Multi-body Simulation Model Research Articles

Rollover Stability of Heavy-Duty AGVs in Turns Considering Variation in Friction Coefficient

This study analysed the impact of turning rate, the centre of mass height, and road adhesion coefficient on the rollover stability of heavy-duty automated guided vehicles (AGVs) using a multi-body dynamics simulation model. The lateral deflection angle of the centre of mass was used as a metric to evaluate the rollover behaviour of the AGVs, and the results were obtained quantitatively. The findings showed that the turning rate had the largest impact on AGV rollover stability, followed by the centre of mass height, while the road adhesion coefficient had the least impact. Despite having the lowest impact, the road adhesion coefficient was one of the key factors contributing to AGV slippage, and severe slippage could easily lead to rollover incidents. To further evaluate the rollover behaviour of the AGVs, a lateral-load transfer rate (LTR) index was derived from the change in wheel load generated by the lateral tilt angle during steering. The range of LTR values was determined for different ranges of turning rate, the centre of mass height, and road adhesion coefficient. The results indicated that the range of LTR values for turning rate was 0.23–0.45, for the centre of mass height was 0.323–0.393, and the minimum value of 0.337 was obtained for a road adhesion coefficient of 0.6.

Simulation methodology for the identification of critical operating conditions of planetary journal bearings in wind turbines

The usage of journal bearings as planetary bearings in wind turbines instead of roller bearings has become more common in recent years. Their usage is advantageous, due to smaller installation space needed compared to roller bearings allowing for higher power densities of wind turbine drive trains. However, this technology presents a challenge since there is currently no standardized approach for the design of planetary journal bearings regarding wear. Due to varying wind speeds and dynamic operating events a large variation of loads has to be considered in the design process of a planetary journal bearing for wind turbines. Some of these loads are considered potentially critical to the journal bearing in terms of wear. Identifying these critical load areas early in the design phase supports a reliable bearing design and wind turbine operation.This paper introduces a method to identify critical operating conditions for planetary journal bearings using a simulation tool chain, which couples a multi body simulation (MBS) model of a wind turbine with an elasto-hydrodynamic (EHD) model of the planetary journal bearing. Based on the EHD results critical operating conditions are determined for the planetary bearing. Furthermore, methods are implemented to reduce the number of required EHD simulations for analysing the bearing design. The combination of the identification of critical operating conditions, while reducing the computational effort leads to a simulation methodology, which enables a faster bearing design assessment considering the wide variation of wind turbine operating conditions. The applicability of this method is demonstrated by a simplified use case.Firstly, this paper introduces the MBS model and the parameter space that describes possible combinations of bearing loads such as forces, moments and rotational speed. Due to the number of combinations and the EHD computing effort, the identified parameter space is secondly sampled statistically to reduce the simulation effort. A risk map is derived from the EHD results, to easily indicate potentially critical operating conditions for the planetary journal bearing.

A Control Algorithm of Active Wave Compensation System Based on the Stewart Platform

Aim at the actual engineering requirements of wind power operation and maintenance under complex sea conditions, a control method of the active wave compensation system for maintenance ships based on the Stewart platform is presented. The kinematics of the platform is analyzed, and the coordinate transformation, pose, and inverse solutions are analyzed and calculated. The multi-body dynamics simulation model is established by using MATLAB. For the problem of the load nonlinearity and strong coupling of the nonlinear Stewart platform, an active wave compensation active disturbance rejection control (ADRC) is built to attain the high-precision control of the six-degree-of-freedom (6-DOF) Stewart platform. The numerical simulation shows that the proposed control scheme has good tracking accuracy and strong anti-interference ability.

