Flexible Wheels Research Articles

Modeling of flexible metal wheel for pressurized lunar rover and traction performance prediction

AbstractThe pressurized lunar rover has become one of the most important equipment in lunar exploration and resource utilization missions. On the terrain of soft lunar regolith, the rover wheels are easy to slip, sink, or even fail to move. To improve the traction performance of the rover on soft lunar soil, it is necessary to study the interaction between the wheels and the lunar soil. The deformation of the flexible wheel provides a larger contact area, which results in greater tractive force. Moreover, flexible wheels have better comfort and stability than rigid wheels, which are needed for manned rovers. However, there are few studies on the wheel soil interaction model of the heavy flexible wheel for the pressurized lunar rover. In this paper, a metal flexible wheel soil interaction model for pressurized lunar rovers was established, and the traction performance of the flexible wheel was predicted by using this model. Then, the accuracy of the wheel soil interaction model was verified by the soil bin test. The experimental results showed that the average error between the theoretical value of sinkage and the experimental value was 13.9%, and the average error between the theoretical and experimental value of drawbar pull was 11.5%, indicating that the model has high prediction accuracy. The new model can be used to predict the traction performance of flexible wheels and the experimental results can provide a reference for the flexible wheel design lunar rovers.

Design and analysis of a high-speed planetary rover with an adaptive suspension and spring damper

The development of deep space exploration has led to new exploration demands that cannot be met by traditional planetary rovers. This paper proposes a new wheeled rover that combines the advantages of passive all-wheel attachment and vibration reduction at high speeds. This rover can achieve vibration reduction in the vertical direction from ground excitation, preventing the instability of pitch and roll. Flexible wheels were used to reduce the high-frequency excitation of the ground on the rover. The design concept and mechanical principle of the proposed rover were comprehensively analyzed. A quasi-static kinematic model was developed to analyze the overstepping performance of the rover with this new design. Further, the response characteristics of the system to the ground excitation were investigated by vibration equations established using the Lagrangian method. The optimal parameters were obtained using a genetic algorithm to optimize the system with multiple objectives. Furthermore, the overstepping performance, all-wheel attachment, and vibration reduction of the planetary rover were verified through multi-body simulation. The proposed rover has considerable potential for missions such as the Mars sample return and planetary station construction.

Control and Design of Dancing Robot based on STM32

The emergence and development of robot technology not only fundamentally changed the traditional industrial production, but also had a profound impact on society. With the rapid development of social technology, the application field of robots is expanding. In this paper, the control core of the proposed dancing robot is STM32F103C8T6 single chip microcomputer, the upper arm is controlled by the steering gear, the feet are two flexible wheels, and the DC deceleration motor is used as the driving motor of the wheels, so that the wheels of the robot can realize free movement and complete the dancing action of the robot. The power needed for robot movement comes from 18650 lithium battery. In the process of robot movement, the LD3320 voice recognition module is used to control the robot's movement direction and state, the MPU6050 is used to control the robot's balance, and the JQ6500 music playback module is added to the robot to control the music playback through voice recognition. After the power of dancing robot is turned on, the dancing robot starts to adjust itself to make its posture in a balanced and upright state, and then waits for the user to issue a command. The dancing robot has simple human body function and can complete simple dance actions such as moving forward and backward, walking left and right, turning left and right, and has voice function, and can also play music. The operation password is simple in the process of application, which makes it convenient for the user to use. In addition, the dancing robot is small in size and can move freely with good practical effect, regardless of the user’s age.

