Generation and control of adaptive gaits in lower-limb exoskeletons for motion assistance

Sanz‐Merodio, Daniel; Cestari, Manuel; Arévalo, Juan Carlos; Carrillo, Xavier; García, Elena

doi:10.1080/01691864.2013.867284

Cited by 56 publications

(24 citation statements)

References 15 publications

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“…In addition, the output torque of the joint was determined by the force along the ball screws and the distance between the center of the joints' rotation and ball screws. Therefore, when transmission loss and mechanism mass were not considered, ratios of output torque for the hip joint and the knee joint could be formulated as follows [29]:

\begin{matrix} \begin{matrix} r_{normalh} = \frac{T_{normalh ‐ normalmax}}{T_{normalh ‐ normalm normalo normalr}} = \frac{2 π r_{normalh ‐ normalb normale normalt} d_{normalh}}{normalΔ L_{normalh ‐ normals normalc normalr normale normalw}} \\ r_{normalk} = \frac{T_{normalk ‐ normalmax}}{T_{normalk ‐ normalm normalo normalr}} = \frac{2 π r_{normalk ‐ normalb normale normalt} d_{normalk}}{normalΔ L_{normalk ‐ normals normalc normalr normale normalw}} . \end{matrix} \end{matrix}

Here, r h and r k denoted the output torque ratios for the hip and knee joint, respectively, and d h and d k were the distances between the joints and ball screws, respectively. Both distances varied with the angles of the associated joint ( θ h and θ k ).…”

Section: Methodsmentioning

confidence: 99%

An Open-Structure Treadmill Gait Trainer: From Research to Application

Chen

Fan

2017

Journal of Healthcare Engineering

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Lower limb rehabilitation robots are designed to enhance gait function in individuals with motor impairments. Although numerous rehabilitation robots have been developed, only few of these robots have been used in practical health care, particularly in China. The objective of this study is to construct a lower limb rehabilitation robot and bridge the gap between research and application. Open structure to facilitate practical application was created for the whole robot. Three typical movement patterns of a single leg were adopted in designing the exoskeletons, and force models for patient training were established and analyzed under three different conditions, respectively, and then a control system and security strategy were introduced. After establishing the robot, a preliminary experiment on the actual use of a prototype by patients was conducted to validate the functionality of the robot. The experiment showed that different patients and stages displayed different performances, and results on the trend variations across patients and across stages confirmed the validity of the robot and suggested that the design may lead to a system that could be successful in the treatment of patients with walking disorders in China. Furthermore, this study could provide a reference for a similar application design.

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\begin{matrix} \begin{matrix} r_{normalh} = \frac{T_{normalh ‐ normalmax}}{T_{normalh ‐ normalm normalo normalr}} = \frac{2 π r_{normalh ‐ normalb normale normalt} d_{normalh}}{normalΔ L_{normalh ‐ normals normalc normalr normale normalw}} \\ r_{normalk} = \frac{T_{normalk ‐ normalmax}}{T_{normalk ‐ normalm normalo normalr}} = \frac{2 π r_{normalk ‐ normalb normale normalt} d_{normalk}}{normalΔ L_{normalk ‐ normals normalc normalr normale normalw}} . \end{matrix} \end{matrix}

Section: Methodsmentioning

confidence: 99%

An Open-Structure Treadmill Gait Trainer: From Research to Application

Chen

Fan

2017

Journal of Healthcare Engineering

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“…Current research addresses various aspects of exoskeleton functionality, such as providing mobility to patients who are confined to a wheelchair (Esquenazi et al, 2012 ) or are suffering from muscular weakness (e.g., the elderly and infirm; Sankai, 2010 ), improving rehabilitation (neurological or orthopedic) and recovery efficacy (Colombo et al, 2000 ; Veneman et al, 2007 ), and augmenting the performance of healthy individuals during heavy load carrying tasks (Guizzo and Goldstein, 2005 ; Walsh et al, 2007 ). Recent achievements in lower-limb exoskeleton assistance include successes in robot-assisted walking (Raj et al, 2011 ; Hassan et al, 2014 ; Sanz-Merodio et al, 2014 ; Griffin et al, 2017 ), stair ascent and descent (Xu et al, 2017 ), and sit-to-stand movements (Tsukahara et al, 2010 ). Additionally, other studies have focused on the reduction of exoskeleton's energy consumption during task performance through the use of elastic and dissipative elements (Wang et al, 2011 ; Kim et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Stability of Mina v2 for Robot-Assisted Balance and Locomotion

et al. 2018

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The assessment of the risk of falling during robot-assisted locomotion is critical for gait control and operator safety, but has not yet been addressed through a systematic and quantitative approach. In this study, the balance stability of Mina v2, a recently developed powered lower-limb robotic exoskeleton, is evaluated using an algorithmic framework based on center of mass (COM)- and joint-space dynamics. The equivalent mechanical model of the combined human-exoskeleton system in the sagittal plane is established and used for balance stability analysis. The properties of the Linear Linkage Actuator, which is custom-designed for Mina v2, are analyzed to obtain mathematical models of torque-velocity limits, and are implemented as constraint functions in the optimization formulation. For given feet configurations of the robotic exoskeleton during flat ground walking, the algorithm evaluates the maximum allowable COM velocity perturbations along the fore-aft directions at each COM position of the system. The resulting velocity extrema form the contact-specific balance stability boundaries (BSBs) of the combined system in the COM state space, which represent the thresholds between balanced and unbalanced states for given contact configurations. The BSBs are obtained for the operation of Mina v2 without crutches, thus quantifying Mina v2's capability of maintaining balance through the support of the leg(s). Stability boundaries in single and double leg supports are used to analyze the robot's stability performance during flat ground walking experiments, and provide design and control implications for future development of crutch-less robotic exoskeletons.

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“…This is because exoexercising tasks for lower limbs are those of sagittal plane movements. Sagittal plane model is therefore most often employed in exoskeletal design as in [34,35] to mention a few. It should be noted that the parameters of the subject's shank and foot links and that of the exoskeleton are built into the model parameters.…”

Section: Knee-ankle Exoskeletonmentioning

confidence: 99%

Bounded Control of an Actuated Lower-Limb Exoskeleton

Ajayi

Djouani

Hamam

2017

Journal of Robotics

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A bounded control strategy is employed for the rehabilitation and assistance of a patient with lower-limb disorder. Complete and partial lower-limb motor function disorders are considered. This application is centered on the knee and the ankle joint level, thereby considering a user in a sitting position. A high gain observer is used in the estimation of the angular position and angular velocities which is then applied to the estimation of the joint torques. The level of human contribution is feedback of a fraction of the estimated joint torque. This is utilised in order to meet the demands for a bounded human torque; that is, ℎ ≤ 2, ≤ 1, . The asymptotic stability of the bounded control law without human contribution and the convergence analysis of the high gain observer is verified using Lyapunov-based analysis. Simulations are performed to verify the proposed control law. Results obtained guarantee a fair trajectory tracking of the physiotherapist trajectory.

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Generation and control of adaptive gaits in lower-limb exoskeletons for motion assistance

Cited by 56 publications

References 15 publications

An Open-Structure Treadmill Gait Trainer: From Research to Application

An Open-Structure Treadmill Gait Trainer: From Research to Application

Stability of Mina v2 for Robot-Assisted Balance and Locomotion

Bounded Control of an Actuated Lower-Limb Exoskeleton

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