His primary research objective is to apply principles of muscle mechanics, neural control and human biomechanics to guide the designs of biomimetic robots, human rehabilitation devices, and augmentation technologies that amplify the endurance and strength of humans.
Professor Herr has built elastic shoes and leg exoskeletons that increase aerobic endurance in walking and running.
In the field of human rehabilitation, his research group has developed gait adaptive knee prostheses for transfemoral amputees and variable impedance ankle-foot orthoses for patients suffering from drop foot, a gait pathology caused by stroke, cerebral palsy, and multiple sclerosis.

In addition to being an inventor and scientist, Hugh is an avid mountain climber.
During a mountain climbing outing in January of 1982, he became stranded on Mount Washington in New Hampshire for nearly four days in -20 °F temperatures and blizzard conditions. Severe frostbite damage took its toll on his lower legs, and both of his feet had to be amputated six inches below the knee.
After the accident, he dreamed of being able to climb mountains once again. But how? The answer was technology; he developed specialized prosthetic feet that enabled him to not only return to his chosen sport of mountain climbing, but to climb at a more advanced level than he had achieved before the accident.
Prosthetic feet with high toe stiffness made it possible to stand on small rock edges the width of a coin, and titanium spiked feet helped him to ascend steep ice walls. He made his height adjustable to avoid awkward body positions and to grab hand and foot holds previously out of reach. He could be as short as five feet or as tall as eight feet.

From the experience, Hugh realized that technology can make a profound impact on the lives of people struggling with physical disability. He was struck by the lack of technological sophistication in prosthetics.

Commercially available artificial limbs were generally inflexible and non-adaptive, making them uncomfortable and difficult to use. These realizations convinced him to pursue a career in science and engineering so that he could be in a position to advance assistive technology and to improve the quality of life of physically challenged people.