[en] Not so long ago a new observation about rolling motion was described: for a rolling wheel, there is a set of points with instantaneous velocities directed at or away from the centre of the wheel; these points form a circle whose diameter connects the centre of the wheel to the wheel's point of contact with the ground (Sharma 1996 Eur. J. Phys. 17 353-6). We provide a detailed experimental verification of this observation, collecting 3D data from a rolling wheel with a commercially available optical tracking system. We also extend the observation to a generalized form: for a rolling wheel, there is a set of points with instantaneous velocities directed at or away from any point P; these points form a circle whose diameter connects the point P to the wheel's point of contact with the ground. This generalization is also verified experimentally

[en] Rutting of asphalt pavement is one of major patters premature damage modes experienced during the service period of pavement. Aggregate characteristics, especially aggregate gradation can affect the rutting performance of asphalt pavement. In order to investigate the influence of spatial structure on rutting performance, the volumetric indices such as VV, VMA and VCA were employed to characterize the spatial structure of asphalt mixture, and five different gradations of asphalt mixtures with three types of aggregate skeleton structure were prepared to conduct rutting measurement by wheel tracking test. It is demonstrated that aggregate particle size of 4.75-9.5mm can affect forming aggregate skeleton structure and rutting performance. Rutting depth at a certain period of time are concerned with VV and types of aggregate skeleton structure, and the VCA_ratio equal to one can be used as critical value to evaluate the types of aggregate skeleton structure. It is also indicated that fine aggregate can decrease the value of VMA and excellent stability in high-temperature of asphalt mixture should match suitable VMA. This study provides a significant reference for asphalt design and choice of aggregate gradation. (paper)

[en] This study aims to optimize the dressing parameters of grinding wheel for 9CrSi tool steel to minimize roughness average and flatness tolerance using Taguchi method and Grey Relational Analysis (GRA). These objectives are minimized by optimizing four four-level and two two-level dressing parameters in sixteen experiments based on an orthogonal array L₁₆(4⁴×2²). Taguchi method and GRA are combined to solve the multi-objective optimization problem and determine optimal dressing parameter level combination. Results show that, the optimal dressing parameters to obtain the minimal roughness average and flatness tolerance are coarse dressing depth of 0.025 mm, coarse dressing times of 3 times, fine dressing depth of 0.005 mm, fine dressing times of 2 times, non-feeding dressing of 3 times and dressing feed rate of 1.6 m/min, respectively. Experiments with the optimized dressing parameters have been done to verify the predict model. Results of the roughness average and flatness tolerance from the experiments match with those values of the models and satisfy practical requirements. (paper)

[en] This paper presents an optimal mechanical design for a chainsaw setting angle to reduce the driving force of wheels in a pruning robot that cuts branches while spiraling up. Analysis and experimental results demonstrate the effectiveness of the optimal mechanical design for the chainsaw setting angle. (paper)

[en] In this research, a outdoor wheel-type walking-assist device is developed to help an elder having a poor muscular strength at legs for walking, sitting and standing up easily at outdoors, and also for going and downing stairs. In conceptually designing, the environments of an elder's activity, the size of an elder's body and a necessary function of helping an elder are considered. This device has 4 wheels for stability. When an elder walks in incline plane with the proposed device, a rear-wing is rotated to keep the supporting device horizontal, regardless of an angle of inclination. A height-controlling device, which can control the height of the supporting device for adjusting an elder's height, is varied vertically to help an elder to sit and stand-up easily. Moreover, a outdoor wheel-type walking-assist device is conceptually designed and is made. In order to design it, the preview research is investigated firstly. On the basis of the proposed walking-assist device, the outdoor walking-assist device is designed and made. The outdoor wheel-type walking-assist device can go and down stairs automatically. This device go up and down the stair of having maximum 20cm height and an angle of 25 degrees with maximum 4 sec/stairs speed, and move at flatland with 60cm/sec speed

[en] The article discusses the issue of determining program forces in drives of a four-wheel robotic platform - the issue of opening the uncertainty of the equations system. The motion laws are synthesized on the basis of application of the calculus of variations. The method of determining the program forces is based on the compilation of equations of the dynamics of a rigid body motion and additional equations - “zero-functions” (displacements) of the points of the application of redundant reactions. (paper)

[en] The development of the radial strain component in railway wheels was investigated by neutron diffraction. In the as manufactured state four railway wheels were investigated. In all four wheels no significant strains were found. After 18,400 km usage first strain gradients close to the outer surface of the wheels were detected. In axial middle ranges the changes in strain are weak. After an usage of 61,000 km the gradients becomes strong at the axial outer position between about +700 με close below the tread and -500 με in a depth of 12.5 mm below the tread. At axial middle positions also strain gradients are formed. The end of live state (510,000 km) differs only slightly from the state measured after a usage of 61,000 km

[en] Electric vehicle (EV) with four independent in-wheel motor is over-actuated systems. The wheel torque distribution can be realized through a large number of methods to satisfy the economic and safety demands. This paper aims at providing a review of the economic-based torque distribution strategies, safety-based torque distribution strategies and coordination control of torque distribution strategies based on both safety and economy. This paper not only provides a comprehensive analysis of torque distribution strategies for in-wheel-motor EVs but also puts forward the future and emphasis of future study, which will promote the development of torque distribution strategy with safety and economy for in-wheel-motor drive EVs. (paper)

[en] The article presents the formulation and solution of the problem of optimization of the internal damping rubber elements of the roller wheel of tracked system. The optimal design search is based on the results of calculating the stress-strain state of the rubber element caused by the assembly of the roller and operational loads. As an objective function, the specific energy of deformation of the rubber was chosen. The geometric parameters of the rubber element of the roller wheel in the initial state and after installation in the structure are taken as variable parameters. Explicit and functional constraints in the form of inequations are imposed on the variable parameters. As a result of solving the optimal design problem, the shape and design parameters of the internal damping rubber elements of the track roller of the tracked system were obtained, which made it possible to reduce the specific strain energy during radial loading by 1.85 times (paper)

[en] The paper systematically researches a new method for non-abrasive cryogenic polishing on camshaft, which includes laboratory furniture, ice wheel making and modifying, experimental device vibration analysis, polishing experiment on camshaft surface in different conditions and measurement of the polished surface. Results show that the process of non-abrasive cryogenic polishing on camshaft can effectively reduce the surface roughness of workpieces. (paper)