Root Mean Square Acceleration Research Articles

Energy dissipation by friction for sliding blocks subjected to near-fault seismic base motion

The objective of this study was to determine friction ratios that maximize energy dissipation on a seismic damper. The aforementioned friction damper basically consists of mass blocks that are able to slide on a flat surface. To carry out this analysis, a numerical-experimental approach was used. Firstly, the theoretical background and equations of motion for a SDOF system consisting of a mass supported on a flat surface with friction are introduced. Special emphasis is made on the fundamentals of stick-slip motion as well as energy considerations. Secondly, experimental studies carried out on a shaking table with harmonic and seismic records are described. These tests consisted of lead blocks contained on a U-shaped channel type aluminum section with its open end facing upwards. This configuration allowed blocks to slide solely in the direction of the base motion. Five different types of contact interfaces were considered to determine potential friction coefficients for the damper's design. Additionally, computational models based on rigid-body dynamics are presented. Numerical results were satisfactory particularly when comparing model's dissipated energy with empirical results. An analysis was carried out by calculating dissipated energy for the experimentally-calibrated models with varying friction ratios. For this purpose, eight near-fault seismic records were selected. Intervals with friction coefficients that maximize energy dissipation are proposed for each record. Finally, relationships between the computed friction ratios and register's peak ground acceleration (PGA) and root mean square acceleration (RMS) are discussed.

Research on ride comfort of vibratory rollers: Part-2 Cab’s semi-active HPM with fuzzy control

In order to further enhance the ride quality of vibratory roller’s cab used by the hydro-pneumatic mounts (HPM), based on a nonlinear dynamics model of the vibratory rollers under interaction of the deformable terrain and drum established based on Matlab/Simulink software, a semi-active cab’s HPM of vibratory rollers are then controlled by using the Fuzzy controller. The root-mean-square (RMS) of the accelerations of the vertical driver’s seat and the cab’s pitch angle have been used as objective studies. The research results indicate that the ride comfort of the driver's seat and the shaking of the cab are greatly affected under the deformable soil grounds, especially under a soft soil ground. However, with the HPM using the Fuzzy control, the RMS accelerations of the driver’s seat and cab pitch angle have been remarkably decreased by 40.1 % and 22.2 % under a hard soil ground. Therefore, the ride quality of the vibratory roller has been enhanced by the semi-active HPM.

Measurement of the three-axis vibration, temperature, and relative humidity profiles of commercial transport trailers for pigs.

The objective of this study was to collect and interpret three-axis acceleration, temperature, and relative humidity data from six locations within commercial transport trailers shipping market-weight pigs. Transport was observed in Kansas (n = 15) and North Carolina (n = 20). Prior to loading, three-axis accelerometers were affixed to six locations on the trailers: top fore (TF), top center (TC), top aft (TA), bottom fore (BF), bottom center (BC), and bottom aft (BA) compartments. Data were post-processed to calculate root-mean-square (RMS) accelerations and vibration dose values (VDV) in the vertical direction and the horizontal plane. These values were compared with exposure action values (EAV) and exposure limit values (ELV), vibration levels deemed uncomfortable and potentially dangerous to humans. Additionally, RMS and VDV were compared among the trailer compartments. The vertical RMS accelerations for all compartments exceeded the EAV for loads measured in Kansas, and for the majority of the compartments measured in North Carolina. Many compartments, specifically the BA compartment from all trips, exceeded the vertical ELV. Regardless of where the data were collected, fewer compartments exceeded the EAV in the horizontal orientation. Only BA compartments exceeded the ELV in the horizontal orientation. There were Area × Level interactions for vertical and horizontal RMS and VDV (P < 0.01). The BF compartment had a greater vertical RMS value than the TF, TC, and BC (P < 0.02) compartments, but did not differ (P = 0.06) from the TA compartment. The vertical RMS of the TA compartment did not differ from the TF, TC, and BC compartments (P > 0.13). The BF compartment had a greater (P = 0.02) vertical VDV value than the TC location, but did not differ from the other locations (P > 0.16). All other locations did not differ in vertical VDV (P > 0.12). The BF compartment had greater horizontal RMS than the TC and TA compartments (P < 0.01), but did not differ from TF and BC compartments (P > 0.12). All other compartments did not differ in horizontal RMS (P > 0.34). All compartments, aside from the BA compartment, did not differ in horizontal VDV (P > 0.19). Vibration analyses indicated the BA compartment had the greatest vertical and horizontal vibrations and a large percentage of the compartments exceed the EAV and ELV, which indicated pigs may have experienced uncomfortable trips that could cause discomfort or fatigue.