ОЦЕНКА РИСКОВ И ПОТЕНЦИАЛЬНЫХ ОТКАЗОВ ПРИ ПРОЕКТИРОВАНИИ ПРОЦЕССА ИЗГОТОВЛЕНИЯ ГИБКИХ КОЛЕС ВОЛНОВЫХ ЗУБЧАТЫХ ПЕРЕДАЧ НА ОСНОВЕ МЕТОДИКИ PFMEA

The article presents a model for assessing the risks of potential failures of the machining process of flexible wheels of wave gears (WG). The constructed model is based on the methodology for analyzing the types and consequences of potential process inconsistencies (PFMEA). Structural, functional analysis and analysis of failures arising in the process of turning, grinding and cutting the teeth of a flexible wheel are carried out. As a result of the analysis, a risk assessment was carried out and a list of measures aimed at improving the quality of the machining process of flexible wheels of the WG was established.

Modeling and Fatigue Characteristic Analysis of the Gear Flexspline of a Harmonic Reducer

The failure of harmonic gear drive is mainly caused by the fatigue fracture of flexible wheels and the fatigue damage of flexible bearings. In this paper, the stress sensitivity and fatigue life characteristics of flexible wheels with thin-walled vulnerable components are studied. Firstly, the structure of the flexible wheel of a B3-80 general harmonic gear reducer is designed, the finite element model of the flexible wheel is established by using ANSYS finite element software, and the finite element analysis results are compared with the theoretical calculations to verify the correctness of the model. Finally, by changing the cylinder length, smooth cylinder wall thickness and load, the maximum equivalent stress curves of the flexible gear ring, smooth cylinder and flexible wheel bottom are obtained, and the influence law of structural parameters on the stress characteristics of flexible wheel is obtained. At the same time, the influence laws of flexible wheel cylinder length and smooth cylinder wall thickness on the fatigue life of flexible wheel is studied, which provides a theoretical basis for the structural optimization design of the cup flexible wheel.

Influence of HIPS Strengthened Story and Trend on Performance of Flexible Spoke Wheels

Influence of HIPS Strengthened Story and Trend on Performance of Flexible Spoke Wheels

Comparative Analysis of Static Loading Performance of Rigid and Flexible Road Wheel based on Finite Element Method

To overcome the shortcomings of traditional rigid road wheel, such as poor damping effect and low load-bearing efficiency, a new type of flexible road wheel, having a unique suspension-bearing mode, was introduced. The three-dimensional nonlinear finite element model of rigid and flexible road wheel, considering the triple nonlinear characteristics of geometry, material and contact, is established for numerical investigation of static loading performance. The accuracy of the finite element model of the rigid and flexible road wheel is verified by static loading experiment. The static loading performance of the rigid and flexible road wheels is numerically analyzed. The influence of vertical load on maximum stress and deformation of the rigid and flexible wheels is also studied. The results show that the contact pressure uniformity of the flexible road wheel is better than that of the rigid road wheel under the static vertical load, but the maximum stress and deformation of the flexible road wheel are greater than that of the rigid road wheel. However, this problem can be solved by increasing the number of hinge sets and optimising the joints. The research results provide theoretical basis for replacing rigid road wheel with flexible road wheel, and also provide reference for structural optimisation of flexible road wheel.

Research of flexible wheels assumed for Mars exploration rover

Research of flexible wheels assumed for Mars exploration rover

RESEARCH OF STABILITY OF METAL-POLYMER FLEXIBLE WHEELS FOR POWER WAVE GEARS

Nowadays, significant successes have been achieved in the development and implementation of wave gears in the world. One of the characteristics of the quality of the wave gears is its noise characteristic. From the point of view of reducing the noise level, the use of flexible wheels made of polymer is of interest. and if it is necessary to maintain a high level of performance - the use of flexible wheels made of metal-polymer. Therefore, the task of researching metal-polymer flexible wheels of power wave gears is actual and practically useful. Its solution will ensure a minimum level of noise and vibration with high load capacity and gear durability. The work is devoted to the development of a methodology for the theoretical study of the stability of a composite metal-polymer flexible wheel. In studying the resistance of cylindrical structurally orthotropic shells with sufficient accuracy for practical use, we can use the theory of shallow shells. The calculated dependences for determining the critical loads characteristic of the operation of power wave gears are obtained. A criterial assessment of the resistance of the shells of metal-polymer flexible wheels through the wave formation parameters λ and η is given. Particular cases of loading power wave gears and ensuring the stability of metal-polymer flexible wheels are considered. It is shown that the parameters λ and η and the number of half-waves of wave formation n and m are determined from the condition of minimum critical load.

