Walking Control Research Articles

Uneven Terrain Walking with Linear and Angular Momentum Allocation.

Uneven terrain walking is hard to achieve for most child-size humanoid robots, as they are unable to accurately detect ground conditions. In order to reduce the demand for ground detection accuracy, a walking control framework based on centroidal momentum allocation is studied in this paper, enabling a child-size humanoid robot to walk on uneven terrain without using ground flatness information. The control framework consists of three controllers: momentum decreasing controller, posture controller, admittance controller. First, the momentum decreasing controller is used to quickly stabilize the robot after disturbance. Then, the posture controller restores the robot posture to adapt to the unknown terrain. Finally, the admittance controller aims to decrease contact impact and adapt the robot to the terrain. Note that the robot uses a mems-based inertial measurement unit (IMU) and joint position encoders to calculate centroidal momentum and use force-sensitive resistors (FSR) on the robot foot to perform admittance control. None of these is a high-cost component. Experiments are conducted to test the proposed framework, including standing posture balancing, structured non-flat ground walking, and soft uneven terrain walking, with a speed of 2.8 s per step, showing the effectiveness of the momentum allocation method.

NeuroWalknet, a controller for hexapod walking allowing for context dependent behavior.

Decentralized control has been established as a key control principle in insect walking and has been successfully leveraged to account for a wide range of walking behaviors in the proposed neuroWalknet architecture. This controller allows for walking patterns at different velocities in both, forward and backward direction-quite similar to the behavior shown in stick insects-, for negotiation of curves, and for robustly dealing with various disturbances. While these simulations focus on the cooperation of different, decentrally controlled legs, here we consider a set of biological experiments not yet been tested by neuroWalknet, that focus on the function of the individual leg and are context dependent. These intraleg studies deal with four groups of interjoint reflexes. The reflexes are elicited by stimulation of the femoral chordotonal organ (fCO) or groups of campaniform sensilla (CS). Motor output signals are recorded from the alpha-joint, the beta-joint or the gamma-joint of the leg. Furthermore, the influence of these sensory inputs to artificially induced oscillations by application of pilocarpine has been studied. Although these biological data represent results obtained from different local reflexes in different contexts, they fit with and are embedded into the behavior shown by the global structure of neuroWalknet. In particular, a specific and intensively studied behavior, active reaction, has since long been assumed to represent a separate behavioral element, from which it is not clear why it occurs in some situations, but not in others. This question could now be explained as an emergent property of the holistic structure of neuroWalknet which has shown to be able to produce artificially elicited pilocarpine-driven oscillation that can be controlled by sensory input without the need of explicit innate CPG structures. As the simulation data result from a holistic system, further results were obtained that could be used as predictions to be tested in further biological experiments.

A NEW TECHNOLOGY FOR RECOVERY OF LOCOMOTION IN PATIENTS AFTER A STROKE

Neural networks in the spinal cord can generate the walking pattern and control posture in the absence of supraspinal influences. A technology has been created using transcutaneous electrical spinal cord stimulation (tSCS). During walking, tSCS activated spinal locomotor networks, as well as leg flexor/extensor motor pools in the swing/support phases, respectively. It was suggested that the use of this technology in people with locomotion disorders would improve walking. Patients with hemiparesis were studied 3–11 months after a stroke, the duration of the course was 2 weeks. Patients of the main and control groups received standard therapy and rehabilitation using technology; in the control group, sham tESCS was used. After the course in the main group, in contrast to the control group, minimal clinically significant changes in walking parameters were achieved. The developed technology is an effective means of restoring walking in patients with hemiparesis.

