Vehicle Center Of Gravity Research Articles

Real-Time Center of Gravity Estimation for Intelligent Connected Vehicle Based on HEKF-EKF

The vehicle center of gravity estimation is the key technology to the vehicle active safety system in intelligent connected vehicles. In this study, an integrated estimation approach for center of gravity (CG) combining Huber Extended Kalman Filter and Extended Kalman Filter (HEKF-EKF) is proposed. First, HEKF algorithm is used to estimate the distance between the CG and the front axle at the current time. Then, the CG height obtained by HEKF and EKF algorithms is weighted to obtain the optimal estimate value. Finally, the results show that the algorithm’s estimation convergence time is 2 s, its longitudinal position estimation error is less than 2%, and its center of gravity height estimation error is less than 3%. The longitudinal and vertical positions of the vehicle CG can be accurately estimated using this method. This method can help advance the development of active safety technology.

Roadside Estimation of a Vehicle’s Center of Gravity Height Based on an Improved Single-Stage Detection Algorithm and Regression Prediction Technology

In this paper, a vehicle center of gravity (CG) height estimation method based on improved You Only Look Once algorithm and AdaBoost regression is proposed by relying on roadside sensors. The CG height of a vehicle plays an important role in the performance evaluation indexes of vehicle handling, ride comfort, and safety. Therefore, the accurate measurement of the CG height is helpful for improving vehicle control and ensuring driving safety. Different from traditional vehicle modeling, in this study, a data-driven roadside estimation method based on machine vision is utilized for the estimation of the vehicle CG height, thereby providing an economic and convenient concept. In terms of vehicle type identification, the improved YOLO algorithm is characterized by flexibility and speed while ensuring high accuracy. This ensures that it can be quickly deployed on roadside equipment and meet real-time requirements. Moreover, through the correlation analysis, parameters including the vehicle’s front track width, rear track width, roof height, and weight, which can be collected by roadside sensors, are selected as input parameters for the regression. An ensemble learning model based on AdaBoost regression realizes the final estimation of the CG height. The test results obtained on the NHTSA experimental data show that the average accuracy of vehicle type identification reaches 97.59% and the regression estimation accuracy of the vehicle CG height reaches 94.64%.

Design, simulation of AUV (VIAM-AUV1000) for research and rescue

Autonomous Underwater Vehicles have gained popularity for the last decades, especially a lot of AUVs were considered as the most suitable tool for the purpose of reducing risks of people in dangerous marine operations. This paper presents the preliminary results of the research on hardware design, the controller of an autonomous underwater vehicle model for the task of survey, search and rescue ... With a compact design, AUV can operate in limited spaces. Through a unique ducted propeller and rudder located at the aft, the AUV can perform horizontal motion. It can also control pitch angle and depth motion by an inside mass shifter mechanism (MSM) which changes the vehicle center of gravity. In addition, The AUV is integrated with powerful eletronic system, highprecision sensors helping it carries on missions from simple to complex. The use of Sliding Mode Control (SMC) to independently design the heading and depth controllers for AUV demonstrates the steady stability of the controllers with the nonlinear model, uncertainty parameters and disturbances. Finally, the simulation results show that the SMC controllers can control the AUV nonlinear model to track the desired steering angle and depth with high accuracy and stability.

Study of the Measurement of Generation 2 Toyota Event Data Recorders in Low-Speed Side Impacts