Modelling of flexible metal wheels for planetary rover on deformable terrain

Abstract： Rovers are one of the most important vehicles used for conducting planetary exploration missions. On deformable terrain, traction is limited by the mechanical properties of the soil; therefore, a lack of traction and wheel slippage causes difficulties during operation of the rover. One possible solution for increasing the traction force is to increase the size of the wheel-terrain contact area. Flexible wheel forms can change depending on terrain conditions. So, flexible wheels exhibit high performance in traversing deformable terrain. However, the flexible metal wheel-terrain model for a planetary rover on deformable terrain has not yet been presented in detail. In this paper, a flexible metal wheel and a flexible wheel model that can quantitatively evaluate the sinkage and traction performance of flexible metal wheels on deformable terrain are designed. The theory has been built over the existing equations and validated with by test results. This paper establishes models for estimating static sinkage and dynamic wheel-terrain interaction mechanics. Experimental results from a single-wheel test show that the model can be used for mobility prediction with good accuracy. Based on the calculated model values and experimental results, the drawbar pull and torque of the flexible wheel clearly increases and sinkage clearly decreases compared with a rigid wheel of the same dimensions. The new model can be used to predict the traction performance of flexible wheels. This study can provide a reference for the flexible wheel design of planetary rovers.

Synthesis of elements for waver gears of tunneling assemblies

Wave gears have high load capacity and small weight and dimensions parameters, therefore they are increasingly used in mining aggregates. The method of synthesis of elements of the wave transfer, which is based on the method of vector contours, is given in the work. The method takes into account the design features of the finger supports and the achievement of continuity of contact of the fingers with the generator, the rigid wheel and the holes of the guide disk. The proposed technique allows creating wave transmissions with a range of transmission ratios of 6 – 80. The adequacy of the synthesis technique is proved by the operability of waveguide samples, whose flexible wheels are made in the form of a finger chain. A new wave transmission is used in the developed microtunneling equipment.

Systematic design and development of a flexible wheel for low mass lunar rover

Low mass compact rovers provide cost effective means to explore extra-terrestrial terrains. Use of flexible wheels in such applications where the wheel size is restricted, improves traction at reduced slip and sinkage. Design of a flexible wheel for a given mission is a challenging task requiring consideration of stiffness of rim and spokes, stress induced in the wheel, chassis movement during wheel rotation and the operating mode of the wheel. Also, accurate mathematical models are required to save design and development time and reduce the number of prototypes for selection. It is observed that most of the research papers deal with performance testing of flexible wheels and information on analytical formulation is scarce. Therefore, in the present work, a methodology has been formulated to systematically design a flexible wheel for a low mass lunar rover. The prototype performance is tested and compared with analytical estimates and reasons for difference are investigated. Paper contains details of design criteria, mathematical modelling, realisation of wheel prototype, test fixture and analysis test comparison. Authors believe that this work provides a useful aid to the designer to systematically design flexible wheels for low mass lunar rovers.

