Wheel Assembly Research Articles

Designing and Optimization of Wheel Assembly of a Formula Student Car

Designing and Optimization of Wheel Assembly of a Formula Student Car

반작용휠 및 휠 교란 모델링에 관한 해석적 연구

Reaction wheel assemblies(RWA) are expected to be one of the largest high frequency disturbance sources to the optical payload of satellites. To ensure the tight pointing-stability budget and high image quality of satellites, a vibration isolation device should be applied to the main disturbances. For developing the isolating system, the disturbances need to be identified and modeled accurately. In the present study, a modeling technique of RWA and its disturbance was described. The micro-vibration disturbances were generated numerically by using an analytical wheel and disturbance model. The parameter estimation scheme of the model was suggested, and the RWA and disturbance modeling technique was verified through the numerical example analysis. The analytical results show that the wheel and disturbance model can be accurately established by using the modeling technique proposed in the present study. The wheel and disturbance model is expected to be useful for development of the RWA isolator system.

Tire wheel assembly and noise-reducing device

Disclosed are a tire wheel assembly and a noise-reducing device whereby cavity resonance sound can be effectively reduced. A noise-reducing device, which includes a shell structure where a rough surface portion having a ten-point height of irregularities (Rz) in a range of 0.1 to 5.0 mm is provided on at least part of a surface, is attached to a wheel rim in a cavity portion of a pneumatic tire, and additionally, a height of the shell structure from a rim sheet is set in a range of 10 to 70% of a cross-sectional height of the tire.

Motorcycle-to-car and scooter-to-car collisions: speed estimation from permanent deformation

This paper proposes from fundamental mechanics that the specific energy ( E/ M) absorption characteristics of motorcycles and scooters in frontal impacts are similar where the primary load path is through the front wheel and fork assembly. Examination of 43 barrier test results for 14 different model types of motorcycle and scooter over the impact speed range from 10km/h to 76km/h shows that the specific energy versus wheelbase shortening characteristics are similar and that a single specific collision energy ( E/ M) regression equation with its associated statistical distribution ( r2=0.845) can be used to represent the motorcycle and scooter populations in frontal impact for wheelbase shortening up to 0.45m where the front-fork and front-wheel assemblies remain intact, albeit deformed. Data from 31 staged tests where motorcycles or scooters impacted stationary cars at 90° are used to obtain the energy absorption characteristics of the sides of cars subject to frontal motorcycle or scooter impact. These two regressions are used to estimate collision energy Eca from the permanent deformation or penetration depth of the collision partners, which, when substituted into the standard impact energy loss equation with the appropriate collision partner masses, yields an estimation of collision speed Vccs. This procedure for calculating collision closing speed Vccs is validated against 13 staged tests (six 90° impacts against stationary cars and seven angled impacts at angles up to 45° from the normal, four of which were against moving cars) and shows that the predicted Vccs speeds bound the actual speeds with a standard deviation of 11.2km/h for collision closing speeds up to 122km/h.

Simulation of wheel impact test using finite element method

In order to achieve better quality, the wheel design and manufacturing use a number of wheel tests to ensure that the wheel meets the safety requirements. The impact performance of wheel is a major concern of new design wheel. The wheel impact test is intended to evaluate the impact performance of wheel, that the striker is dropped from a specified height above the tire–wheel assembly. In this study, nonlinear dynamic finite element is used to simulate the SAE wheel impact test. The wheel modeled as an elastic–plastic body is mounted at an incline of 13° to horizontal, and the striker is prescribed an initial velocity to simulate a drop height. The total plastic work concept of ductile fracture mechanics is used to predict the impact failure of wheel. Three-dimensional finite element method is employed to obtain the strain energy density of wheel at impact, and the critical strain energy density is based on the total plastic work of wheel material. Compared with actual tests, the finite element results show the total plastic work approach can be used to predict the wheel fracture during the impact test.

