Novel Designs for Passive Elastic Lower Limb Exoskeletons

Engineers and scientists have long tried to build powered robotic lower limb exoskeletons without success (at least commercially). A major limitation has been the need for large amounts of mechanical power from the actuators. Simply put, human muscles are amazing motors. The size and mass of robotic actuators that can match human muscle limit exoskeleton hardware designs. An alternative to heavy motors that engineers have relied on throughout history has been power amplification from passive elastic mechanisms. We review examples of successful passive elastic systems that have been previously used by humans and discuss how elastic mechanisms can be incorporated into lower limb exoskeletons for assisting human locomotion.