Intersession reliability of GPS-based and accelerometer-based physical variables in small-sided games with and without the offside rule

This study aimed to analyze the intersession reliability of global positioning system (GPS-based) distances and accelerometer-based (acceleration) variables in small-sided soccer games (SSG) with and without the offside rule, as well as compare variables between the tasks. Twenty-four high-level U-17 soccer athletes played 3 versus 3 (plus goalkeepers) SSG in two formats (with and without the offside rule). SSG were performed on eight consecutive weeks (4 weeks for each group), twice a week. The physical demands were recorded using a GPS with an embedded triaxial accelerometer. GPS-based variables (total distance, average speed, and distances covered at different speeds) and accelerometer-based variables (Player Load™, root mean square of the acceleration recorded in each movement axis, and the root mean square of resultant acceleration) were calculated. Results showed that the inclusion of the offside rule reduced the total distance covered (large effect) and the distances covered at moderate speed zones (7–12.9 km/h – moderate effect; 13–17.9 km/h – large effect). In both SSG formats, GPS-based variables presented good to excellent reliability (intraclass correlation coefficients – ICC &gt; 0.62) and accelerometer-based variables presented excellent reliability (ICC values &gt; 0.89). Based on the results of this study, the offside rule decreases the physical demand of 3 versus 3 SSG and the physical demands required in these SSG present high intersession reliability.

Comfort improvement in railway vehicles via optimal control of adaptive pneumatic suspensions

ABSTRACT This paper presents an adaptive optimal control strategy focused on improving ride comfort by minimising the root mean square of accelerations measured at seven locations on the carbody floor. It requires preview knowledge of both the train speed and the standard track quality (not the deterministic track disturbances) and differs from other works in considering pointwise constraints (upper and lower secondary suspension travel limits). Adaptive control is achieved by varying the diameter of the restriction orifice which connects the pneumatic spring to the auxiliary air reservoir, which confers different dynamic stiffness and damping to the front and rear secondary suspensions. Decision maps with the front and rear optimal diameters for five track irregularity levels and six different speeds were obtained using a Monte Carlo strategy based on solving the optimal control problem for 240 stochastic realisations of time-varying track irregularities of 300 s. Results show that the adaptive optimal control provides a successful compromise between comfort and safety which overshadows the conventional passive approach: it improves comfort up to 50% with respect to stiff passive configurations and it guarantees constraint fulfilment unlike compliant passive configurations.

On the feasibility of IoT-based smart meters for earthquake early warning

The microelectromechanical systems (MEMS) accelerometer built into a smart meter (SM) has a nominal digital resolution of 16 bits. However, this resolution collapses to 7 bits of information per sample when used in an urban environment. This collapse in resolution limits the sensitivity required to effectively operate the earthquake early warning platform (EEWP). In this study, we evaluate the performance of the MEMS sensor in present SMs with respect to a reference sensor, with a special focus on its poor noise power spectral density (PSD, [Formula: see text]). We also explore the general capacity of the SM in an IoT-based EEWP and provide explicit information regarding the 16-bit digital MEMS accelerometer. Then, we investigate the functionality of the sensor in the context of event detection in the presence of background vibration. When the value of acceleration root mean square (RMS) exceeds 20 mg, the meter’s error decreases to &lt;20%, whereas the peak ground acceleration error decreases to &lt;20% for the peak value greater than ~70 mg. The MEMS sensor is unreliable for motions with a peak acceleration of less than 148 mg or those with an RMS value less than 46 mg. However, we note that SMs exhibit reasonable amplitude and phase coherence for frequencies above 1 Hz with respect to the reference accelerometer. To enhance the sensitivity, averaging 1000 coherent accelerometer observations enhances the digital resolution to 14 bits, which allows the efficient usage of the network bandwidth. Since the accelerometer is used as an anti-tampering mechanism, the SM is similar to a tiltmeter. Therefore, it is necessary to reconfigure SMs for early warning systems. Despite the challenges, the use of SM for an IoT-based EEWP is technically feasible.

