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As the transmission component of a locomotive, the traction gear pair system has a direct effect on the stability and reliability of the whole machine. This paper aims to provide a detailed dynamic analysis for the traction system under internal and external excitations by numerical simulation.

A non-linear dynamic model of locomotive traction gear pair system is proposed, where the comprehensive time-varying meshing stiffness is obtained through the Ishikawa formula method and verified by the energy method, and then the sliding friction excitation is analyzed based on the location of the contact line. Meantime, the adhesion torque is constructed as a function of the adhesion-slip feature between wheelset and rail. Through Runge–Kutta numerical method, the system responses are studied with varying bifurcation parameters consisting of exciting frequency, load fluctuation, gear backlash, error fluctuation and friction coefficient. The dynamic behaviors of the system are analyzed and discussed from bifurcation diagram, time history, spectrum plot, phase portrait, Poincaré map and three-dimensional frequency spectrum.

The analysis results reveal that as control parameters vary the system experiences complex transition among a diverse range of motion states such as one-periodic, multi-periodic and chaotic motions. Specifically, the significant difference in system bifurcation characteristics can be observed under different adhesion conditions. The suitable gear backlash and error fluctuation can avoid the chaotic motion, and thus, reduce the vibration amplitude of the system. Similarly, the increasing friction coefficient can also suppress the unstable state and improve the stability of the system.

The numerical results may provide a systemic understanding of dynamic characteristics and present some available information to design and optimize the transmission performance of the locomotive traction system.

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.

This paper aims to present an underwater climbing robot for wiping off marine life from steel pipes (e.g. jackets of oil platforms). The self-adaption mechanism that consists of a passive roll joint and combined magnet adhesion units provides the robot with better mobility and stability.

Adhesion requirements are achieved by analyses of falling and slipping. The movement status on pipes is analyzed to design the passive roll joint. The optimized structure parameters of the combined magnet adhesion unit are achieved by simulations. An approximation method is established to simplify the simulations conditions, and the simulations are conducted in two steps to save time effectively.

The self-adaption mechanism has expected performance that the robot can travel on pipes in different directions with high mobility. Meanwhile, the robot can clean continuous region of underwater pipes’ surface of offshore platforms.

The proposed underwater robot is needed by offshore oil platforms as their jackets require to be cleaned periodically. Compared with traditional maintenance by divers, it is more efficient, economic and safety.

Due to the specific self-adaption mechanism, the robot has good mobility and stability in any directions on pipes with different diameters. The good performance of striping attachments from pipes makes the underwater robot be a novel solution to clean steel pipes.

An article by Carra and Cavallotti [L'Industria della Vernice, 30, 11 (1976) p. 9] discussed the fundamental aspects of corrosion protection by organic coatings with emphasis on two parameters, adhesion and permeability to corrosive agents. Included is a mathematical treatment of the thermodynamics of adhesion.

The purpose of this paper is to present a design of climbing robot with magnetic wheels which can move on the surface of steel bridge. The locomotion concept is based on adapted lightweight magnetic wheel units with relatively high attractive force and friction force.

The robot has the main advantages of being compact (352 × – 215 × – 155 mm), lightweight (2.3 kg without battery) and simple mechanical structure. It is not only able to climb vertical walls and follow circumferential paths, but also able to pass complex obstacles such as bolts, steps, convex and concave corners with almost any inclination regarding gravity. By using a servo as a compliant joint, the wheel base can be changed to enable the robot to overcome convex corners.

The experiment results show that the climbing robot has a good performance on locomotion, and it is successful in negotiating the complex obstacles. On the other hand, the limitations in locomotion of the robot are also presented.

Compared with the past researches, the robot shows good performance on overcoming complex obstacles such as concave corners, convex corners, bolts and steps on the steel bridge. Magnetic wheel with the characterization of compact size and lightweight is able to provide bigger adhesion force and friction coefficient.

The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated driving conditions. Energy crisis and environment pollution are two key pressing issues faced by mankind. Pure electric buses are recognized as the effective method to solve the problems. Distributed drive electric buses (DDEBs) as an emerging mode of pure electric buses are attracting intense research interests around the world. Compared with the central driven electric buses, DDEB is able to control the driving and braking torque of each wheel individually and accurately to significantly enhance the handling stability. Therefore, the torque vectoring control (TVC) system is proposed to allocate the driving torque among four wheels reasonably to improve the handling stability of DDEBs.

The proposed TVC system is designed based on hierarchical control. The upper layer is direct yaw moment controller based on feedforward and feedback control. The feedforward control algorithm is designed to calculate the desired steady-state yaw moment based on the steering wheel angle and the longitudinal velocity. The feedback control is anti-windup sliding mode control algorithm, which takes the errors between actual and reference yaw rate as the control variables. The lower layer is torque allocation controller, including economical torque allocation control algorithm and optimal torque allocation control algorithm.

