Sandpit: Mobile Energy Harvesting Systems

这是一项来自7所大学的合作提案，旨在推进动能收集技术，以减轻下马士兵的电池负担。英国军队的下马士兵携带各种电气和电子系统，包括火炬、个人无线电、鲍曼通信系统和电子对抗装置。这些设备由一次电池和二次电池供电，从无处不在的AA电池到大型锂离子电池。对于平均持续6小时的徒步巡逻，一个人携带的电池重量可达10公斤。这可能是总重量达75公斤的一部分，其中大部分是不可减少的（即水、弹药等）。如此沉重的负担严重限制了士兵的行动能力，并可能导致长期的健康问题。因此，必须在诸如电池之类的不可减重部件上节省重量。由于电池能量密度和移动系统功耗的预期改善，设想不仅可以显着减少电池负担，而且下车士兵的总电力需求的相当大一部分可以从环境能源（如热能、太阳能或动能）中获得。该提案解决了从移动士兵身上收集动能的问题，以便为他/她的电子系统供电的二次电池提供充电电流。有人建议，在低功率电子技术进步的背景下，这种收集系统可以帮助消除或减少士兵更换电池的负担。虽然动能收集系统先前已被证明与理论预期相比表现不佳，但开发的系统很少在整个系统中进行优化。也就是说，它们无法将系统的所有部分——机械、传感器和电子设备——相互匹配，也许最关键的是，无法与动力源（在这种情况下是人体）匹配。因此，这个项目的目标是通过解决整个系统，利用生物力学、动力学、换能器设计、材料选择和电子技术来生产一个优化的系统。该项目将探讨如何最好地从三种不同的身体来源中获取能量：脚步、肢体关节和负重加速度。然而，在制作实际演示时，它将侧重于使用负担（或证明质量）加速来为个人通信无线电提供动力。因此，该演示将结合低功率射频设计的进步，使无线电能够完全由动能收集产生的存储能量供电。以前从身体运动中获取能量的尝试通常会导致用户的负面反应，因为次优系统会对运动施加明显的反应负荷，导致步态的变化，从而增加疲劳。因此，该项目的目标是开发一种系统方法，不仅可以减少对佩戴者的障碍，甚至可以用来减少负载对身体的影响。例如，有人提出可以使用收获装置来支持和减少膝盖的负荷。从这些装置中提取的电力将得到管理，使它们在膝盖受压时吸收冲击，但在伸展时产生最小的阻抗。该项目的总体目标是为下马士兵设计、开发和演示动能收集系统，该系统可以同时提供约10瓦的可再生能源。虽然大部分项目将基于传统的换能器类型（压电），但一个工作包将专注于开发一种新型的动能和电能转换形式，利用反向电渗透效应。

This is a collaborative proposal from 7 universities aimed at progressing the technology of kinetic energy harvesting in order to reduce the battery burden on dismounted soldiers. Dismounted soldiers in the British army carry a variety of electrical and electronic systems including torches, personal radios, the Bowman communications system and electronic counter measures. These devices are powered by both primary and secondary cells, from the ubiquitous AA cell to large Li-ion batteries. For an average foot patrol lasting 6 hours the weight of batteries carried by an individual can be up to 10 kg. This may be part of a total burden of up to 75 kg, much of which is irreducible (i.e. water, ammunition, etc). Such large burdens severely limit the mobility of the soldier and can lead to long term health problems. Hence it is imperative that weight be saved in the non-irreducible parts of the burden such as the batteries. Due to the expected improvements in battery energy density and the power consumption of mobile systems, it is envisaged that not only can the battery burden be reduced significantly, but that a considerable fraction of the total power demand of the dismounted soldier can be harvested from ambient energy sources such as thermal, solar or kinetic. This proposal addresses the issue of the harvesting of kinetic energy from the mobile soldier in order to provide charging currents for the secondary cells powering his/her electronic systems. It is proposed that such harvesting systems, in the context of advances in low power electronics, could help eliminate or reduce the replacement battery burden of the soldier.Whilst kinetic energy harvesting systems have previously been shown to under-perform compared to theoretical expectations, the systems developed have rarely been optimised throughout the whole of the system. That is they fail to match all parts of the system - mechanics, transducer and electronics - to each other and, perhaps crucially, to the source of power, in this case the human body. Hence this project aims to succeed by addressing the whole system, harnessing skills in biomechanics, dynamics, transducer design, materials selection and electronics to produce an optimised system. The project will address how energy can best be harvested from three different corporeal sources: footfall, limb articulation and burden acceleration. However, in producing a practical demonstration, it will focus on the use of burden (or proof mass) acceleration to power a personal communications radio. The demonstration will therefore incorporate advances in low power RF design to enable the radio to be powered solely from the stored energy produced from kinetic energy harvesting.Previous attempts at harvesting energy from body motion have often resulted in a negative reaction from users as suboptimal systems impose a noticeable reactive load to the movement, resulting in changes of gait which can increase fatigue. Hence it is an aim of the project to develop a system methodology that will not only reduce the impediment to the wearer but may even be used to reduce the impact of loading on the body. For example, it is proposed that harvesting devices can be used to support and reduce load to the knees. The electrical power extraction from such devices would be managed so that they absorb impact during compression of the knee, but present minimal impedance during extension.The overall aim of the project is design, develop and demonstrate kinetic energy harvesting systems for the dismounted soldier which could in concert provide renewable power of the order of 10 W. Whilst much of the project will be based around a conventional transducer type (piezoelectrics), one workpackage will concentrate on developing a novel form of transduction between kinetic and electrical energy, employing the converse electro-osmosis effect.