Dr Raphael Grech

Position, Navigation and Timing in a Connected Automated World

Dr Raphael Grech, Spirent Communications

In a connected world, reliance of accurate positioning and environmental awareness is becoming increasingly important.

The use of ride-hailing applications where a relatively accurate position is required of both the person requesting the ride and the vehicle itself. This poses challenges in an urbanised environment. Self-driving vehicles also require accurate positioning this is of critical importance. GNSS is still the only absolute-positioning system compared to the other relative-positioning systems, it’s considered as the only “formal” positioning mechanism when used in eCall and Intelligence Speed Assistance. GNSS has its limitations and is normally partnered with a robust Inertial Measurement Unit (IMU).  Sensors such as Cameras, Lidar and Radar complement the more traditional GNSS and inertial setup alongside HD- maps. These integrated systems need to be properly tested and validated simultaneously to guarantee a robust system implementation.

Why accurate positioning?

Autonomous vehicles require decimetre level positioning for highway operation and near centimetre level for operation on residential streets. Safety-critical localisation systems specify their performance in terms of accuracy, integrity and availability. In the world of autonomous vehicles, the GNSS receiver is just one subsystem in a complex system of sensors, actuators, software applications and algorithms.

Why we need realism in simulation?

Any system integrator, developer or user will want to be assured that the sensor fusion localisation system being developed will function effectively within its expected environment. Systems must be designed and tested to ensure degradation of any sensor can be detected while maintaining safe operation. Currently, a huge amount of effort is driving Radar, Lidar and Camera development and testing. GNSS can also be compromised by anything from tall buildings to deliberate jamming and spoofing by a threat source. Therefore, GNSS must be tested with the same level of attention as any other sensor on the autonomous vehicle as a holistic PNT (Position, Navigation and Timing) testing solution.

Future thoughts and directions

Testing the fusion of multiple positioning sources is a new requirement for autonomous vehicle developers. A co-simulation platform must simultaneously simulate all the sources of absolute position with real-world conditions. By using a positioning co-simulation platform, a vehicle developer can test real-world scenarios to ensure safe and reliable design of the vehicle navigation systems. As well as the normal environment, co-simulation should be able to simulate many different types of interference and disruption.