Belief Space Planning for Robust Humanoid Locomotion

We have implemented a BSP (Belief Space Planning) controller inspired by human walking behaviour's neurophysiological mechanisms on the PAL Robotics REEM-C humanoid robot. BSP controllers assuming maximum likelihood have been previously successfully utilized by our group for various similar demanding applications. The posture and locomotion performance of the REEM-C robot with BSP controllers has been experimentally tested and validated in the Eurobench@IIT humanoid testing facility by means of the benchmarking framework and software already developed in Eurobench. The main purpose of the work reported here is to assess if and how the application of a BSP controller is viable and useful in the humanoid robotics domain. The BSP walking controller has shown remarkably good performance in tracking tasks. However, it has not performed well on slopes in simulation. A new more advanced approach aiming to cope with slopes and unstable terrain is under development.

The effects of swing assistance in a microprocessor-controlled transfemoral prosthesis on walking at varying speeds and grades.

This article proposes, describes, and tests a swing-assist walking controller for a stance-controlled, swing-assisted knee prosthesis that aims to combine benefits of passive swing mechanics (e.g., quiet operation, biomimetic function, and low power requirements) with benefits of powered swing assistance (e.g., increased robustness of swing-phase motion and specifically increased toe clearance). A three-participant, multislope, multispeed treadmill walking study was performed using the swing-assist prosthesis and controller, as well as using the participants' prescribed microprocessor knee devices. The swing-assist device and approach were found to improve user minimum foot clearance during walking at slopes and speeds, and also to improve symmetry of knee motion. Hip power inputs from stance knee release to heel strike indicated that, on average, less hip power was required when using the swing-assist prosthesis, indicating that the observed benefits were likely the result of the knee device and its control methodology, rather than a result of increased hip joint effort.

Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis.

Individuals using passive prostheses typically rely heavily on their biological limb to complete sitting and standing tasks, leading to slower completion times and increased rates of osteoarthritis and lower back pain. Powered prostheses can address these challenges, but have control methods that divide sit-stand transitions into discrete phases, limiting user synchronization across the motion and requiring long manual tuning times. This paper extends our preliminary work using a thigh-based phase variable to parameterize optimized data-driven impedance parameter trajectories for sitting, standing, and walking, with only two classification modes. We decouple the stand-to-sit and sit-to-stand equilibrium angles through a knee velocity-dependent scaling term, reducing the model fitting error by approximately half compared to our previous results. We then experimentally validate the controller with three individuals with above-knee amputation performing sitting and standing transitions to/from three different chair heights. We show that our controller implemented on a powered knee-ankle prosthesis produced biomimetic joint mechanics, resulting in significantly reduced sit/stand loading symmetry and time to complete a 5x sit-to-stand task compared to participants' passive prostheses. Integration with a previously developed walking controller also allowed sit/walk transitions between different chair heights. The controller's biomimetic assistance may reduce the overreliance on the biological limb caused by inadequate passive prostheses, helping improve mobility for people with above-knee amputations.

Effects of passive interpersonal light touch during walking on postural control responses: An exploratory study

The effects of passive interpersonal light touch (PILT) on postural stability can be observed through improved postural coordination through haptic feedback from the contact provider to the contact receiver while walking. It is unclear, however, whether PILT affects the contact receiver's detailed physical responses, such as muscle activity, body sway, and joint movements. In this study, surface electromyography and an inertial measurement unit were used simultaneously to explore changes in walking speed and control responses induced by PILT. We evaluated fourteen healthy participants for their walking speed and physical responses under two walking conditions: no-touch (NT) and PILT. As a physical response during walking, we measured muscle activity (rectus femoris, semitendinosus, tibialis anterior, and soleus muscles), body sway (pelvis and neck), and joint angles (direction of hip, knee, and ankle joint movements). In PILT condition, fingertip contact force was measured while the contact provider touched the third level of the recipient's lumbar spine. In comparison with the NT condition, PILT condition increased walking speed and decreased body sway on neck position. There were significant correlations between walking speed and neck sway regarding NT and PILT change values. Passive haptic information to the contact receiver may assist in the smooth shift of the center of gravity position during gait through interpersonal postural coordination. These findings suggest that PILT may provide an efficient and stable gait.