<div class="section abstract"><div class="htmlview paragraph">Automotive Event Data Recorders (EDRs) are often utilized to determine or validate the severity of vehicle collisions. Several studies have been conducted to determine the accuracy of the longitudinal change in velocity (ΔV) reported by vehicle EDRs. However, little has been published regarding the measurement of EDRs that are capable of reporting lateral ΔVs in low-speed collisions. In this study, two 2007 Toyota Camrys with 04EDR ECU Generation modules (GEN2) were each subjected to several vehicle-to-vehicle lateral impacts. The impact angles ranged from approximately 45 to 135 degrees and the stationary target vehicles were impacted at the frontal, central, and rear aspects of both the driver and passenger sides. The impact locations on the bullet vehicles were the front and rear bumpers and the impact speeds ranged from approximately 7.9 to 16.1 km/h. Instrumentation was mounted at the approximate center of gravity (CG) of the target vehicles, as well as on the front reinforcement bar, rear body panel, airbag ECU, B-pillars, and C-pillars to evaluate the varying lateral ΔV (ΔV<sub>y</sub>) readings from the 3 sensor locations (ECU, B-pillar, C-pillar) represented in the Toyota EDR and to account for rotational (yaw) effects on the data. The lateral ΔVs reported by the Toyota EDRs were then compared to the recorded ΔV<sub>y</sub>s from the reference instrumentation mounted within the test vehicles. A comparison of the data revealed a general under-reporting of impact severity from the Toyota EDRs at the ECU sensor when compared to reference instrumentation at the vehicle CG for impacts near the center of the target vehicle where the vehicle typically rotated about its frontal aspect. There was a general over-reporting of impact severity from the Toyota EDRs at the ECU sensor when compared to reference instrumentation at the vehicle CG for impacts near the front (heavy) axle of the target vehicle where the vehicle rotated about its rear aspect. Rotational data from the reference instrumentation and the distance between the ECU and reference instrumentation at the CG was also utilized to calculate the corresponding ΔV<sub>y</sub> at the ECU location for a direct comparison to the Toyota EDR measurement at the ECU (maximum of 12.0% difference). A comparison of the data recorded at the Toyota ECU sensors and the reference instrumentation mounted to the ECUs revealed accurate measurements by the Toyota ECU sensor (maximum of 7.6% difference). Differences in reported values between the 3 aforementioned Toyota sensor locations, as well as non-recordings and longitudinal ΔV recordings from the Toyota EDRs were also evaluated.</div></div>

Sensitivity Analysis of Vehicle Parameters on Dynamic Stability and Vehicle Handling Performance

In this paper, a linear two degrees of freedom linear bicycle model is proposed to investigate the vehicle handling criterion. The study is based on simulation developed using MATLAB / Simulink to predict the vehicle dynamic stability. Steering angle is given as an input to the mathematical model for various vehicular manoeuvres. This model is validated using a step input which is adjusted to give 0.3g lateral acceleration. The system model is simulated under a typical front wheel steering to examine the highway vehicle prediction output within its manoeuvre. This input is also adjusted to keep lateral acceleration value in steady state region. It is found that changing the vehicle center of gravity (CG) position, vehicle mass, tire cornering stiffness and vehicle speed all have a significant influence on the vehicle dynamic stability.

Frame loads accuracy assessment of semianalytical multibody dynamic simulation methods of a recreational vehicle

The design of a vehicle frame is largely dependent on the loads applied on the suspension and heavy parts mounting points. These loads can either be estimated through full analytical multibody dynamic simulations, or from semi-analytical simulations in which tire and road sub-models are not included and external vehicle loads, recorded during field testing, are used as inputs to the wheel hubs. Several semi-analytical methods exist, with various modeling architectures, yet, it is unclear how one method over another improves frame loads prediction accuracy.This study shows that a semi-analytical method that constrains the vehicle frame center of gravity movement along a recorded trajectory, using a control algorithm, leads to an accuracy within 1% for predicting frame loads, when compared to reference loads from a full analytical model. The control algorithm computes six degrees of freedom forces and moments applied at the vehicle center of gravity to closely follow the recorded vehicle trajectory. It is also shown that modeling the flexibility of the suspension arms and controlling wheel hub angular velocity both contribute in improving frame loads accuracy, while an acquisition frequency of 200 Hz appears to be sufficient to capture load dynamics for several maneuvers. Knowledge of these loads helps engineers perform appropriate dimensioning of vehicle structural components therefore ensuring their reliability under various driving conditions.

Development of selective criteria for the verification of whiplash-associated disorders.

Whiplash injury (distortion of the cervical spine) is the most commonly diagnosed type of injury sustained in car accidents, and it ranks first in the structure of compensation claims for personal injury resulting from traffic incidents. The verification of whiplash-associated disorders (WADs) continues to be agreat problem in the formulation of medico- legal expert opinions, as injuries of this type, cannot, by definition, be captured using available imaging methods ("radiologically negative effects of acceleration/deceleration mechanism with awide variety of clinical manifestations"). The present study aims to define aset of criteria that might represent threshold conditions for WAD verification, enabling preliminary cohorting (preselection) of evaluated cases and facilitating the adoption of legal decisions. The available scientific literature addressing problems relating to WAD verification was reviewed to identify factors that differentiate an extremely broad spectrum and varying severity of symptoms depending on the circumstances of incidents, the results of physical evaluation of patients and additional instrumental examinations, as well as technical indicators. Based on the literature search, arange of criteria with the highest potential significance for application in routine medical and forensic expert practice were selected (with afocus on aspects related to verification, quantification and outcomes). The primary prerequisite for recognising the presence of moderate impairment to health (according to the Polish penal code) due to distortion of the cervical spine should involve confirmation of grade 3 WAD according to the Quebec Task Force (QTF) classification, and exceeding the threshold values of Δv (> 15 km/h), acceleration of the victim's vehicle centre of gravity (> 4 g), and NIC criterion (> 15 m2/s2). Additional criteria used by experts should include the verification of the correct head restraint position as well as results of biomechanical examinations evaluating the level of safety of agiven vehicle, and epidemiological data retrieved from databases including the statistics for claims filed by victims of real-life accidents.