Simulation and Initial Experiment of a Twist-Tilt Quadcopter for Fully Actuated Motion

Although conventional quadcopters are well developed and are used in many applications, they are limited to 4 degree-of-freedom motion. For instance, the underactuated quadcopters cannot hover with inclined roll or pitch angles. To achieve fully actuated 6 degree-of-freedom motion, this paper presents a design, construction, and initial experimental results of an overactuated twist-and-tilt quadcopter configuration proposed in the group's previous work. The copter is comprised of four rotors, where each rotor's twist and tilt angles are independently adjustable over one full rotation by servo actuators. The copter weighs 5.78kg and is designed to carry an additional 5kg payload. A comprehensive multi-body virtual plant simulation model was also created with identified parameters from the rotor-arm drive dynamics to verify the control, which is designed based on a lumped single rigid body model. Also, an experimental rig was constructed to facilitate flight testing in a small physical space with safety to both the copter and environment. The initial experimental results for 6 degree-of-freedom motion is then presented.

Estimation of Vehicle Dynamic Response from Track Irregularity Using Deep Learning Techniques

To improve the quality of track maintenance work, it is a desire to estimate vehicle dynamic behavior from track geometry irregularities. This paper proposes a deep learning model to predict vehicle responses (e.g., vertical wheel-rail forces, wheel unloading rate, and car body vertical acceleration) using deep learning techniques. In the proposed CA-CNN-MUSE model, convolutional neural networks (CNNs) are used to learn features of track irregularities, and multiscale self-attention mechanisms (MUSE) are employed to capture the long-term and short-term trends of sequences. Coordinate attention (CA) is introduced into CNN to focus on important interchannel relationships and important spatial mileage points. The experiments were performed on a multibody simulation model of the vehicle system and the measured data of the actual high-speed line. The results show that the CA-CNN-MUSE has high prediction accuracy for vertical vehicle responses and fast computation speed. The predicted time-domain waveforms and power spectral densities (PSDs) agree well with the actual vehicle responses. The main features of the lateral vehicle responses can also be captured by the proposed method, yet the results are not as good as the vertical ones.

FRF-based non-simultaneous real-time hybrid testing of multiple subsystems with moderate nonlinearities

The existing cyber physical testing methods have been extended in a recent publication by non-simultaneous real-time hybrid testing, see Witteveen et al. [1]. There, an overall system is decomposed into two subsystems, one experimental and one numerical. The subsystems are loaded by certain inputs and simulated or tested separately in loops until compatibility conditions are fulfilled. If not, an input update based on the error of the kinematic compatibility in the frequency domain is computed for the next loop run. Each single test run is independent from the numerical model and therefore both is possible: Slow speed and real-time testing. In this work, the generalization to a systematic approach for an arbitrary number of subsystems is presented. The subsystems can be of numerical or experimental nature. While in the last publication the subsystems had to be tested one after the other within a loop run, they can be processed totally independently from each other in this generalized method. Further, both compatibility conditions (kinematic and cutting force) are considered for the update of the input signals. Finally, approximate models of the tested components can be considered in the numerical subsystems to improve convergence. The update for the inputs is again computed in the frequency domain based on FRFs of the isolated subsystems. The theory section is followed by two examples. The first one is of academic nature, and it is demonstrated that in case of convergence, all subsystems behave as they were part of one assembled overall system. The second one is a full vehicle hybrid testing where two shock absorbers are considered as real hardware while the vehicle is a multibody simulation model on a virtual four-poster test rig.

Computer-based analysis of different component positions and insert thicknesses on tibio-femoral and patello-femoral joint dynamics after cruciate-retaining total knee replacement

