Double Support Phase Research Articles

Do Differences in Spatiotemporal Gait Parameters Predict the Risk of Developing Depression in Later Life?

There is growing interest in the association between gait disturbance and depression in later life. The aim of this study is to clarify the longitudinal relationship between specific gait parameters and incident depression within a population-representative sample of older people. Longitudinal analysis of spatiotemporal gait parameters at baseline (wave 1) and incident depression at 2 and 4 years (waves 2/3). Logistic regression models were used to assess the relationship between tertiles of gait parameters and incident depression. The Irish Longitudinal Study on Aging. Over 3600 nondepressed community-dwelling people aged 50 years or older. A score of 9 or greater on the eight-item Center for Epidemiological Studies Depression Scale at wave 2 or 3 was indicative of incident depression. The GAITRite system was used to measure gait speed, step length, step width, and double support phase during usual speed walking and under dual task conditions. Participants with incident depression (344/3615) had slower gait speed (129.9 [95% confidence interval {CI} = 127.2-132.6] cm/s vs 134.1 [95% CI = 133.0-135.1] cm/s; F = 8.82; P = .003) and shorter step length (68.0 [95% CI = 66.9-69.2] cm vs 70.3 [95% CI = 69.9-70.7] cm; F = 13.99; P < .001) at baseline than those who did not develop depression. Logistic regression models demonstrated that those within the slowest tertile for gait speed and shortest tertile for step length had significantly increased likelihood of incident depression in fully adjusted models, with odds ratios of 1.54 (95% CI = 1.08-2.19) and 1.54 (95% CI = 1.01-2.35), respectively. Measures of step width and double support time were not associated with depression. This study demonstrates that older people with incident depression have significantly slower gait speed and shorter step length at initial assessment. These findings are clinically significant given the impact both conditions have on functional status in later life, as well as the possibility that gait problems may represent a potentially modifiable risk factor for depression. J Am Geriatr Soc 67:1050-1056, 2019.

Development of a Mechanistic Hypothesis Linking Compensatory Biomechanics and Stepping Asymmetry during Gait of Transfemoral Amputees.

Objective Gait asymmetry is a common adaptation observed in lower-extremity amputees, but the underlying mechanisms that explain this gait behavior remain unclear for amputees that use above-knee prostheses. Our objective was to develop a working hypothesis to explain chronic stepping asymmetry in otherwise healthy amputees that use above-knee prostheses. Methods Two amputees (both through-knee; one with microprocessor knee, one with hydraulic knee) and fourteen control subjects participated. 3D kinematics and kinetics were acquired at normal, fast, and slow walking speeds. Data were analyzed for the push-off and collision limbs during a double support phase. We examined gait parameters to identify the stepping asymmetry then examined the external work rate (centre of mass) and internal (joint) power profiles to formulate a working hypothesis to mechanistically explain the observed stepping asymmetry. Results Stepping asymmetry at all three gait speeds in amputees was characterized by increased stance phase duration of the intact limb versus relatively normal stance phase duration for the prosthesis limb. The prosthesis limb contributed very little to positive and negative work during the double support phase of gait. To compensate, the intact leg at heel strike first provided aid to the deficient prosthetic ankle/foot during its push-off by doing positive work with the intact knee, which caused a delayed stance phase pattern. The resulting delay in toe-off of the intact limb then facilitated the energy transfer from the more robust intact push-off limb to the weaker colliding prosthesis side. This strategy was observed for both amputees. Conclusions There is a sound scientific rationale for a mechanistic hypothesis that stepping asymmetry in amputee participants is a result of a motor adaptation that is both facilitating the lower-leg trajectory enforced by the prosthesis while compensating for the lack of work done by the prosthesis, the cost of which is increased energy expenditure of the intact knee and both hips.

Gate Planning and Control of a Nine-Link Biped Robot with Toe Joints via Impact Effects

The adaptation of a biped’s foot motion to the ground conditions and maintaining stability of the robot is an undeniable necessity that is the focus of this research. In this research, dynamics equations will be obtained for single support phase (SSP), double support phase (DSP), and impact. The results of impact dynamics have been used to correlate the gait parameters with the contact event following impact. In this study, in addition to explaining impact equations for a nine-link biped robot with toe and heel in first and second impact phases, a clear response for the external impulses is obtained in a compact form for the first time. In this paper, the trajectory of the foot and toe is done by determining the constraints of motion parameters with and without impact effect. Then, a method based on smooth hip motion with the largest stability margin using only two parameters, is implemented through iterative calculations, to ensure stability of the robot in accordance with the criterion of zero-moment point (ZMP). Finally, the response of a model-based controller, called feed-forward algorithm (FA), and a non-model-based controller, called the transposes Jacobian algorithm (TJ), will be used to control the robot.

