During trips and outdoor adventures, there are a lot of electric equipment and thus power supply for those devices is critical. At the same time, the burden on shoulders from heavy baggage is substantial. This paper presents a one-way energy harvesting backpack with ball-screw mechanism to generate electricity with high efficiency and reliability, while relieves the burden on shoulders. The one-way energy harvesting method only harvests negative work from human body and potentially reduce metabolic cost while carrying backpack. Simulations show that 4.5W of electrical energy can be obtained from human walking. Bench test results indicate this system can obtain an average power of 7.3 W with excitation of 2Hz and 25mm direct drive. Treadmill test to verify the performance of burden relieve on shoulders indicates this one-way design combing with elastic support strap can reduce the force on shoulders, which reduce fatigue in human.
Lifejacket is an indispensable life-saving equipment for ships and airplanes. Traditional lifejacket is designed to prevent human from drowning. However, the water temperature is usually low, especially in winter, which significantly reduces the human body temperature and leads to death. Meanwhile, power is critical for drowning people to use emergency communication equipment. This paper proposed an ocean wave powered lifejacket using 2DOF floating boards to provide both buoyance and electricity for drowning people. Hence, they can use this continuous electric power to keep key body warm and send distress signal. This lifejacket is featured with two 2DOF floating boards and the mechanical motion rectifier (MMR) can convert the 2-DOF motions to the unidirectional rotation of generator. The design principle is illustrated and the dynamic modelling for the 2-DOF motions has been analyzed. Bench test and lake test have been conducted to validate the design concept.