Acceleration Curves Research Articles

Kinematics modeling and trajectory planning of KUKA manipulator based on MATLAB

For the purpose of engraving, KUKA KR60 mechanical arm was used in the laboratory for research and analysis.Firstly, the improved D-H parameter method was used to establish the D-H coordinate system of the manipulator, and the kinematic equation of the manipulator was obtained by calculating the homogeneous transformation matrix.Secondly, mathematical modeling was carried out with MATLAB Robbtics Toolbox, and the forward and inverse kinematics problems were analyzed and demonstrated to verify the correctness of the kinematic model of the mechanical arm. Thirdly, Monte Carlo method was used to calculate the movement Angle of the mechanical arm joint to reach the working area. Finally, trajectory planning was adopted.The variation curves of Angle, angular velocity and angular acceleration were obtained, and the rationality of its trajectory planning was verified by simulation analysis, which provided a research basis for the next step of carving trajectory path optimization.

A drive system global control strategy for electric vehicle based on optimized acceleration curve

The existing researches of electric vehicle (EV) drive system mainly focus on the motor itself, without considering the EV energy consumption and battery life simultaneously. Thence, in this paper, a control method of EV drive system based on its energy consumption and battery life is proposed. Combining the EV driving state with the motor control, the relationship between the velocity and acceleration and the optimal dq-axis currents is established. Then, a drive system global control strategy for EV based on optimized acceleration curve is proposed, in which the maximum torque per ampere (MTPA) control is used below motor base speed and the voltage closed-loop feedback flux weakening control is used above motor base speed. Furthermore, the proposed control strategy is verified by both MATLAB/Simulink simulation and experiment. The simulation and experimental results show that compared with original working conditions, the energy consumption per kilometer and the percentage of battery capacity loss per kilometer of the global control strategy based on optimized acceleration curve are both reduced, which verifies the feasibility and effectiveness of the proposed control strategy.

Analysis of characteristics about far-side occupant’s chest injury during oblique side impact

The chest is one of the most frequently injured body parts during a side impact. In this study, the effects of impact angle, impact speed, and D-ring position on the occupant’s chest injury in the far-side crash were analyzed. First, a model with a sled and a Test Human Occupant Restraint (THOR) dummy was established. Second, the acceleration curves with peaks of 6.6 and 9.0 g were applied to the sled. Then 12 sets of simulations with different impact angles and D-ring positions were conducted to evaluate the occupant’s chest responses. Results indicate that the peak chest deflection at Lower Left (LL) decreased by 11.6% on average, and that at Lower Right (LR) increased by 11.7% on average when the D-ring position moved backward. Meanwhile, with the D-ring position moving upward, the peak chest deflection at LL grew by 24.8% on average, while it decreased by 14.7% at LR.

Research on Segmented Belt Acceleration Curve Based on Automated Mechanical Transmission

An automated mechanical transmission (AMT) is proposed as a new soft starter for medium-scale belt conveyors in this paper. The AMT is used to start the belt conveyor and shift gears step by step to make the belt conveyor accelerate softly. Based on analyzing common soft-starting acceleration curves, a segmented belt acceleration curve is proposed as a new soft-starting acceleration curve. By analyzing the AMT soft-starting system, the system modeling is built and the AMT output shaft’s angular acceleration is proposed to be controlled to control the belt acceleration. The AMT soft-starting simulation model is established in the environment of AMESim, and simulation results of the soft-starting process from the first to eighth gear positions are given. The main parameter curves of the AMT soft-starting system including the belt, driving pulley, and AMT output shaft are analyzed. The simulation model can indicate the viscoelastic property of the belt. The simulation results prove that the segmented belt acceleration is appropriate for a medium-scale belt conveyor and provide a theoretical and reasonable basis for using an AMT as a soft starter.

