Step Motion Research Articles

Parametric optimization of a multi-output electromagnetic mechatron module

The article is devoted to the problem of determining the optimal dimensions of the design of reciprocating linear electromagnetic engine. As an optimization criterion, the parameters of the mechatron module based on the multi-output linear electromagnetic motor are determined by means of a constructive calculation scheme and its variable parameters are determined by the method of non-linear programming, the geometric dimensions are simplified, the mass of the electromagnetic motor body, the mass of the motor armature and the masses of the motor stator and the restrictions on their dimensions are determined the issues of finding optimal solutions are considered. Optimization of mechatronic modules based on multi-output linear electromagnetic motors on various parameters leads to increase in dynamic performance of the executive organ, saving energy consumption, and allows to improve performance and service quality. Also, based on the analysis of the existing electromagnetic linear motors, the structural scheme of the mechatron module based on the multi-output linear electromagnetic engines, which allows to perform step movements according to spatial coordinates with high accuracy and speed, is presented. The algorithmic basis of computing is based on the weight and size characteristics of execution mechanisms, and it has been proposed to allow solving optimal design tasks of execution mechanisms taking into account zvenolar lengths, displacements, speeds and accelerations during movement, as well as creating robotic systems with high performance in service. This structure serves to ensure the interaction of the executive body with the object in the links of industrial robots.

An investigation of methods to improve the accuracy of classical dance steps based on machine vision recognition technology

Abstract Methods that use motion capture data to analyze human behavior are highly interpretable and offer significant advantages in vision-based dance step analysis. In this study, we propose a fusion feature extraction method that describes the rotational information embedded in the skeleton and combines the advantages of single-skeleton feature extraction and Li group feature extraction methods for recognition. The feasibility and validity of the proposed model are verified by conducting recognition experiments on BVH data of classical dance steps performed by subjects. In the ablation experiments, the average accuracy of the classical dance step recognition model based on fused features for step movement recognition is improved by 3.01% and 1.86% compared with the neural network model and the Lie group network model, respectively. It has been proven that adding rotation information to skeletal features can effectively differentiate 3D motion trajectories in similar dance steps. Furthermore, the dance movement trajectories derived from this model are very clear and can be utilized to direct the correct joint point positions throughout the movement. The recognition accuracy of the fusion feature extraction-based recognition method for all seven classical dance basic foot positions is greater than 90%, which reflects the accuracy of the proposed machine vision model in recognizing classical dance steps.

High-temperature indium adsorption on Bi2Se3(0001) surface studied by in situ reflection electron microscopy

Using in situ reflection electron microscopy, transformations of Bi2Se3(0001) surface during In deposition have been studied. We first report the formation of an In-induced surface phase that precedes nucleation and growth of a layered In2Se3 at substrate temperatures around 400 °C. The surface phase nucleates on Bi2Se3(0001) terraces as islands having high In content and a height of 0.4 nm. During continuous In deposition, the area of these islands increases and suppresses Bi2Se3 sublimation from the regions covered by the In-induced surface phase. This locally suppressed sublimation and sublimation-induced ascending motion of Bi2Se3 atomic steps create multilayer triangular star-shaped islands.

Neurorehabilitation of post-stroke patients using a noninvasive spinal neuroprosthesis

