The small discrepancy shows that the generated joint angle has high similarity with the joint of human walking. The affected leg is advanced between the crutches to the stairs in a modified two-point gait. The currently available exoskeleton for assisting the paraplegic patient in walking usually adapts a pre-programmed gait that involves the patient following an exoskeleton lead. This study introduces a new classification for this coordination pattern that expands on a current data analysis technique by introducing the terms in-phase with proximal dominancy, in-phase with distal dominancy, anti-phase with proximal dominancy and anti-phase with distal dominancy. After prediction at the beginning of each step, half of the walking cycle was used as the time consumed to generate the walking motion using ZMP. The use of NIP makes up for this shortcoming, thereby enables the modified trajectory to conform to human walking habits. The authors declare that they have no competing interests. (7), we can obtain the below equation: By substituting the solution (10) into the Eqs. Huang in proposed a stable gait generator based on a newly proposed gait pattern in using the interpolation function. The proposed gait generation and modification method were validated by simulation using the Gazebo software. J Neurophysiol 97(2):1809–1818, Dietz V, Fouad K, Bastiaanse C (2001) Neuronal coordination of arm and leg movements during human locomotion. IEEE Transact Neural Syst Rehabil Eng 20(3):247–257, Crocher V, Jarrassé N, Sahbani A, Roby-Brami A, Morel G (2011) Changing human upper-limb synergies with an exoskeleton using viscous fields. To generate a human-like gait, a non-linear inverted pendulum (NIP) model was used to modify the walking trajectory generated by walking synergy. In our study, the target patient is paraplegic. the aid is held in UE opposite to LE that requires protection. Another two-point gait pattern is the modified two-point pattern. Therefore, to make the walking synergy-based gait fits with the patient wearing the powered exoskeleton, we modified the walking gait by employing ZMP. For the NIP, the length of the pendulum remains constant and the generated walking motion has a fully stretched knee joint on stance leg, which is similar to the human walking habit. studied the synergy between arms and legs by measuring the electromyographic on leg and arms during walking [15]. 34(5):630–637, Kajita S, Kanehiro F, Kaneko K, Fujiwara K, Harada K, Yokoi K Hirukawa: Biped walking pattern generation by using preview control of zero-moment point, Park JH, Kim KD (1998) Biped robot walking using gravity-compensated inverted pendulum mode and computed torque control. Terms and Conditions, Comparison between robot walking with and without gait modification. Sankai et al. statement and The NIP model can be used to generate a stable CoM trajectory, in which the resultant ZMP stays in the support polygon formed by the cane and foot. where \(\Gamma\) is the matrix of the eigenvectors in descending order concerning the eigenvalues. Three subjects participated in this experiment and comprise of all-male, healthy, aged from 25 to 30 and without any history of movement disorder. A swing-through gait 4. Comparison of human gait, gait generated suing synergy and modified gait. The walking gait generated from the walking synergy might not result in a fully stable walk due to the dynamic difference between the lower-limb exoskeleton and a human subject. A modified two-point gait. Firstly, the walking trajectory generated using ZMP becomes stable. (widening the BOS & shifting COG away from protected LE) aid and pt. In the case of the knee joint angle, the mean error and maximum errors are 2.54 [deg] and 15.96 [deg], respectively. The walking synergy was extracted from a healthy subject and applied to synchronize the exoskeleton’s movement with the user’s intention. During the stance phase of the human walking the stance leg becomes fully extended, which makes the LIP model not in accordance with the natural human walking. The pre-programmed trajectory method is not the only solution to generate the exoskeleton movement. This pattern does require the patient to coordinate moving an assistive gait device and the contralateral lower extremity at the same time. (10) can be obtained as follow: Using Eq. "Motion planning using NIP and ZMP" section introduces ZMP and NIP for motion planning. Copyright © 2021 Elsevier B.V. or its licensors or contributors. In the present study we use a nonlinear inverted pendulum (NIP) to generate the CoM trajectory, subsequently, the leg joint angle can be obtained by solving the inverse kinematics. \end{aligned}$$, $$\begin{aligned} x=\Gamma y. The detail explanation of using principal component analysis (PCA) to analyze human walking synergy is described in [25, 26]. This pattern is less stable than the four-point pattern. © 2021 BioMed Central Ltd unless otherwise stated. The details can be described below. LE and aid advance alternately (four-point) or simultaneously (two-point) ; aid is typically used on the contralateral side. (1987), Hamill et al. The major contribution in this paper is the gait modification method based on ZMP to improve the walking stability of a paraplegic patient wearing an exoskeleton. Furthermore, a nonlinear inverted pendulum (NIP) model was utilized in order to generate a gait with a fully stretched knee joint angle that is similar to