BackgroundPositioning of the implant components and tibial insert thickness constitute critical aspects of total knee replacement (TKR) that influence the postoperative knee joint dynamics. This study aimed to investigate the impact of implant component positioning (anterior-posterior and medio-lateral shift) and varying tibial insert thickness on the tibio-femoral (TF) and patello-femoral (PF) joint kinematics and contact forces after cruciate-retaining (CR)-TKR. MethodA validated musculoskeletal multibody simulation (MMBS) model with a fixed-bearing CR-TKR during a squat motion up to 90° knee flexion was deployed to calculate PF and TF joint dynamics for varied implant component positions and tibial insert thicknesses. Evaluation was performed consecutively by comparing the respective knee joint parameters (e.g. contact force, quadriceps muscle force, joint kinematics) to a reference implant position. ResultsThe PF contact forces were mostly affected by the anterior-posterior as well as medio-lateral positioning of the femoral component (by 3 mm anterior up to 31 % and by 6 mm lateral up to 14 %). TF contact forces were considerably altered by tibial insert thickness (24 % in case of + 4 mm increase) and by the anterior-posterior position of the femoral component (by 3 mm posterior up to 16 %). Concerning PF kinematics, a medialised femoral component by 6 mm increased the lateral patellar tilt by more than 5°. ConclusionsOur results indicate that regarding PF kinematics and contact forces the positioning of the femoral component was more critical than the tibial component. The positioning of the femoral component in anterior-posterior direction on and PF contact force was evident. Orthopaedic surgeons should strictly monitor the anterior-posterior as well as the medio-lateral position of the femoral component and the insert thickness.

Multi-body dynamics modeling and driving performance evaluation of oil recovery vehicle

In this study, the design and driving performance evaluation of a driving system for driving on deformable terrain was performed using terramechanics theory and multi-body dynamics simulation. For the design of the driving system, the mechanical interaction of track-terrain was analyzed using a Bekker-based model. Based on the analyzed results, the design of a track suitable for the deformable terrain to be driven and selection of a power source (engine, transmission, etc.) were carried out. A multi-body simulation model of the tracked vehicle reflecting the designed track and the selected power source was developed, and a ground model reflecting the mechanical property of terrain was also developed to analyze the mechanical interaction of the track-terrain through simulation. In addition, each link constituting the track was modeled as a 6 DOF spring/damper system to consider the track's tension force and load distribution under the track, and through this, different ground pressure and soil thrust were applied according to the motion state of each link. Finally, driving performance analyses were performed using the developed tracked vehicle, and as a result, it was confirmed that the driving requirements of the tracked vehicle were satisfied.

Research on the Obstacle-Avoidance Steering Control Strategy of Tracked Inspection Robots

Tracked inspection robots possess prominent advantages in dealing with severe environment rescue, safety inspection, and other important tasks, and have been used widely. However, tracked robots are affected by skidding and slipping, so it is difficult to achieve accurate control. For example, the control parameters of a tracked robot are the same during driving, but the pressure, shear force and steering resistance of the robot on the road surface are different, which affects the steering characteristics of the robot on complex terrain. Based on analysis of the structural parameters and steering radius of the robot, the traction force and resistance torque models of the tracked robot were established, and the plane dynamics of the robot’s steering were analyzed and solved. The corresponding relationships between the road parameters, relative steering radius, and lateral relative offset of the robot on three typical roads were obtained. Mathematical models of the robot’s track speed and relative steering radius with and without skid and slip were established. Through simulation analysis of Matlab software, the corresponding relationship between the relative steering radius of the robot and the velocity difference of the two tracks were obtained. Taking angular obstacles as an example, three obstacle-avoidance steering control strategies, once turning in situ center, twice turning in situ center, and large-radius steering were developed. The tracked robot and obstacle multi-body dynamic simulation models were constructed using ADAMS simulation software. The simulation results show that all three methods can complete the steering tasks according to the requirements; however, under the influence of skid and slip, the trajectory of the robot deviates from the ideal trajectory, which has a great impact on large-radius steering, even though the large-radius obstacle-avoidance steering control strategy has the advantages of a smooth trajectory, fast steering speed, and high efficiency. The obstacle-avoidance steering experiments were completed by the robot prototype, which verifies the rationality of robot steering theory, which could provide the corresponding theoretical basis for autonomous obstacle-avoidance navigation control of a tracked robot.