Evaluation of tractor driving comfort according to the steering angle and speed using a virtual prototype

As tractors mainly transit rural roads, drivers can suffer from harmful vibrations transmitted though their seats. Thus, the driving comfort in tractors with agricultural equipment should be evaluated. To investigate the effects of forward motion and front-wheel steering on the driving comfort of two-wheel-drive tractors with agricultural equipment, we establish a man–machine–road virtual prototype for simulations and validate it experimentally. First, a tractor that has suspended agricultural equipment and is operating at front-wheel steering angles of 0°, 12°, 24°, and 36° is driven on a random level-D road. Simultaneously, the vibration accelerations experienced by the driver are obtained along the X, Y, and Z axes with the coordinate system defined according to the ISO 2631-1 standard. The combined weighted root-mean-square (RMS) acceleration corresponding to the driver’s whole-body vibration increases from 0.205 to 0.909 m/s2 when increasing the steering angle. Then, considering the forward speed as the variable, the front-wheel steering angle is set at 30°, and the vibration accelerations experienced by the driver are obtained when the tractor travels at 4, 5, and 6 km/h on a random level-D road. The combined weighted RMS acceleration corresponding to the driver’s whole-body vibration increases from 0.68 to 1.03 m/s2 when increasing the speed. Therefore, we found that the velocity of a tractor should be reduced while steering, and excessively large front-wheel steering angles should be avoided to increase driving comfort.

Vibration research of heavy trucks. Part 1: Sensitivity analysis of dynamic parameters on ride comfort

In order to study the influence of heavy truck dynamic parameters on the vehicle’s ride comfort under the random road excitation, the weighted RMS (root-mean-square) acceleration responses of the vertical driver’s seat and cab pitch angle are chosen as objective function, a dynamic model of the vehicle with 10 degrees of freedom is established to simulate and analyze the results. The influence of different parameters of all the suspension systems of the vehicle, such as the stiffness and damping of the suspensions of the seat, cab, vehicle, and wheel, on the vertical driver’s seat and cab pitch angle are respectively analyzed. The study results show that the influence of the stiffness and damping parameters in the suspension systems on the vehicle ride comfort is very obvious. The vehicle’s ride comfort changes worse with the increase of the suspension stiffness and the reduction of the suspension damping, and vice versa. The study proposes an optimal range of the stiffness and damping parameters for the optimal design and control of the vehicle suspension systems, concurrently, the study can also provide a theoretical basis for the suspension system designed for heavy trucks.

Vibration research of heavy trucks. Part 2: Optimization of vehicle dynamic parameters

In order to enhance the ride comfort, stability, and safety of heavy trucks. Based on the dynamic characteristics of the parameters of heavy trucks and its dynamic model, a multi-objective genetic algorithm are developed in the MATLAB environment and applied to optimize the dynamic parameters of vehicles. The weighted root-mean-square (RMS) accelerations of the cab and driver seat vibrations are chosen as the study goals to evaluate the results under different vehicle conditions. The obtained results show that the optimal parameters of vehicles are significantly enhanced the vehicle ride comfort under different operation conditions. Particularly, the weighted RMS accelerations of the awz and awφc are significantly reduced by 26.3 % and 35.3 % under the ISO level B of the road surface, and a vehicle speed region from 17.5 m/s to 20 m/s (63 km/h to 72 km/h).

Semi-Active Scissors-Seat Suspension With Magneto-Rheological Damper

A cab seat suspension with a magneto-rheological (MR) fluid damper is introduced in this paper. A unified-format model for the MR damper is proposed to describe the dynamic characteristics of the MR damper. Also, a simple force-inverse model and a viscous damping tracking model are used for the coil current solution. A digital integrator and an extended Kalman filter are respectively adopted to obtain the vibration velocity of the chair frame and the relative motion velocity of the MR damper piston. A new skyhook control base with viscous damping tracking is applied to the semi-active seat suspension. In the simulation, compared with passive seat suspension under different displacement excitation (2, 4, 6, 8 Hz-sine, and random), the acceleration root mean square of the seat suspension with the MR damper is reduced by 52.2%, 32.2%, 41.3%, 50.8%, and 34.6%, respectively. In the experiment, the acceleration root mean square is reduced by 11.2%, 41.2%, 45.8%, and 31.5%, respectively under different displacement excitation (2, 4, 6, and 8 Hz-sine).

