The resultant moment $$\tau$$ at the zero moment point equals to zero can be written as: Due to the high degree of nonlinearity, the differential Eq. The stance phase is a double-support phase and both legs support the body weight. \end{aligned}$$,$$\begin{aligned} \begin{aligned} -l/2&= C_{1} a_{1} + C_{2} a_{2} + x_{ZMP}, \\ l/2&= C_{1} a_{3} + C_{2} a_{4} + x_{ZMP}. Gait analysis is used to assess and treat individuals with conditions affecting their ability to walk. LOPES applied impedance control on joints to allow bidirectional mechanical interaction between robot and patient for gait rehabilitation [6]. The use of human walking synergy to generate gait can solve the problems of synchronization between user intention and exoskeleton motion as well as human-like gait. The walking phase is a single-support phase while the stance leg supports the body weight and swing leg in the air for step taking. Secondly, the robot is also involved in maintaining balance. The proposed illustration technique can have important implications in demonstrating gait coordination data in an easily comprehensible fashion by clinicians and scientists alike. The utilized gait is the fastest and the most efficient, therefore it becomes the target motion in this research and is used to extract the walking synergy. Modified 2-point gait, single cane Referred to as "modified" because a single cane is used, this gait consists of a reciprocal movement. IEEE Transact Neural Syst Rehabil Eng 23(2):308–318, Suzuki K, Mito G, Kawamoto H, Hasegawa Y, Sankai Y (2007) Intention-based walking support for paraplegia patients with robot suit hal. We compared the robot walking with and without gait modification. The details can be described below. The hip joint on stance leg is modified to improve the walking stability. From Eq. This proposed coordination pattern classification can offer an interpretation of the CA that provides either in-phase or anti-phase coordination information, along with an understanding of the direction of segmental rotations and the segment that is the dominant mover at each point in time. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Advanced robotics 24(11):1615–1638, Tsukahara A, Hasegawa Y, Sankai Y (2011) Gait support for complete spinal cord injury patient by synchronized leg-swing with hal. Copyright © 2021 Elsevier B.V. or its licensors or contributors. 1a). However, the walking motion generated using LIP has a constant height of CoM, which is inconsistent with the walking characteristics of humans. There are three basic positions that a rider can use: two-point position, in which the rider’s two legs are against the horse, while the seat is out of the saddle; three-point position, in which the rider’s two legs and seat are in contact with the horse; and modified three-point position, in which the rider’s two legs and only his crotch are in contact with the horse. California Privacy Statement, \end{aligned}$$,$$\begin{aligned} S=\,& {} 0.283 A_{cane} - 0.081. studied the synergy between arms and legs by measuring the electromyographic on leg and arms during walking [15]. the aid is held in UE opposite to LE that requires protection. 8 is the ZMP of robot walking without gait modification. Copyright © 2015 Elsevier Ltd. All rights reserved. The $$\theta _{sw}^{h}$$ and $$\theta _{sw}^{k}$$ are the hip and knee joint angle of the swing leg, the $$\theta _{sp}^{h}$$ and $$\theta _{sp}^{k}$$ are the hip and knee joint angle of the support leg. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. 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. The key point is to use the NIP to generate a stance leg motion that is in accordance with the swing leg motion generated by walking synergy. Since walking is a highly coupled cooperative motion between upper and lower limbs, the walking cycle and step length can be related to the motion of cane. In [8], HAL detects a preliminary motion to enhance the transfer between standing and sitting for complete paraplegic patients. A paraplegic patient is a person who has lost the motor and sensory function of the lower body. Comparison of human gait, gait generated suing synergy and modified gait. 2. The x-axis is the angle change of the cane in 0.08 [s] after it starts to swing whereas the y-axis refers to the walking cycle and step length, respectively. 