Walking speed does not affect age-differences in ankle muscle beta-band intermuscular coherence during treadmill walking

Background: By examining whether age and speed each differently affects beta-coherence during walking, we can extend the limited evidence on age-related impairment in neural control of walking. We determined the effects of age and walking speed on intermuscular beta band coherence between lower limb muscle pairs and the association between stride characteristics and intermuscular beta band coherence between these muscle pairs.
 Methods: Older (n=12) and younger (n=14) individuals walked on a treadmill at fixed (1.2 m/s) and fast (~1.3x preferred) speeds for 3min. For 100 dominant leg strides, we measured length, width, stance, swing time, cadence and intermuscular beta-coherence (15-35Hz) for the synergistic (biceps femoris (BF)-semitendinosus, rectus femoris (RF)-vastus lateralis (VL), gastrocnemius lateralis (GL)-soleus (SL), Tibialis anterior (TA)-peroneus longus (PL)) and the antagonistic (RF-BF and TA-GL) muscle pairs at swing and stance.
 Results: Comparing fast vs. fixed speed, participants walked with increased length (21%), cadence (12%), and coefficient of variation (CV) of stride length (14%), decreased stride width (-20%), and stance (-5%) and swing time (-14%) and with stronger TA-GL beta-coherence during early stance (69%, all p<0.01). Older vs. Younger individuals walked with slower fast gait speed (~9%), higher CV of stride length (21%), weaker GL-SL (-47%) and TA-PL (-60%) beta-coherences during the late swing and early stance phase, respectively (all p<0.01). No Group*Condition interactions occurred
 Conclusion: Oscillatory coupling between synergistic ankle muscle pairs during walking is lower in older vs. young individuals, but this difference is independent of walking speed while walking on a treadmill.

Analysis of the movements of the upper extremities during gait: Their role for the dynamic balance

BackgroundThe movement of the upper extremities is important for balance control in human walking. However, it is still unknown which mode of arm swing ensures the most stable gait due to the lack of appropriate measures which can quantify the movement of the upper extremities. In this study, we formulate a new parameter to numerically describe the arm swing. We investigated the effect of walking speed, sports activities and the subject’s BMI on the movement of the upper limbs. MethodsData of healthy 50 subjects from an external database was used. We used a human gait database for this analysis. All experimental trials were performed in Centre National de Rééducation Fonctionnelle et de Réadaptation – Rehazenter in Laboratoire d′Analyse du Mouvement et de la Posture in Luxembourg. Participants were asked to walk on a straight level walkway at 5 different speeds: 0–0.4 m/s, 0.4–0.8 m/s, 0.8–1.2 m/s, self-selected spontaneous and fast speeds. The human motion was recorded by using a 10-camera optoelectronic system. FindingsThe amplitude of arm swing was greater in gait with self-selected fast speed then in slow walking. Higher walking speeds entailed also the more structured and repetitive movement of the upper extremities. For self-selected fast speed, the mean value of Pearson's correlation coefficient between arm swing amplitude of the left and right side was 0.935 ± 0.102, 0.943 ± 0.073 and 0.973 ± 0.020 for the young, middle aged and elderly group respectively, while in slow walking it was in the range 0.393–0.633 (for the representatives of the three groups). Our results could suggest other factors which influence arm swing, such as obesity and doing asymmetric sports. InterpretationsOur results suggest that choosing the lowest possible walking speed is not the best strategy as the most symmetric arm swing occurs during gait with self-selected speed.

Association between walking energy utilisation and longitudinal cognitive performance in older adults.