A Study on Vibration Isolator for Reaction Wheel Assembly

A Study on Vibration Isolator for Reaction Wheel Assembly

Development of a Hardware-In-Loop (HIL) Simulator for Spacecraft Attitude Control Using Momentum Wheels

In this paper, a Hardware-In-the-Loop simulator to simulate attitude control of space craft using momentum wheels is developed. The simulator consists of a spherical air bearing system allowing rotation and tilt in all three axes, three momentum wheels for actuation, and an AHRS (Attitude Heading Reference System). The simulator processes various types of data in PC104 and wirelessly communicates with a host PC using TCP/IP protocol. A simple low-cost momentum wheel assembly set and its drive electronics are also developed. Several experiments are performed to test the performance of the momentum wheels. For the control performance test of the simulator, a PID controller is implemented. The results of experimental demonstrations confirm the feasibility and validity of the Hardware-In-the-Loop simulator developed in the current study.

Catastrophic Failure of a Wheel Assembly in a Heavy Duty Off-Road 6X6 Vehicle

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

반작용 휠의 최대 가용 토크 분배법칙

본 논문에서는 저사양의 반작용 휠을 이용하여 토크 가용성을 높이는 두 가지 기법이 제안 하였다. 첫 번째는 기존의 의사역행렬을 이용한 토크 제어 분배 법칙 대신 가중치가변 의사역행렬과 모멘텀을 최소화하는 제어 분배 법칙을 제안하여 반작용 휠의 토크, 모멘텀 제한 조건 내의 해를 찾도록 했다. 두 번째는 휠의 장착각을 변경하여 토크가 많이 필요한 축의 토크 가용성 자체를 증가시키는 방법을 제안하였다. 제안된 법칙들은 위성체의 자세 천이에 적용되었으며, 시뮬레이션을 통하여 성능 향상과 실제 위성의 적용 가능성을 기술했다. A new approach for maximizing torque capability of low efficient reaction wheel assembly is addressed in this paper. At first, to find out a solution in constrainted field, weighted pseudo-inverse and momentum minimized allocation are suggested instead of a general control allocation called pseudo-inverse. The second method is a structural manner to enlarge torque capability of specific axis by changing installed skew angle of wheels. Two proposed methods are applied to large angle maneuvers of satellite. Improvement of control performance and feasibility for applying to commercial satellite attitude control are demonstrated by numeric simulations.

Crack Detection in an Embedded Spindle using Broadband Modal Excitation

This paper demonstrates a methodology for detecting cracks in a metal spindle, which is housed within a military vehicle wheel end assembly. A finite element model is used to estimate the undamped natural frequencies of the raw spindle. Additional mass and stiffness is then added to a simplified model of the spindle to simulate sources of variability within the assembly. Spindles are tested outside the wheel end assembly to compare the responses of undamaged and cracked spindles. A hypothesis testing approach is developed to detect the presence of a crack based on damage indices involving the summation and multiplication of spectral energies. Experiments on wheel assemblies mounted on a vehicle with the vehicle lifted off the ground are performed to demonstrate that the wheel assemblies can be nondestructively evaluated to identify cracks of varying depths despite sources of variability due to the presence of the brake drum, lack of repeatability in the sensor attachment, and other issues.

Dynamics of a High-Agility, Low-Power Imaging Payload

Control-moment gyroscopes (CMGs) are power-efficient attitude-control actuators that produce high torques for agile spacecraft. We propose the use of CMGs in actuating joint degrees of freedom in a spacecraft-mounted agile imaging payload, whose tasks include acquiring and tracking a high-speed target. High agility, on the order of several radians per second, characterizes the system of interest here; however, such capabilities are achieved with traditional actuators only at the expense of excessively high electrical power. The proposed design provides agile slewing of an imaging payload for a very small fraction of the power required by fixed rotors in a reaction wheel assembly. This study provides a dynamics analysis for a general system, but we focus on an example in which the inertia dyadics are spherical. We demonstrate by simulation that a CMG-driven system offers the same agility with less than 1% of the power of a telescope actuated by reaction wheels.

A Review of Patents in Tyre Cooling

A number of patents on tyre cooling have been reviewed with a focus on those which can be applied to earthmoving tyres for the mining industry. The mechanisms of heat transfer within the tyre carcass are introduced as well as the basic tyre structure and effects of overheating on tyre operation. The tyre cooling patents are separated into five functional groups and reviews are made based on practicality and potential for significant heat transfer. This analysis has made it evident that potential cooling effectiveness is often compromised by practicality of an invention. The patents deemed to have the most potential for cooling are those which incorporate a working fluid which undergoes a phase change to transfer heat between different regions of the wheel assembly. Finally, these inventions are also related to current research projects which aim to develop a new cooling technique and extend the working life of earthmoving tyres.