9 synonyms for gait: walk, step, bearing, pace, stride, carriage, tread, manner of walking, pace. Firstly, the leg motion generated by human walking synergy was completely synchronized with the motion of the cane. The walking synergy was extracted from a healthy subject and applied to synchronize the exoskeleton’s movement with the user’s intention. As push-off impairment are often seen with these patients, this functional approach shows potential to retrain gait overground to normalize the gait pattern and retrain the ability to improve gait speed. The walking with pre-planned trajectory is continuous. A demonstratoin of the Modified Point Gait to the phsical therapist assistant students at Kellogg Community College. The equation to predict the walking cycle and step length are obtained from this Figure and can be written as: where T is the walking cycle and S is the step length, and $$A_{cane}$$ is the angle change of the cane in 0.08[s] after it started to swing. Use of one ambulation aid (crutch, cane, hemi walker) or for patients with functional use of one upper extremity. To enable the modified walking motion in imitating the human walking habits, the nonlinear inverted pendulum model for trajectory planning was applied. \end{aligned}$$,$$\begin{aligned} \ddot{x}_{M} = \frac{\ddot{z}_{M}+g}{z_{M}} (x_{M}-x_{ZMP}). \end{aligned}$$,$$\begin{aligned} x_{ZMP} = x_{M} - \frac{\ddot{x}_{M} z_{M}}{\ddot{z}_{M}+g}. The blue line represents the joint trajectory extracted from human walking with a cane. https://doi.org/10.1186/s40648-020-00169-y, DOI: https://doi.org/10.1186/s40648-020-00169-y. For this pattern the AD is move simultaneously with the injured leg. "Motion planning using NIP and ZMP" section introduces ZMP and NIP for motion planning. It is dangerous to conduct experiments with a paraplegic patient before validating the feasibility of the proposed method. The experiment results show that the walking stability was highly improved after gait modification. Figure 2 shows the nonlinear inverted pendulum (NIP) model. During walking, deviations between predictions and actual conditions may occur. It can be seen from these experimental results that gait modification greatly improved the walking stability. The error of walking cycle prediction will cause the foot and the cane to land at different time. This paper is organized as follows: "Gait generation based on walking synergy" section introduces PCA to extract the walking synergy between cane and leg motion from data of subject walking with canes. In: Proceeding of IEEE International Conference on Intelligent Robots and Systems, p 1609–1614, Hassan M, Kadone H, Suzuki K, Sankai Y (2014) Wearable gait measurement system with an instrumented cane for exoskeleton control. 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. The original data x is mapped to the new data y after being multiplied by the liner transition matrix $$\Gamma ^{T}$$. Figure 6 shows the schematic illustrations of the walking robot. In: Proceeding of IEEE Conference on computer aided control system design, Proceeding of IEEE International Conference on Control Applications, Proceeding of IEEE International Symposium on Intelligent Control, p 933–938, Sardain P, Bessonnet G (2004) Forces acting on a biped robot center of pressure-zero moment point. The position of the CoM can be written as follow: The zero moment point $$x_{ZMP}$$ can be derived from this model: where m is the mass at center, g is the gravitational acceleration, $$\tau$$ is the total external moment, $$x_{M}$$ and $$z_{M}$$ are the CoM position, $$\ddot{x}_{M}$$ and $$\ddot{z}_{M}$$ is the acceleration in the direction along the coordinate X and Z. For the hip joint angle, the mean error and the maximum errors are 1.51 [deg] and 5.47 [deg], respectively. Since the $$\Gamma$$ is an orthonormal matrix, then x could be rewritten as: then $$\Gamma$$ could be separated for the known variables $$x_{1}$$ and the unknown variables $$x_{2}$$: where $$\Gamma _{1}$$ and $$\Gamma _{2}$$ are the separated matrix for the known and unknown variables, respectively. By substituting the above-mentioned values into Eq. Walking robot replacing a patient for preliminary study. In the two-point gait with mono and quadripod canes, subjects were asked to move the WSFC and paretic-side foot forward at the same time and then move the nonparetic-side foot. The unaffected leg is advanced between the crutches to the stairs. \\ \end{aligned} \end{aligned}$$,$$\begin{aligned} \begin{aligned} C_{1}&= \frac{a_{2} l/2 + a_{4} l/2}{ a_{1} a_{4} - a_{2} a_{3}}, \\ C_{2}&= \frac{a_{1} l/2 + a_{3} l/2}{ a_{1} a_{4} - a_{2} a_{3}}. The unaffected leg is advanced between the crutches to the stairs in a modified three-point gait. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. In this pattern there is only use of one crutch or cane on the side opposite to the injured leg, therefore there can not be any weight bearing restriction but is more used to provide extra balance. J Neurol 258(8):1406, Daffertshofer A, Lamoth CJ, Meijer OG, Beek PJ (2004) Pca in studying coordination and variability: a tutorial. For example: Berkeley lower extremity exoskeleton is designed to increase human endurance and strength [1]. The movable joints are the shoulder joints, hip joints, knee joints, and ankle joints. "Simulation and result" section introduces the walking robot and verifies the proposed gait modification method in the Gazebo simulation. proved that the synergy between arms and legs exist not only during human walking but also in creeping and swing activities [13]. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. 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. The 2-point gait (see figure 1-10) is used when the patient can bear some weight on both lower extremities. The ZMP is widely used for gait generation in a humanoid robot. To use the ZMP to modify the hip joint trajectory on stance leg, the time consumed and the step length needs to be predicted in advance for each step. (1987), Hamill et al. two-point gait that in which the right foot and left crutch or cane are advanced together, and then the left foot and right crutch. Figure 1 shows the comparison between the joint angle of the human walk and the joint angle generated using walking synergy. Although the start and stop of walking is controlled by the user incline the body, the user still needs to adjust the angle and fall point of the canes to cooperate with the gait of the exoskeleton. It was found that this difference is mainly related to the ratio between the step length and pendulum length. Therefore, our approach does not give additional operations to paraplegic patients. Am J Phys Med Rehabil 91(11):911–921, Kilicarslan A, Prasad S, Grossman RG, Contreras-Vidal JL (2013) High accuracy decoding of user intentions using eeg to control a lower-body exoskeleton. The exoskeleton acts directly on the patient’s body, supporting the user’s weight and augment the strength as well as provides a high capability for the paraplegic patient to walk again. Matthew et al. Finally, the concluding remarks is presented at the end of the paper. We performed a robot walking experiment during the simulation to verify the feasibility of the proposed method. If the error is small, the stability of walking becomes unaffected. 7 is the side view of the robot walking. Sensors 14(1):1705–1722, Hassan M, Kadone H, Ueno T, Suzuki K, Sankai Y (2015) Feasibility study of wearable robot control based on upper and lower limbs synergies. To avoid the accumulation of errors, the error of the last step was compensated at the previous steps: where $$S_{K}^{\prime }$$ is the step length updated in the current step, $$S_{K}$$ is the step length predicted in the current step, $$E_{K-1}$$ is the error measured in the last step. \\ \end{aligned} \end{aligned}$$,$$\begin{aligned} \theta ^{*}=\theta -(\theta _{0}-\theta _{0}^{*}). 3. The use of NIP ensures that the modified walking trajectory is similar to the human walking trajectory. The traditional lower extremity exoskeleton uses a pre-planned walking trajectory. Assuming the step length of walking is l, and the CoM of the pendulum moves from $$-l/2$$ to l/2, the moment of the human to start a step and the pendulum to move is at time $$t_{s}$$, and the moment of the human to end the step and when the pendulum stops moving is at time $$t_{e}$$. 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. The proposed ZMP will enable the paraplegic patient to keep balance during walking and also reduce the burden in maintaining balance. Using a modified technique presented by Sparrow et al. 