Determining the structural life of an electric vehicle battery from road loads

Abstract Although the electrical system is important in the development of electric vehicles, the durability of the battery system against mechanical loads and the performance of the battery against shock reactions are just as important. The objective of this study is to develop a methodology to determine the structural life of the battery of the C-platform sports utility vehicle (SUV). For this purpose, a power spectral density (PSD) durability test profile is generated and compared to battery test standards such as ISO 6469:2019, AK-LH 5.21 and SAE J2380. Analytical Virtual Proving Ground (VPG), a multibody dynamics simulation model, is also developed and correlated to test data. The results show that FDS values for AK-LH is higher than the fatigue damage of the collected vehicle data, while the FDS results for ISO standard are lower compared to the vehicle data. The results also indicate that the loads in the longitudinal (x-direction) and lateral (y-direction) directions are different. Therefore, loads of different amplitudes should be used for these directions, contrary to SAE J2380 and USABC standards. Finally, it is concluded that the VPG model can be used for determining the fatigue life when there is no test data, thanks to its high accuracy.

Sensor Screening Methodology for Virtually Sensing Transmission Input Loads of a Wind Turbine Using Machine Learning Techniques and Drivetrain Simulations

The ongoing trend of building larger wind turbines (WT) to reach greater economies of scale is contributing to the reduction in cost of wind energy, as well as the increase in WT drivetrain input loads into uncharted territories. The resulting intensification of the load situation within the WT gearbox motivates the need to monitor WT transmission input loads. However, due to the high costs of direct measurement solutions, more economical solutions, such as virtual sensing of transmission input loads using stationary sensors mounted on the gearbox housing or other drivetrain locations, are of interest. As the number, type, and location of sensors needed for a virtual sensing solutions can vary considerably in cost, in this investigation, we aimed to identify optimal sensor locations for virtually sensing WT 6-degree of freedom (6-DOF) transmission input loads. Random forest (RF) models were designed and applied to a dataset containing simulated operational data of a Vestas V52 WT multibody simulation model undergoing simulated wind fields. The dataset contained the 6-DOF transmission input loads and signals from potential sensor locations covering deformations, misalignments, and rotational speeds at various drivetrain locations. The RF models were used to identify the sensor locations with the highest impact on accuracy of virtual load sensing following a known statistical test in order to prioritize and reduce the number of needed input signals. The performance of the models was assessed before and after reducing the number of input signals required. By allowing for a screening of sensors prior to real-world tests, the results demonstrate the high promise of the proposed method for optimizing the cost of future virtual WT transmission load sensors.

Modelling of wind turbine gear stages for Digital Twin and real-time virtual sensing using bond graphs

In this paper a wind turbine high-speed gear stage model is developed for the purpose of real-time virtual sensing of gear and bearing loads in a Digital Twin framework. The model requirements are: accurate representation of gear meshing and shaft dynamics, high computational efficiency and compatibility with other Digital Twin components, such as physical sensors signals and virtual sensing methods. State equations are derived analytically using the Bond Graph method and implemented in the software 20sim for simulation. As opposed to standard multi-body simulation (MBS) software, 20sim allows for higher flexibility in implementing interfaces to other Digital Twin components. The model fidelity is close to state-of-the-art MBS models considering 6 DOF body motion, however a simplified gear contact formulation is used, which assumes ideal kinematic meshing. Nonetheless, the Bond Graph model is able to accurately reproduce the inhomogeneous load distribution over the tooth flank, as well as the cyclic compression and decompression for each meshing period. The results suggest that the presented model is capable of monitoring fatigue loads in gear contacts and bearings in a Digital Twin framework.