The steady static circular test has been carried out to demonstrate the effectiveness and control effort of the proposed TVC system. Compared with the field experiment results of tested bus with TVC system and without TVC system, the slip angle of tested bus with TVC system is much less than without TVC. And the actual yaw rate of tested bus with TVC system is able to track the reference yaw rate completely. The experiment results demonstrate that the TVC system has a remarkable performance in the real practice and improve the handling stability effectively.

In view of the large load transfer, the strong coupling characteristics of tire , the suspension and the steering system during coach corning, the vehicle reference steering characteristics is defined considering vehicle nonlinear characteristics and the feedforward term of torque vectoring control at different steering angles and speeds is designed. Meanwhile, in order to improve the robustness of controller, an anti-integral saturation sliding mode variable structure control algorithm is proposed as the feedback term of torque vectoring control.

The purpose of this paper is to describe a new solution for wheel‐robot's adhesion and passing‐obstacles mechanism and the optimal design of magnetic adhesion unit with finite element methods. The new mechanism makes the robot have a simpler structure, finer passing obstacles and larger payload capabilities.

After researching literature and analyzing in detail the disadvantages and advantages of magnetic wheel and structure magnet mounted under the chassis of a robot, the structure magnet is selected as the robot's adhesion style. Then the paper introduces the robot's structure and locomotion mechanism, the design of the new mechanism and the optimization of structure parameters for magnetic adhesion unit are described in detail in this paper. The new design can lift the robot's wheel unit and change adhesion force using only a motor.

A prototype of robot has been developed and successful test results prove that the proposed technology is feasible. The climbing robot can overcome 70‐mm high obstacles and has a large enough payload capability while climbing on vertical surfaces.

The new design reduces the number of actuators used in the robot and increases the magnetic adhesion force.

Thanks to the excellent passing‐obstacles and payload capabilities, the climbing robot with the new mechanism has a widely applying prospect in the field of welding and inspecting large equipment.

The lifting mechanism can lift the wheel unit and change magnetic adhesion force using only one motor. This makes the robot have a simple structure as well as the large payload capability.

The purpose of this study is to investigate the adhesion characteristics of the wheel–rail under water and large sliding conditions. This is carried out by conducting a series of tests on a full-scale roller rig. The measured data provides an experimental base for conducting further theoretical research.

The influence of the slip ratio, rolling speed and the axle load on the adhesion coefficient between the wheel and the rail is analyzed under wet conditions using a full-scale roller rig.

From the research, it is found that the adhesion coefficient–slip ratio curve varies from the traditional theoretical description under water and large sliding conditions. Moreover, it is also observed that after the adhesion coefficient reaches the saturation point, the adhesion coefficient does not decrease, but continues to increase as the slip ratio increases.

The adhesion improvement phenomenon in this paper may provide new ideas for designing anti-skid control and braking system mechanisms for trains.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0236/

Provide tribological information about the applicability of multi‐layer carbon‐chromium composite coatings to gears. Discuss the protection provided against scuffing failures, wear and the influence on gear power losses.

Several screening tests, such as Rockwell indentations, ball cratering, pin‐on‐disc and reciprocating wear tests, were performed in order to evaluate the adhesion to the substrate and the tribological performance of the carbon/chromium composite coating. Afterwards, twin‐disc tests were performed at high contact pressure and high slide‐to‐roll ratios to confirm the good adhesive and tribological properties of the coating under operating conditions similar to those found in gears. Gear tests were performed in the FZG machine in order to evaluate the anti‐scuffing performance of the carbon/chromium coating using additive free gear oils. Finally, the carbon/chromium composite coating was also applied to the gearing in a gearbox and its influence on the gearbox efficiency was analysed.

The C/Cr has got very good adhesion to the steel substrate, provides low friction coefficients between contacting solids in relative movement, gives excellent protection against scuffing and wear reduction in gears, and promotes a slight improvement of the gears efficiency.

The protection of this carbon/chromium coating against gear micro‐pitting should be investigated.

This study confirms the applicability of this coating to industrial gear applications, especially in two particular applications: severe applications involving high contact pressures and high sliding, frequent start‐ups and inefficient lubrication; and acting as tribo‐reactive material and substituting non‐biodegradable and toxic additives in environmental lubricants.

This work validates and quantifies the influence of this C/Cr multi‐layer composite coating in gear applications in terms of adhesion to the substrate, anti‐scuffing performance and efficiency.

The purpose of this paper is to present a novel miniature magnetic climbing robot for industrial inspection. The robot has high mobility with low complexity.

The robot has a miniature cylindrical shape with 28 mm of diameter and 62 mm of width. The robot has two wheels. The adhesion is achieved with an advanced magnetic circuit fixed on the frame of the robot.

From an horizontal sheet, the robot can make transition to almost any intersecting sheet from 10 to 360°. The robot passes inner and outer straight corners in almost any inclination of the gravity.

The novel robot opens new possibilities to use mobile robots in ferromagnetic environments with stringent size limitations, as found in power plants. The new mechanism increases mobility and opens a new avenue for inspection robotics. A patent is pending on this system.