A Physiologist's Perspective on Robotic Exoskeletons for Human Locomotion

Abstract

Technological advances in robotic hardware and software have enabled powered exoskeletons to move from science fiction to the real world. The objective of this article is to emphasize two main points for future research. First, the design of future devices could be improved by exploiting biomechanical principles of animal locomotion. Two goals in exoskeleton research could particularly benefit from additional physiological perspective: 1) reduction in the metabolic energy expenditure of the user while wearing the device, and 2) minimization of the power requirements for actuating the exoskeleton. Second, a reciprocal potential exists for robotic exoskeletons to advance our understanding of human locomotor physiology. Experimental data from humans walking and running with robotic exoskeletons could provide important insight into the metabolic cost of locomotion that is impossible to gain with other methods. Given the mutual benefits of collaboration, it is imperative that engineers and physiologists work together in future studies on robotic exoskeletons for human locomotion.

Biorobotics: Using robots to emulate and investigate agile locomotion

“…Active exoskeletons (for limb support) and prostheses (for limb replacement) are fields in which robotics, biomechanics, and human motor control converge (83). In order to restore or augment human locomotion a series of actuated exoskeletons have been designed, including BLEEX (84), HAL (85), Sarcos' exoskeleton, MIT Exoskeleton (86), MINDWALKER (87), and RoboKnee (88); see (83,89) for reviews.…”

“…In order to restore or augment human locomotion a series of actuated exoskeletons have been designed, including BLEEX (84), HAL (85), Sarcos' exoskeleton, MIT Exoskeleton (86), MINDWALKER (87), and RoboKnee (88); see (83,89) for reviews. Several can be bought as commercial products, such as the ReWalk from ReWalk Robotics and Ekso from Ekso Bionics.…”

Enhancing performance during inclined loaded walking with a powered ankle–foot exoskeleton

“…Exoskeletons that assist the lower limbs during locomotion have improved much in the last decade and experts in the field believe that they will soon have an important role in daily life (Ferris 2007). While most research is focused on technical enhancements, a quantitative evaluation of the effectiveness is often missing (Dollar and Herr 2008).…”

“…The metabolic energy expenditure, often calculated as metabolic power (W•kg -1 ) based on oxygen consumption and carbon dioxide using a standard equation (Brockway 1987) and body weight normalization, is a key value in the evaluation of several exoskeleton devices (Galle et al 2013a;Malcolm et al 2013;Mooney et al 2014;Norris et al 2007a;Sawicki and Ferris 2008, 2009a, 2009bWehner et al 2013). Regardless of the functional goal of the device, reducing the metabolic power will improve the usability of the exoskeleton (Ferris et al 2007) and can therefore be considered a prime outcome when evaluating exoskeleton effectiveness, that can even be used to drive kinematic behavior with exoskeletons (Collins and Jackson 2013).…”

“…on the efficiency and the consistency of the assistance over increasing intensities. Higher intensities would also contribute to taking exoskeletons out of their 'normal' environment and allow to use them as a tool to resolve fundamental questions in biomechanics, motor control and physiology, as suggested by Ferris et al (2007). In example, the influence of muscle fatigue on overall fatigue could be studied by assisting or resisting specific muscles (Malcolm 2009) with an exoskeleton during exercise until exhaustion.…”