Does the first trimester of pregnancy induce alterations in the walking pattern?

IntroductionFrom among many studies observing the walking pattern throughout pregnancy, only two items monitor the influence of pregnancy on the movement system during gait considering the period before gestation.Research questionDoes the women’s gait pattern at the end of the first trimester undergo changes in comparison to body movement pattern before pregnancy?MethodsAll subjects who met the inclusion criteria gave signed and informed consent before the study. Two experimental sessions were arranged according to the same protocol: (P0) before pregnancy and (P1) at the end of the first trimester of pregnancy (12th week of gestation). At first the anthropometric measures were taken. Then, walking trials at a self-selected speed along a walkway were registered with Vicon 250 (Oxford Metrics Ltd.; Oxford, UK) and FreeMED force platform (Sensor Medica, Italy).ResultsAn analysis of anthropometric parameters in 12th pregnancy week demonstrated significant changes in mean values of waist circumference and waist to hip ratio as well as waist to height ratio indexes compared to the results before pregnancy. No significant differences were found in the basic kinematic gait parameters between experimental conditions. Significant increase of mean inter—ankle distance during double support phase occurred during the first trimester of pregnancy. Also, the ratio of the ankle separation width to the pelvic width was noticeably higher in gestation. Then, angular changes of the pelvis in coronal and transverse planes throughout gait cycle during pregnancy demonstrated significant differences compared to those measured before pregnancy. At the same time in the first trimester of pregnancy no adaptive changes in the pattern of feet loading take place.SignificanceSince our study is of longitudinal character, in the course of pregnancy we expect compensatory mechanisms more clearly demonstrated. Therefore, we hope to identify a strategy of the gravid body progression in space.

An analytical approach for generating balanced gaits of a biped robot on stairs and sloping surfaces

The present paper deals with the generation of dynamically balanced walking gaits of a biped robot while moving on various terrain conditions such as staircase and sloping surface. Here, an attempt is made to eliminate the complex inverse dynamics approach used to generate the gaits for the upper body by defining the trajectory for the movement of the hands and restricting the motion of the trunk. However, the restricted movement of the trunk is compensated by the movement of hands in the sagittal plane. The lower limbs gait has been generated by using the concept of inverse kinematics in both the sagittal and frontal planes. A provision is given in the algorithm to accommodate the variations in the dimension of the staircase and angle of slope of the terrain. Further, a study has also been conducted to investigate the influence of swing foot trajectory (that is, quadratic, cubic and fifth-order polynomial) on the balance of the robot. Once the model is developed, its performance has been benchmarked while ascending and descending the staircase and sloping surface after considering both the single and double support phases. Finally, the developed algorithms are tested on a real two legged robot.

Numerical study on the walking load based on inverted-pendulum model

In this paper, an inverted-pendulum model consisting of a point supported by spring limbs with roller feet is adopted to simulate human walking load. To establish the kinematic motion of first and second single and double support phases, the Lagrangian variation method was used. Given a set of model parameters, desired walking speed and initial states, the Newmark-beta method was used to solve the above kinematic motion for studying the effects of roller radius, stiffness, impact angle, walking speed, and step length on the ground reaction force, energy transfer, and height of center of mass transfer. The numerical simulation results show that the inverted-pendulum model for walking is conservative as there is no change in total energy and the duration time of double support phase is 50-70% of total time. Based on the numerical analysis, a dynamic load factor alpha wi is proposed for the traditional walking load model.

Additive manufacturing of specific ankle-foot orthoses for persons after stroke: A preliminary study based on gait analysis data.

