Dispersed sensing enabling autonomous cars. What role can new batteries play?

Autonomous vehicles are currently dominating the future of the automotive space with Google, Apple and Tesla leading the way. However, whilst road trials have started, the actual roll out of autonomous cars will be a staged process due to two main reasons:

• Technology is evolving at different rates making it easier for car manufacturers to add autonomous features as they become ready and proven. This opens up the opportunity for postproduction features to be more frequently introduced and trialled.
• Consumers are still concerned about the safety of fully autonomous vehicles. This will be addressed by a gradual introduction of features with proof of their safety. As a result, we’ll initially see assisted driving functionality coming into cars, with the move to full automation later.

The Society of Automotive Engineers has defined the levels of autonomous vehicles as:

• Level 1 includes features such as adaptive cruise control, automatic emergency braking – already seen in main-stream cars.
• Level 2 features are starting to appear in premium brands such as automated steering and speed control for short periods.
• Level 3 still requires some driver intervention.
• Level 4 will be fully autonomous but can still be driven by humans.
• Level 5 will be designed not to have a driver.

Sensing technology is key to the success at each stage of this evolution, but sensors will need to be standalone, potentially independent of the rest of the car’s power systems. This enables the option for car manufacturers to offer retrofit ADAS features to older cars.

Autonomous vehicles will ultimately be crammed with sensors to monitor their surroundings, detect potential and actual obstacles and to plan the vehicle’s route. There are a variety of ways of implementing these sensing features, however the main sensors are linked to these four areas:

• Ultrasonic: enables detection of obstacles in the immediate vicinity.
• Vision: monitored via camera technology – the car can see its environment.
• Obstacle detection: normally provided by radar technologies.
• Distant monitoring: laser and light technology to determine distance to an object – super eyes for cars.

There are a variety of sensors currently available, each with its own advantages and disadvantages:

Ultrasonic sensors

• Provide a lower implementation cost and whilst currently used for automated parking, could be used for other obstacle detection. However limited to use at lower speeds.

Image sensors

• A mature technology with a range of solutions supporting high enough resolutions to read text and colours. Can also be used as a backup system to other sensory functions, such as parking assist. The main limitation is the reach of camera accuracy, which needs to increase to about 250m. Environmental aspects, such as weather, can impact its accuracy and their large data processing requirements (30-60 frames per second) can be costly.

Radar

• Has a lighter weight than a camera and uses radio waves to determine distance to objects, travelling speed and angle they are facing. Doesn’t need line of sight to identify an object as it can use reflections – particularly useful in urban settings. Since it is less data processing heavy, it can be implemented around the car. There are some angular accuracy limitations with 2D sensors but these will be addressed by the new generation of 3D radars.

LiDAR (Light Direction And Ranging)

• Large amounts of investment are being focused in this space. LiDAR generates a 3D map of its surroundings through a combination of radar, scanner and GPS functionality. This increases the awareness levels of the car up to 100m in all directions. This avoids blind spots – a problem for other sensing types. The main thing currently holding back adoption is the cost – however Google is one of the companies working to reduce this vehicle level cost. It will also require large amounts of data to be processed real time.

So how can these sensing elements be powered?

The benefits these sensors enable also bring with them numerous challenges. The most prolific sensor types expected to be adopted over the next 10 years are ultrasonic sensors and both short and long-range radar. These sensors are dispersed over the whole vehicle, which results in additional communications and wiring requirements, adding complexity and weight to the vehicle.

Energy efficiency is at the core of autonomous vehicles. Most of the focus so far has been on battery technology to power the vehicle, however energy efficiency is key throughout the entire vehicle. The ability to harness the energy being released through the movement of the vehicle offers new power sources. Energy such as heat and vibration created by the motion of the vehicle or wind and light from the environment, give opportunities to harvest this energy for the sensing features. However these energy sources are not always present and this is where Ilika’s solid state battery technology can step in.

Different sensor types have different power requirements and having battery backup will soon become a requirement. Some of the sensor types currently are power intensive however they are evolving to become more power efficient. Powering them must not affect the integrity of the existing wiring, nor must it increase the overall weight of the car. Advancements in Ilika’s Stereax battery technology have resulted in the Stereax P180 – small size solid state batteries with a lifespan of up to 10 years enabling them to be placed in sealed units. Their small footprint means they reduce both the size and weight of any sensor unit enabling the compounds used in the bodywork to include the battery technology. Unlike standard liquid lithium ion batteries, the P180 can tolerate high moisture conditions and temperatures between -40˚C to +150˚C. It offers efficient, reliable functionality in miniature, low weight form enabling the sensors required in autonomous cars to be powered without adding additional cabling and therefore weight to the vehicle.

“The Stereax product family brings a range of solid state battery solutions which customers can license to enable battery technology that meets the demanding needs of Industrial IoT and automotive environments,” said Graeme Purdy, CEO, Ilika. “Ilika continues its commitment to bringing market leading solutions to address the wide needs of battery technology in the connected world.”

Battery technology is key to the success of the autonomous car and its continuous evolution – the small, thin, highly-efficient Stereax P180 batteries will be a vital addition to the electronics designs for these dispersed sensing networks, enabling manufacturers to bring more features to the vehicle with minimal impact on its performance.

www.ilika.com