Human-like motion is a primary goal for many robotic assistive devices. Emulating the strategy of the human neuromuscular system may aid the control of such powered devices, yet many challenges remain. In this study, we investigated the potential for using the winding filament model (WFM) of muscle to predict the net muscle moment of the ankle. The long-term goal is to use this model to improve ankle control of a commercial powered exoskeleton. The innovation aspects of this study are: First, there have been no commercialized active ankle exoskeletons available in the market. All the available exoskeletons have passive ankle joints, which cannot mimic human movement, especially in normal and fast walking [1]. Second, the Winding Filament Model Controller (WFMC) is the first control strategy based on a muscle model that does not use an electromyographic (EMG) signal as an input. The activation, which is calculated from EMG, is a crucial input parameter for almost all of the control strategies based on muscle modeling. However, the winding filament muscle model can predict muscle force by using muscle length as the primary input, and the activation input signal could be either a square wave [33] or a simple bell shape function like our study. This is one of the most important benefits of the WFMC strategy, since it makes this bioinspired strategy applicable for all patient populations, even those with impaired muscle activities or without muscle activities (e.g. stroke, spinal cord injury, Parkinson disease, etc.). Third, the WFMC is adaptive to different tasks like walking at different speeds, as well as walking over the incline and over stairs.
California Institute of Technology（加州理工学院）；Wandercraft SAS（旺德工艺有限公司）
This paper presents an active stabilization method for a fully actuated lower-limb exoskeleton. The method was tested on the exoskeleton ATALANTE, which was designed and built by the French start-up company Wandercraft. The main objective of this paper is to present a practical method of realizing more robust walking on hardware through active ankle compensation. The nominal gait was generated through the hybrid zero dynamic framework. The ankles are individually controlled to establish three main directives; (1) keeping the non-stance foot parallel to the ground, (2) maintaining rigid contact…
This work presents a description of the EXOSMOOTH project, oriented to the benchmarking of lower limb exoskeletons performance. In the field of assisted walking by powered lower limb exoskeletons, the EXOSMOOTH project proposes an experiment that targets two scientific questions. The first question is related to the effectiveness of a novel control strategy for smooth assistance. Current assist strategies are based on controllers that switch the assistance level based on the gait segmentation provided by a finite state machine. The proposed strategy aims at managing phase transitions to provid…
Positive biomechanical outcomes have been reported with lower-limb exoskeletons in laboratory settings, but these devices have difficulty delivering appropriate assistance in synchrony with human gait as the task or rate of phase progression change in real-world environments. This paper presents a controller for an ankle exoskeleton that uses a data-driven kinematic model to continuously estimate the phase, phase rate, stride length, and ground incline states during locomotion, which enables the real-time adaptation of torque assistance to match human torques observed in a multi-activity datab…
Institute for Human and Machine Cognition（人类与机器认知研究所）
Exoskeletons are a promising technology that enables individuals with mobility limitations to walk again. As the 2016 Cybathlon illustrated, however, the community has a considerable way to go before exoskeletons have the necessary capabilities to be incorporated into daily life. While most exoskeletons power only hip and knee flexion, Team Institute for Human and Machine Cognition (IHMC) presents a new exoskeleton, Mina v2, which includes a powered ankle dorsi/plantar flexion. As our entry to the 2016 Cybathlon Powered Exoskeleton Competition, Mina v2's performance allowed us to explore the e…
Department of Mechanical Engineering, Northeastern University（东北大学机械工程系）；College of Engineering, Northeastern University（东北大学工程学院）；Khoury College of Computer Sciences, Northeastern University（东北大学计算机科学学院）；Department of Electrical & Computer Engineering, Khoury College of Computer Sciences, and the Institute for Experiential Robotics, Northeastern University（计算机科学学院电子与计算机工程系及体验机器人研究所，东北大学）；Woodruff School of Mechanical Engineering and the Institute for Robotics and Intelligent Machines, Georgia Institute of Technology（沃德夫机械工程学院及机器人与智能机器研究所，佐治亚理工学院）；Department of Mechanical Engineering, the Department of Physical Therapy, Movement, and Rehabilitation Science, and the Institute for Experiential Robotics, Northeastern University（机械工程系、物理治疗、运动与康复科学系及体验机器人研究所，东北大学）