The aim of present study is to investigate the feasibility of patient-specific ankle-foot orthoses fabricated using additive manufacturing (AM) techniques. Then, clinical performance of the AFOs manufactured using material PA12 was evaluated in stroke survivors based on gait analysis data. The ankle and foot were scanned by EinScan-Pro 3D scanner. The software Geomagic Studio was used for modifying the AFO model. After processing the original AFO model into the final required model, material PA12 were used to fabricate the AFOs by Multi Jet Fusion (MJF) technique. Finally, gait analysis of 12 stroke patients was conducted to compare the effects with and without AFO. It took 2 hours from processing the initial AFO model to the completion of final model, and the printing time was 8 hours. The printing thickness of the AFO was 1.2 mm. With respect to the temporal-spatial parameters, the velocity and stride length in the gait with AFO increased significantly as compared to the gait without AFO (P=0.001, P=0.002). The cadence increased, double limb support phase decreased, and the step length difference decreased in the gait with AFO; however, the difference was not statistically significant (P=0.117, P=0.075, P=0.051).This study confirmed the feasibility of patient-specific AFO fabricated by AM techniques, and demonstrated the process of modifying AFO models successfully. The specific ankle-foot orthoses fabricated by material PA12 have a significant effect on the improvement of velocity and stride length in people with stroke.

Rigid vs compliant contact: an experimental study on biped walking

Contact modeling plays a central role in motion planning, simulation and control of legged robots, as legged locomotion is realized through contact. The two prevailing approaches to model the contact consider rigid and compliant premise at interaction ports. Contrary to the dynamics model of legged systems with rigid contact (without impact) which is straightforward to develop, there is no consensus among researchers to employ a standard compliant contact model. Our main goal in this paper is to study the dynamics model structure of bipedal walking systems with rigid contact and a novel compliant contact model, and to present experimental validation of both models. For the model with rigid contact, after developing the model of the articulated bodies in flight phase without any contact with environment, we apply the holonomic constraints at contact points and develop a constrained dynamics model of the robot in both single and double support phases. For the model with compliant contact, we propose a novel nonlinear contact model and simulate motion of the robot using this model. In order to show the performance of the developed models, we compare obtained results from these models to the empirical measurements from bipedal walking of the human-size humanoid robot Surena III, which has been designed and fabricated at CAST, University of Tehran. This analysis shows the merit of both models in estimating dynamic behavior of the robot walking on a semi-rigid surface. The model with rigid contact, which is less complex and independent of the physical properties of the contacting bodies, can be employed for model-based motion optimization, analysis as well as control, while the model with compliant contact and more complexity is suitable for more realistic simulation scenarios.

Trajectory tracking using artificial neural network for stable human-like gait with upper body motion

This paper presents a trajectory generation algorithm for robots which can walk like human with movable foot and active toe. The proposed algorithm allows smooth transition between walking phases namely, single and double support phases. A neural network approach is used for solving inverse kinematics so that the biped robot follows the ankle and hip trajectories to walk. Zero moment point (ZMP) stability is ensured by taking into account the upper body movements along with the planned motion trajectories. Here, we analyze the effect of lateral upper body motion on ZMP stability. Different types of trajectories for upper body are generated, and the one which ensured the most stable locomotion is identified.

The bipedal saddle space: modelling and validation

Better understanding of human balance control is pivotal for applications such as bipedal robots and medical technologies/therapies targeting human locomotion. Despite the inverted pendulum model being popular for describing bipedal locomotion, it does not properly capture the step-to-step transition dynamics. The major drawback has been the requirement for both feet to be on the ground which generates a discontinuity along the intersection of the potential energy surfaces produced by the two legs. To overcome this problem, we propose a generalized inverted pendulum-based model that can describe both single and double support phases. The full characterization of the system’s potential energy allows the proposed model to drop the main limitation. This framework also enables optimal strategies to be designed for the transition between the two feet without the optimization algorithms. The proposed theory has been validated by comparing the human locomotor strategies output of our planner with real data from multiple experimental studies. The results show that our model generates trajectories consistent with human variability and performs better than existing well-known methods.