Applied design methodology for lunar rover elastic wheel

In recent years an increasing interest in the Moon surface operations has been experienced. In the future robotic and manned missions of Moon surface exploration will be fundamental in order to lay the groundwork for more ambitious space exploration programs. Surface mobility systems will be the key elements to ensure an efficient and safe Moon exploration. Future lunar rovers are likely to be heavier and able to travel longer distances than the previously developed Moon rover systems. The Lunar Roving Vehicle (LRV) is the only manned rover, which has so far been launched and used on the Moon surface. Its mobility system included flexible wheels that cannot be scaled to the heavier and longer range vehicles. Thus the previously developed wheels are likely not to be suitable for the new larger vehicles.Taking all these considerations into account, on the basis of the system requirements and assumptions, several wheel concepts have been discussed and evaluated through a trade-off analysis. Semi-empirical equations have been utilized to predict the wheel geometrical characteristics, as well as to estimate the motion resistances and the ability of the system to generate thrust. A numerical model has also been implemented, in order to define more into the details the whole wheel design, in terms of wheel geometry and physical properties. As a result of the trade-off analysis, the ellipse wheel concept has shown the best behavior in terms of stiffness, mass budget and dynamic performance.The results presented in the paper have been obtained in cooperation with Thales Alenia Space-Italy and Sicme motori, in the framework of a regional program called STEPS11STEPS–Sistemi e Tecnologie per l'EsPlorazione Spaziale is a research project co-financed by Piedmont Region and firms and universities of the Piedmont Aerospace District in the ambit of the P.O.R-F.E.S.R. 2007–2013 program. .

Study on Effect of Grousers Mounted Flexible Wheel for Mobile Rovers

This paper presents the effectiveness of the flexible wheels for lunar exploration rovers. The flexible wheels give high performance while traversing loose soil. The flexible wheel is an effective scheme to traverse loose soil without poor performance. The flexible wheel has a surface which can be changed flexibly for rough terrain. When the surface of wheel performs matching the shape of ground it is crossing, the normal stress between the wheel and loose soil becomes small. It is prevented from sinking because this normal stress is small. However, the flexible wheel doesn’t have high performance without grousers. The grouser is very important to get thrust for rovers. From running experiments using a single wheel tester, we found that the flexible wheel with grousers gave a high performance. The mounted positions of grousers on the surface of the wheel are defined by the same angle (ex) 36 deg). This means that there are two patterns to mount grousers. One is under the rib while the other is between the ribs. The spring force under the rib is different from between the ribs, it is greater. Moreover, each distortion is different. From these considerations, we need to find the optimal position for grousers. We carried out running experiments using wheels with both patterns. From our experiments, we understood the wheel with the position mounted between ribs gave a better performance than when it was set under the rib. When the area giving normal stress is wide, soil under the wheel becomes hard. Therefore, the wheel with grousers mounted between ribs gives a higher performance compared with the one mounted under the ribs.

Prediction of tractive response for flexible wheels with application to planetary rovers

Planetary rovers are typically developed for high-risk missions. Locomotion requires traction to provide forward thrust on the ground. In soft soils, traction is limited by the mechanical properties of the soil, therefore lack of traction and wheel slippage cause difficulties during the operation of the rover. A possible solution to increase the traction force is to increase the size of the wheel-ground contact area. Flexible wheels provide this due to the deformation of the loaded wheel and hence this decreases the ground pressure on the soil surface. This study focuses on development of an analytical model which is an extension to the Bekker theory to predict the tractive performance for a metal flexible wheel by using the geometric model of the wheel in deformation. We demonstrate that the new analytical model closely matches experimental results. Hence this model can be used in the design of robust and optimal traction control algorithms for planetary rovers and for the design and the optimisation of flexible wheels.