Neurorehabilitation of post-stroke patients with motor impairments is a significant and yet unresolved issue in restorative medicine. We propose a novel approach to rehabilitating such patients using transcutaneous electrical spinal cord stimulation (scTS), which targets the neural locomotor networks of the lumbar enlargement of the human spinal cord [1]. The Spinal Neuroprosthesis device was developed to control stimulation, providing noninvasive and phase-dependent activation of motoneuronal pools of flexors and extensors during a certain phase of the stepping cycle, combined with the activation of neuronal locomotor networks [2]. The aim of this study is to assess the efficacy of Spinal Neuroprosthesis in regulating locomotor functions among post-stroke patients with motor disorders. The study is designed to provide an objective evaluation of the medical device’s effectiveness. The study was conducted at the Russian Research Institute of Neurosurgery named after Prof. A.L. Polenov. The study enrolled 20 patients who had been experiencing severe motor disorders of the lower extremities in the form of hemiparesis. The duration of stroke among these patients ranged from 3 to 12 months. They were divided into two groups: control and experimental. The control group underwent sham (scTS-) stimulation during a motor rehabilitation session, while the experimental group received real scTS, establishing the difference between the groups. The rehabilitation program comprised 15 sessions of stimulation to the spinal cord. The treatment protocol comprised an initial evaluation of patients’ neurological and rehabilitation status and an investigation of spatial-temporal and kinematic parameters of walking. Subsequently, patients participated in rehabilitation sessions, which entailed walking on the treadmill and over-ground stepping with scTS. Finally, patients underwent a follow-up examination that included a re-evaluation of their neurological and rehabilitation status, as well as an investigation of spatial-temporal and kinematic parameters of walking. At the beginning of the program, the distance traveled by patients in the control and experimental groups during a six-minute walk test, according to the study results, did not differ significantly. However, following the treatment, patients in the experimental group demonstrated a substantially lengthier distance covered during the 6-minute test than the control group. Both groups of patients in the 10-meter walk test demonstrated an increase in distance walking speed, although the patients in the experimental group had a greater increase in speed compared to those in the control group. These improvements were more pronounced in patients from the experimental group. The results from neurological scales indicated an increase in muscular strength, improvement in balance functions, and an increase in functional independence in both groups. The findings provide evidence that the Spinal Neuroprosthesis effectively regulates stepping movements and restores locomotor function in patients post-stroke. Clinically significant improvements are observed within two weeks of neuroprosthesis use. Additionally, training increases patients’ exercise tolerance while walking, speed of movement, and functional independence.

MENINGKATKAN HASIL BELAJAR SISWA MENGGUNAKAN MEDIA BOLA DENGAN TEKNIK LAY UP SHOOT PADA MATERI SURAT LAMARAN PEKERJAAN

A lay up shoot is a shot that is taken at very close range to the basketball hoop, so that it is as if the ball is being placed into the basketball hoop which is preceded by a two step movement, ball media using the lay up shoot technique is able to improve student learning outcomes in in class because it makes students happy with the method used, teaching and learning in class using the lecture method alone often makes students bored and not infrequently some of them are sleepy, this means that the material delivered by the teacher cannot be fully absorbed by the participants. students which will ultimately result in the learning objectives not being achieved. This research was conducted to determine the effectiveness of using football media using the Lay Up Shoot technique in job application letter material in class XII, precisely at MA WALISONGO. The use of ball media using the Lay Up Shoot technique is carried out in class involving the teacher and all students. In addition to achieving learning objectives, this method is intended for students to concentrate. Using this method also makes the material easier to understand and learning in class more enjoyable.

Treatment Plan Creation and Delivery with and without BgRT for Static and Motion Trajectories

In this work we try to validate the motion tracking capabilities of BgRT for periodic and step motion trajectories. SBRT plans that matches the corresponding BgRT plans are created and delivered to the same phantom with and without motion and results are evaluated. Using BgRT based SBRT plans eliminates any user bias and creates SBRT plans that would represent treatment delivery scenarios that could have happened if the PET guided BgRT was not present for that treatment. To validate SBRT plans that matches the BgRT plans, we used three different types of motion patterns (1) static, (2) lung tumor motion and (3) one-centimeter step-shift. The lung tumor motion (∼25 mm in IEC-Y, ∼7 mm in IEC-X and ∼ 10 mm in IEC-Z) was used as it represents a continuous motion of the target for the entire length of the study while the step-shift case corresponds to the patient or tumor shifting between the localization CT and the start of treatment. First, a 10 Gy per fraction BgRT plan was created for each of the three experiments based on the corresponding PET image. Then, the BgRT plans were delivered to the corresponding targets with and without motion and results are evaluated. To perform a comparative study that assess the performance of BgRT and traditional SBRT (planning and delivery methods), the exact same plan fluence of BgRT plan for each experiment was used to create the corresponding SBRT plans. The newly created SBRT plans were delivered to the corresponding phantom experiments and were compared against BgRT delivery in terms of dose coverage and target margin loss using radiochromic film that moves with the target. The margin loss was calculated as the difference between the distance from the CTV contour to the 97% isodose contour in the treatment plan and the CTV contour to the 97% isodose contour on the film. Dosimetric coverage was on the other hand calculated as the percentage of the voxels within the CTV that lies within 97% and 130% of the prescribed dose. The results showed that the margin loss for BgRT is less than 3 mm, while for the SBRT plans were more than 3 mm when target motion is present. The dosimetric coverage for BgRT was 100% for all three cases, however less than 100% for the SBRT cases with motion. Table showing margin loss for the various experiments for a prescription dose of 10 Gy. The results shows that BgRT is capable of tracking the tumor motion and delivering the prescribed dose to the moving target.