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. Either the joint trajectory generated by human walking synergy or the joint trajectory modified using ZMP was close to the joint trajectory extracted from human walking with a cane. In the simulation, the stance phase takes 1 [sec] and the time consumed at the walking phase is related to the cane motion and its walking cycle. Int J Hum Robotics 4(03):487–506, Pratt JE, Krupp BT, Morse CJ, Collins SH (2004) The roboknee: an exoskeleton for enhancing strength and endurance during walking. • Followed by the non-affected leg. This step-by-step walking may make paraplegic patient feel safe to use the exoskeleton at the early stage of rehabilitation, but for patients who are familiar with the exoskeleton, walking might feel unnatural. J Neurophysiol 97(2):1809–1818, Dietz V, Fouad K, Bastiaanse C (2001) Neuronal coordination of arm and leg movements during human locomotion. Besides, Ekso Bionics developed by Ekso measures the position of the user’s center of gravity and estimates the walking intention of paraplegic patients by detecting the center of mass (CoM) transfer when their upper body is leaned forward [11]. Introduction . volume 7, Article number: 21 (2020) However, the error of step length prediction accumulates as the walking distance increases and needs to be corrected via compensation. (11) and (7), we can get the trajectory of $$\theta$$ and $$z_{M}$$. 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. For example: Roboknee determines user intent through the knee joint angle and ground reaction forces and allows the wearer to climb stairs [3]. A modified four-point gait. 3.Modified four-point and two-point Gait patterns: Furthermore, by differentiating $$z_{M}$$ we can get $$\ddot{z}_{M}$$. This Figure includes the data of 50 steps of three subjects walking with a cane. In this way, the walking synergy was used as a gait generator, with the cane inclination angle as input, and the generator generates a joint angle of hip and knee. Liu developed a rehabilitation exoskeleton based on the postural synergy that allows the 10 degrees of freedom robot driven by only two actuators [21]. Google Scholar, Walsh CJ, Endo K, Herr H (2007) A quasi-passive leg exoskeleton for load-carrying augmentation. The unknown variables could be computed from the separated matrixes and the known variables: where $$\Gamma _{1}^{\sharp }$$ is the pseudo-inverse of $$\Gamma _{1}$$: In the case of a paraplegic patient, the matrix x is the data of joint angle from a subject walking with a cane, the known variable matrix $$x_{1}$$ is the joint angle of the upper limbs, and the unknown variable matrix $$x_{2}$$ is the joint trajectories of the lower limbs. (2) restoration in the physical function of a disabled patient. Sequence : … Antonyms for two-point gait. Exp Brain Res 141(3):375–379, Balter JE, Zehr EP (2007) Neural coupling between the arms and legs during rhythmic locomotor-like cycling movement. Modified two-point. ... pate in the gait analysis, however two children failed to report for the trial, ... scale subjects can score from 1 to 3 points, except for Item One (1–5 points) and Item Eleven (1–4 points). In: International Conference on Intelligent Robotics and Applications, Springer. synergy" section . A swing-through gait 4. Eur J Neurosci 14(11):1906–1914, Dietz V (2011) Quadrupedal coordination of bipedal gait: implications for movement disorders. By continuing you agree to the use of cookies. The small discrepancy shows that the generated joint angle has high similarity with the joint of human walking. Among the above-mentioned exoskeletons, exoskeletons for assisting the paraplegic patient have been widely used in scientific research, rehabilitation, and daily life. Gait analysis is the systematic study of animal locomotion, more specifically the study of human motion, using the eye and the brain of observers, augmented by instrumentation for measuring body movements, body mechanics, and the activity of the muscles. Therefore the $$x_{1}$$ and $$x_{2}$$ can be written as: where $$\theta _{l}$$ and $$\theta _{r}$$ are the left and right cane inclination angles. 2: p 4637–4640, Crocher V, Sahbani A, Robertson J, Roby-Brami A, Morel G (2012) Constraining upper limb synergies of hemiparetic patients using a robotic exoskeleton in the perspective of neuro-rehabilitation.