The ExoMars rover locomotion subsystem

ExoMars is the European Space Agency (ESA) mission to Mars planned for launch in 2018, focusing on exobiology with the primary objective of searching for any traces of extant or extinct carbon-based micro-organisms. The on-surface mission is performed by a near-autonomous mobile robotic vehicle (also referred to as the rover) with a mission design life of 180 sols. The rover has a 6 × 6 × 6 with 6 wheel-walking drive configuration (all 6 wheels are driven, steered and have a ‘walking’ capability) and has flexible wheels providing enhanced traction compared to rigid wheels of the same diameter. The suspension is a passive ‘3-bogie’ system which offers the same 6 wheel contact on uneven ground and mobility performance as the NASA–JPL ‘rocker-bogie’ suspension used on previous Mars rovers, but permits elimination of the differential linkage present in that design. Mars presents several challenges to the rover locomotion subsystem with its rock-strewn surface, sand dunes, rocky outcrops, craters and slopes. The unknown nature of the terrain to be traversed imposes several constraints on the locomotion subsystem design that need to be evaluated and incorporated within the flight model for its successful operation on Mars. In addition, accommodation within the confines of the lander and successful egress from it over deflated airbags places stringent constraints on locomotion subsystem mass, stowage envelope, deployment and wheel design. This paper documents the evolution of the ExoMars rover vehicle locomotion configuration from an early design concept to the current mission baseline design. The discussion involves various tradeoffs supported by mechanical and terramechanical analyses, simulations and testing performed on full-scale locomotion breadboard models at single wheel level and system level.

The development of wheels for the Lunar Roving Vehicle

The Lunar Roving Vehicle (LRV) was developed for NASA’s Apollo program so astronauts could cover a greater range on the lunar surface, carry more science instruments, and return more soil and rock samples than by foot. Because of the unique lunar environment, the creation of flexible wheels was the most challenging and time consuming aspect of the LRV development. Wheels developed for previous lunar systems were not sufficient for use with this manned vehicle; therefore, several new designs were created and tested. Based on criteria set by NASA, the choices were narrowed down to two: the wire mesh wheel developed by General Motors, and the hoop spring wheel developed by the Bendix Corporation. Each of these underwent intensive mechanical, material, and terramechanical analyses, and in the end, the wire mesh wheel was chosen for the LRV. Though the wire mesh wheel was determined to be the best choice for its particular application, it may be insufficient towards achieving the objectives of future lunar missions that could require higher tractive capability, increased weight capacity, or extended life. Therefore lessons learned from the original LRV wheel development and suggestions for future Moon wheel projects are offered.

Study of Flexible Wheels for Lunar Exploration Rovers

Lunar rovers are required to traverse rough terrains with craters and sheer cliffs—often seen in locations of scientific importance. Recently, wheeled rovers have been gaining popularity in conducting planetary exploration missions. However, wheeled rovers are likely to get stuck in the soil while traversing such terrains. One way to solve this problem is to use flexible wheels. In this study, experiments were carried out to simulate actual running conditions using flexible wheels. The results showed that flexible wheels had a high level of performance when traversing loose soil on a slope. The experiments were carried out using various flexible wheels that allowed different amounts of deflection. The flexible wheels were made from beryllium copper, magnesium, and stainless steel. In these experiments, we measured slip ratio and sinkage for each of these materials.

829 弾性ホイールの動的挙動の解析

Flexible wheels have been developed to improve the ride comfort. This wheel is equipped with unique fiber reinforced rubber rings between the disc and the rim, in order to reduce noise and vibration without any compromises with handling and stability. This paper discusses effectiveness of the flexible wheel when weight unbalance added through the uniformity tests, and proposes a new uniformity test method which can simulate more realistic conditions of driving than the conventional method. Simulation analysis was carried out for the new test method, showing that flexible wheels could reduce more radial force variation compared with the conventional wheels.

Wheel/Rail Contact Forces for Flexible versus Solid Wheels due to Tread Irregularities

SUMMARY The vertical dynamic behaviour of a railway vehicle with flexible wheels is compared to that of a vehicle with standard solid wheels. Full-scale field experiments performed on a portion of a recently built railway track for high-speed trains are reported. Flexible and solid wheels without and with wheel flats were instrumented for measurement of transient vertical wheel/rail contact forces. Accelerations and strains in the track structure were measured in parallel. The location of the instrumented wheelset in relation to the instrumented portion of the track was determined at each instant of time. Flexible wheels are shown to considerably reduce the contact forces. A linear mathematical model of the track is suggested based on a previously reported technique for solving vertical interaction problems. Track parameters determined at the test-site are used as input to die model. Numerical results show acceptable agreement with measured responses.