A Lagrangian method for slurry flow modeling in hydraulic fractures

We developed a new numerical simulator of slurry flow in hydraulic fractures. It is based on a continuum model developed under the assumptions of lubrication theory. We consider slurry containing fluid and proppant components. Proppant particles settle under gravity and bridge in the flow domain. Fluid fluxes are calculated from an elliptic boundary value problem for given fracture geometry and sources/sinks distribution. We solve it using a conservative finite volume method and then apply empirical closure relations to get the velocity field for solids. The transport of slurry components is described by nonlinear hyperbolic equations with fluxes depending on proppant concentration and particle size/fracture width ratio. These equations admit solutions with concentration shock waves and rarefaction fans. They must be represented accurately in the computational algorithm. We utilize an Eulerian approach for the discretization of nonlinear proppant fluxes. After getting the fluxes on the interfaces between Eulerian grid cells we follow a Lagrangian approach to simulate the proppant transport along the given velocity field. In this study we discuss key implementation aspects: time step selection, regularization, fluxes discretization, seeding, reseeding, and movement of Lagrangian particles. We verify the simulator on benchmark solutions focused on advection, batch proppant settling, slurry slumping and fluid displacement by proppant.

Direct Observation of Atomic Step-Assisted Stabilization of Polar Surface.

Polar surface is intrinsically unstable and thus highly reactive due to the uncompensated surface charges. The charge compensation is accompanied by various surface reconstructions, establishing novel functionality for its applications. Our in-situ atomic-scale electron microscopy study directly shows that the atomic step and step-assisted reconstruction play central roles in the charge compensation of polar oxide surface. The flat (LaO)+-terminated LaAlO3 (001) polar surface, when annealed at high temperature in vacuum, transits to the (015) vicinal surface via the dynamic motion and interaction of atomic steps. While the (015) vicinal surface possesses zero polarization along the surface normal, the thermodynamic ground state is achieved when the in-plane polarization is fully compensated via the reconstruction of step edge atoms; the step edge La atoms are displaced from their ordinary atomic sites toward the adjacent Al step edge site, resulting in the formation of negatively charged La vacancy at the corresponding step edges. As confirmed by first-principles calculations, the observed step reconstruction of (015) vicinal surface can completely cancel both out-of-plane and in-plane electric fields. This hitherto unknown mechanism reveals the central role of step reconstruction in stabilizing polar surfaces, providing valuable insights for understanding the novel charge compensation mechanism accompanied by the step reconstruction. This article is protected by copyright. All rights reserved.

The Atomic Observation of the Structural Change Process in Pt Networks in Air Using Environmental Cell Scanning Transmission Electron Microscopy.

The structural change in Pt networks composed of multiple chain connections among grains was observed in air at 1 atm using atomic-resolution environmental cell scanning transmission electron microscopy. An aberration-corrected incident electron probe with a wide convergence angle made it possible to increase the depth resolution that contributes to enhancing the signal-to-noise ratio of Pt network samples in air in an environmental cell, resulting in the achievement of atomic-resolution imaging. The exposure of the Pt networks to gas molecules under Brownian motion, stimulated by electron beams in the air, increases the collision probability between gas molecules and Pt networks, and the Pt networks are more intensely stressed from all directions than in a situation without electron irradiation. By increasing the electron beam dose rate, the structural change of the Pt networks became significant. Dynamic observation on an atomic scale suggested that the structural change of the networks was not attributed to the surface atomic-diffusion-induced step motion but mainly caused by the movement and deformation of unstable grains and grain boundaries. The oxidized surface layers may be one of the factors hindering the surface atomic step motion, mitigating the change in the size of the grains and grain boundaries.

Step unbunching phenomenon on 4H-SiC (0001) surface during hydrogen etching

We here report a step unbunching phenomenon, which is the inverse of the phenomenon of step bunching. When a 4H-SiC (0001) surface is annealed at a high temperature, step bunching arises due to the different velocities of the step motion in adjacent steps, resulting in steps with a height of more than several nanometers. We found that the bunched steps, thus, obtained by hydrogen etching in an Ar/H2 atmosphere were “unbunched” into lower height steps when annealed subsequently at lower temperatures. This unbunching phenomenon can be well explained by the consequence of the competition between energetics and kinetics. Our findings provide another approach for the surface smoothing of SiC by hydrogen etching and may give significant insight into the application of SiC power devices and two-dimensional materials growth techniques in general.