Dynamic Monitoring of the Effect of Passenger Occupancy on the Vehicle Center of Gravity (CG) In a Lightweight Electric Vehicle

In lightweight vehicles, the passenger weight has a substantial contribution to the vehicle gross weight. This paper presents a simulation, evaluation, and application of vehicle model developed to estimate the shift in the center of gravity (CG) of the vehicle on various terrains, driving conditions and different passenger occupancy combinations. The designed Neighbourhood Electric Vehicle (NEV) comprises various sensors including load sensors and speed sensors at each wheel. Vehicle dynamics is influenced by various factor like speed, goad grade, lateral acceleration, longitudinal acceleration, passenger occupancy, etc. Here a simple model has been presented where the movement of the vehicle CG is mapped based on the load experienced by each wheel in dynamic driving conditions. The wheel forces are used to identify the instantaneous CG by virtue of a system identifier on board the vehicle. The validation of the proposed model has been done on a lightweight NEV. In addition, several simulations have been carried out to illustrate the effect on vehicle dynamic stability. It was found that the passenger occupancy status can influence vehicle performance and handling to a large extent.

Effect of the Gyroscopic Moment, Centrifugal Force and Hydroplaning on the Critical Speed of the Vehicle

Driving vehicles on curved roads is dangerous because of the risk of accidents. This is due to the centrifugal force, gyroscopic moment and hydroplaning of the vehicle, ending with vehicle slipping or tipping. The aim of this research is to find the critical speed under any one of the above mentioned risks. The water pressure under the vehicle tires was calculated using Matlab R2017a in order to find the pressure value that able to lift the vehicle causing slipping and then going out of control. The effect of many parameters, on the vehicle hydroplaning have been studied. These parameters are tire width, wheel load and water layer thickness. While for vehicle slipping due to the centrifugal force or the gyroscopic moment, the following parameters have been studied. These parameters are height of vehicle gravity center, vehicle width, radius of the circular path, and track angle. The results showed that the gyroscopic torque negatively affects the critical velocity of the vehicle, and it reduced it about 0.549%.The centrifugal effect is the has the greatest influence on the gyroscopic effect, and the gyroscopic effect pushes the vehicle outward and increases the radius of the rotation, while the gyroscopic couple effect ,at low radius. of low rotation, is very small. Gyroscopic impact is increased by increasing the radius of the rotation path. The result also showed the increase of the road surface angle and surface at the turning the influence positively on the safe speed of the vehicle at all the above variables.

Occupant Kinematics and Loading in Low Speed Lateral Impacts

<div class="section abstract"><div class="htmlview paragraph">Instrumented human subject and anthropomorphic test device (ATD) responses to low speed lateral impacts were investigated. A series of 12 lateral collisions at various impact angles were conducted, 6 near-side and 6 far-side, with each test using an ATD and one human subject. Two restrained female subjects were utilized, with one positioned in the driver seat and one in the left rear seat. Each subject was exposed to 3 near-side and 3 far-side impacts. The restrained ATD was utilized in both the driver and left rear seats, undergoing 3 near-side and 3 far-side impacts in each position. The vehicle center of gravity (CG) change in velocity (delta-V) ranged from 5.5 to 9.4 km/h (3.4 to 5.8 mph). Video analysis was used for quantification and comparison of the human and ATD motions and interactions with interior vehicle structures. Human head, thorax, and low back accelerations were analyzed. Peak human subject head resultant accelerations ranged from 0.9 to 36.8 g’s. Peak human subject thorax and low back lateral accelerations ranged from 1.0 to 17.1 g’s and 1.3 to 12.7 g’s, respectively. The ATD was instrumented with various sensors, including a tri-axial head accelerometer and 6-axis load cells in the upper neck, lower neck, and lumbar spine. Peak ATD head resultant accelerations ranged from 3.6 to 33.5 g’s. Peak ATD upper and lower neck compression ranged from -47.4 to -991.5 N and -52.1 to -740.6 N, respectively. Peak ATD lumbar compression ranged from -72.3 to -402.1 N. Cervical and lumbar shear loading and moments are also reported.</div></div>

