Intelligent Speed Assistance may sound like a given, but the technology is versatile enough to enhance many more Autonomous Vehicle functions.
Autonomous vehicle research and development has been gaining traction globally. However, there are still several hurdles to overcome before autonomous vehicles (AVs) can navigate autonomously across our extensive road networks.
Safety remains a top priority when it comes to operationalizing AVs, and compliance with prescribed speeds on the roads is crucial to avoid incidents. In the emerging era of AVs, the use of smart technology such as Advanced Driver Assistance Systems (ADAS) in vehicles can offer riders more comfort, safety, and efficiency.
One peripheral technology of interest is Intelligent Speed Assistance (ISA). To implement ISA adequately, certain technical prerequisites must be met. This includes a well-thought-out system that combines cameras, an electronic horizon, and digital maps.
ISA as a safety net
Intelligent Speed Assistance is an in-vehicle assistance system that informs AV operators about the speed limit compliance on the road, and even prevents breaches of the limits. This is particularly helpful when AV operators have missed traffic signs or warnings, are distracted, and experience impaired visibility due to weather, or other difficult circumstances.
With ISA, the intention is to prevent accidents and increase overall road safety, based on three contingencies:
- Firstly, ISA displays the current speed limit in the operator’s direct line of sight.
- Secondly, drivers are warned via audio-visual cues if they exceed the speed limit. In both stages, drivers retain full control over their speed.
- Lastly, ISA will also automatically adjust the driving speed to fall within the prevailing limit. When activated, IS only allows operators to accelerate beyond the speed limit if they apply additional pressure to the accelerator pedal. When they do so, they will receive warnings from the ISA system.
Key ISA challenges
When it comes to AV operation, not all speed limits can be detected via traffic cameras.
For example, in Singapore, speed limit signs are largely explicit, but they vary with vehicle type and in heavy weather conditions, signs can be imperceptible to cameras.
In large cities this problem is more prevalent, where speed signs can be less obvious—sometimes implied—and may vary at different times of the day. As a result of this, modern ISA systems rely on a variety of data points to determine and comply with speed limits:
- ISA systems access various data points to determine the currently permitted speed. Forward-facing cameras and Global Navigation Satellite System (GNSS) for identifying locations are the minimum requirement for ISA systems today.
- Additional information about the immediate driving environment and distances to obstacles or other objects is provided by in-vehicle sensors such as ultrasonic, radar, and LiDAR systems. These are important for advanced ADAS functions such as adaptive cruise control and lane departure warning, providing advanced data for ISA.
- However, since not all speed limits can be detected by sensors, a digital map and an electronic horizon are recommended for ISA. A digital map not only contains information about the route or the number of lanes the road has, but also has the ability to determine applicable speed limits, with possible conditioning factors coded to the respective road segments. This means that speed limits are available for all roads on the map, regardless of visibility or availability of signs, weather, vehicle type, and time of day.
- The electronic horizon is software that combines digital map data with information about position and road conditions from sensors to create a model of the road ahead. This includes sections of road ranging from a few hundred meters to several kilometers. The data from the electronic horizon is made available to the ISA system to ensure it functions without error, meeting ISA requirements that cannot be done purely via sensors.
EU safety standards and ISA
The European Commission has made it mandatory for all new vehicles sold within the European Union (EU) from July 2022 to comply with enhanced safety standards, and ISA is going to play a huge role in this new regulation.
With ISA systems, technologies such as camera systems and digital maps will become the new norm in almost every vehicle.
In Singapore, autonomous bus services are expected to debut soon, and ISA will be critical in ensuring safety on the roads. This includes recognizing passengers waiting at bus stops and hence, slowing down the bus, and activating assistive features of the AV when elderly or disabled passengers need to board.
Well beyond simply detecting and displaying speed limits, ISA’s features can augment ADAS solutions through supplementing Adaptive Cruise Control, Lane Keeping Assistant System, and automated systems for more efficient switching between the electric motor and combustion engine (in hybrid AVs).