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This work introduces the concept of a shape reconfigurable brush robot used for work in collapsed buildings or tunnels. This paper presents the bristle mechanism and traction experiments relating to a robot, which is designed to be able to negotiate pipes with variable cross section or ill constrained tunnel‐like voids within rubble. Traction experiments in the laboratory were used to investigate the characteristics of bristles and the performance of the brush units of different shapes. The experimental results are used to analyse the interaction between brush units and different shaped boxes and related to bristle characteristics with a view to give guidance for the design of a future brush‐based shape reconfigurable robot.

Explains how the Tracminer project aimed to provide a robust, low cost device to be mounted as an accessory on the motorized wheels of traction machines, in order to increase grip on loose soils. The main goal was to provide a device increasing by 30‐40 per cent the traction capacity of the given machine in soft or marshy soil working conditions. The intended device was designed to be robust and simple to adapt to existing machines. A key element of the development strategy was to provide an accessory easy to mount on the machine, which can remain “idle” (in this case, retracted) while not needed. The machine may then be operated as usual, with the opportunity to engage the accessory in action when a better ground grip is required. Such a possibility offers significant advantages for the Tracminer accessory when compared with other permanent traction enhancement solutions such as metallic frames with grids attached to the wheels, accessory caterpillars, etc.

The traction behaviours of lubricating oil significantly affect the stability and lubrication regime of aviation high-speed ball bearings. Rolling elements will slide at a low traction force (TF). Therefore, traction behaviours need to be studied, and a fitting expression for traction curves to rapidly calculate the traction coefficient (TC) should be developed.

The traction behaviours of an aviation lubricating oil were studied in severe operating conditions with a self-designed two-disc testing rig. Based on the least squares method and the Levenberg–Marquardt theory, a rapid calculation expression was developed by fitting the obtained traction curves. The correction of this expression was experimentally verified by comparing the TCs under different operating conditions. This expression was also used to modify the commonly accepted quasi-dynamic model of rolling bearings.

An increase of the load led to an increase in the TC. In comparison, the temperature and entrainment speed showed inverse effects. The proposed expression exactly predicted the trend of the experimentally acquired traction curve. The calculation with the modified dynamic model showed that the action of the TF on a single rolling element varied and that the temperature increase of the outer raceway is higher than the inner raceway, which is caused by the TF and relative sliding speed between the elements and raceways.

The proposed fitting expression is able to simplify the TC calculation of synthetic aviation lubricating oil in practical engineering applications. This paper can provide an important reference for the traction behaviour of synthetic aviation lubricating oil under severe conditions and assist with its rapid calculation and practical application in engineering.

Overhead high-voltage transmission line (HVTL) inspection robots are used to inspect the transmission lines and/or maintain the infrastructures of a power transmission grid. One of the most serious problems is that the load on the front wheel is much larger than that on the back one when the robot travels along a sloping earth wire. Thus, ongoing operation of the inspection robot mainly depends on the front wheel motor’s ability. This paper aims to extend continuous operation time of the HVTL inspection robots.

By introducing a traction force model, the authors have established a dynamic model of the robot with slip. The total load is evenly distributed to both wheels. According to the traction force model, the desired wheel slip is calculated to achieve the goal of load balance. A wheel slip controller was designed based on second-order sliding-mode control methodology.

This controller accomplishes the control objective, such that the actual wheel slip tracks the desired wheel slip. A simulation and experiment verify the feasibility of the load balance control system. These results indicate that the loads on both wheels are generally equal.

By balancing the loads on both wheels, the inspection robot can travel along the earth wire longer, improving its efficiency.

Dynamic low adhesion (DLA) has become an urgent problem for the high-speed wheel-rail system because of continuous decrease of adhesion redundancy in the past decades. This article aims to provide a simulation method to reveal the mechanism of DLA under high-frequency vibrations.

A transient wheel-rail rolling contact model is developed for a typical Chinese high-speed railway system using the explicit finite element (FE) method. Instantaneous adhesion exploitation levels are studied in the time domain, for which driving cases over corrugated rails are taken as an example. A speed up to 500 km/h is considered together with different traction coefficients and corrugation dimensions. DLA is expected when the instantaneous adhesion exploitation level reaches 1.0, that is adhesion saturates and full sliding contact occurs.

The instantaneous adhesion exploitation level can be very high in the presence of corrugation, even at low traction coefficients. DLA is found to occur as great vertical unloading takes place and causes a significant increase of creepage. An approach is further developed to determine the critical depth of corrugation over which DLA occurs.

