station

RT-Base

RT-Base GPS Base Station

The RT-Base is a portable GPS Base Station suitable for transmitting Differential corrections (DGPS) to the RT3000, RT4000, RT2002 and other products that use GPS. The position accuracy of Differential and RTK GPS receivers is improved when using the RT-Base.

Two models of the RT-Base exist; the RT-Base-20 can supply L1 corrections suitable for 20cm positioning and the RT-Base-2 can supply L1/L2 corrections suitable for 2cm positioning. Both models are identical in their operation.

Features

The RT-Base is a self-contained unit that includes:

– The Base-Station GPS receiver
– Battery suitable for over 10 hours of operation
– Radio Modem
– Mains Power Supply and Battery Charger
– GPS Antenna, 15m Cable and Tripod
– Radio Modem Aerial, 5m Cable and Magnetic Mount

Overview

The figure below gives an overview of how Differential GPS works. The information from each satellite is measured by both the RT-Base and by the GPS in the car. The RT-Base works out the error in the satellite’s information and transmits it to the car using a radio link. The GPS in the car then applies the correction to each satellite’s measurement before it computes position and time.

  Overview of DGPS, including RT-Base GPS Base Station

For RTK (Real-Time Kinematic) Carrier-Phase measurements the principle is the same, but the GPS in the car also has to figure out the difference in the number of carrier-phase cycles between the RT-Base and the car. The RT-Base measures the carrier-phase of the signals from each satellite and transmits it to the car.

Differential GPS works in real-time because the corrections from each satellite vary slowly and predictably. The GPS in the car uses a model to predict the error from each satellite. It can update its model when the radio link transmits new data. It is not necessary for the GPS in the car to wait until the radio has transmitted the correction before it outputs its latest value.

For Pseudo-Range (not carrier-phase) Differential GPS the corrections can be up to 60s old (depending on the GPS in the car). For RTK corrections (20cm and 2cm) the corrections can be up to 30s old (again, depending on the GPS in the car).

Radio Modems

Different countries have different licensing laws and different frequencies for radio transmissions. Many countries have license-free frequencies that can be used for Differential GPS signals. We can supply a range of different radios that can be used, license-free, in many countries.

DGPS Correction Type(s)

By default the RT-Base uses the RTCA standard for transmitting its differential corrections.

 

RT Range

RT Range

RT-Range and RT3000 Images

The RT-Range is used for two functions: accurate (3cm) measurement of the relative motion between two vehicles and precise (2cm) measurement of lane position. All measurements are online, in real-time and output on a CAN bus, including the Target vehicle measurements being relayed in the Hunter vehicle's CAN bus.

Verifying the accuracy of radar and other sensors can be performed subjectively. The RT-Range is a precision tool for evaluating these measurements numerically and objectively. Typical applications include adaptive cruise control, accident avoidance and other advanced technologies.

Lane departure warning systems are being developed and fitted to vehicles now. The RT-Range can be used to verify their accuracy and to increase the understanding of lane positioning.

Vehicle-to-vehicle Measurements

Vehicle-to-vehicle measurements are performed by measuring the position of the two vehicles and then transmitting the position of the Target to the Hunter using Wireless LAN radio. This is fast, has very low delay and can be used worldwide, license-free. Any additional delays or lost packets from the Target are extrapolated with minimal loss in precision. Wireless LAN can operate over 200m in noise-free environments.

The position of the radar (or sensor) on the Hunter can be defined at any location. Similarly, the measurement point on the Target can be defined at any point. There is no need to mount the RT3000 products at special locations in the vehicle. These measurement points are independent of the Lane Position measurement points.

Overview of the RT-Range function showing the lateral and longitudinal ranges

Lane Position Measurements

There are three steps to measuring Lane Position. First the lane markings are surveyed; then up to 8 lane markings are combined into a map; finally the actual vehicle position is compared to the map. This leads to exceptionally accurate and reliable Lane Position measurements. All the tools to survey the lane markings and build the map are provided.

The measurements from three points in the vehicle are available simultaneously. This allows the system to test several sensors at the same time. The RT-Range automatically selects the correct lines in the map and measures to them.

The RT-Range also computes the reference distance along the map so that graphs can easily be overlaid.

Image of vehicle with 5 measurement points of the RT-Range shown

Fast Installation

The RT-Range can be installed quickly into a vehicle. Training is simple and the system is very easy to use. Results can be obtained within hours of receiving the equipment.

On-site training can be provided to help engineers get to work quickly.

Accurate Specifications

The measurements in the RT-Range are based on proven RT3000 products. The specifications for the RT3000 products can be found in the RT3000 User Manual. Extensive testing has been performed to verify the accuracy of these measurements, contact Oxford Technical Solutions for further details.

Technical Specification for Vehicle-to-vehicle Measurements

Parameter Conditions Specification

Longitudinal Range

±200m

0.03m

Lateral Range

±20m

0.03m

Resulting Range

200m

0.03m

Longitudinal Range Rate

±50m/s

0.02m/s

Lateral Range Rate

±20m/s

0.02m/s

Resulting Range Rate

±50m/s

0.02m/s

Resulting Yaw Angle

360°

0.1°

 

Technical Specification for Lane Measurements

Parameter Conditions Specification

Lateral Distance to Lane

±30m

0.02m

Lateral Velocity to Lane

±20m/s

0.02m/s

Lateral Acceleration to Lane

±30m

0.1m/s²

 

Note: More detailed specifications can be found in the RT-Range User Manual


Software

The RT-Range comes with Windows Software. The software surveys the lines, makes the maps, configures the RT-Range and provides real-time measurements on the PC screen.

RT-Range Map Creation Software