Development and Analysis of Multi-Degree-of-Freedom Piezoelectric Actuator Based on Elephant Trunk Structure.

In most of the piezoelectric stacked motors studied, the stator usually adopts two compound modes to drive the rotor to do step motion. This design method not only improves the utilization rate of the stator but also improves the torque output to a certain extent and increases the output displacement. In this study, a new type of multi-degree of freedom piezoelectric actuator is proposed for the utilization of a stator. The actuator realizes three compound vibration modes of bending-longitudinal-bending on a single stator, which changes the two compound modes of longitudinal bending and also changes the single motion mode of the stepper motor along a straight line. The rotor is set as a ball to drive it to rotate. The designed motor presents a different driving signal under which the rotor will no longer be accompanied by a return displacement. The finite element method is used to complete the design analysis, and the experimental analysis of the designed motor is carried out after the prototype is made. The multi-degree-of-freedom piezoelectric actuator can achieve a speed of 8.56 mm/c and a driving load of 1200 g at a voltage of 400 v and a working frequency of 42.7 kHz.

Adjuvant Arthroscopy Does Not Improve the Functional Outcome of Volar Locking Plate for Distal Radius Fractures: A Randomized Clinical Trial

To evaluate the outcomes of adding arthroscopy to osteosynthesis of distal radius fractures (DRF) with volar locking plate (VLP), by Patient-Rated Wrist Evaluation (PRWE) 1 year after surgery. In total, 186 functionally independent adult patients who met the inclusion criteria (DRF and a clinical decision for surgery with a VLP) were randomized to arthroscopic assistance or not. Primary outcome was PRWE questionnaire results 1 year after surgery. For the main variable, PRWE, we obtained the minimal clinically important difference based on a distribution-based method. Secondary outcomes included Disabilities of the Arm, Shoulder and Hand and 12-Item Short Form Health Survey questionnaires, range of motion, strength, radiographic measures, and presence of joint step-offs by computed tomography. Data were collected preoperatively and at+1 and+4 weeks,+3 and+6 months, and+1 year after surgery. Complications were recorded throughout the study. In total, 180 patients (mean age: 59.0 ± 14.9 years; 76% women) were analyzed by modified intention to treat. A total of 82% of the fractures were intra-articular (AO type C). No significant difference between arthroscopic (AG) and control (CG) groups in median PRWE was found at+1 year (median AG: 5.0, median CG: 7.5, difference in medians 2.5; 95% confidence interval [CI] -2.0, 7.0, P= .328). The proportion of patients who exceeded the minimal clinically important difference of 12.81 points in the AG and CG was 86.4% vs 85.1%, P= .819, respectively. Percentage of associated injuries and step-offs reduction maneuvers was greater with arthroscopy (mean differences: 17.1 95% CI -0.1, 26.1, P < .001) and 17.4 (95% CI 5.0, 29.7, P= .007). The difference in percentage of residual joint step-offs at the postsurgical computed tomography in radioulnar, radioscaphoid, and radiolunate joints was not significant (P= .990, P= .538, and P= .063). Complications were similar between groups (16.9% vs 20.9%, P= .842). Adjuvant arthroscopy did not significantly improve PRWE score+1 year after surgery for DRF with VLP, although the statistical power of the study is below the initially estimated to detect the expected difference. Level I, randomized controlled trial.