Multi-Physical Simulation Toolchain for the Prediction of Acoustic Emissions of Direct Drive Wind Turbines

To address the acoustic behaviour of wind turbines, particularly tonalities, in an early design stage, accurate simulation toolchains have to be developed. In this work a novel simulation approach for the prediction of tonalities of direct drive wind turbines is presented. Comprehensive work is carried out in the fields of electromagnetic force excitation, structural sound transfer and radiation as well as airborne sound propagation. The developed methods are combined to a simulation toolchain to formulate a multi-physical system model of a direct drive wind turbine in order to predict tonal sound behaviour. These methods will be presented and discussed in detail in the course of this work. First, the approach, integrating the electromagnetic airgap forces of the large generator into a multi body simulation model of the mechanical turbine, is explained and validated with test bench measurements. Following, the modeling of the respective mbs is presented which calculates the resulting surface velocities. This model is solved in the time domain to account for the interaction between the external loads that are highly nonlinear and low-frequency and the high-frequency excitation forces of the generator. Subsequently, the methods for calculating the airborne sound emission in the vincinity of the turbine resulting from the surface velocities are discussed.

Musculoskeletal Modeling of the Wrist via a Multi Body Simulation.

In this study, three different musculoskeletal modeling approaches were compared to each other. The objective was to show the possibilities in the case of a simple mechanical model of the wrist, using a simple multi-body-simulation (MBS) model, and using a more complex and patient-specific adaptable wrist joint MBS model. Musculoskeletal modeling could be a useful alternative, which can be practiced as a non-invasive approach to investigate body motion and internal loads in a wide range of conditions. The goal of this study was the introduction of computer-based modelling of the physiological wrist with (MBS-) models focused on the muscle and joint forces acting on the wrist.

Design, Modeling and Validation of a Tendon-Driven Soft Continuum Robot for Planar Motion Based on Variable Stiffness Structures

Robotic structures based on variable stiffness enable high-performance and flexible motion systems that are inherently safe and thus allow safe Human-Robot Collaboration. This letter presents the design of a robotic structure based on variable stiffness. A robotic manipulator is developed using three variable stiff segments based on particle jamming with a backbone architecture and two tendons for an underactuated motion control of the whole structure. By switching the structural stiffness, the manipulator is able to perform complex planar motion with only one pair of tendons, reducing the number of actuators required. A kinematic modeling approach for the calculation of the forward kinematics of this soft continuum structure is presented, and the validation on the real system is explained. The kinematic simulation is performed with a multibody simulation model (MBS) using rigid body elements in combination with rotational springs. The validation of the model is carried out with visual measurements of the real system using defined target shapes. Simulation and experimental results are discussed and compared also with a common constant curvature model. The developed MBS-model demonstrates a promising modeling approach with a position error lower 3% for the calculation of the presented manipulator under gravity.

Coordination and matching of tire system of new straddle-type rapid transit vehicle

Under the trend of promoting economy, environmental protection and high efficiency in the urban rail transit industry, this paper proposes a new type of straddle-type rapid transit system. Compared with most straddle-type monorail systems, it has the advantages of low construction cost and low operating cost, which makes it more suitable for urban rail transit system in small and medium-sized cities. In the process of vehicle development and design, in order to achieve the coordination and matching of tire systems and reduce the wear of tire systems, this work uses a multi-objective optimisation method to reduce the guiding torque of each tire system when the vehicle passes through the curve. Based on the vehicle dynamics model, the multi-body dynamics simulation model of the vehicle is established. The guiding torque of each tire system is taken as the optimisation objective, and the position and dynamic parameters of each tire system are taken as the optimisation parameter. Based on the NSGA-II algorithm, the ISIGHT and SIMPACK software are used for co-simulation. Finally, the guiding torque of each tire system is effectively reduced, and the coordination and matching of tire system is realised.

