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Sensors to Power Autonomous Vehicles

Sensors to Power Autonomous Vehicles

By TA News Bureau:

For autonomous vehicles to deliver peak performance, it is important to have intelligence tyres. It is one of the cutting-edge fields where Dr Deepam Maurya is working. As a member of research faculty in the Department of Materials Science and Engineering and the Department of Mechanical Engineering at Virginia Tech, he is researching new frontiers of science. Besides intelligent tyres, his research interests include 3-Dprinting of sensors, energy harvesting, multifunctional nanomaterials, solid-state refrigeration, acousto-optic devices and memory devices. He has published 74research papers in peer-reviewed journals, five book chapters, and 13 refereed conference papers. He holds one US patent in processing method for grain-oriented lead-free piezoelectric materials. He has chaired many sessions at international conferences. Excerpts from an interview

In the context of accelerated work on autonomous and connected vehicles, do you think the importance of intelligent tyres has heightened?

Absolutely! For automobiles, tyres act as an interface between the vehicle control system and the external environment. To achieve tyre-based sensing of the external environment, intelligent tyres play a critical role. The sensor arrays in smart tyres can be used for monitoring and evaluating important parameters such as road/terrain characteristics, air pressure, road/tyre friction, loading, wear, and hydroplaning etc. These parameters could be used by machine learning based intelligent algorithms for enhancing the reliability, endurance, safety, stability and fuel efficiency of a vehicle. In case of connected vehicle, this information can be further shared with other vehicle to warn about the hazardous environmental conditions in advance. The smart tyres are not only beneficial for the autonomous cars, but also will be helpful in controlling tyre-related crashes in traditional vehicles.

What is the current scenario in the design and manufacture of intelligent tyres?

There is a tremendous amount of development taking place in both academia and industry to provide devices, systems, and techniques that lead to energy efficient self-governing automobile environment. However, most of the available solutions to achieve intelligent tyres are not cost-effective because of the complex architectures and multistep fabrication process of the sensors, which would dramatically increase the cost of the tyres. At Virginia Tech, we have demonstrated a cost-effective solution to achieve smart tyres. We have been discussing with the industry partners to scale up the fabrication process and realise affordable solution for smart tyres.

In this background your research demonstrating the feasibility of the strain energy harvesting from the automobile tyres has assumed importance. Can you detail your work, including attempts at powering wireless data transfer with enhanced frame rates, and self-powered strain sensing?

In autonomous vehicles, the energy requirement has been increasing rapidly with the ever increasing number of power-hungry onboard sensors, and the enhanced requirement for an increased rate of wireless data transfer for safe and reliable driving. The enhanced number of sensors requires additional power, which further depends on the rate of the data transfer. For example, if you are driving a car with wireless data transmission system that transmits data every 30 seconds, it means you will get important information related to the tyre after 30 seconds. And if something wrong happens with the tyre, you will lose important reaction time to control the vehicle. You can increase the frame rate of data transfer from 30 seconds to 5 seconds for example, but it will require more power. The limited availability of energy restricts the use of increased frame rate for the wireless data transfer, which renders reduced reaction time for the driver in case of an emergency. Although batteries are the easy and inexpensive source for providing constant power supply, they have a major drawback of their limited utilization time, and high labour cost for replacement. In our work, we demonstrated use of strain energy of the tyres to generate electricity using our cost-effective sensor-cum-energy harvester. This energy was sufficient to power wireless data transfer with enhanced frame rate without relying on external power source. Interestingly, these strain energy harvesters also worked as strain sensors without relying on external power.

What are the manufacturing challenges facing tyre makers as the embedded electronics has to withstand the high heat during the curing and moulding process of tyre making?

It is really challenging to achieve embedded electronics in tyres, especially, considering the harsh manufacturing process. To save from high heat and mechanical shock during the tyre process, the electronics can be packaged with appropriate enclosures of high temperature, mechanically robust and mechanically compatible materials. This will also require change in the tyre fabrication process flow. However, electronics can be integrated with tyre economically after completing the tyre fabrication process. This will not disturb the current process flow of tyre manufacturing. Though, the electronics should be inexpensive and easy to integrate to allow high volume manufacturing. For example, recent advances in 3D printing technology provide hope to achieve cost-effective integration of electronics with smart tyres. This also means at some point in the near future, intelligent tyres can be directly printed with on board electronics. At Virginia Tech, we have already started working on developing 3D printing technology for intelligent tyres.
Please elaborate your statement that the research has focused on flexible organic piezoelectric material for continuous power generation and monitoring of the variable strain experienced by a tyre under different driving conditions.
Piezoelectric materials generate voltage under variable strain and most of the piezoelectric materials are ceramics. Ceramic materials are generally very hard, and, therefore have very different mechanical properties as compared to tyre rubber, which makes its integration difficult with the tyre rubber. On the other hand, in our work, we used flexible piezoelectric PVDF material (polymer) for continuous power generation from variable tyre strain, while, simultaneously self-sensing tyre strain. The variable tyre strain is influenced by several external factors like road/tyre friction, presence of water or snow on the road surface, uneven terrain etc. This provides us opportunity to indirectly sense external factors through change in variable strain using our cost-effective sensor cum harvester.
A full paper discussing the research detailed in this interview is published in Applied Energy, titled “Energy harvesting and strain sensing in smart tire for next generation autonomous vehicles”. The research is authored by me with Prashant Kumar, Seyedmeysam Khaleghian, Rammohan Sriramdas, Min Gyu Kang, Ravi Anant Kishore, Vireshwar Kumar, Hyun-Chloe Song, Jung-Min (Jerry) Park, Saied Taheri and Shashank Priya.
I take this opportunity to thank all of my team members for their help and support. Thanks to National Science Foundation (USA) for providing financial support during this work. I am also thankful to Center for Tire Research (CenTiRe) at Virginia Tech and Virginia Tech Transportation Institute (VTTI) for providing experimental support.

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