Validation of a smartphone embedded inertial measurement unit for measuring postural stability in older adults

BackgroundIdentifying older adults with increased fall risk due to poor postural control on a large scale is only possible through omnipresent and low cost measuring devices such as the inertial measurement units (IMU) embedded in smartphones. However, the correlation between smartphone measures of postural stability and state-of-the-art force plate measures has never been assessed in a large sample allowing us to take into account age as a covariate. Research questionHow reliably can postural stability be measured with a smartphone embedded IMU in comparison to a force plate? MethodsWe assessed balance in 97 adults aged 50–90 years in four different conditions (eyes open, eyes closed, semi-tandem and dual-task) in the anterio-posterior and medio-lateral directions. We used six different parameters (root mean square and average absolute value of COP displacement, velocity and acceleration) for the force plate and two different parameters (root mean square and average absolute value of COM acceleration) for the smartphone. ResultsTest-retest reliability was smaller for the smartphone than for the force plate (intra class correlation) but both devices could equally well detect differences between conditions (similar Cohen’s d). Parameters from the smartphone and the force plate, with age regressed out, were moderately correlated (robust correlation coefficients of around 0.5). SignificanceThis study comprehensively documents test-retest reliability and effect sizes for stability measures obtained with a force plate and smartphone as well as correlations between force plate and smartphone measures based on a large sample of older adults. Our large sample size allowed us to reliably determine the strength of the correlations between force plate and smartphone measures. The most important practical implication of our results is that more repetitions or longer trials are required when using a smartphone instead of a force plate to assess balance.

International Roughness Index Thresholds Based on Whole-Body Vibration in Passenger Cars

This study analyzed whole-body vibration (WBV) on a car seat (seat surface and feet) in passenger cars as a function of longitudinal road roughness. Measurements were provided on nine different cars in six categories and included a total travel distance of 1,860 km. The root mean square (RMS) of the frequency-weighted acceleration was used to quantify WBV. The relationship between seat acceleration response and comfort reactions according to the ISO 2631-1 and the International Roughness Index (IRI) was estimated. IRI thresholds were proposed as a function of vehicle speed and road category. Proposed IRI thresholds decreased with vehicle velocity and were similar with published IRI threshold proposals based on simulation. IRI thresholds as a function of speed limit should decrease with power by approximately –0.75. Substantially lower (by ~ 40%) IRI thresholds were calculated for the total vibration value (six signals) in comparison with vertical vibration on the seat surface.

A Novel Accelerometer Mounting Method for Sensing Performance Improvement in Acoustic Measurements From the Knee.

In this study, we propose a new mounting method to improve accelerometer sensing performance in the 50 Hz-10 kHz frequency band for knee sound measurement. The proposed method includes a thin double-sided adhesive tape for mounting and a 3D-printed custom-designed backing prototype. In our mechanical setup with an electrodynamic shaker, the measurements showed a 13 dB increase in the accelerometer's sensing performance in the 1-10 kHz frequency band when it is mounted with the craft tape under 2 N backing force applied through low-friction tape. As a proof-of-concept study, knee sounds of healthy subjects (n = 10) were recorded. When the backing force was applied, we observed statistically significant (p < 0.01) incremental changes in spectral centroid, spectral roll-off frequencies, and high-frequency (1-10 kHz) root-mean-square (RMS) acceleration, while low-frequency (50 Hz-1 kHz) RMS acceleration remained unchanged. The mean spectral centroid and spectral roll-off frequencies increased from 0.8 kHz and 4.15 kHz to 1.35 kHz and 5.9 kHz, respectively. The mean high-frequency acceleration increased from 0.45 mgRMS to 0.9 mgRMS with backing. We showed that the backing force improves the sensing performance of the accelerometer when mounted with the craft tape and the proposed backing prototype. This new method has the potential to be implemented in today's wearable systems to improve the sensing performance of accelerometers in knee sound measurements.

Comfort evaluation of bridge based on stochastic process theory

Vehicle or pedestrian loads can cause bridge vibration. The pedestrian load is essentially a stochastic process, and the vibration response of pedestrian bridges is also a stochastic process. In order to evaluate the human comfort of a pedestrian bridge comprehensively, this paper presents a comfort evaluation method based on stochastic process theory. The autocorrelation function of the displacement response of a pedestrian bridge under random pedestrian load is derived in this paper. On this basis, the root mean square (RMS) of acceleration is proposed as the comfort evaluation index. Taking an asymmetric single-tower cable-stayed bridge as an example, the modal analysis of the bridge is proceeded by finite element method (FEM). Then the acceleration time histories of four measuring points are obtained by fi eld experiment. FEM results and fi eld experiment results are used to analyse random vibration of the bridge. Through a fi eld experiment and random vibration analysis of the bridge, the acceleration peak value evaluation index and the RMS of acceleration value evaluation index are compared. The results show that the RMS of acceleration index is more comprehensive and reasonable because it considers the whole-time history of the vibration response. The RMS of acceleration index is based on stochastic process theory, so it is more rigorous in mathematical expression and clearer in physical concept. It provides a reference for the evaluation of pedestrian bridge comfort.