Objective molecular dynamics study of cross slip under high-rate deformation

In this paper, we investigate high-strain-rate deformations in crystalline materials using a novel implementation of Objective Molecular Dynamics (OMD). The OMD method is exact and has a rigorous foundation based on the fundamental invariance of the underlying potential energy surface: all atoms out to infinity satisfy the equations of molecular dynamics to high accuracy. Using this OMD method, we compute how dislocations filling all of the space in a crystalline material undergo time-dependent, three-dimensional motions during deformation. We apply this method to investigate the dynamics of screw dislocations in FCC nickel. Our key finding is that the macroscopic motion (i.e., loading conditions) and initial conditions greatly affect the atomic scale deformation mechanisms—such as the formation, motion, multiplication, annihilation, and abrupt changes of the slip plane and Burgers vector of dislocations. Small changes in the macroscopic loading conditions generate a rich variety of atomic deformation pathways. In certain macroscopic motions, we observe the growth of a stacking fault into a mechanical twin, which subsequently thickens by a process of step motion. In other macroscopic motions, we observe the initiation and subsequent development of cross-slip by the Friedel–Escaig (FE) or Fleischer mechanisms (FL). Under mixed loading conditions, a novel mechanism, with a combination of both FE and FL mechanisms was also observed. Our findings on the effect of external strain rate and temperature on the critical stress for homogeneous cross-slip quantitatively agree with a version of transition state theory with a stress-dependent activation barrier. Beyond dislocation motion, we demonstrate the modeling of sliding surfaces using the OMD framework. These examples highlight potential applications of the OMD framework to the mechanisms underlying plastic deformation and friction in material systems.

The Growth Pits Filling Mechanism of CdZnTe Epitaxial Film Prepared by Close-Spaced Sublimation Based on the First-Principles Calculation

The preparation of high quality II-VI semiconductor single crystal still is a challenging task. The II-VI ternary compound Cd1-xZnxTe is an outstanding candidate for room temperature nuclear radiation detectors. Therefore, the epitaxial mechanism of its film is profound to clarify for accurate growth regulation and quality improvement. However, determining the essence of epitaxial growth remains challenge only using experiments to explore the effects of growth conditions on film epitaxy. In this work, the growth pits filling mechanism of CdZnTe epitaxial film has been elucidated by combining the experimental results with the first-principles calculation. Based on the Atomic Force Microscope data, the structural characteristics of growth pits were analyzed, and the layered growth model and the lateral step growth model were proposed. According to Gibbs-Wulff crystal growth law, the stability of two growth pits filling models was compared through the first-principles simulations. By comparing surface energies, we identified that the filling process of growth pits relies on the movement of steps along the interface. These results well describe the deposition mechanism of CdZnTe film prepared by close-spaced sublimation and provide inspirations to accurately regulate the II-VI film growth and obtain high quality films.

Bipedal driven inertial type piezoelectric motor working under quasi-static and resonant states

An inertia piezoelectric motor based on bipedal driven, which can work in not only quasi-static but also resonant states, is proposed, designed, fabricated and studied considering the high resolution of quasi-static piezoelectric motor and the high speed of resonant piezoelectric motor. The two stators of the piezoelectric motor are drived by two sinusoidal electrical signals with 1:2 frequency ratio to generate sinusoidal vibration on the corresponding driving foot. A continuous step motion without frequency limitation is realised under the action of inertia and friction forces after synthesising the sinusoidal vibration of different frequencies into mechanical sawtooth vibration. The natural resonant frequencies of the piezoelectric motor are adjusted to a specific proportion to combine the vibrations in the resonant state through finite element analysis. In the structure of two stators, each stator has a corresponding inertia block, and the corresponding resonant frequency can be altered by adjusting the mass of the inertial block without affecting the other resonant frequency, thus markedly simplifying the design difficulty of the piezoelectric motor which can work in quasi-static and resonant states. The motion characteristics of the prototype are tested by building the prototype and experimental platform. Experimental results show that the maximum speed of the prototype is 29.3 mm s−1 and the maximum load is 2 N in the resonant state, the minimum displacement resolution of prototype motor is 0.26 μm in the quasi-static state. The motion characteristics of the prototype are consistent with the theoretical analysis, which provides an effective idea to improve the comprehensive performance of the piezoelectric motor.

Enhanced DOA Estimation With Augmented CADiS by Exploiting Array Motion Strategies

With its increased aperture and enlarged minimum spacing among sensors, coprime array with displaced subarrays (CADiS) receives a great deal of attention among sparse arrays. However, the holes in the difference co-array of CADiS extremely degrade the achievable number of uniform degrees of freedom (uDOFs). In recent years, increasing researches of direction of arrival (DOA) estimation with moving sparse arrays have brought new insights into the releasing the holes problem. In this paper, we first explore the structure of difference co-array generated from array motion, and propose a hole-free motion strategy that can fill all the holes in difference co-array of coprime arrays, and resulting increased number of uDOFs as well as array aperture. Secondly, based on the analysis of hole positions, we propose another motion strategy that needs only one step motion of CADiS to generate a difference co-array with no holes in the central part. We find all the qualified steps length of the one-step motion method and provide the closed-form expression of the corresponding achievable number of uDOFs. Finally, the number of uDOF and DOA estimation accuracy of the proposed motion strategies are compared with several state-of-the-art motion methods. Numerical results show the superiority of the proposed methods.