Preparation of targets for the gas-filled recoil separator TASCA by electrochemical deposition and design of the TASCA target wheel assembly

The Transactinide Separator and Chemistry Apparatus (TASCA) is a recoil separator with maximized transmission designed for performing advanced chemical studies as well as nuclear reaction and structure investigations of the transactinide elements ( Z>103) on a one-atom-at-a-time basis. TASCA will provide a very clean transactinide fraction with negligible contamination of lighter elements from nuclear side reactions in the target. For TASCA a new target chamber was designed and built at GSI including the rotating target wheel assembly ARTESIA for beam intensities up to 2 μA (particle). For the production of longer-lived isotopes of neutron-rich heavier actinide and transactinide elements, hot fusion reactions with actinide targets are required. Here, possible target materials range from thorium up to curium or even heavier elements. For the deposition of lanthanide and actinide elements on thin aluminum and titanium backings by means of Molecular Plating (MP), a new deposition cell has been constructed that allows precise temperature control of the organic solvent and stirring of the solution. The electrode geometry ensures homogeneity of the electric field inside the cell. With the new set-up, holmium and gadolinium layers (500 μg/cm 2) on 2–5 μm thin titanium backings have been produced with deposition yields of the order of 90%. Systematic investigations are under way to further optimize the deposition conditions for other lanthanide and actinide elements including uranium and plutonium on different backing materials.

Laser Doppler anemometry measurements in the near-wake of an isolated Formula One wheel

An experimental investigation was conducted to identify the main structures in the near wake of an isolated Formula One wheel rotating in ground contact. A 50 percent-scale isolated wheel assembly, geometrically similar to the configuration mounted on a Formula One racing car, was tested in a closed-return three-quarter open-jet wind tunnel. The test Reynolds number, based on wheel diameter was 6.8 × 105. Using laser doppler anemometry, three velocity components were measured with a total of 1966 data points across four planes and within one diameter downstream of the wheel axis. Based on analysis of these data, the main characteristics of the near-wake of an isolated wheel rotating in ground contact are presented. A revised model of the trailing vortex system induced in the wake of such a wheel is proposed, which clarifies the contradictory ones published in the literature to date.

Ambulance Cot Recalled; Wheel Assembly Cited

Ambulance Cot Recalled; Wheel Assembly Cited

Development and Experimental Validation of a Shipboard Helicopter On-Deck Maneuvering Simulation

Routine shipboard helicopter operation on many classes of ships requires that helicopters be maneuvered and traversed along the ship deck using installed helicopter securing and handling equipment. This paper describes the derivation, implementation, and validation of a four-degrees-of-freedom mathematical model for predicting and analyzing the behavior of shipboard aircraft under the influence of external aircraft handling forces. The resulting model is suitable both for engineering analysis and training applications. The helicopter model includes the coupled dynamics of the aircraft, landing gear, and optionally steerable or castorable auxiliary wheel assembly. Detailed tire modeling addresses the transient development and release of tire deflection and cornering forces related to yawed and unyawed relaxation lengths as well as direct application of forces by the handling system. Verification and both qualitative and full-scale experimental validation of the model, performed using a number of simple maneuvers to validate specific aspects of the simulation, are discussed. It is shown that the resulting HeliMan simulation captures the underlying dynamics of the shipboard helicopter maneuvering process. Full-scale validation data show that in many cases the simulation is able to reproduce closely the measured data. The effect of tire side loading on longitudinal rolling resistance has been identified as a shortcoming of existing rolling tire models and the most probable cause for differences that exist between simulated and measured results in some validation cases. Nomenclature A = vector representing the accelerations for the two bodies

Development of methods identifying parameters in reaction wheel assembly disturbance model

PurposeTo set up the analytical model of reaction wheel assembly (RWA) by using the other theory and to provide a new method to identify the parameters of the empirical model of RWA.Design/methodology/approachSetting up the analytical model of RWA using virtual work theory, and presents the energy compensation method. The energy compensation method to improve the computation accuracy of amplitude coefficients of the empirical model of RWA. In the empirical model of RWA, the assumption is that the disturbances consist of discrete harmonics, and the amplitudes is proportion to the square of the wheel speed.FindingsThe errors of amplitude coefficients adopting energy compensation window excel the amplitude spectrum method. The energy compensation method improves the parameters identification accuracy, and provides a new method to set up more accurate empirical disturbance model of RWA.Practical implicationsProviding a valuable identification method of amplitude coefficients of the empirical model of RWA, and improving the accuracy of identification.Originality/valuePutting forward up the method of energy compensation to identify the amplitude coefficients of the empirical model of RWA, and improving the accuracy. This method is simple, practical for the system design.