Evaluation of dynamic responses of bridges considering traffic flow and surface roughness

The variations in the vehicle types, speeds, and passing order in the traffic flow and roughness conditions cause the dynamic effects of live loads on the bridges. In this study, a numerical calculation scheme is proposed to evaluate the bridge dynamic response under random traffic flow, considering the surface roughness condition. Traffic vehicles with a random passing order are constructed as the time history of the transient force functions assigned at each discretised deck node of the numerical model. The random effects of the vehicle types, speeds, and surface roughness are represented by the amplitude levels of the transient force functions. The validity of the calculation scheme is verified by applying it to an existing steel box-girder bridge using dynamic monitoring data, traffic data, and a finite element model. The behaviour of the calculated root mean square (RMS) of the accelerations agrees with that of the measurement data, particularly in the traffic situation with a high truck ratio. Moreover, a parametric study is conducted to investigate the effects of the traffic flow characteristics and surface roughness conditions on the bridge dynamic responses. The results demonstrate that the RMS of acceleration depends on the truck ratio and traffic flow speed; however, the maximum acceleration may be influenced by the vehicle speed and passing order, as well as the surface roughness condition. It is concluded that the calculation scheme is applicable for evaluating the dynamic responses of existing bridges with the given dynamic monitoring data, traffic flow, and surface roughness conditions.

The direction of postural threat alters balance control when standing at virtual elevation.

Anxiogenic settings lead to reduced postural sway while standing, but anxiety-related balance may be influenced by the location of postural threat in the environment. We predicted that the direction of threat would elicit a parallel controlled manifold relative to the standing surface, and an orthogonal uncontrolled manifold during standing. Altogether, 14 healthy participants (8 women, mean age = 27.5years, SD = 8.2) wore a virtual reality (VR) headset and stood on a matched real-world walkway (2m × 40cm × 2cm) for 30s at ground level and simulated heights (elevated 15m) in two positions: (1) parallel to walkway, lateral threat; and (2) perpendicular to walkway, anteroposterior threat. Inertial sensors measured postural sway acceleration (e.g., 95% ellipse, root mean square (RMS) of acceleration), and a wrist-worn monitor measured heart rate coefficient of variation (HR CV). Fully factorial linear-mixed effect regressions (LMER) determined the effects of height and position. HR CV moderately increased from low to high height (p = 0.050, g = 0.397). The Height × Position interaction approached significance for sway area (95% ellipse; β = - 0.018, p = 0.062) and was significant for RMS (β = - 0.022, p = 0.007). Post-hoc analyses revealed that sagittal plane sway accelerations and RMS increased from low to high elevation in parallel standing, but were limited when facing the threat during perpendicular standing. Postural response to threat varies depending on the direction of threat, suggesting that the control strategies used during standing are sensitive to the direction of threat.

Material optimization of tuned liquid column ball damper (TLCBD) for the vibration control of multi-storey structure using various liquid and ball densities

In this study, a modified form of tuned liquid column damper (TLCD) for multi-degree of freedom (MDOF) structure is presented, which is termed as tuned liquid column ball damper (TLCBD). TLCBD is a passive vibration control device used for the reduction of response induced from earthquake or wind loads. Instead of orifice, a spherical ball is used in the TLCBD for increase in the damping effect by resisting the water motion. TLCBD is placed on the top storey of a 4-storey steel frame, and its effect on vibration response is investigated experimentally. For performance optimization, a combination of varying densities of ball and liquid are used in the TLCBD. The optimal performance of TLCBD is studied under different excitations including harmonic and seismic loadings, through a series of shake table tests. Root mean square (RMS) acceleration is calculated against each loading and for each storey, for all combinations of balls and liquids. In order to better understand the response, percentage reduction of RMS acceleration is also determined, for all combinations. The results confirm that the response reduction for TLCBD controlled structure with liquid and ball having high densities is significantly better as compared to other combinations of liquids and ball having low densities. Moreover, the response reduction for TLCBD is more effective in the seismic excitations as compared to harmonic excitations.