Accelerometer-based prediction of ground reaction force in head-out water exercise with different exercise intensity countermovement jump

BackgroundWater jumping exercise is an alternative method to achieve maintenance of bone health and reduce exercise injuries. Clarifying the ground reaction force (GRF) of moderate and high cardiopulmonary exercise intensities for jumping movements can help quantify the impact force during different exercise intensities. Accelerometers have been explored for measuring skeletal mechanical loading by estimating the GRFs. Predictive regression equations for GRF using ACC on land have already been developed and performed outside laboratory settings, whereas a predictive regression equation for GRF in water exercises is not yet established. The purpose of this study was to determine the best accelerometer wear-position for three exercise intensities and develop and validate the ground reaction force (GRF) prediction equation.MethodsTwelve healthy women (23.6 ± 1.83 years, 158.2 ± 5.33 cm, 53.1 ± 7.50 kg) were recruited as participants. Triaxial accelerometers were affixed 3 cm above the medial malleolus of the tibia, fifth lumbar vertebra, and seventh cervical vertebra (C7). The countermovement jump (CMJ) cadence started at 80 beats/min and increased by 5 beats per 20 s to reach 50%, 65%, and 80% heart rate reserves, and then participants jumped five more times. One-way repeated analysis of variance was used to determine acceleration differences among wear-positions and exercise intensities. Pearson’s correlation was used to determine the correlation between the acceleration and GRF per body weight on land (GRFVLBW). Backward regression analysis was used to generate GRFVLBW prediction equations from full models with C7 acceleration (C7 ACC), age, percentage of water deep divided by body height (PWDH), and bodyweight as predictors. Paired t-test was used to determine GRFVLBW differences between values from the prediction equation and force plate measurement during validation. Lin’s CCC and Bland–Altman plots were used to determine the agreement between the predicted and force plate-measured GRFVLBW.ResultsThe raw full profile data for the resultant acceleration showed that the acceleration curve of C7 was similar to that of GRFv. The predicted formula was − 1.712 + 0.658 * C7ACC + 0.016 * PWDH + 0.008 * age + 0.003*weight. Lin’s CCC score was 0.7453, with bias of 0.369%.ConclusionThe resultant acceleration measured at C7 was identified as the valid estimated GRFVLBW during CMJ in water.

UNSTEADY PROCESSES OF ION EXCHANGE SORPTION OF COPPER IONS IN A CONTINUOUS IDEAL MIXING APPARATUS

The article is devoted to the study of transient processes of ion-exchange sorption of heavy metal ions on a sulfonic acid cation exchanger in a vessel with a stirrer. A mathematical description of the ion exchange process is proposed, taking into account the following simplifying assumptions: at the initial moment of time, a solution and an ion exchanger containing heavy metal ions are inside the apparatus; the rate of ion exchange is limited by both internal and external diffusion; the process equilibrium is described by the Nikolsky adsorption isotherm equation; the structure of the movement of the solution and the ion exchanger in the apparatus is described by the ideal mixing model. In accordance with the accepted assumptions, a mathematical description of the process is formulated, including the equation of the material balance of the apparatus, the equation of the adsorption isotherm, the equation of diffusion kinetics, as well as the initial and boundary conditions of the third kind. The solution of the problem is carried out on an electronic computer by a numerical method, in which the characteristic equation of a continuous-action apparatus of complete mixing is used to find the unknown concentration of the solution. To test the adequacy of the developed model to the real process, experimental studies of transient processes of ion-exchange sorption of copper ions on the Lewatit S-100 sulfonic acid cation exchanger in a laboratory capacitive apparatus with a stirrer were carried out. During the research, acceleration curves were taken, on the basis of which the parameters of the non-stationary ion-exchange process were calculated: acceleration time, time constant, gain of the object and the maximum rate of change in the concentration of the solution at the outlet of the apparatus. Comparison of the results of calculation and experiment made it possible to conclude that the developed mathematical description is adequate to the real process. The discrepancy between the calculation and the experiment does not exceed 14%. Recommendations are given on the application of the obtained dependences for practical application.

