Walking | EPFL Graph Search

Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the usable number of limbs—even arthropods, with six, eight, or more limbs, walk. In humans, walking has health benefits including improved mental health and reduced risk of cardiovascular disease and death. Difference from running Running Jogging The word walk is descended from the Old English wealcan "to roll". In humans and other bipeds, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support. In contrast, running begins when both feet are off the ground with each step. This distinction has the status of a formal requirement in competitive walking events. For quadruped

Human-Human, Human-Robot and Robot-Robot Interaction While Walking: Data Analysis, Modelling and Control

Jessica Lanini

In everyday life humans perform many tasks with other partners which involve coordination, involuntary communication and mutual control adaptation, as the case of carrying objects together with another person. Humanoid robots may help with such activities by collaborating with humans or even substitute them. With this in mind, understanding how humans perform such tasks would be useful not only to better understand human motor control strategies but also to extract useful information for the implementation of robotic controllers. This Thesis aims to investigate if and how the haptic interaction among two subjects cooperating with each other while walking (e.g. while carrying objects) (a) alter their walking gaits, (b) is exploited by humans to understand the intentions of the other partners (e.g. to start/stop walking, accelerate/decelerate, etc.), (c) determine a walking synchronization and (d) whether such a synchronization can improve the overall task (e.g. by reducing the interaction forces). Moreover the feasibility of applying human-human strategies to develop robotic controllers is investigated. \Human-human studies are performed to assess the research objectives and replicate them through simple mechanical models. The main features extracted from the human experiments are then used to develop control modules for humanoid robots doing similar tasks with humans or with other robots. Robotic experiments are then used not only to assess the feasibility of using humans strategies in robotic control but also to try to answer some questions related to human behaviour. The obtained results show that most of the subjects analyzed (a) alter their walking gait while mechanically paired with another human subject, (b) communicate their intention through a combination of interaction forces and hand velocity, (c) coordinate their walking gait with their partner, (d) selecting specific quadrupedal animals types of gaits. Moreover human-humanoid robot and humanoid robot-robot experiments are successfully performed and used to show the importance of walking synchronization in reducing the interaction forces and guaranteeing more symmetric motion of the two bipedal agents.

EPFL2019

An Adaptive Neuromuscular Controller for Assistive Lower-Limb Exoskeletons: A Preliminary Study on Subjects with Spinal Cord Injury

Tycho Jan Henricus Brug, Florin Dzeladini, Auke Ijspeert, Amy Roning Wu

Versatility is important for a wearable exoskeleton controller to be responsive to both the user and the environment. These characteristics are especially important for subjects with spinal cord injury (SCI), where active recruitment of their own neuromuscular system could promote motor recovery. Here we demonstrate the capability of a novel, biologically-inspired neuromuscular controller (NMC) which uses dynamical models of lower limb muscles to assist the gait of SCI subjects. Advantages of this controller include robustness, modularity, and adaptability. The controller requires very few inputs (i.e., joint angles, stance, and swing detection), can be decomposed into relevant control modules (e.g., only knee or hip control), and can generate walking at different speeds and terrains in simulation. We performed a preliminary evaluation of this controller on a lower-limb knee and hip robotic gait trainer with seven subjects (N = 7, four with complete paraplegia, two incomplete, one healthy) to determine if the NMC could enable normal-like walking. During the experiment, SCI subjects walked with body weight support on a treadmill and could use the handrails. With controller assistance, subjects were able to walk at fast walking speeds for ambulatory SCI subjects-from 0.6 to 1.4 m/s. Measured joint angles and NMC-provided joint torques agreed reasonably well with kinematics and biological joint torques of a healthy subject in shod walking. Some differences were found between the torques, such as the lack of knee flexion near mid-stance, but joint angle trajectories did not seem greatly affected. The NMC also adjusted its torque output to provide more joint work at faster speeds and thus greater joint angles and step length. We also found that the optimal speed-step length curve observed in healthy humans emerged for most of the subjects, albeit with relatively longer step length at faster speeds. Therefore, with very few sensors and no predefined settings for multiple walking speeds or adjustments for subjects of differing anthropometry and walking ability, NMC enabled SCI subjects to walk at several speeds, including near healthy speeds, in a healthy-like manner. These preliminary results are promising for future implementation of neuromuscular controllers on wearable prototypes for real-world walking conditions.

Frontiers Research Foundation2017

Symbitron Exoskeleton: Design, Control, and Evaluation of a Modular Exoskeleton for Incomplete and Complete Spinal Cord Injured Individuals

Florin Dzeladini, Auke Ijspeert, Amy Roning Wu

In this paper, we present the design, control, and preliminary evaluation of the Symbitron exoskeleton, a lower limb modular exoskeleton developed for people with a spinal cord injury. The mechanical and electrical configuration and the controller can be personalized to accommodate differences in impairments among individuals with spinal cord injuries (SCI). In hardware, this personalization is accomplished by a modular approach that allows the reconfiguration of a lower-limb exoskeleton with ultimately eight powered series actuated (SEA) joints and high fidelity torque control. For SCI individuals with an incomplete lesion and sufficient hip control, we applied a trajectory-free neuromuscular control (NMC) strategy and used the exoskeleton in the ankle-knee configuration. For complete SCI individuals, we used a combination of a NMC and an impedance based trajectory tracking strategy with the exoskeleton in the ankle-knee-hip configuration. Results of a preliminary evaluation of the developed hardware and software showed that SCI individuals with an incomplete lesion could naturally vary their walking speed and step length and walked faster compared to walking without the device. SCI individuals with a complete lesion, who could not walk without support, were able to walk with the device and with the support of crutches that included a push-button for step initiation Our results demonstrate that an exoskeleton with modular hardware and control allows SCI individuals with limited or no lower limb function to receive tailored support and regain mobility.

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2021