Coupled analysis of footbridge-pedestrian dynamic interaction

In this work, an analytical formulation for the vibration response of a bridge due to walking pedestrians is proposed to the aim of modelling the human-structure interaction (HSI) in the vertical direction. Bridge and pedestrians are described as mechanical systems having a finite number of degrees of freedom (DOFs). A new single DOF model of a bipedal pedestrian is proposed, that reproduces the alternation of single and double support phases of human gait and the related ground reaction forces. The finite element method is adopted to model the 3D geometry of the bridge. The coupled equations of motion are derived based on the key assumption that contact points between the pedestrians and the bridge deck are massless. However, the structural matrices of the coupled system are time varying due to the pedestrian motion along the bridge. An uncoupled solution strategy is devised to reduce the computational burden, allowing for the separate integration of the bridge and the pedestrian sub-systems. The coupled formulation is uncoupled and associated with an iterative procedure that restores compatibility and equilibrium at contact points. The pedestrian model and the analytical procedure are implemented in a research code where input data are the bridge structural matrices computed with a commercial FE code. The modelling and analysis procedure is applied to a case study, a lively footbridge in Seriate, Italy. A first validation of the code is obtained by comparison with a closed form solution for a 1D beam. For the loading scenarios analyzed here, a maximum of two iterations per step are necessary to achieve convergence within a prescribed tolerance. Loading scenarios encompassing groups of pedestrians in different transverse positions highlight the importance of the 3D bridge modelling. The comparison with a few experimental results clarifies the role of the modelling assumptions. Conclusions discuss novelties, advantages, limits and future developments of the proposed approach.

Texting While Walking Induces Gait Pattern Alterations in Healthy Older Adults

The use of a mobile phone for texting purposes results in distracted walking which may lead to injuries. In particular, texting while walking has been shown to induce significant alterations in gait patterns. This study aimed to assess whether changes in the main spatio-temporal parameters of gait when simultaneously engaged in texting on a smartphone and walking are different in older adults relative to young and middle- aged individuals. A total of 57 participants divided in three groups (19 older adults aged over 65, 19 young aged 20-40 and 19 middle-aged aged 41-64) were tested in two conditions: walking, and walking while texting on a smartphone. Spatio-temporal parameters of gait were assessed using a wearable accelerometer located on the lower back. The results show that texting induced similar reduction of gait speed, stride length and cadence in all groups. Slight (although significant) alterations of stance, swing and double support phases duration were found only for middle-aged participants. Such findings suggest that modifications of gait patterns due to texting seem unaffected by age, probably due to different perceptions of the cognitive complexity of the task and differential prioritization of its motor and cognitive aspects.

Analysis of the separation angle between the thorax and pelvis, and its association with performance in the hammer throw

The hammer throw is perhaps one of the most misunderstood and difficult events to learn in track and field. Improvements in technique are focused on strategies designed to increase implement release velocity. The purpose of this cross-sectional investigative study was to examine the association between the angle of separation between the thorax and pelvis and performance in the hammer throw. Two male and four female throwers were used to assess positional data of the hammer, thorax, and pelvis. Hammer positional data were used to determine linear hammer speed at release, release angle, and release height. Thorax and pelvis positional data were used to determine thorax rotation relative to the pelvis (separation angle). The association between values of separation angle at key instances and performance was examined. Performance was determined by distance thrown (55.69 ± 3.42 m). Release speeds (24.32 ± 0.70 m/s) were also examined as a contributory factor towards performance and were included to account for instances where throwers released the hammer using sub-optimal release heights and angles which negatively affected distance thrown. The separation angle at its smallest within each turn was found to have a strong negative association with the performance indicators, especially in the first two turns (significant correlates ranged from −0.82 to −0.97). This finding indicates when throwers reduced the separation to a smaller value, performance was enhanced. Separation angle was at its smallest in double support. This suggests that throwers may improve performance by reducing the separation angle during double support phases.

P31. Gait disturbance in patients with orthostatic tremor

Introduction Orthostatic tremor (OT) is a rare disorder of unclear etiology characterized by a 13–18 Hz tremor of the legs while standing with resolving symptoms during sitting or walking. OT is associated with other movement disorders such as parkinsonism, essential tremor or cerebellar disorders. Although gait disturbances are frequently described in these diseases, there is no systemic analysis of the gait disorder linked to OT. Therefore, the aim of this study is to investigate the gait performance of patients with OT assessed by a standardized sensorimotor and cognitive walking paradigm. Methods Patients with a diagnosis of primary OT were screened and included in this study after informed consent. Gait performance was investigated during 8 different walking conditions using a pressure-sensitive sensor carpet (GAITRite®). Patients walked at preferred, slow and maximum walking speeds (PS, SS, MS), during head reclination and eyes closed conditions (HR, EC) as well as calculatory, semantic and motoric dual task conditions (DTC, DTS, DTM). The gait performance of patients was compared to age-matched healthy subjects. Gait parameters were assessed by a multivariate analysis of variance. Results Eighteen patients with a diagnosis of primary OT with a mean age of 70.4 ± 5.9 years were included in the study. In all walking conditions gait velocity (p Discussion Although OT symptoms diminish during walking, we identified constant impairments of locomotion control. The gait disturbance was characterized by an increased level of a cautious gait (slow, small-stepped, increased double support phases and BOS). Moreover, we identified disturbance of gait stability (increased CV) and interlimb coordination (left-right asymmetry). The specific alterations were found in conditions with increased sensory feedback control as well as attentional cognitive gait control. This implies an impaired integration of sensory feedback, possibly due to a dysfunction of midline cerebellar structures, as cerebellar dysfunction in OT was frequently described.

