Direct Wheel Research Articles

Monitoring of ground and building vibrations caused by train wheel defects

This paper describes a study performed on train wheel defects and their effect on rail vibrations. The paper describes a test setup allowing the researchers to capture ground vibrations at the desired level of detail to prove to what extend wheel quality influences ground vibration levels and associated nuisance to people. The analysis of the measurement signals shows that the individual axles of a passing train can be detected excellently with the signal from the axle detection and the vibration sensors. The signals from various sensors in the measurement setup are synchronized with high time accuracy, making it possible to overlay the time interval of an axis passage over the signal from the vibration measurements. This makes it possible to track vibrations at bogie and axle level. The distance of measurement points from the track is ultimately the determining factor for the extent to which vibrations are dominated by an axle, a bogie, a wagon or the entire train. In addition, direct wheel roundness measurements have been performed for trains that appear to have defect wheels based on ground vibration data. With the track based measurements, the ground vibration measurements and the direct wheel measurements an unique data set has been generated, allowing for an evaluation of the importance of defect train wheel from the perspective of vibrations nuisance to the environment. Relations of measured vibrations to other parameters, both rolling stock related and environmental parameters were investigated based on the generated set of data. The analysis on the data reveals interesting relations between train wheel parameters and ground vibrations, which are discussed in this paper.

EASS: An automatic steering system for agricultural wheeled vehicles using fuzzy control

Automatic steering is a crucial technology for achieving automatic navigation and unmanned driving of agricultural machinery. In this research, agricultural wheeled vehicles with the HPAS (Hydraulic Power Assistant Steering) system were selected as the research object and the EASS (Electric Automatic Steering System) was proposed by using fuzzy control to realize effective steering instead of human drivers. The PID (Proportional Integral Differential) algorithm was used to process the difference between the desired and actual steering angles and to realize automatic control of rotation of directional wheels. Fuzzy control was adopted to achieve self-adjusting of PID parameters and to optimize working state of the steering motor in real-time for different agricultural wheeled vehicles under various operating conditions. Fuzzy control rules were explored and formulated by analyzing variation of the steering angle under different resistive torque values. For evaluation of its feasibility, the newly developed EASS was applied in automatic navigation of a rice transplanter, a tractor, and a high-clearance sprayer. Field testing results showed that the maximum path tracking lateral error and heading error were 4.39 cm and 2.13°, respectively. And the maximum RMS (Root Mean Square) errors were 3.75 cm and 1.02°, respectively. Therefore, the fuzzy control-based the EASS in this research was applicable to various agricultural wheeled vehicles.

Optimization of stretch film former of fresh food packaging machine

Current research on fresh food packaging machines focuses on vertical and horizontal sealing. Compared with the conventional pillow packaging machine, the fresh food packaging machine still presents deficiencies regarding the feeding and forming ability of stretch film. This paper presents a step former for the stretch film to integrate the existing forming mechanism. First, by analyzing the movement diagram of the stretch film on the support plate, the optimal inclination angle of the stretch film during the process of feeding on the upper part of the support plate, and the center position of the second directional wheel on the upper part of the support plate was found, it can ensure that the stretch film in the process of feeding and forming has the minimum tension and not be broken. In addition, based on the above-mentioned, the support plate and the directional wheel were simulated in software. The 2 mm 304 stainless steel support plate and different plastic combinations of directional wheels were the optimal choices.

Modelling and dynamic analysis of slippage level for large-scale skid-steered unmanned ground vehicle.

To analyze the turning characteristics of a large-scale skid-steered unmanned ground vehicle (UGV), a mathematical model based on geometric characteristics and kinematics was developed in this work. The turning characteristics, as well as some important geometric and moving features, were seriously considered in the model. A self-designed UGV was employed to conduct targeted experiments. Initial experiment showed that the width of UGV was much larger than that of actual value, because slippage phenomenon made the errors of actual velocity and trajectory length between two sides of the UGV were lower than those obtained from direct wheel velocities measurements and calculations. Further experiments which obtained moving velocity of the UAV by means of a highly accurate Inertial Navigation System (INS) were conducted. Combining this velocity, the slippage levels of the four wheels can be quantitatively measured. In addition, using standard velocities derived from the accurate moving velocity, a true turning radius can be accurately calculated in real time when the slippage characteristics were seriously considered, hence, the mathematical model can be sufficiently validated. The work can realize modelling and dynamic analysis and estimation of the slippage characteristics of this type of UGV.