Interaction between Water Wave and Geometrical Structures of Floating Triboelectric Nanogenerators

AbstractAlthough triboelectric nanogenerators (TENGs) are highly efficient and adaptable in harvesting ocean wave energy, the dynamics of floating TENGs in underwater wave stimulations have so far rarely been studied. Herein, the interactions between centimeter‐scaled floating structures and water waves are experimentally revealed. By integrating inertial measurement units into the shells of various floating TENG structures, the primary acceleration data associated with different parameters are obtained. Based on the data of 63 literature reported floating TENGs, a series of experimental parameters are elaborately probed, including shell shape, shell size, weight, barycenter, wave strength/frequency, and wave‐producing methods. Through dynamic calculations, each can offer the kernel data of acceleration and frequency distribution curves, revealing several regularities in water–structure interactions associated with TENGs. These calculations could serve as guidance for the design of the future floating TENGs in blue energy harvesting.

A cusp-core-like challenge for modified Newtonian dynamics

We show that modified Newtonian dynamics (MOND) predicts distinct galactic acceleration curve geometries – in the space of total observed centripetal accelerations, gtot, versus the inferred Newtonian acceleration from baryonic matter, gN, which we refer to as g2 space – and corresponding rotation speed curves. MOND modified gravity predicts cored geometries for isolated galaxies, while MOND modified inertia yields neutral geometries (i.e. neither cuspy nor cored), based on a cusp-core classification of galaxy rotation curve geometry in g2 space, rather than on inferred dark matter (DM) density profiles. The classification can be applied both to DM and modified gravity models as well as data and implies a ‘cusp-core’ challenge for MOND from observations (e.g., of cuspy galaxies), which is different from the so-called cusp-core problem of DM. We illustrate this challenge with a number of cuspy and cored galaxies from the SPARC rotation curve database that deviate significantly from the MOND modified gravity and MOND modified inertia predictions.

A source and ground motion study of earthquakes in and near Delhi (the National Capital Region), India.

We study source parameters of 10 local earthquakes (2.7 ≤ M_{w} ≤ 4.5) that have occurred in the National Capital Region (NCR) since 2001 and the ground motions produced by these events. Moment rate spectra of the earthquakes retrieved from the recordings at hard sites after applying corrections for geometrical spreading (1/R, R ≤ 100 km), anelastic attenuation (Q = 253f0.8) and cutoff frequency (fm = 35 Hz) are reasonably well fit by the Brune ω2-source model with stress drop ranging between 0.9 and 13 MPa. Neglecting the outlier low-stress drop value, the average stress drop is 6 MPa. We apply a modified standard spectral ratio technique to estimate site effect at 38 soft sites in the NCR as well as the geometrical mean site effect with respect to a reference hard site. Application of the stochastic method, with source characterized by the Brune ω2- model with stress drop of 6 MPa and the mean site effect for soft sites, yields peak horizontal ground acceleration and velocity curves that are in good agreement with the observed values. These results provide the parameters needed for the application of the stochastic method to predict ground motions at hard and soft sites in the NCR during postulated M_{w} ≤ 5.5 earthquakes.

Ecological control strategy for cooperative autonomous vehicle in mixed traffic considering linear stability

Purpose This paper aims to present a cooperative adaptive cruise control, called stable smart driving model (SSDM), for connected and autonomous vehicles (CAVs) in mixed traffic streams with human-driven vehicles. Design/methodology/approach Considering the linear stability, SSDM is able to provide smooth deceleration and acceleration in the vehicle platoons with or without cut-in. Besides, the calibrated Virginia tech microscopic energy and emission model is applied in this study to investigate the impact of CAVs on the fuel consumption of the vehicle platoon and traffic flows. Under the cut-in condition, the SSDM outperforms ecological SDM and SDM in terms of stability considering different desired time headways. Moreover, single-lane vehicle dynamics are simulated for human-driven vehicles and CAVs. Findings The result shows that CAVs can reduce platoon-level fuel consumption. SSDM can save the platoon-level fuel consumption up to 15%, outperforming other existing control strategies. Considering the single-lane highway with merging, the higher market penetration of SSDM-equipped CAVs leads to less fuel consumption. Originality/value The proposed rule-based control method considered linear stability to generate smoother deceleration and acceleration curves. The research results can help to develop environmental-friendly control strategies and lay the foundation for the new methods.

