The first HAL prototype was proposed by
Yoshiyuki Sankai, a professor at Tsukuba University. Fascinated with robots since he was in the third grade, Sankai had striven to make a robotic suit in order "to support humans". In 1989, after receiving his PhD in robotics, he began the development of HAL. Sankai spent three years, from 1990 to 1993, mapping out the
neurons that govern leg movement. It took him and his team an additional four years to make a prototype of the hardware. The third HAL prototype, developed in the early 2000s, was attached to a computer. Its battery alone weighed nearly and required two helpers to put on, making it very impractical. By contrast, later HAL-5 model weighs only and has its battery and control computer strapped around the waist of the wearer. Cyberdyne began renting the HAL suit out for medical purposes in 2008. By October 2012, over 300 HAL suits were in use by 130 medical facilities and
nursing homes across Japan. The suit is available for institutional rental, in Japan only, for a monthly fee of US$2,000. In December 2012, Cyberdyne was certified
ISO 13485 – an international quality standard for design and manufacture of medical devices – by
Underwriters Laboratories. In late February 2013, the HAL suit received a global safety certificate, becoming the first powered exoskeleton to do so. In August 2013, the suit received an EC certificate, permitting its use for medical purposes in Europe as the first medical treatment robot of its kind. ==Design and mechanics==