PocketQube Pico-Satellite Attitude Control: Implementation and Testing

Attitude control for CubeSats and small satellites has been widely researched. Nonetheless, most of the literature is based on simulations, with limited availability of actual implementation results. This article tries to fill this gap by highlighting implementation difficulties and proposing appropriate workable solutions. The difficulty of direct reaction wheel (RW) torque feedback for attitude control of a 1p PocketQube (PQ) pico-satellite is noted and addressed. A simple control strategy implementable on a microcontroller is then proposed, showing how direct RW torque control can be achieved through angular velocity measurement without using derivative feedback. A linear quadratic Gaussian controller with integral action in quaternion formulation is used for attitude control, and a reference input boundary caused by the use of the standard integral action scheme is highlighted. A simple solution is then proposed, showing how using the error quaternion removes this boundary. An extended Kalman filter in quaternion formulation is used for attitude determination by fusing data from three sensors, namely, a magnetometer, solar cells, and a gyroscope. An accelerometer is used in place of the solar cells for simplified laboratory testing. Magnetometer error due to surrounding interference is addressed through calibration. A string-suspended model of the UoMBSat-1 PocketQube pico-satellite is used for attitude control testing. Preliminary single-axis tests are performed using a PID controller to determine the satellite parameters and actuators verification. The proposed linear quadratic Gaussian controller is then tested and validated experimentally in the laboratory setting.

Fatigue behavior of orthotropic bridge decks with two types of cutout geometry based on field monitoring and FEM analysis

This paper provides comparative results on stress behavior and fatigue performance of two types of cutout geometry on orthotropic bridge decks based on simultaneous field monitoring and finite-element method (FEM) analysis. The two types of cutout are incorporated in two closely spaced diaphragms with distance of 6 m and at the same transverse location on a real bridge, allowing simultaneous stress measurement under random traffic flows. The research was conducted on the Pingsheng Bridge in Southern China, a self-anchored suspension bridge with a main span of 350 m and a steel box girder with orthotropic steel bridge decks (OSBD). Results of the study reveal that the two types of cutout geometry present high stress response and severe stress concentration at the floorbeam (FB) cutout, and that the excessively large stress at the original FB cutout contributes greatly to the early cracks of this detail. Compared to the original cutout geometry, the new cutout geometry with large radius increases the stress level at the FB cutout, resulting in a further low fatigue life at this detail. Meanwhile, the new cutout geometry also deteriorates the fatigue resistance at the rib-to-floorbeam (RF) weld connection, particularly at the detail of rib wall at cutout, where the stress level is significantly increased and its fatigue life becomes substantially lower than the design life of 100 years. In addition, the new cutout geometry only slightly improves the out-of-plane distortion under direct wheel loading, and the in-plane stress still dominates the total stress at the FB cutout. Since the new cutout geometry weakens the FB web, the total stress at FB cutout will increase due to the increased in-plane stress. The research also finds that if the free edge of cutout did not satisfy the fabrication requirement per the AASHTO LRFD, category B is suggested for fatigue evaluation at the FB cutout, which is confirmed by the observed fatigue life of the original FB cutout on the real bridge. It is concluded that the new cutout geometry lowers the fatigue resistance both at the FB cutout and at the RF weld connection, hence it will no longer be recommended to retrofit the present bridge in the future.

Robust Integrated Control of Wheel Slip and Direct Yaw Moment for Stabilizing the Dynamics of Skid-Steering Vehicles

This paper presents a robust integrated control system to improve the stability and the handling performance of skid-steering vehicles. The control strategy is based on two layers: direct yaw moment control and wheel slip control. In the first layer, the direct yaw moment is obtained based on the nonlinear sliding mode control theory using the exact second order yaw rate response of the conventional steering vehicle. In the second layer, the direct yaw moment is optimally distributed to the four wheels in order to calculate the torque command needed at each wheel individually. Then, the sliding mode control theory is used again to control the torque command at each wheel individually and maintain the wheel slip at the desired value. A closed-loop driver-vehicle system subjected to a turning maneuver accompanied with braking at different surface conditions is simulated in Matlab/SIMULINK to validate the effectiveness of the proposed integrated control system. The simulation results show that the combination of wheel slip control and direct yaw moment is essential for stabilizing the motion of skid-steering vehicles. Moreover, the proposed control system is robust against uncertainty in the adhesion between the road surface and the wheel.