Adaptation to repeated standing-slips in professional ballet dancers

Ballet training is being increasingly used to improve physical functions in older adults. Our previous work showed that ballet dancers react to a novel standing-slip more effectively than their non-dancer counterparts through better control of the recovery step and trunk movement. The purpose of this study was to test if and to what extent ballet dancers adapt differently to repeated standing-slips relative to non-dancers. Protected by a harness, twenty young adults (10 professional ballet dancers and 10 age/sex-matched non-dancers) experienced five repeated and standardized standing-slips on a treadmill. Changes from the first slip (S1) to the fifth slip (S5) in dynamic gait stability (primary outcome) and other variables, including the center of mass position and velocity, step latency, slip distance, ankle angle, and trunk angle (secondary outcomes) were compared between groups. Results revealed that both groups adopted similar proactive controls to improve dynamic gait stability by using the ankle and hip strategies. However, dancers showed a better reactive improvement in stability after the repeated slips than non-dancers. From S1 to S5, dancers reactively improved their dynamic gait stability more than non-dancers at the recovery step liftoff (p = 0.003). Dancers decreased their recovery step latency (p = 0.004) and shortened the slip distance (p = 0.004) significantly more than non-dancers from S1 to S5. These findings suggest that ballet dancers could facilitate the adaptation to repeated slips, which may be attributed to their ballet practice experience. This finding augments our understanding of the underlying mechanisms of ballet practice reducing falls.

Direct observation of motor protein stepping in living cells using MINFLUX.

Dynamic measurements of molecular machines can provide invaluable insights into their mechanism, but these measurements have been challenging in living cells. Here, we developed live-cell tracking of single fluorophores with nanometer spatial and millisecond temporal resolution in two and three dimensions using the recently introduced super-resolution technique MINFLUX. Using this approach, we resolved the precise stepping motion of the motor protein kinesin-1 as it walked on microtubules in living cells. Nanoscopic tracking of motors walking on the microtubules of fixed cells also enabled us to resolve the architecture of the microtubule cytoskeleton with protofilament resolution.

Angry and happy expressions affect forward gait initiation only when task relevant.

Whole-body movements represent an ecologically valid model for assessing the effect of emotional stimuli valence on approach/avoidance reactions as they entail a change of the physical distance between such stimuli and the self. However, research in this field has provided inconsistent results as the task relevance of the emotional content of the stimuli was not properly controlled, and very often, it is impossible to dissociate the effect of arousal from that of valence. To overcome these limitations, we studied the effect of facial emotional expressions (anger and happiness) on forward gait initiation using an experimental paradigm that allows us to compare the impact of the stimuli emotional content when they are task relevant and when they are not. We found that angry and happy expressions altered forward gait initiation parameters differently only when relevant for ongoing goals. In particular, both the reaction times and the percentages of omission errors increased when the go signal was an angry face compared to when the go signal was a happy face. These results indicate that forward step movements share the same features as reaching arm movements regarding emotional stimuli, that is, facial emotions do not automatically influence behavioral responses. Instead, their effects depend critically on their conscious appraisal. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

소뇌성 운동실조증 환자의 자발적 및 보상적 스텝 특성 규명 : Ⅰ. 발 동작의 운동학적 특성을 중심으로

Taking a step is a fundamental human movement to maintain balance and execute functional activities in daily living, while such movement is challenging to properly perform in patients with cerebellar ataxia (CA). We examined the kinematic characteristics of foot movement and ranges of body mass center (COM) by comparing voluntary and reactive stepping actions in patients with CA. A total of 12 individuals with CA and 12 age-matched normal controls participated in the study. We used a forward “lean-and-release” balance perturbation method to evaluate the balance recovery responses using foot step. We had 2 step task conditions (2% of body weight for voluntary step and 10% of body weight for reactive step tasks) and 3 step distance conditions (near, middle, and far). The results indicated that reaction time was not much different between groups, but cerebellar patients were slower and took longer to recover their body stability using foot step than normal controls. The movement range of the body COM was significantly larger than that of the normal controls during recovering their balance. These findings suggest that CA patients exhibited a tendency to use inefficient first step movement strategies and more variable to maintain body stability after balance perturbation.