Optimal control design for comfortable-driving of hybrid electric vehicles in acceleration mode

This paper discusses a control design for improving ride comfort while maintaining the powertrain performance and power demand of a hybrid electric vehicle in a specific acceleration scenario. A parallel hybrid powertrain system with two electric machines and a single turbo-charged engine is built. The acceleration scenario is designed under the assumption that the desired acceleration rate cannot be achieved by using an electric motor alone. Therefore, improving ride comfort while also managing the torque split is challenging. This work involves two steps. First, a black-box module that is typically used in the automotive industry is exploited to quantitatively evaluate ride comfort. A genetic algorithm (GA) is used to generate an optimal acceleration curve and gear schedule by analyzing the characteristics of the black-box module. Second, two optimization problems are formulated to provide a reasonable power split with the purpose of tracking the reference acceleration provided by the GA. The problems are solved by dynamic programming and sequential quadratic programming. Comparison of the simulation results between the two different solutions is conducted on a simulator with a practical background and demonstrates the significance and efficiency of the proposed control design.

AMT Starting Control as a Soft Starter for Belt Conveyors Using a Data-Driven Method

Automated mechanical transmission (AMT) is used as a soft starter in this paper. To improve the soft starting quality, a novel data-driven method is studied. By analyzing and comparing five common soft-starting acceleration curves, a segmented acceleration curve is put forward to be used as the soft-starting acceleration curve for the AMT. Based on the prototype model free adaptive control (MFAC) method, a modified MFAC method with jerk compensation is given to control the AMT output shaft’s angular acceleration and reduce driveline shock. Compared with the methods of prototype MFAC and traditional proportion integration differentiation (PID), the modified MFAC method with jerk compensation can better control the AMT output shaft’s angular acceleration and has excellent characteristics in terms of small tracking error and smaller shock. The research results provide a novel data-driven method for AMT as a soft starter.

Influence of nonlinear fluid viscous dampers in controlling the seismic response of the base-isolated buildings

Recently, many buildings have originally been designed as base-isolated to mitigate the structural vibration. However, buildings with base isolation systems can undergo displacement/amplification demand due to the inherent nonlinear behaviour of the base isolators, especially in earthquake-prone regions. Hence, in some cases it could be necessary to control the seismic response of the base-isolated buildings using supplemental damping device. This paper investigated the effectiveness of nonlinear fluid viscous damper (NFVD) considering design parameters for the base-isolated buildings with lead rubber bearing (LRB). For this, 10-storey benchmark steel moment resisting frame isolated with LRB having a series of isolation periods (T) of 3, 3.5, 4, and 5 s was used. These base-isolated frames consist of three bays and NFVDs having different damping exponents (α) of 0.15, 0.30, 0.50, and 0.70 were inserted in the mid, corner, and all bays of each base-isolated frame at the ground level. The case studied frames were modelled with a finite element program in which LRB elements were characterized by bi-linear hysteretic behaviour while NFVD elements were represented considering the Maxwell model having an elastic spring and a viscous dashpot in series. The nonlinear response of the frames with LRB and NFVD were evaluated by the nonlinear time history analyses using five ground motion records. The analysis of the results were comparatively evaluated considering certain engineering demand parameters such as the storey, bearing, and relative displacements, roof and inter-storey drift ratios, absolute acceleration, base shear, base moment, input energy, and hysteretic curves. One of the main findings of this study is that the base-isolated building with the passive damping device as control attenuation satisfactorily responded when associated with appropriated design parameters.