Optimization of a multi-link steering mechanism using a continuous genetic algorithm

A steering mechanism is one of the main components of a vehicle that is responsible of controlling the directional wheels. The optimal design of a steering mechanism is not a trivial problem because the equations involved in the modeling are highly nonlinear. Therefore, this paper proposed a method for global optimization using a genetic algorithm for a multi-link steering mechanism, which can also be applied to other problems of optimal synthesis of mechanisms.

Genetic algorithm as a tool for multi-objective optimization of permanent magnet disc motor

Abstract The analysed permanent magnet disc motor (PMDM) is used for direct wheel drive in an electric vehicle. Therefore there are several objectives that could be tackled in the design procedure, such as an increased efficiency, reduced iron weight, reduced copper weight or reduced weight of the permanent magnets (reduced rotor weight). In this paper the optimal design of PMDM using a multi-objective genetic algorithm optimisation procedure is performed. A comparative analysis of the optimal motor solution and its parameters in relation to the prototype is presented.

Numerical and experimental study on dynamic behaviour of concrete sleeper track caused by wheel flat

ABSTRACTImpact loads caused by flat spots on railcar wheels impose a major maintenance burden on railroads and can cause severe damage to both railcar and track components. This paper discusses the dynamic behaviour of the railroad track system under impact loads. A finite element (FE) model with multiple crossties and their accompanying fastening systems is developed and validated using field data. The results of the parametric study indicate that impact loading consists of direct wheel impact loads and track system vibration–induced impact loads. Both of these impact mechanisms are sensitive to the stiffness of rail pad. It is observed that rail pad with a moderate stiffness provides the most effective impact attenuation.

Wheel slip control for all-wheel drive electric vehicle with compensation of road disturbances

Development of wheel slip control for ground vehicles with electric powertrain belongs to the one of the most challenging problems in automotive control engineering. The realization of the wheel slip control for anti-lock brake (ABS) and traction control (TC) systems is a more complex task in the case of vehicles designed both for on-road and off-road conditions. In this situation a control strategy must be able to handle different tyre-surface contact dynamics. Within this context, the presented paper introduces the wheel slip control and corresponding ABS algorithm developed for the all-wheel drive sport utility electric vehicle with four individually controlled on-board motors. The proposed paper, in particular, includes: Analysis of state-of-the art solutions for off-road ABS; Description of the developed ABS architecture based on the direct wheel slip control with predictive and reactive wheel torque contributions; Results of ABS operation in the vehicle simulator software with special attention given to the braking on rough surface; Procedure of the system tuning using hardware-in-the-loop technique; Experimental results of the system testing on the vehicle demonstrator in real operational conditions. The theoretical and experimental outcomes have confirmed improved functionality of the developed wheel slip control in terms of vehicle safety and energy efficiency.

A fuzzy logic sliding mode controlled electronic differential for a direct wheel drive EV

In this study, a direct wheel drive electric vehicle based on an electronic differential system with a fuzzy logic sliding mode controller (FLSMC) is studied. The conventional sliding surface is modified using a fuzzy rule base to obtain fuzzy dynamic sliding surfaces by changing its slopes using the global error and its derivative in a fuzzy logic inference system. The controller is compared with proportional–integral–derivative (PID) and sliding mode controllers (SMCs), which are usually preferred to be used in industry. The proposed controller provides robustness and flexibility to direct wheel drive electric vehicles. The fuzzy logic sliding mode controller, electronic differential system and the overall electrical vehicle mechanism are modelled and digitally simulated by using the Matlab software. Simulation results show that the system with FLSMC has better efficiency and performance compared to those of PID and SMCs.

Directed one-pot syntheses of crown ether wheel-containing main chain-type polyrotaxanes with controlled rotaxanation ratios.

The directed synthesis of main chain-type polyrotaxanes possessing crown ether wheels was successfully achieved through two methods, A and B. Method A involved the direct wheel threading of poly(sec-ammonium salt) followed by end-capping with a bulky group, while method B utilized polyaddition of a pseudo[2]rotaxane monomer to facilitate the control of the structure, i.e. the rotaxanation ratio.

