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Speed Assist Systems (SAS)

Technical Articles July 11, 2018

SAS Speed Limit Information Function (SLIF) 

The Euro NCAP SAS SLIF protocol is designed to asses the effectiveness of a vehicle’s speed limit information function warning and speed control. The SLIF warning is tested by driving at a speed 10 km/h over the posted limit and evaluating the entire warning sequence. The speed control function is evaluated at City, Inter-Urban and Highway speeds in several different scenarios. In all cases, the protocol is interested in when and how the system engages as well as the vehicle’s speed.

Protocol accuracy requirements

  • Speed accuracy to 0.1 km/h
  • Update rate at least 10 Hz
  • Speed resolution to 0.01 km/h

Speed limit information test with OxTS RT

Getting the measurements you need 

All of our automotive RT INS products are capable of capturing the measurements required by the protocol, and there is technically no need to use an RT-Range Hunter, as the protocol is predominantly interested in the speed of the vehicle and when events occur, which can all be logged to the RT.

However, during development, it is often easier to use the RT-Range S as the system can track the position of up to 65,000 feature points, which can be tracked when they come in to view of the speed control system. This provides an easy way of capturing not only how the system responds to speed limit information but also how well it detects road signs. As the protocol also calls for some open-road testing, which is often used during the development stage, the ability to use NTRIP corrections is of interest to some customers as it removes the need for a local base station to achieve RTK integer 1 cm accuracy.

All data captured by either the RT or RT-Range S can be downloaded back at the office and post-processed, tested and exported as CSV files for further analysis, using our free software tools.

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