Analysis of Injury Potential of Three-year-old Child Occupants Caused by Inappropriate Installation of Enhanced Child Restraint System with Top Tether in Frontal Crash Accidents

Objective: Frontal crash accidents remain a significant factor in causing the preventable injury and fatality for child occupants aged 3 in China. Despite the increased public awareness and utilization of child restraint system (CRS), inappropriate installations still exist and lead to a potential to result in injuries of head, thorax and abdomen regions of child occupants, especially when it comes to enhanced child restraint system (ECRS) with top tether. The current study focuses on the influence of top tether upon safety performance of ECRS with top tether in dynamic tests with different set-ups and explores the relationship between inappropriate installation of ECRS with top tether and the injury potential of child occupants aged 3 in a frontal crash. Methods: A testing scheme including 4 dynamic tests was devised to ascertain the extent to which the top tether affected the accelerations of thorax, the abdominal penetration and the head displacements. Different kinds of acceleration curves were employed to conduct the tests and to simulate the real status and situation of child occupants aged 3 in the CRS installed with top tether and without top tether respectively. Parameters of accelerations, abdominal penetrations, and head displacements were measured to analyze quantitatively the influence of inappropriate installations of ECRS with top tether under different conditions. Results: The safety performance of ECRS with the use of top tether was found better than that of ECRS without the use of top tether either in the normal condition or in the extreme condition. The test using the acceleration curves defined by regulations, the accelerations of thorax, abdominal penetrations, and head displacements of P3 manikin in the ECRS with the top tether connected to the anchor point revealed results that all met the requirements. While in the test using acceleration curves of the same kind, and when the top tether was not connected, the parameters measured displayed that the safety performance of the sample was worse than the former one. As for the tests using the more severe acceleration curves defined at will, it was more obvious that top tether could affect the function and safety performance of ECRS greatly, and the functional failure and severe damages occurred to the ECRS without the use of top tether. ECRS with the use of top tether was partly qualified even under the more severe conditions. Conclusions: Inappropriate installation of ECRS such as omitting the step of connecting top tether to anchor point could cause severe injuries and fatalities in frontal crash accidents. Effective measures should be taken to minimize the chances of inappropriate installations of ECRS.

Dynamic Characteristics Analysis of Cover System

Up to now, although a lot of research has been done on the control algorithm of cover motion, no systematic analysis has been carried out on the trajectory planning of cover opening yet. In order to improve the dynamic characteristics of the cover in the process of cover opening, a velocity planning algorithm based on trigonometric function is proposed in this paper, which improves the poor smoothness of the acceleration curve of the traditional S-shaped feedrate planning algorithm. The simulation model of the cover system is established to verify the effectiveness of the algorithm, and the results show that the algorithm is effective.

Study on the buffering properties of composites during high-speed penetration

In order to solve the problems of heavy overload, poor buffer performance of cushion and low reliability of fuze in high-speed penetration process of the projectile, this paper proposes a composite structural cushion using foamed aluminum and rubber. Through the establishment of the projectile model with different material cushions, the Ls-dyna software is used to simulate the high-speed penetration process and analyze the fuze acceleration curve. The results show that the composite cushion has a significant buffering effect in the process of high-speed penetration, which can reduce the impact overload of fuze and improve the reliability of fuze.