Can a Priori Unknown Values of Biomechanical Parameters Be Determined with Sufficient Accuracy in MBS Using Sensitivity Analysis? Analyzing the Characteristics of the Interaction between Cervical Vertebra and Pedicle Screw

Finite element (FE) modeling is a commonly used method to investigate the influence of medical devices, such as implants and screws, on the biomechanical behavior of the spine. Another simulation method is multibody simulation (MBS), where the model is composed of several non-deformable bodies. MBS solvers generally require a very short computing time for dynamic tasks, compared with an FE analysis. Considering this computational advantage, in this study, we examine whether parameters for which values are not known a priori can be determined with sufficient accuracy using an MBS model. Therefore, we propose a many-at-a-time sensitivity analysis method that allows us to approximate these a priori unknown parameters without requiring long simulation times. This method enables a high degree of MBS model optimization to be achieved in an iterative process. The sensitivity analysis method was applied to a simplified screw–vertebra model, consisting of an anterior anchor implant screw and vertebral body of C4. An experiment described in the literature was used as the basis for developing and assessing the potential of the method for sensitivity analyses and for validating the model’s action. The optimal model parameters for the MBS model were determined to be c = 823,224 N/m for stiffness and d = 488 Ns/m for damping. The presented method of parameter identification can be used in studies including more complex MBS spine models or to set initial parameter values that are not available as initial values for FE models.

Vibration Analysis and Control of the Suspension System of the Drum Washing Machine by Applying SMA

The suspension system of the drum washing machine is the object of study. To reduce the vibration of drum washing machines during high-speed dehydration, a shape memory alloy is proposed to be used to make suspension spring. The spring stiffness can be controlled according to the characteristic that the elastic modulus of SMA varies with temperature to achieve damping effect. The mathematical model and multi-body dynamics simulation model are established for the suspension system of the drum washing machine, the vibration generation mechanism of the drum washing machine and the SMA active vibration control principle are analyzed, and the vibration control effect of the SMA suspension spring is studied for different speed simulations. The results show that the SMA variable stiffness suspension spring has a significant vibration control effect compared with the spring of general material.

Condition Monitoring of Railway Crossing Geometry via Measured and Simulated Track Responses.

This paper presents methods for continuous condition monitoring of railway switches and crossings (S&C, turnout) via sleeper-mounted accelerometers at the crossing transition. The methods are developed from concurrently measured sleeper accelerations and scanned crossing geometries from six in situ crossing panels. These measurements combined with a multi-body simulation (MBS) model with a structural track model and implemented scanned crossing geometries are used to derive the link between the crossing geometry condition and the resulting track excitation. From this analysis, a crossing condition indicator is proposed. The indicator is defined as the root mean square (RMS) of a track response signal γ that has been band-passed between frequencies corresponding to track deformation wavelength bounds of and for the vehicle passing speed (f = v/). In this way, the indicator ignores the quasi-static track response with wavelengths predominantly above and targets the dynamic track response caused by the kinematic wheel-crossing interaction governed by the crossing geometry. For the studied crossing panels, the indicator ( and ) was evaluated for γ = u, v, or a as in displacements, velocities, and accelerations, respectively. It is shown that this condition indicator has a strong correlation with vertical wheel–rail contact forces that is sustained for various track conditions. Further, model calibrations were performed to measured sleeper displacements for the six investigated crossing panels. The calibrated models show (1) a good agreement between measured and simulated sleeper displacements for the lower frequency quasi-static track response and (2) improved agreement for the dynamic track response at higher frequencies. The calibration also improved the agreement between measurements and simulation for the crossing condition indicator demonstrating the value of model calibration for condition monitoring purposes.

Building a multibody dynamics simulation model of railway vehicle considering wheel slide re-adhesion control

The contact between wheel and rail of railway has a strong influence on the running safety. But under the wet condition, adhesion coefficient between wheel and rail decease, and skid may occur when railway vehicle is breaking. This is a serious safety risk to the operation of vehicle. Therefore, many research to reveal the adhesion between wheel and rail have been performed. In this paper, we built a multibody dynamics simulation model of railway vehicle considering wheel slide re-adhesion control using Simpack, in order to study on the best way of breaking of railway vehicle under wet condition reflecting the previous research results. In addition, breaking simulation under low adhesion coefficient condition was performed using the simulation model with wheel slide re-adhesion control.