과학기술위성 2호 Reaction Wheel Assembly Interface Unit Proto Flight Model 개발

과학기술위성 2호 사용되는 구동기인 반작용 휠(Reaction Wheel Assembly, RWA)과 위성 시스템을 연결해주는 인터페이스를 담당하는 Reaction Wheel Assembly Interface Unit(RIU)의 Proto Flight Model의 개발이 완료되고 동작시험을 마쳤다. RIU는 RWA에 공급되는 전원을 켜고 끄는 스위치와 명령을 주고 받는 위성탑재 컴퓨터(OBC)의 통신 회선을 선택하는 멀티플렉서, 그리고 RWA에 연결되는 물리적 통신라인으로 구성된다. Proto Flight Model of Reaction Wheel Assembly Interface Unit(RIU) for STSAT-2 was developed. The RIU of STSAT2 has three major functions for interface between satellite system and RWAs. It has switches for RWA main power, communication Mux. and communication line driver.

Predicting the Optical Performance of the Space Interferometry Mission Using a Modeling, Testing, and Validation Methodology

This paper presents the modeling, testing, and validation methodologies developed to predict the optical performance of the Space Interferometry Mission (SIM) at the Jet Propulsion Laboratory (JPL). The modeling methodology combines structural, optical, and control system design within a common state space framework and incorporates reaction wheel assembly (RWA) disturbances to evaluate the end-to-end performance of the system requirements. The validation methodology uses the Micro-Precision Interferometer (MPI) testbed, which is a ground-based, representative hardware model of SIM. In this study, the integrated model of the MPI testbed was used to calculate the transfer functions from RWA input to optical performance output. The model-predicted transfer functions were compared with the MPI testbed measurements, and the accuracy of the integrated model was quantified using a metric that was based on output power of the transfer functions. The RWA disturbances were then propagated through the modeled and measured transfer functions to predict the optical performance of the MPI testbed. This method is called the “decoupled disturbance analysis” and relies on the “blocked” RWA disturbances, measured with the RWA hardmounted to a rigid surface. These predictions were compared with the actual (measured) optical performance of MPI, measured with the RWA mounted to MPI, to evaluate the accuracy of the decoupled disturbance analysis method. The results show that this method is not an accurate representation of the coupled boundary conditions that occurs when the RWA is mounted to the flexible MPI structure. In order to correct for the blocked RWA disturbance boundary conditions, the “coupled disturbance analysis” method was developed. This method uses “force filters” that depend on estimates of the interface accelerances of the RWA and the MPI structure to effectively transform the blocked RWA disturbance measurements into their corresponding “coupled” disturbances (the disturbances that would occur at the coupled RWA-MPI interface). Compared to the decoupled method, the coupled method more accurately predicts the system’s performance. Additionally, the RWA cross-spectral density terms were found to be influential in matching the performance predictions to the measured optical performance of MPI.

Design of an active suspension system for a quarter-car road vehicle model using model reference control

The use of skyhook damping for reduction of the vibration in the suspension systems is well documented. The drawback is that it is not practically feasible to obtain the equivalent of a reference point in the sky. The alternative method of using a damper between the sprung mass (the vehicle hull) and the unsprung mass (the wheel assembly) leads to a deterioration in the performance of the unsprung mass. In this paper a new method is proposed that tries to overcome the limitation of the practical skyhook damping method by the use of the model reference control (MRC) method, where the control input is utilized to achieve near-ideal skyhook sprung mass performance in a practical skyhook damping set-up. The MRC method is also applied to a quarter-car suspension model, where the control input is used to achieve the response of a system with damping and stiffness values different from those of the actual system. This allows for variation of the system constants as dictated by dynamic response needs. The proposed methods are applied on a typical quarter-car suspension system and the necessary time and frequency domain simulations are carried out to validate the theoretical predictions.