Human motor function is optimised for energetic efficiency, however, age-related neurodegenerative changes affects neuromotor control of walking. Energy utilisation has been associated with motor performance, but its association with cognitive performance is unknown. The study population included 979 Baltimore Longitudinal Study of Aging participants aged $\ge$50years (52% female, mean age: 70$\pm$10.2years) with a median follow-up time of 4.7years. Energy utilisation for walking was operationalised as a ratio of the energy cost of slow walking to peak walking energy expenditure during standardised tasks ('cost-ratio'). Cognitive functioning was measured using the Trail Making Tests, California Verbal Learning Test, Wechsler Adult Intelligence Scale (WAIS), letter and category fluency and card rotation tests. Linear mixed models adjusted for demographics, education and co-morbidities assessed the association between baseline cost-ratio and cognitive functioning, cross-sectionally and longitudinally. To investigate the relationship among those with less efficient energy utilisation, subgroup analyses were performed. In fully adjusted models, a higher cost-ratio was cross-sectionally associated with poorer performance on all cognitive tests except WAIS (P < 0.05 for all). Among those with compromised energy utilisation, the baseline cost-ratio was also associated with a faster decline in memory (long-delay free recall: β = -0.4, 95% confidence interval [CI] = [-0.8, -0.02]; immediate word recall: β = -1.3, 95% CI = [-2.7, 0.1]). These findings suggest cross-sectional and longitudinal links between energy utilisation and cognitive performance, highlighting an intriguing link between brain function and the energy needed for ambulation. Future research should examine this association earlier in the life course to gauge the potential for interventive mechanisms.

A New Technology for Recovery of Locomotion in Patients after a Stroke

Neural networks in the spinal cord can generate the walking pattern and control posture in the absence of supraspinal influences. A technology using transcutaneous electrical spinal cord stimulation (tSCS) was created. During walking, tSCS activated spinal locomotor networks, as well as leg flexor/extensor motor pools in the swing/stance phases, respectively. It was assumed that the use of this technology in subjects with locomotion disorders would improve walking. Patients with hemiparesis were studied 3-11 months after stroke, the duration of the course was 2 weeks. Patients of the main and control groups received standard therapy and rehabilitation using the technology; in the control group, sham tSCS was used. After the course, minimal clinically important differences in walking parameters were achieved in the main group, in contrast to the control group. The developed technology is an effective means of restoring walking in patients with hemiparesis.

Training and retention effects of paced and music-synchronised walking exercises on pre-older females: an interventional study

BackgroundPhysical activity at pre-older ages (55–64 years) can greatly affect one’s physical fitness, health, physical-activity behaviour, and quality of life at older ages. The objective of this study was to conduct a 24-week walking-exercise programme among sedentary pre-older females and investigate the influence of different walking cadences on cardiorespiratory fitness and associated biomarkers.MethodsA total of 78 pre-older sedentary female participants were recruited and randomly assigned to normal (n = 36), paced (n = 15), music-synchronised (n = 15) walking, and no-exercise control (n = 12) groups, respectively. The normal, paced, and music-synchronised walking groups walked at a cadence of 120 steps/min, 125 steps/min, and 120–128 steps/min, respectively, under supervised conditions. Anthropometric characteristics, step length, nutrient intake, blood pressure and composition, and cardiorespiratory fitness were measured at baseline, the 12th week of the programme, the 24th week of the programme (completion), and after a 12-week retention period, which began immediately upon completion of the programme and did not feature any supervised exercises.ResultsAll walking conditions improved high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, step length, maximum oxygen consumption (VO2max), and oxidative capacity at anaerobic threshold (all P < 0.001); however, after the 12-week retention period only the training effects of HDL-C (P < 0.05) and VO2max (P < 0.05) remained robust. Additionally, music-synchronised walking was found to reduce the fat ratio (P = 0.031), while paced walking was found to reduce body mass (P = 0.049).ConclusionsThe significant pre–post changes in health-related outcomes across the 24-week walking intervention, including improved blood composition, longer step length, and better cardiorespiratory capacity, show that this intervention is promising for improving health and fitness. When, during the retention period, the participants resumed their usual lifestyles without supervised exercise, most physiological biomarkers deteriorated. Thus, for sedentary middle-aged females, persistent behavioural change is necessary to retain the health benefits of physical exercise.

