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82 April/May 2017 | Unmanned Systems Technology PS | Intelligent tyres O ne of the many challenges faced by autonomous vehicle developers is to replicate human senses to allow the vehicles to manoeuvre around the Earth’s surface (writes Stewart Mitchell). Human-environment interaction is immensely convoluted, but the brain is capable of a vast number of computations in a very short amount of time, and can dynamically prioritise each calculation according to the change in type of sensory feedback, its strength or speed. Also, we use any number of the five traditional senses in series (one before the other in a particular order) or parallel (two or more at the same time). The parallel operation is particularly relevant when driving, for example, where we use sight to determine the desired trajectory of the car, and touch or ‘feel’ to operate the vehicle. This ‘feel’ is not just the roll, pitch and yaw of the vehicle – which can be picked up by a basic accelerometer and is considered low-frequency high- amplitude feedback – it is also the extremely high-frequency low-amplitude feedback (vibration) that occurs even in steady-state conditions. From an accelerometer point of view, the vibration data is not always analysed or considered. However, it is critical as it directly correlates to the surface the vehicle is travelling over, and can therefore correspond to the coefficient of friction available between the tyres and the road surface. To that end, several technology research companies have developed autonomous vehicle ‘feel’ systems, which combine dynamic sensing parameters presented by accelerometer data with intelligent tyre technology that features sensitive flexible vibration, pressure, temperature and moisture sensors embedded in dielectric layers of micro- structured rubber tyres. This in-tyre sensor technology enables a tyre to communicate its pressure and temperature status to the car; it also ‘senses’ the type of road surface and the weather conditions, and sends that data to the vehicle’s electronic control system. The car’s control system filters the feedback from the tyres using fuzzy logic and machine learning technology, accounting for such variables as inflation pressure and tyre temperature, to develop an estimate of the tyres’ adhesion coefficient. As a result, the system can optimise the autonomous control of the vehicle on any surface and ensure the car is operating safely. For example, when the tyre senses moisture on the road surface, the vehicle will respond by slowing down and lowering its maximum rate of acceleration and deceleration accordingly. It will thus operate for maximum stability, and the system will work to bolster the sensitivity of the collision prevention systems. The data collected from monitoring the road surface, and the interaction between the tyre and the road, can be transmitted to a tyre-to-vehicle information exchange via the cloud (and in the near future, the Internet of Things) to enable other vehicles to benefit from the data. According to sources contacted in connection with this article, this intelligent tyre technology is set to allow autonomous vehicles of the near future to provide dynamic capabilities similar to those of a professional human driver, while reducing the unpredictability of driving on the open road. Now, here’s a thing “ ” The system can optimise the autonomous control of the vehicle on any surface and ensure it is operating safely