Mechanical Energy Scavenging for in-Wheel Sensors

This project proposes to use the centrifugal force imparted to a mass, rotating within a car wheel to wind a clockwork system that can then be used to power in wheel sensors. Power is generated by the spring unwinding and driving a micro-generator.The project will investigate the feasibility of the mechanical spring system to scavenge and store enough energy to power typical in-wheel sensors. At present typical MEMS based electromagnetic and electrostatic vibrational scavenging systems offer power outputs in the 10-100 microWatt range. The energy harvester proposed here offers the possibility of over 1 milliWatt of power. The fully wound spring system stores up to 2.6 milliWatt-hr of energy and with a conversion factor of 50% for the generation; and the system designed to fully unwind over 1 hour, then there will be a 1.3 milliWatt supply for that hour. The system maintains this power level by being continually rewound by the start-stop motion of the car and any cumulative vibrational motion of the wheel in the radial direction. This generated power can be varied in the 10-10000 microWatt range by changing the speed with which the spring unwinds from seconds to hours. The system can therefore provide the short high power burst required for wireless transmission as well as the lower power of the measurement and sleep states. As part of the project the actual real journey dynamics of a car wheel will also be measured using a remote sensor pod attached to the car. This measured data will be made freely available to researchers for use in energy harvester performance modelling via an open access online database.To achieve the project goal the research will draw upon the unique skills and expertise from the Bio-medical & MicroEngineering group and the Vehicle Technology Research Centre, both situated in the School of Mechanical Engineering at the University of Birmingham.

It is the intention of the applicant of this first grant proposal to utilise the Knowledge Transfer Networks of the technology strategy board and the workgroups of the Institute of Engineering Technology to directly communicate and engage with other researchers and industry. These forums such as the quarterly Intelligent Sensing programme meeting; and the meetings of Micro and Nano Sensing Interest Group, both of the Sensors and instrumentation KTN, are industry biased and provide the ideal opportunity for networking and knowledge transfer. Results at all stages will also be published in appropriate journals e.g. Journal of Micromechanics and MicroEngineering; IEEE Microsensors Journal. They will also be presented at European conferences such as Eurosensors and Micromechanics Europe (MME), giving a wider exposure to the work to academia and industry in Europe. It is also one of the objectives of the project to establish a project website where the car dynamics results will be available this will then act as an opportunity also to present results of the generator; and generally promote the project background, design ideas and project successes. Opportunities for collaboration will be strongly sought through the current collaborations within the Vehicle Technology research Centre and Micro and Nano Engineering group. This will be managed by presenting work to collaborators at visits and meetings. The Vehicle Dynamics Research Centre specifically has strong links with the UK and International Automotive industry including OEMs and Tier 1 suppliers including: Jaguar - Land Rover Goodyear Tyres Technical Centre, Luxemburg Michelin Americas R&D Corp Dunlop Aircraft Tyres Ltd Gibbs Technologies Ltd Benetton Formula Ltd UK industry will benefit from the outcomes of this programme through the exploitation of the spring system energy scavenger. If there was acceptance and take up of the technology then there would be a large requirement for precision springs and micro-gear components that could be met by UK manufacturing industry. The impacts for the wider society include improved safety, reliability, performance and environmental-friendliness of their vehicles. There will also be benefits in the reduction of batteries used in equivalent TPMS systems and, potentially, in the premature scrapping of tyres which have not been inflated correctly during use. Further exploitation possibilities would be sought by the application of the technology to rotating machinery monitoring. Advice on this aspect would be sought from the members of the Advanced Machining group at Birmingham and the opportunity presented to the wider market via the commercialisation activities within Alta Innovation. Where required, the help and advice of the School's Knowledge Transfer champion Dr David Boardman and Alta innovations, the University of Birmingham's technology transfer company, for identifying and exploiting opportunities will be sought in how best to exploit the results of the research. This relationship with Alta innovations is managed through a school knowledge transfer champion, who provides local advice and assistance on exploiting ideas and selling to industry. The press office of the university will also be used for advice and assistance in communicating significant results to a wider audience.