Testing output variables for sensitivity study of nonlinear vibration systems

Abstract:In this study the detailed One-at-a-Time sensitivity analysis of nonlinear mass spring-damper systems is carried out with numerical simulation. The degree of sensitivity was measured with a sensitivity index and based on its sensitivity Fuzzy-sets were established. The sensitivity of a parameter then can be expressed by the membership to the Fuzzy-sets. In this study the root mean square of acceleration, the maximum amplitude of acceleration and the peak frequency were chosen as output variables to measure sensitivity. With this research it was proven, that the root mean square of acceleration and the peak frequency can be used for sensitivity study of nonlinear vibration systems effectively.

A-25 The Effect of Cognitive Dual-Tasks on Dynamic Postural Sway During Sub-Maximal Gait on a Treadmill

Abstract Objective To investigate the effect of a cognitive task on postural control during treadmill walking. We hypothesized that postural sway acceleration would decrease during dual-task compared to single-task gait. Method Ten (5 females, 5 males) physically active, healthy young adults (Age: 22.50 ± 3.01) with no history of cognitive deficits or head injury were recruited from a University campus for this cross-sectional study. Participants reported to a biomechanics laboratory for a single testing session and completed two, 5-minute walking trials on a treadmill at 90% of maximal gait-speed under single and dual-task conditions while instrumented with a single inertial measurement unit (IMU) on the lower-back. During dual-task gait, participants concurrently performed a Stroop Test displayed on a mounted screen in front of the treadmill during the entire trial. Root mean square (RMS) of acceleration was analyzed in the medial-lateral, anterior-posterior, superior-inferior, and resultant planes during the dual-task trial. Paired t-tests and effect sizes (ES) were calculated for each sway plane between single and dual-tasks. Results No differences were identified between single and dual-task RMS acceleration in the medial-lateral (p = 0.98, ES = 0.01), anterior-posterior (p = 0.49, ES = 0.23) or superior-inferior (p = 0.98, ES = 0.01) planes. However, the RMS acceleration in the resultant plane was lower in the dual-task condition (Mean Difference: 0.031 ± 0.037; p = 0.02, ES = 0.85). Conclusions This novel dual-task gait paradigm utilized constant sub-maximal gait speed to investigate the influence of a sustained cognitive dual-task on postural sway using a single IMU. These preliminary results indicate that this dual-task gait paradigm may affect gross postural sway in healthy adults.

A Mobile Phone-Based Gait Assessment App for the Elderly: Development and Evaluation.

BackgroundGait disorders are common among older adults. With an increase in the use of technology among older adults, a mobile phone app provides a solution for older adults to self-monitor their gait quality in daily life.ObjectiveThis study aimed to develop a gait-monitoring mobile phone app (Pocket Gait) and evaluate its acceptability and usability among potential older users.MethodsThe app was developed to allow older adults to track their gait quality, including step frequency, acceleration root mean square (RMS), step regularity, step symmetry, and step variability. We recruited a total of 148 community-dwelling older adults aged 60 years and older from two cities in China: Beijing and Chongqing. They walked in three ways (single task, dual task, and fast walking) using a smartphone with the gait-monitoring app installed and completed an acceptability and usability survey after the walk test. User acceptability was measured by a questionnaire including four quantitative measures: perceived ease of use, perceived usefulness, ease of learning, and intention to use. Usability was measured using the System Usability Scale (SUS). Interviews were conducted with participants to collect open-ended feedback questions.ResultsTask type had a significant effect on all gait parameters, namely, step frequency, RMS, step variability, step regularity, and step symmetry (all P values <.001). Age had a significant effect on step frequency (P=.01), and region had a significant effect on step regularity (P=.04). The acceptability of the gait-monitoring app was positive among older adults. Participants identified the usability of the system with an overall score of 59.7 (SD 10.7) out of 100. Older adults from Beijing scored significantly higher SUS compared with older adults from Chongqing (P<.001). The age of older adults was significantly associated with their SUS score (P=.048). Older adults identified improvements such as a larger font size, inclusion of reference values for gait parameters, and inclusion of heart rate and blood pressure monitoring.ConclusionsThis mobile phone app is a health management tool for older adults to self-manage their gait quality and prevent adverse outcomes. In the future, it will be important to take factors such as age and region into consideration while designing a mobile phone–based gait assessment app. The feedback of the participants would help to design more elderly-friendly products.