This study employs the transient wheel-rail rolling contact model to predict the instantaneous adhesion exploitation level under high-frequency vibrations. The presented results reveal a mechanism of DLA being beneficial to guidelines for future railway practice.

To address the problem that the current train operation mode that train selects one of several offline pre-generated control schemes before the departure and operates following the scheme after the departure, energy-saving performance of the whole metro system cannot be guaranteed.

A cooperative train control framework is formulated to regulate a novel train operation mode. The classic train four-phase control strategy is improved for generating specific energy-efficient control schemes for each train. An improved brute force (BF) algorithm with a two-layer searching idea is designed to solve the optimisation model of energy-efficient train control schemes.

Case studies on the actual metro line in Guangzhou, China verify the effectiveness of the proposed train control methods compared with four-phase control strategy under different kinds of train operation scenarios and calculation parameters. The verification on the computation efficiency as well as accuracy of the proposed algorithm indicates that it meets the requirement of online optimisation.

Most existing studies optimised energy-efficient train timetable or train control strategies through an offline process, which has a defect in coping with the disturbance or delays effectively and promptly during real-time train operation. This paper studies an online optimisation of cooperative train control based on the rolling optimisation idea, where energy-efficient train operation can be realised once train running time is determined, thus mitigating the impact of unpredictable operation situations on the energy-saving performance of trains.

The purpose of this paper is to propose a new propeller-type climbing robot called EJBot for climbing various types of structures that include significant obstacles, besides inspection of industrial vessels made of various materials, including non-ferromagnetic material. The inspection includes capturing images for important spots and measuring the wall thickness.

The design mainly consists of two coaxial upturned propellers mounted on a mobile robot with four standard wheels. A new hybrid actuation system that consists of propeller thrust forces and standard wheel torques is considered as the adhesion system for this climbing robot. This system generates the required adhesion force to support the robot on the climbed surfaces. Dynamic simulation using ADAMS is performed and ensures the success of this idea.

Experimental tests to check the EJBot’s capabilities of climbing different surfaces, such as smooth, rough, flat and cylindrical surfaces like the real vessel, are successfully carried out. In addition, the robot stops accurately on the climbed surface at any desired location for inspection purposes, and it overcomes significant obstacles up to 40 mm.

This proposed climbing robot is needed for petrochemical and liquid gas vessels, where a regular inspection of the welds and the wall thickness is required. The interaction between the human and these vessels is dangerous and not healthy due to the harmful environment inside these vessels.

This robot utilizes propeller thrusts and wheel torques simultaneously to generate adhesion and traction forces. Therefore, a versatile robot able to climb different kinds of structures is obtained.

One of the major shortcomings in the data process of the traditional wheel force transducers (WFTs) is the theoretical errors of initial value determination. A new method to identify the initial values of the WFT for the solution of this problem is proposed in this paper. The paper aims to discuss these issues.

With this method, the initial values can be obtained by equations which are established based on multiple stops on horizontal road.

The calibration and contrast tests on the MTS calibration platform illustrate the better performance with the new method. Moreover, the real vehicle test confirms the effectiveness in practice.

The test results show that the new method of initial calibration has an advanced performance compared to the traditional one. In addition, it is effective in the brake test with a real vehicle.

The vehicle–track interaction and the resulting dynamic response of the vehicle involve a number of complex nonlinear problems. Large vertical loads act through a small contact patch leading to very high contact pressures. Transverse loads acting through this contact induce a relative velocity between wheel and rail expressed in non-dimensional form as a creepage. The wheel and rail profiles determine the contact patch shape and affect the ability of the vehicle to run stably. If the yaw stiffness of the axles is too low, the vehicle will become unstable at a relatively low speed; conversely, if the yaw stiffness is too high, the curving behaviour will be adversely affected. The vehicle suspension, especially the secondary suspension, also affects the ride comfort of passengers. Finally, it is shown how the speed profiles of accelerating and decelerating trains can be calculated from basic assumptions about the train power, adhesion and rolling resistance.

In this paper a continuum description of deformable magnetized material including long‐range magnetic forces and magnetostriction is presented. Herein, magnetostriction and long‐range forces on the one hand, and magnetization and deformation on the other hand are considered simultaneously. Therefore, neither a strict distinction between the deformation due to magnetic forces and due to magnetostriction, nor a separation of the total free energy into magnetic and elastic energy is involved.