The Influence of Deck Flexibility on the Dynamic Response of Railway Bridges

A simplified methodology is proposed for railway bridge vibration analysis under train loading. Dynamic models of both train and bridge were assumed to be initially uncoupled, yet bound by contact forces. These forces were evaluated from the dynamic response of the vehicle subjected to support excitation caused by rail and wheel geometric irregularities. Such forces were statically condensed in the vehicle centre of gravity and applied to a 3D-beam finite-element model of the bridge. The influence of the rigid-deck hypothesis on the dynamic response is assessed via an iterative procedure to redefine updated an equivalent rail irregularities� as the sum of he deck displacements and the actual� rail irregularities. The new interaction forces are re-applied to the bridge model to determine new displacements, repeating the procedure until the results converge.

Design of Variable Vehicle Handling Characteristics Using Four-Wheel Steer-by-Wire

This paper presents a vehicle handling modification approach that tracks the dynamics of a general nonlinear planar reference model. The control structure is a combination of linear and nonlinear state feedback with feedforward of reference model yaw moment, lateral force, and longitudinal force at the vehicle center of gravity. The modified closed-loop system is demonstrated to be stable and has robust tracking performance to reasonable levels of model uncertainty. The handling modification method is applied to the task of emulating the dynamics of a reference vehicle on a low friction surface, with particular attention to actuator constraints. Experimental results demonstrate successful emulation of the low friction reference model’s planar dynamics for a variety of driving maneuvers and reference friction coefficients. This handling emulation technique enables further investigation of vehicle handling performance improvements and use as a variable dynamic testbed for human factors studies.

Design, control, and implementation of a new AUV platform with a mass shifter mechanism

This paper presents a design, control, and implementation of a new autonomous underwater vehicle (AUV) platform, which is designed as a torpedo shape with small and light enough to be handled easily by one person. Through a unique ducted propeller and rudder located at the aft, the AUV can perform horizontal motion. It can also control pitch angle and depth motion by an inside mass shifter mechanism (MSM) which changes the vehicle center of gravity. Hardware and software architectures of the control system are addressed and the functions of all parts are clarified. With a developed navigation algorithm, strategies for waypoint guidance, steering and diving controls are suggested. After that, a series of experiment results compared with the simulation outputs are presented.

Steady-State Cornering Modeling and Analysis of Three-Wheel Narrow Vehicle

Electric mobility seems to be an innovative alternative to future urban transport. In this study, a steady-state cornering model of a three-wheel narrow electric vehicle is derived. The steady-state cornering analysis is conducted by varying the location of the vehicle center of gravity, speed and tilt angle. From this analysis, the center of gravity location and tilt angle that gives better cornering characteristics can be obtained. Therefore, this analysis helps and can be used as starting point to design the chassis and the tilting control system of the three-wheel narrow electric vehicle.

Analytical design for mobile anchor systems

Cable yarding systems are a common method for transporting materials in mountainous terrain in situations that do not allow for ground-based skidding, forwarding or shovel-logging. Cable yarding, although effective in steep locations, requires anchored guylines to support the skyline and operating lines. The skyline and operating lines rely on a fixed anchor, or tailhold, to provide adequate tension for effective yarding. Anchored guylines and skylines usually depend on available stumps or trees. Where these are not available, mobile anchors such as bulldozers can be used. Mobile equipment anchors have an advantage of known resisting capacity, as opposed to trees and stumps, but there are no well-defined design criteria for the application of the system. Here an analytical design solution for mobile anchor capacity is presented, based on force equilibrium analyses, and accompanied by a series of design charts. A moment equilibrium analysis involving vehicle center of gravity and anchor attachment points is used to bracket feasible designs. It is shown that when the guyline angle is relatively high, the primary factor in anchor capacity is equipment weight. At lower cable angles, the passive resistance of the soil in front of the blade can play a major role, especially with deeper embedment, stronger soils and with an uphill vehicle placement. Finally, the anchor attachment point must be kept relatively low to the ground, especially if smaller equipment is used as an anchor. The results demonstrate that use of equipment as a primary or auxiliary anchoring system can be effective when adhering to design constraints based on equipment and in-situ soil properties.

