Vehicle testing in enclosed test facilities without GNSS
The number of ADAS tests is increasing, and simulated night-time testing is growing in prominence. This presents a specific challenge to Automotive Test facilities to provide a dedicated indoor environment in which to run automotive test projects where the environment is managed. These include simulated night-time NCAP tests.
For many years the combination of GNSS and IMU sensor technology has been adopted to provide high accuracy vehicle measurements for ADAS and vehicle dynamic testing. Test work takes place mostly in good open-sky conditions suited to GNSS. When paired with inertial sensors as part of an Inertial Navigation System, engineers can achieve high accuracy position data with low latency and precise pitch/roll measurements.
As the need for indoor testing increases, automotive engineers are looking for indoor measurement solutions that deliver the same accuracies they are used to.
Unlike standalone GNSS automotive systems, which are unable to output measurements during GNSS blackout, or are affected by multipath errors, OxTS products are still able to compute position, orientation and velocity measurements because the system is built on inertial measurements that do not rely on external signals. That is also the reason the system can update its measurements so quickly.
However, systems that only rely on inertial measurements are also prone to drift with time. That is why OxTS products are GNSS-aided, and why several other inputs can be used alongside the inertial measurement platform to create a hybrid system where each technology mitigates weaknesses in others. The end result is an accurate and reliable measurement system that continues to work in challenging real-world conditions. This makes it suitable to robotic applications where sudden loss of position information, or sudden jumps in location or heading, can have serious implications.
OxTS offers different indoor navigation solutions which can be tailored to our customers needs.
IMU+ reflective Strip Technology
For indoor ADAS testing we’ve developed a reflective strip solution that uses light sensor technology to aid our INS within 3cm accuracy. Developed in collaboration with automotive test system supplier AB Dynamics, it is designed to be used in an enclosed environment where a satellite-aided inertial navigation system can’t function.
- Same low-latency as GNSS-aided INS
- Provides path-following position accuracy better than 3cm
- Full consultation, set-up and training included
- Low-cost infrastructure utilising reflective strips.
The indoor positioning solution utilising our reflective strip technology provides an innovative solution. It comprises a development of the RT1003 inertial navigation system, updated with new firmware and mounted to the test vehicle externally via a bespoke frame. The mounting frame incorporates two light sensors that are able to detect a specially developed retro-reflective strip material, which is fixed to the test site floor.
Also included is a checker board-marked mat, which is used to initialise measurements with a starting position and heading via a NAVsuite plug-in.
OxTS’ Indoor Positioning System combines data from the RT’s inertial measurement unit with absolute positioning information provided via the light sensors as they detect the pre-surveyed retro-reflective strips to provide real-time, centimetre-level-accurate data.
The system is offered with a full hands-on installation service by OxTS engineers, including an on-site survey, retro-reflective strip positioning, system set-up and customer training.
IMU+ Radio-Location Technology
Locata Corporation is a privately-owned Australian company that has invented new radio-location technology (LocataTech) that gives precise positioning in many environments where GNSS is either marginal or unavailable for modern applications.
A network of terrestrially-based LocataLite transceivers transmits extremely well-synchronized signals. These form a positioning network called LocataNet that operates independent of GNSS.
Read our white paper in GPS World
Where the IMU comes in
When configured to work with the Locata system, the built in GNSS information is replaced with measurement input from the Locata receiver. The OxTS system then simply uses this information as it would normally and is able to output accurate and reliable vehicle measurements while maintaining excellent position accuracy thanks to the Locata system. Measurements are output via Ethernet and CAN, where they can be utilized by other equipment such as driving robots or logged. Raw measurements are also logged internally by OxTS products, allowing the data to be downloaded and reprocessed post-test, in order to test different scenarios or make changes.
Locata’s alternative to GNSS/GPS was conceived to overcome the limitations of a satellite signal-based navigation system. Key to Locata’s system is a time-synchronization capability, called TimeLoc, which allows its ground-based transmitters, known as LocataLites (LLs), to synchronize with each other to picosecond precision.
A network of LLs forms a GPS-like constellation of transmitters that allows signal-based positioning within a serviced area. These networks can cover deep canyons, indoor facilities and other challenging environments where GPS struggles to operate, delivering centimetre-level accuracy with high reliability and guaranteed high repeatability. Locata-based commercial networks can operate as an alternative or an augmentation to GPS.
When an OxTS INS is configured to work with the Locata system, the built-in GNSS information is replaced by measurement input from the Locata receiver to produce accurate and reliable measurements while maintaining excellent position accuracy. Data is output via Ethernet and CAN to be used by other equipment, such as driving robots, or logged. Raw measurements are also logged internally to be downloaded for post-processing.
Our indoor positioning system firmware has been developed to accept different forms of external aiding. Our Application Engineering Team can help to develop a cost-effective indoor positioning solution for you, built on our proven technology.
Our indoor positioning solutions easily connect to steering and pedal robots via Ethernet, Serial and/or CAN bus, for ultimate test repeatability.
Capture Every Movement
Without GPS we still output data at up to 250 Hz, so you can measure position, orientation and velocity during high-dynamic movements.
Accurate and Reliable
Our indoor positioning solutions share the same core inertial technology as our leading automotive products. Measure to global NCAP standards with confidence.
The IMU+ radio-location technology is compatible with our RT-Range S ADAS system, so you can run tests which involve target vehicles.
We offer different indoor positioning solutions depending on your requirements.
We have 20 years experience in inertial navigation and external aiding sources.
Whatever your indoor positioning challenge – our team will work with you on a solution that works for you.
You can follow this link to download our indoor positioning leaflet.
You can download our indoor positioning presentation here.