Effects of exercise types on white matter microstructure in late midlife adults: Preliminary results from a diffusion tensor imaging study.

Higher aerobic fitness during late midlife is associated with higher white matter (WM) microstructure. Compared with individuals engaged in irregular exercise, those who engage in regular aerobic exercise show higher fractional anisotropy (FA), a diffusion tenor imaging (DTI) measure that provides an index of WM microstructural integrity. However, whether other types of exercise, such as Tai Chi, can also facilitate WM changes in adults during late midlife remains unknown. The present study compares two types of exercise, Tai Chi and walking, with a sedentary control group, in order to examine the effects of exercise on WM microstructure and determine the regional specificity of WM differences. Thirty-six healthy adults between the ages of 55 and 65 years participated in the study. Based on the participants' exercise habits, they were allocated into three groups: Tai Chi, walking, or sedentary control. All participants were required to complete physical fitness measurements and completed magnetic reasoning imaging (MRI) scans. Our results revealed that the Tai Chi group exhibited a higher FA value in the left cerebral peduncle, compared to the sedentary control group. We also observed that both the Tai Chi and walking groups exhibited higher FA values in the right uncinate fasciculus and the left external capsule, in comparison to the sedentary control group. Increased FA values in these regions was positively correlated with higher levels of physical fitness measurements (i.e., peak oxygen uptake [VO2peak], muscular endurance/number of push-up, agility, power). These findings collectively suggest that regular exercise is associated with improved WM microstructural integrity, regardless of the exercise type, which could guide the development and application of future prevention and intervention strategies designed to address age-related cognitive impairments during late midlife.

Bilateral constrained control for prosthesis walking on stochastically uneven terrain

The stochastic characteristic of uneven terrain is the leading cause of stochastic ground reaction forces, hindering gait coordination between the lower-limb prosthesis and healthy limb. Therefore, dedicated modeling and control methods for prosthesis walking on uneven terrain should be urgently provided. Noting that the stochastic feature originates from uneven ground contact, this paper first applies data-driven modeling to accurately represent the stochastic ground reaction forces. Then, an extended stochastic dynamic model for the amputee walking on uneven terrain is established based on this representation. Accordingly, a stochastic-gait-coordination (SGC) oriented control architecture is proposed and realized via the bilateral constrained adaptive neural controller (BC-ANC), where BC is designed to ensure disturbance boundness, and ANC is employed to handle system uncertainty. Rigorous stochastic stability analysis of the proposed architecture, i.e., BC-ANC, is also provided by deriving an asymmetric barrier Lyapunov function based on the backstepping technique. The study reveals that the controlled states in the stochastic dynamic system promise semi-globally uniformly ultimately bounded (SGUUB) in probability. Furthermore, prediction studies are deployed, showing that BC-ANC is more efficient than existing controllers.

Influence of brake-disc friction characteristics on anti-skid braking control system of aircraft

The low-frequency landing gear walk of aircraft during braking processis studied. Firstly, by virtual of LMS Virtual.Lab motion software, the multi-body dynamic model of the landing gear is established, the motion pair and internal and external loads are applied, and the torsion spring is set at the connection between the landing gear and the fuselage to simulate the flexibility of the landing gear. Then, the variation of friction coefficient of brake discis considered in the model of braking pressure and torque. When the braking control system works, if the braking pressure is less than the limit value, the gear walk is less affected by the friction characteristics of the brake disc. If the braking pressure reaches the limit value, the law of gear walk is the same as that of the pilot's manual control of the braking pressure. At this time, the gear walk is only affected by the positive and negative slope of the friction coefficient of the brake disc. If the friction coefficient curve of the brake disc presents a negative slope, it may cause gear walk, and the greater the absolute value of the slope, the more obvious the gear walk is. Improving the friction characteristics of brake discs can provide a new strategy forgear walk control.

An integrative insight into the synsacral canal of fossil and extant Antarctic penguins.