The Role of a Novel Discrete-Time MRAC Based Motion Cueing on Loss of Control at a Hexapod Driving Simulator

The objective of this paper is to present the advantages of Model reference adaptive control (MRAC) motion cueing algorithm against the classical motion cueing algorithm in terms of biomechanical reactions of the participants during the critical maneuvers like chicane in driving simulator real-time. This study proposes a method and an experimental validation to analyze the vestibular and neuromuscular dynamics responses of the drivers with respect to the type of the control used at the hexapod driving simulator. For each situation, the EMG (electromyography) data were registered from arm muscles of the drivers (flexor carpi radialis, brachioradialis). In addition, the roll velocity perception thresholds (RVT) and roll velocities (RV) were computed from the real-time vestibular level measurements from the drivers via a motion-tracking sensor. In order to process the data of the EMG and RVT, Pearson’s correlation and a two-way ANOVA with a significance level of 0.05 were assigned. Moreover, the relationships of arm muscle power and roll velocity with vehicle CG (center of gravity) lateral displacement were analyzed in order to assess the agility/alertness level of the drivers as well as the vehicle loss of control characteristics with a confidence interval of 95%. The results showed that the MRAC algorithm avoided the loss of adhesion, loss of control (LOA, LOC) more reasonably compared to the classical motion cueing algorithm. According to our findings, the LOA avoidance decreased the neuromuscular-visual cues level conflict with MRAC algorithm. It also revealed that the neuromuscular-vehicle dynamics conflict has influence on visuo-vestibular conflict; however, the visuo-vestibular cue conflict does not influence the neuromuscular-vehicle dynamics interactions.

低重心型平行二輪ビークルにおける搭乗者の体格を考慮した車体揺動抑制制御

This paper addresses the development of an advanced parallel two-wheel vehicle that has an underslung vehicle body. The developed parallel two-wheel vehicle has the functions such as the self-standing structure by stable pendulum structure, the seat positioning system for compensating the deviation of the vehicle's gravity center including the passenger, and the active mass system for suppressing swaying of the vehicle body. The vehicle will be used by diverse passengers in the future. However, the sway suppression control of the vehicle body was developed without consideration for differences of the passenger's physical constitution in the conventional study. In this paper, the mathematical model of the swaying of vehicle body with passenger and its model parameters identification are proposed. In the model parameters identification, it is clarified that the model parameters of each passenger are similar except for the passenger's mass. Furthermore, the control parameters designed by backstepping method are independent to interference from the model parameters. Therefore, in design of the sway suppression control to the diverse passengers, the only passenger's mass is given to the control system. Finally, effectiveness of the proposed control system is verified by experiments using the parallel two-wheel vehicle.

Investigation on Emergency Brake Property of a Heavy-Duty Vehicle Based on Functional Virtual Prototyping Model

A Functional Virtual Prototyping full vehicle model for a tri-axial heavy-duty truck is built, and the non-linearity of suspension dampers and tires is also considered. With the trajectory of full vehicle gravity center, longitudinal tire force of front wheel, longitudinal acceleration, lateral acceleration, yaw rate and pitch angle as the evaluation indexes of brake property, the influences of system parameters including wheelbase, load shift, road surface roughness and separated road friction coefficient on brake efficiency, stability and ride comfort are analyzed. In addition, the interaction of brake and full vehicle dynamics is studied. Results show that small wheelbase and load shift may improve the brake efficiency of vehicles, small road surface roughness is beneficial to brake stability and ride comfort, and great frictional coefficient difference of separation road will worsen the brake efficiency and stability.

Study on Tractor Semi-Trailer Roll Stability Control

The rollover accidents in the tractor semi-trailer are often fatal and many factors could cause the tractor semi-trailer rollover. In this paper, a rollover prevention control method was proposed based on real-time calculation of rollover index. The vehicle Center of Gravity (CG) height from the ground is an important parameter in the rollover index and it is estimated through lateral acceleration sensor and suspension deflection sensors. Comparing the rollover index with the preset threshold, the differential braking will be applied to corresponding wheels once the trigger conditions are met. A roll stability control simulation was performed on the dynamic model based on virtual prototyping. The results show that the rollover prevention control proposed in this paper can stabilize the tractor semi-trailer and prevent from rollover on high speed curve driving.

The Study on the Influence of Gust Wind on Vehicle Stability

In this paper, the vehicle driving characteristics are investigated under different Force level of gust wind based on the CFD theory. The distributed pressure acted on the vehicle side surface is equivalent to the six-component force on vehicle gravity center. The six-component force are explored and compared in different Force level of gust wind. The results show that the lateral force Fy and yaw moment Mz vary with v shape and shape under gust wind, respectively. The slopes of the result curves increase with greater Force level of gust wind. Gust wind gives most influence on Fy and Mz while has little effect on other component force. The work will provide a methodology for vehicle stability research under gust wind.