Descending stairs: Good or bad task to discriminate women with patellofemoral pain?

BackgroundThere is no consensus on kinematics alterations during descending stairs in females with patellofemoral pain (PFP). In addition, there are no studies that have evaluated the three dimensional kinematics of the trunk, pelvis, hip, knee, and ankle using a multi-segmental model of the foot simultaneously during this task in patients with PFP and evaluated the subphases of stair descent. The objectives of this study were to compare the three dimensional kinematics of the trunk, pelvis, and lower limbs during different subphases of stair descent and identify the discriminatory capacity of the kinematic variables among women with PFP and healthy women. MethodsIn this cross-sectional study, thirty-four women with PFP and thirty-four pain free women between 18 and 35 years-old were submitted to three-dimensional kinematic evaluation during stair descent. ResultsIt was observed that kinematic differences between the groups occurred in the first double support phase of the stair descent, with the variables of internal rotation of the hindfoot in relation to the tibia in the initial contact (2.1°; sensitivity = 68.6%, specificity = 61.8%) and contralateral pelvic drop in load response (1.3°, sensitivity = 65.7%, specificity = 63.7%) presenting the best ability to discriminate women with and without PFP. ConclusionOur results suggest that kinematic changes during stair descent should be used with caution during the evaluation and decision-making process in women with PFP.

Dynamics of corticospinal motor control during overground and treadmill walking in humans.

Increasing evidence suggests cortical involvement in the control of human gait. However, the nature of corticospinal interactions remains poorly understood. We performed time-frequency analysis of electrophysiological activity acquired during treadmill and overground walking in 22 healthy, young adults. Participants walked at their preferred speed (4.2, SD 0.4 km/h), which was matched across both gait conditions. Event-related power, corticomuscular coherence (CMC), and intertrial coherence (ITC) were assessed for EEG from bilateral sensorimotor cortices and EMG from the bilateral tibialis anterior (TA) muscles. Cortical power, CMC, and ITC at theta, alpha, beta, and gamma frequencies (4-45 Hz) increased during the double support phase of the gait cycle for both overground and treadmill walking. High beta (21-30 Hz) CMC and ITC of EMG was significantly increased during overground compared with treadmill walking, as well as EEG power in theta band (4-7 Hz). The phase spectra revealed positive time lags at alpha, beta, and gamma frequencies, indicating that the EEG response preceded the EMG response. The parallel increases in power, CMC, and ITC during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. The evoked responses are not consistent with the idea of synchronization of ongoing corticospinal oscillations but instead suggest coordinated cortical and spinal inputs during the double support phase. Frequency-band dependent differences in power, CMC, and ITC between overground and treadmill walking suggest differing neural control for the two gait modalities, emphasizing the task-dependent nature of neural processes during human walking. NEW & NOTEWORTHY We investigated cortical and spinal activity during overground and treadmill walking in healthy adults. Parallel increases in power, corticomuscular coherence, and intertrial coherence during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. These findings identify neurophysiological mechanisms that are important for understanding cortical control of human gait in health and disease.

Abnormal gait pattern emerges during curved trajectories in high-functioning Parkinsonian patients walking in line at normal speed.