Method to Correct the Velocity Variation Information of an Automatic Crash Notification System in Vehicle-to-Rigid Barrier Frontal Collisions

Automatic crash notification systems (ACNSs) play a key role in post-accident safety. To improve the accuracy and efficiency of ACNSs, a method to correct the velocity variation information of ACNSs was established. First, after the acceleration data of sled crash tests were analysed, the factors affecting the accuracy of the velocity variation information were determined, and the influence of the discrimination threshold and acceleration curve shape on the velocity variation information was examined. Second, according to the acceleration data generated by the simulation model of a sled crash, the correlation between the accuracy of the velocity variation information and influencing factors was modelled. Third, an automatic crash notification algorithm involving a velocity variation correction function (VVCF) was proposed based on the correlation model. Finally, to verify its reliability, the improved algorithm was applied to an automatic crash notification system (ACNS) terminal. The validation results show that the ACNS terminal can accurately identify collisions and transmit accident information. Moreover, more accurate velocity variation information can be retrieved.

Research on characteristics of occupant’s chest responses in oblique impact

The oblique impact is the second most common frontal impact, in which both the forward and lateral accelerations are applied to the occupant. It is noticed that the oblique impact is a primary source of serious injuries, in which the chest injuries are mostly fatal through the statistics of traffic accidents. This study aims to investigate the characteristics of the occupant’s chest injury in the frontal oblique impact. First, a model with a sled and a Test Human Occupant Restraint (THOR) dummy is established. Second, an acceleration curve with a peak of 9.0 g is applied to the sled. Then 11 sets of simulations with different impact angles and belt peak loads are conducted to evaluate the occupant’s chest responses. Results indicate that there is a negative correlation between belt peak force and injury outcomes, while there is a weak correlation between chest injury and impact angle. With the increase of the belt force limit, the chest deflection at Lower Left (LL) would increase by 37.9%, and the acceleration at LL would increase by 23.1%. Meanwhile, the Viscous Criterion (VC) at LL would increase by 61.4%. However, the relationship between the impact angle and injury drawn by VC and acceleration is inconsistent. Additionally, in all simulations, the maximum deflections are captured at the LL, while the maximum VCs happens at Upper Right (UR) or LL. It is demonstrated that a seatbelt with a lower peak force is friendly to the occupant’s chest under all the impact angles. This study can provide a reference to the study of chest injury in the oblique impact.

Nonlinear dynamic response of an isolation system with superelastic hysteresis and negative stiffness

The negative stiffness exhibited by bi-stable mechanisms together with the tunable superelasticity offered by shape memory alloy (SMA) wires can enhance the dynamic resilience of a structure in the context of vibration isolation. The effects of negative stiffness and superelastic damping in base-isolated structures are here explored by carrying out an extensive study of the nonlinear dynamic response via pathfollowing, bifurcation analysis, and time integration. The frequency-response curves of the isolated structure, with and without the negative stiffness contribution, are numerically obtained for different excitation amplitudes to construct the acceleration and displacement transmissibility curves. The advantages of negative stiffness, such as damping augmentation and reduced acceleration/displacement transmissibility, as well as the existence of rich bifurcation scenarios toward quasi-periodicity and chaos, are discussed.

Attenuation Law of Train-Induced Vibration Response of Subgrade in Beijing–Harbin Railway

To investigate environmental vibration in the case of railway subgrade in seasonally frozen regions, field experiments were conducted on the Beijing–Harbin railway subgrade of China in autumn and winter. Vibration acceleration and vibration level attenuation law were analysed based on monitoring results. Accordingly, the influence of the subgrade freeze-thaw states, vehicle load, train formation, and running speed on the subgrade surface environmental vibration was analysed. The vibration response of the subgrade decreased with an increase in the distance from the track. The attenuation curve of the vibration acceleration can be fitted using the negative exponential function, and the attenuation curve of the vibration level can be fitted using the linear function. Additionally, the subgrade vibration response during the frozen period was greater than that during the unfrozen period owing to increased strength and rigidity and decreased damping ratio after subgrade freezing, which increased the vibration response. Moreover, the vibration intensity of the subgrade increased with increase in the vehicle load and formation and decreased with an increase in the driving speed within a particular speed range. The findings of this study provide an objective basis for railway subgrade design and disaster assessment in cold regions of China.