To enable the broad adoption of wearable robotic exoskeletons in medical and industrial settings, it is crucial they can adaptively support large repertoires of movements. We propose a new human-machine interface to simultaneously drive bilateral ankle exoskeletons during a range of 'unseen' walking conditions and transitions that were not used for establishing the control interface. The proposed approach used person-specific neuromechanical models to estimate biological ankle joint torques in real-time from measured electromyograms (EMGS) and joint angles. A low-level controller based on a di…
Force Myography based Torque Estimation in Human Knee and Ankle Joints
High Performance Humanoid Technologies Lab, Institute for Anthropomatics and Robotics, Karlsruhe Institute of Technology (KIT), Germany（高性能人形机器人实验室，人机学与机器人研究所，卡尔斯鲁厄理工学院（KIT））；BioMotion Center, Institute of Sports and Sports Sciences, Karlsruhe Institute of Technology (KIT), Germany（生物运动中心，体育与体育科学研究所，卡尔斯鲁厄理工学院（KIT））
Impedance controllers are popularly used in the field of lower limb prostheses and exoskeleton development. Such controllers assume the joint to be a spring-damper system described by a discrete set of equilibria and impedance parameters. Said parameters are estimated via a least squares optimization that minimizes the difference between the controller's output torque and human joint torque. Other researchers have used perturbation studies to determine empirical values for ankle impedance. The resulting values vary greatly from the prior least squares estimates. While perturbation studies are …
New Jersey Institute of Technology（新泽西理工学院）；Kessler Foundation（凯斯勒基金会）；The City University of New York（纽约城市大学）
A significant challenge for the control of a robotic lower extremity rehabilitation exoskeleton is to ensure stability and robustness during programmed tasks or motions, which is crucial for the safety of the mobility-impaired user. Due to various levels of the user's disability, the human-exoskeleton interaction forces and external perturbations are unpredictable and could vary substantially and cause conventional motion controllers to behave unreliably or the robot to fall down. In this work, we propose a new, reinforcement learning-based, motion controller for a lower extremity rehabilitati…
University of Michigan（密歇根大学）；Shanghai Jiao Tong University（上海交通大学）
Task-dependent controllers widely used in exoskeletons track predefined trajectories, which overly constrain the volitional motion of individuals with remnant voluntary mobility. Energy shaping, on the other hand, provides task-invariant assistance by altering the human body's dynamic characteristics in the closed loop. While human-exoskeleton systems are often modeled using Euler-Lagrange equations, in our previous work we modeled the system as a port-controlled-Hamiltonian system, and a task-invariant controller was designed for a knee-ankle exoskeleton using interconnection-damping assignme…
University of Twente（特温特大学）；Delft University of Technology（代尔夫特理工大学）
Knowledge on joint impedance during walking in various conditions is relevant for clinical decision-making and the development of robotic gait trainers, leg prostheses, leg orthotics and wearable exoskeletons. Whereas ankle impedance during walking has been experimentally assessed, knee and hip joint impedance during walking have not been identified yet. Here we developed and evaluated a lower limb perturbator to identify hip, knee and ankle joint impedance during treadmill walking. The lower limb perturbator (LOPER) consists of an actuator connected to the thigh via rods. The LOPER allows to …
In this paper, 3D humanoid walking is decoupled into periodic and transitional motion, each of which is decoupled into planar walking in the sagittal and lateral plane. Reduced order models (ROMs), i.e. actuated Spring-loaded Inverted Pendulum (aSLIP) models and Hybrid-Linear Inverted Pendulum (H-LIP) models, are utilized for motion generation on the desired center of mass (COM) dynamics for each type of planar motion. The periodic motion is planned via point foot (underactuated) ROMs for dynamic motion with minimum ankle actuation, while the transitional motion is planned via foot-actuated RO…