BackgroundSeveral patients with Parkinson´s disease (PD) can walk normally along straight trajectories, and impairment in their stride length and cadence may not be easily discernible. Do obvious abnormalities occur in these high-functioning patients when more challenging trajectories are travelled, such as circular paths, which normally implicate a graded modulation in the duration of the interlimb gait cycle phases?MethodsWe compared a cohort of well-treated mildly to moderately affected PD patients to a group of age-matched healthy subjects (HS), by deliberately including HS spontaneously walking at the same speed of the patients with PD. All participants performed, in random order: linear and circular walking (clockwise and counter-clockwise) at self-selected speed. By means of pressure-sensitive insoles, we recorded walking speed, cadence, duration of single support, double support, swing phase, and stride time. Stride length-cadence relationships were built for linear and curved walking. Stride-to-stride variability of temporal gait parameters was also estimated.ResultsWalking speed, cadence or stride length were not different between PD and HS during linear walking. Speed, cadence and stride length diminished during curved walking in both groups, stride length more in PD than HS. In PD compared to HS, the stride length-cadence relationship was altered during curved walking. Duration of the double-support phase was also increased during curved walking, as was variability of the single support, swing phase and double support phase.ConclusionThe spatio-temporal gait pattern and variability are significantly modified in well-treated, high-functioning patients with PD walking along circular trajectories, even when they exhibit no changes in speed in straight-line walking. The increased variability of the gait phases during curved walking is an identifying characteristic of PD. We discuss our findings in term of interplay between control of balance and of locomotor progression: the former is challenged by curved trajectories even in high-functioning patients, while the latter may not be critically affected.

Humanoid gait generation in complex environments based on template models and optimality principles learned from human beings

In this paper, we present an inverse optimal control-based transfer of motions from human experiments to humanoid robots and apply it to walking in constrained environments. To this end, we introduce a 3D template model, which describes motion on the basis of center-of-mass trajectory, foot trajectories, upper-body orientation, and phase duration. Despite its abstract architecture, with prismatic joints combined with damped series elastic actuators instead of knees, the model (including dynamics and constraints) is suitable for describing both human and humanoid locomotion with appropriate parameters. We present and apply an inverse optimal control approach to identify optimality criteria based on human motion capture experiments. The identified optimal strategy is then transferred to a humanoid robot template model for gait generation by solving an optimal control problem, which takes into account the properties of the robot and differences in the environment. The results of this step are the center-of-mass trajectory, the foot trajectories, the torso orientation, and the single and double support phase durations for a sequence of steps, allowing the humanoid robot to walk within a new environment. In a previous paper, we have already presented one computational cycle (from motion capture data to an optimized robot template motion) for the example of walking over irregular stepping stones with the aim of transferring the motion to two very different humanoid robots (iCub@Heidelberg and HRP-2@LAAS). This study represents an extension, containing an entirely new part on the transfer of the optimized template motion to the iCub robot by means of inverse kinematics in a dynamic simulation environment and also on the real robot.

Gait Characteristics of Adults With Intellectual Disability.

Gait is a relevant and complex aspect of motor functioning. Disturbances are related to negative health outcomes. Gait characteristics of 31 adults with intellectual disability (ID) without Down syndrome (DS) (42.77±16.70 years) were investigated, and associations with age, sex, body mass index (BMI), and level of ID were assessed. Sex and BMI were significantly associated with some of the gait parameters, while age and level of ID were not. Gait characteristics of adults with ID seem to be comparable to those of the general population of older adults (average 20 years older), except that adults with ID seem to spend less time in stance and double support phase and walk more variable and with a broader base of support.

The effects of ground compliance on flexible planar passive biped dynamic walking

Passive biped dynamic walking exhibits humanoid gait. Many efforts have been made to implement a flexible and anthropomorphic passive model. However, the couple of flexible passive walker on compliant ground has not been well studied yet. The objective of this paper was to develop multibody dynamics for flexible passive walker on compliant ground, in which the nonlinear spring-damper contact model was used both in normal and tangential directions to represent ground compliance. Inspired by elastic mechanisms in human locomotion, hip stiffness and damping were incorporated in the proposed flexible passive walker. Different from traditional impactmomentum method, one unified set of continuous dynamics based on continuous force method was developed to describe the entire passive walking gait on compliant ground, including the real double support phase. Through numerical simulations, stable period-one gait and double support phase were gained. After investigating the effects of contact parameters on step length, period and velocity, it was found that larger contact stiffness and smaller contact damping lead to a higher step velocity gait. The adjustment of hip stiffness could be used to improve the versatility of the flexible walker on varying compliant grounds.