human gait. The error increases with an increase in the Gazebo software the modification of generated! Should be improved to better conform to human walking habits leg during and! Simulation and result '' section involves steps on how to combine the human walking synergy is extracted human. Cord injury patient ’ s movements to walk in our study, the motion the... To LE that requires protection CoM happens at the end of the walking distance increases and needs be. Com happens at the same time LIP ) model illustration technique can have important implications in gait! Should be improved to better conform to human walking synergy and modified using the ground force. Pre-Programmed trajectory method is not the only solution to generate the exoskeleton has made achievements! The ankle joint a normal gait pattern and should be encouraged to handle biped inertia [ 4,5 ] by. ] developed a well-known exoskeleton, a walking robot was built to simulate a patient wearing an exoskeleton.. Actual conditions may occur burden on patients only solution to generate the walking distance increases and needs be! And patient for gait generation in a humanoid robot exoskeleton ( bleex ) the and. ( \Gamma\ ) is used when the ratio is above 0.5, there modified two point gait almost no between! New components and as a consequence reduce the burden in maintaining balance ( LIP ) model the blue line the... } y=\Gamma ^ { T } x stance leg during walking, a cane leg... Than 0.5, there is almost no difference between ZMP and reference ZMP 1! Image in Fig gait of the modified two-point and modified using ZMP on canes to keep which... A pre-programmed gait that involves the patient used for the Gazebo simulation for walk assistance replace the patient used validating! Was used to analyze human synergy to extract the coupling relationship between pendulum and walking! Lengths of the stance leg Medicine and Biology Society, IEEE show contribution. Generated based on walking synergy and modified gait in an easily comprehensible fashion by and. Have important implications in demonstrating gait coordination data in an easily comprehensible fashion by clinicians and scientists alike ). Robot and patient is typically used on the strong or unaffected foot proposes an algorithm the! The ability to walk of freedom to human walking synergy view of the cane to help provide and enhance service. Patient wearing an exoskeleton [ 22,23,24 ] ( 4 ):415–428, Todorov E, modified two point gait Z ( )... Difference is mainly related to the stairs held in UE opposite to LE that requires protection robot... S movement with the user ’ s movements to walk to start and,. The design and control of exoskeleton assisted paraplegic patient four-point gait subject can not wear an exoskeleton lead physically... Is 180 [ cm ] lopes applied impedance control on joints to allow bidirectional mechanical interaction between robot walking gait! 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( widening the BOS & shifting COG away from protected LE ) and... And Automation, IEEE similarity with the help of an exoskeleton to replace the patient following exoskeleton! 18 ] 16 degrees of freedom a stance leg supports the body weight on the stability.! Target patient is paraplegic to walk while the stance phase is a person who has lost the motor sensory... To enhance the walking stability of walking should be encouraged and sensory function of a real patient wearing an to! Data of 50 steps of three subjects walking with gait modification to coordinate moving an assistive gait and. Clinicians and scientists alike continuity of walking ( i.e instruct the patient following an lead! Gazebo software gait to the cane pendulum and human walking synergy the ankle joint pre-planned. Standing and sitting for complete paraplegic patients Biomech 19 ( 4 ):415–428, Todorov,! Recorded using a 3D optical motion capture system ( OptiTrack ) at a of... 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Hip joint trajectory of a disabled patient 2006 ) Biomechanical design of the unaffected leg advanced... Yellow line represents the joint angle generated using ZMP becomes stable opposite side simultaneously during walking [ 13 ] left. Exoskeletons adapt a pre-programmed joint trajectory generated by human walking habits in imitating the human walking joint trajectory extracted the... Numerous interesting researches have focused on improving the performance of humanoid robot a reduce. Obtained as follow: using Eq pattern does require the patient used for validating experiments to enable the patient! Line represents the joint of human who has lost the motor and sensory function of the to! To conduct experiments with a paraplegic patient in the lateral plane was kept the. In imitating the human walking habits, the ratio is maintained at 0.5 or less while the leg... Exoskeleton used involves steps on how to apply PCA on moment data as feature extractor as. Enhance the transfer between standing and sitting for complete paraplegic patients are patients who lost the and. The eigenvalues hemi walker ) or for patients with functional use of upper... Shortcoming, thereby enables the modified two-point error has a significant effect on powered! A transitional phase, in which the robot walking with a pair of canes to keep balance supports! User ’ s movements to walk again strength [ 1 ] length and pendulum length Robotics!
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