Modeling and Simulating of Omni Directional SoccerRobot

Abstract — Modeling and simulation in robotics research has always been one of the most beneficial ways of evaluating structural and behavioral designs before implementation in real world. Robot soccer is a research domain started from 1998 as a practical league of RoboCup international competitions. Simulating omni-directional wheels of such robots has recently been a controversial issue among developers. In this paper an innovative simulator including all the features of small size soccer robots in a 5 on 5 game, is introduced. In addition, a novel technique in modeling omni directional wheels is applied with considering just two parameters of wheels: longitude and lateral. The advantages of this simulation environment are shown via investigation of its feasible computation time and accuracy in robots' performance estimation. Index Terms — Omni-directional wheel, robocup, soccer robot, wheel simulation. I. I NTRODUCTION Generating a simulation environment is an inevitable approach for testing and developing proposed algorithms to be verified to implement in reality. This is highly applicable robotic projects like small size soccer robot as one of Robocup competitions league. Different branches of researches from mechanical and electrical designs to image processing, control and decision making in a dynamic time critical environment converted such competitive matches to a challenging scientific robotic test bed. Evaluation of strategies based on artificial intelligence in multi agent environment besides the control and practical constraints make complex problem with different aspects. Thus, a comprehensive simulator with characteristics, near reality as much as possible, is a significant requirement.

Sequence Stereoisomerism in Calixarene-Based Pseudo[3]rotaxanes

Two calix[6]arene directional wheels can be ordered in the right stereosequence by their through-the-annulus threading with a rationally designed bis(benzylalkylammonium) axle. These stereoisomeric pseudo[3]rotaxanes can be considered as a minimal "informational system" because the "written information" on the thread is transferred to a specific sequence stereoisomer.

Control of an EV drive with reduced unsprung mass

Traditionally, the motors used in electric vehicles as direct wheel drives were built entirely into the vehicle wheel; this, however, increases the weight of the wheel. The drive arrangement described here utilises a permanent magnet, brushless, axial field double-sided disc motor. This type of machine, particularly the double-sided stator configuration, is attractive because rotor misaligninents perpendicular to the motion of the drive shaft can be accommodated. In such an arrangement, the stators of the machine can be mounted onto the chassis of the car and the rotor is allowed two degrees of freedom (rotational and transverse), and thereby directly drives the road wheel. Hence, a reduction in the unsprung mass of the wheel drive is achieved. However, there is a drawback: since the wheel is perturbed by the road surface roughness effects, the rotor moves between the outer stator assemblies (transversely), and consequently induces torque pulsations in the machine. Two separate control strategies to eliminate the torque pulsations caused by the rotor perturbation are investigated: modulation of the input motor current, and instantaneous torque control using a variable structure controller. The experimental results in each case show that both control strategies are effective in eliminating the torque pulsations.

The effect of tractor wheel passes on herbage production from diploid and tetraploid ryegrass swards

AbstractDiploid and tetraploid perennial ryegrass swards were managed under an intensive silage system over 3 years. The swards were subjected to five tractor wheel pass treatments to simulate combinations of silage operations in the field from cutting, tedding, lifting and fertilizing. Wheel tracking was applied uniformly over the swards after June, July, August and October cuts each year.Tractor wheel passes caused mean reductions in herbage dry matter (DM) yield during successive years of 14%, 6% and 9% compared with their absence, and frequent or delayed wheel passes affected yield more adversely than infrequent or undelayed wheel passes. Nitrogen and mineral concentrations in herbage and nutrient offtakes were also generally reduced but organic matter digestibility (OMD) was unaffected. Soil assessments each autumn showed that soil bulk density increased in the wheel‐pass treatments, particularly when frequently applied. The two sward types responded in a similar manner to the wheel‐tracking treatments, probably because they had similar cushioning capability, the disadvantage of the tetraploid in terms of fewer tillers in relation to the diploid being compensated for by larger tiller size. Soil compaction, with its adverse effect on sward growth vigour, and direct wheel damage to young regrowth will be lessened by minimizing wheel traffic on silage swards and undertaking operations over short rather than long periods.

Elimination of torque pulsations in a direct drive EV wheel motor

Double sided axial field machines are attractive for direct wheel drives in electric vehicles. This is due to the fact that stator/rotor misalignments can be accommodated. In this case the stator of the machine is envisaged mounted on the chassis of the car whilst the rotor directly drives the road wheel. Since the wheel is perturbed by the road surface the rotor will move vertically between the outside stator assemblies and thus give rise to torque pulsations. A vector control scheme has been implemented whereby the torque pulsations are eliminated by (i) calculation of the flux variation due to the rotor perturbation and (ii) using this signal for the modulation of the motor input current.