The lumbosacral-canal system in birds most likely operates as a sense organ involved in the control of balanced walking and perching, but our knowledge of it is superficial. Penguins constitute interesting objects for the study of this system due to their upright walking, but only the Humboldt penguin, Spheniscus humboldti, and some incomplete fossil penguin synsacra have been studied in this respect. Here, we give an integrative comparative insight into the synsacral canal of extant Emperor penguin, Aptenodytes forsteri, Adelie penguin, Pygoscelis adeliae, and Eocene giant Anthropornis and/or Palaeeudyptes Antarctic penguins, using computed tomography imaging and associated data-extraction methodologies, complemented by analytical approaches ranging from geometric morphometrics to modularity, curvature, and wavelet analyses. We document that the variability in the number of synsacro-lumbar vertebrae is evolutionarily conserved, and all studied synsacra possess osteological correlates of the lumbosacral-canal system. We also found that Eocene and extant Antarctic penguins were separable on the basis of the main direction of the shape-related (size-independent) variability within said system, and A. forsteri was unique in the entire studied set in terms of the relative cranial shift of this compound structure. Moreover, we suggest that the evolutionary processes, shaping both the terrestrial posture and gait, were responsible, in extant penguins, for the increased simplicity and stability of the synsacral canal cross-sectional periodic patterns, as well as pave the way for the lumbosacral-canal system modularity characterized by reduced atomization/complexity.

The relationship between motor pathway damage and flexion-extension patterns of muscle co-excitation during walking.

Mass flexion-extension co-excitation patterns during walking are often seen as a consequence of stroke, but there is limited understanding of the specific contributions of different descending motor pathways toward their control. The corticospinal tract is a major descending motor pathway influencing the production of normal sequential muscle coactivation patterns for skilled movements. However, control of walking is also influenced by non-corticospinal pathways such as the corticoreticulospinal pathway that possibly contribute toward mass flexion-extension co-excitation patterns during walking. The current study sought to investigate the associations between damage to corticospinal (CST) and corticoreticular (CRP) motor pathways following stroke and the presence of mass flexion-extension patterns during walking as evaluated using module analysis. Seventeen healthy controls and 44 stroke survivors were included in the study. We used non-negative matrix factorization for module analysis of paretic leg electromyographic activity. We typically have observed four modules during walking in healthy individuals. Stroke survivors often have less independently timed modules, for example two-modules presented as mass flexion-extension pattern. We used diffusion tensor imaging-based analysis where streamlines connecting regions of interest between the cortex and brainstem were computed to evaluate CST and CRP integrity. We also used a coarse classification tree analysis to evaluate the relative CST and CRP contribution toward module control. Interhemispheric CST asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.023), propulsion symmetry (p = 0.016), and fewer modules (p = 0.028). Interhemispheric CRP asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.009), Dynamic gait index (p = 0.035), Six-minute walk test (p = 0.020), Berg balance scale (p = 0.048), self-selected walking speed (p = 0.041), and propulsion symmetry (p = 0.001). The classification tree model reveled that substantial ipsilesional CRP or CST damage leads to a two-module pattern and poor walking ability with a trend toward increased compensatory contralesional CRP based control. Both CST and CRP are involved with control of modules during walking and damage to both may lead to greater reliance on the contralesional CRP, which may contribute to a two-module pattern and be associated with worse walking performance.

Is there frequency-specificity in the motor control of walking? The putative differential role of alpha and beta oscillations.

Alpha and beta oscillations have been assessed thoroughly during walking due to their potential role as proxies of the corticoreticulospinal tract (CReST) and corticospinal tract (CST), respectively. Given that damage to a descending tract after stroke can cause walking deficits, detailed knowledge of how these oscillations mechanistically contribute to walking could be utilized in strategies for post-stroke locomotor recovery. In this review, the goal was to summarize, synthesize, and discuss the existing evidence on the potential differential role of these oscillations on the motor descending drive, the effect of transcranial alternate current stimulation (tACS) on neurotypical and post-stroke walking, and to discuss remaining gaps in knowledge, future directions, and methodological considerations. Electrophysiological studies of corticomuscular, intermuscular, and intramuscular coherence during walking clearly demonstrate that beta oscillations are predominantly present in the dorsiflexors during the swing phase and may be absent post-stroke. The role of alpha oscillations, however, has not been pinpointed as clearly. We concluded that both animal and human studies should focus on the electrophysiological characterization of alpha oscillations and their potential role to the CReST. Another approach in elucidating the role of these oscillations is to modulate them and then quantify the impact on walking behavior. This is possible through tACS, whose beneficial effect on walking behavior (including boosting of beta oscillations in intramuscular coherence) has been recently demonstrated in both neurotypical adults and stroke patients. However, these studies still do not allow for specific roles of alpha and beta oscillations to be delineated because the tACS frequency used was much lower (i.e., individualized calculated gait frequency was used). Thus, we identify a main gap in the literature, which is tACS studies actually stimulating at alpha and beta frequencies during walking. Overall, we conclude that for beta oscillations there is a clear connection to descending drive in the corticospinal tract. The precise relationship between alpha oscillations and CReST remains elusive due to the gaps in the literature identified here. However, better understanding the role of alpha (and beta) oscillations in the motor control of walking can be used to progress and develop rehabilitation strategies for promoting locomotor recovery.

Perception of object motion during self-motion: Correlated biases in judgments of heading direction and object motion.

This study investigated the relationship between perceived heading direction and perceived motion of an independently moving object during self-motion. Using a dual task paradigm, we tested whether object motion judgments showed biases consistent with heading perception, both across conditions and from trial to trial. Subjects viewed simulated self-motion and estimated their heading direction (Experiment 1), or walked toward a target in virtual reality with conflicting physical and visual cues (Experiment 2). During self-motion, an independently moving object briefly appeared, with varied horizontal velocity, and observers judged whether the object was moving leftward or rightward. In Experiment 1, heading estimates showed an expected center bias, and object motion judgments showed corresponding biases. Trial-to-trial variations were also correlated: on trials with a more rightward heading bias, object motion judgments were consistent with a more rightward heading, and vice versa. In Experiment 2, we estimated the relative weighting of visual and physical cues in control of walking and object motion judgments. Both were strongly influenced by nonvisual cues, with less weighting for object motion (86% vs. 63%). There were also trial-to-trial correlations between biases in walking direction and object motion judgments. The results provide evidence that shared mechanisms contribute to heading perception and perception of object motion.

Effects of rhythmic auditory cueing on gait variability and voluntary control of walking -a cross-sectional study.

Temporal gait variability is strongly associated with motor function and falls in the context of numerous diseases. Rhythmic auditory cueing (RAC) can influence stride-to-stride time, although its effects on temporal gait variability remain unclear. Therefore, the aim of the present cross-disease study was to examine the effects of RAC on stride time variability (STV), as well as the factors affecting changes in STV during walking with RAC. Participants with post-stroke (n=12) and orthopedic disease (n=23) performed a random block design under four conditions: comfortable walking speed (CWS) and walking with RAC (RAC 0%, RAC +10%, RAC -10%). STV was measured along with co-contraction and inter-muscular coherence of the shank muscles during walking for each condition. The contributions of the muscle activity pattern and voluntary control to the change in STV between the CWS and RAC 0% conditions were examined using hierarchical multiple regression analysis. STV was significantly lower in the RAC 0% condition than in the CWS condition (p=0.03). Hierarchical multiple regression analysis revealed that the change in STV was explained by STV in the CWS condition (β=-0.36) and by changes in co-contraction (β=0.43) and inter-muscular coherence (β=0.38) during the stance phase between the CWS and RAC 0% conditions (R2=0.56, p<0.001). These findings indicate that walking training with RAC is effective in reducing gait variability and immediately improves muscle activity patterns and excessive corticospinal activity.