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High-speed dual-motor electric drive tracked vehicles (DDTVs) have emerged as a research hotspot in the field of tracked vehicles in recent years due to their advantages in fuel economy and the scalability of electrical equipment. The emergency braking of a DDTV at high speed can lead to slipping or even yawing (which is caused by a large deviation of forces at each track directly), posing significant challenges to the vehicle’s stability and safety. Therefore, the accurate real-time acquisition of critical driving parameters, such as the longitudinal force and vehicle speed, is crucial for the stability control of a DDTV. This paper developed a novel estimating algorithm of critical driving parameters for DDTVs equipped with conventional sensors such as rotary transformers at PMSMs and onboard accelerometers on the basis of their dynamics models. The algorithm includes a sensor signal preprocessing module, a longitudinal force estimation method based on a nonlinear observer, and a speed estimation method based on an adaptive Kalman filter. Through hardware-in-loop experiments based on a Speedgoat real-time target machine, the proposed algorithm is proven to estimate the longitudinal force of the track and vehicle speed accurately, whether the vehicle has stability control functions or not, providing a foundation for the further development of vehicle stability control algorithms.

Aiming at the problems of “local minimum” and “unreachable target” existing in the traditional artificial potential field method in path planning, an improved artificial potential field method was proposed after analyzing the fundamental causes of the above problems. The method solved the problem of local minimum by modifying the direction and influence range of the gravitational field, increasing the virtual target and evaluation function, and the problem of unreachable targets is solved by increasing gravity. In view of the change of motion state of robot fish in amphibious environments, the improved artificial potential field method was fused with a dynamic window algorithm, and a dynamic window evaluation function of the optimal path was designed on the basis of establishing the dynamic equations of land and underwater. Then, the simulation experiment was designed under the environment of Matlab2019a. Firstly, the improved and traditional artificial potential field methods were compared. The results showed that the improved artificial potential field method could solve the above two problems well, shorten the operation time and path length, and have high efficiency. Secondly, the influence of different motion modes on path planning is verified, and the result also reflects that the amphibious robot can avoid obstacles flexibly and reach the target point accurately according to its own motion ability. This paper provides a new way of path planning for the amphibious robot.

In order to solve the disconnecting fault of high-speed shift gear box, this paper uses finite element analysis to study the wear of transmission fork, the transmission of axial force by gear and the cause analysis of gear synchronizer disconnecting fault. A kind of oil film technology is put forward to form oil film between the contact working face of gear sleeve and shifting fork slider, so as to achieve the friction effect of separating the two friction surfaces by liquid. At the same time, the improvement scheme of shift fork material is changed to solve the problem of gearbox fork wear and disconnection. The reliability and stability of the transmission shift mechanism are improved.

Dual-motor Electric Drive Tracked Vehicles (DDTVs) have attracted increasing attention due to their high transmission efficiency and economical fuel consumption. A test bench for the development and validation of new DDTV technologies is necessary and urgent. How to load the vehicle on a DDTV test bench exactly the same as on a real road is a crucial issue when designing the bench. This paper proposes a novel dynamic load emulation method to address this problem. The method adopts dual dynamometers to simulate both the road load and the inertia load that are imposed on the dual independent drive systems. The vehicle’s total inertia equivalent to the drive wheels is calculated with separate consideration of vehicle body, tracks and road wheels to obtain a more accurate inertia load. A speed tracking control strategy with feedforward compensation is implemented to control the dual dynamometers, so as to make the real-time dynamic load emulation possible. Additionally, a MATLAB/Simulink model of the test bench is built based on a dynamics analysis of the platform. Experiments are finally carried out on this test bench under different test conditions. The outcomes show that the proposed load emulation method is effective, and has good robustness and adaptability to complex driving conditions. Besides, the accuracy of the established test bench model is also demonstrated by comparing the results obtained from the simulation model and experiments.

The precise mathematical model for the tooth surface and transition surface of spiral bevel gears is derived. Taking a pair of spiral bevel gears of a heavy vehicle as an example of calculation and analysis, a finite element model of spiral bevel gears transmission system is established. Through the finite element tooth contact analysis under quasi-static loading and high loading condition, the influences of torque on the root stress distribution, contact stress, and transmission error are discussed, and the results are compared with the empirical formula results. Finally, a contact performance test bench of spiral bevel gear pair is developed, then the root bending stress, contact pattern, and transmission error tests are carried out. These experiment results are compared with analyzed ones, which showed a good agreement.

The load simulation test bench plays an important role in tracked vehicle development. The stability and accuracy of the system have a vital impact on the experimental results. To accurately reproduce the power performance of a tracked vehicle on the test platform, this paper aims to investigate the model, control, and calibration method of the test bench. Firstly, the dynamic model of a tracked vehicle under complex driving conditions is analyzed and established, which takes driving torque as the input and driving wheel speed as the output. Then, considering the uncertainties and disturbances in the system model, a 2-degree-of-freedom (2-DOF) control method combined with a disturbance observer is proposed to solve the stability problem of the system. Furthermore, in order to investigate the accuracy of the simulation on the test bed, a method of calibrating the system by a flywheel set with standard inertia is proposed. In the calibration process, the influence of the system resistance torque and the original mechanical inertia on the results is considered, and the response time of the inertia simulation is analyzed in both a steady and dynamic state. Finally, the load simulation test is carried out with the corrected system. The test results show that the system has a high load simulation accuracy under various load simulation tests.

A dimensionality reduction load torque observed is designed to provide compensation control for the motor with the observation value of load torque converted over for the problem that load disturbance decreases the control precision of servo system. A three-loop mathematical model is established for the servo control system. Use of two-/three-order optimal model theory contributed to the derivation of the tuning formula for three-loop control parameters. A simulation model is established for the space vector control of AC servo system. The simulation experiment validates that the tuned three-loop parameter provides the system with good dynamic performance. An experiment platform is built. The load sudden change experiment of the motor demonstrates the feasibility that torque compensation control improves the control precision of servo system in the presence of load disturbance.

In order to optimize the accuracy of the vehicle load simulation system, the control framework of the system is established based on the speed tracking method. Based on H ∞ mixed sensitivity method, a disturbance observer is established. In order to solve the problem that the order of disturbance observer is too high to restrain disturbance directly, a design constraint framework of disturbance observer is proposed, and the optimization of disturbance observer is realized in the constraint framework. The simulation and experimental results show that the optimized disturbance observer has stronger disturbance rejection ability.

Purpose The purpose of this paper is to reduce the drag loss and study the effects of operating conditions and groove parameters such as flow rate and temperature of automatic transmission fluid, clearance between plates, groove depth and groove ratio on the drag torque of a wet clutch for vehicles, parametric analysis of the drag torque model of wet multi-plate friction clutch with groove consideration. Design/methodology/approach Both experimental and numerical research was carried out in this work. Parametric groove models, full film lubrication flow model and pressure distribution model are established to investigate the effects of the grooves on drag torque of a wet clutch. Multigrid method is used to simplify the solution. Findings In this paper, a drag torque model of a wet multi-plate friction clutch based on the basic theory of viscous fluid dynamics is examined through experimental and numerical methods that take grooves into account, and the change trend of drag torque with operating conditions and groove parameters is analyzed. Originality/value Multigrid method is used to solve the governing equations, which simplifies the solution process because of the restrictions and interpolation operations between the adjacent layers of coarser and fine grids. These works provide insight into the effect regularity of operating conditions and groove parameters on drag torque of a wet multi-plate friction clutch. Furthermore, variable test conditions and sufficient experimental data are the main functions in the experimental research.

Sodium‐ion batteries (SIBs) have been extensively studied as the potential alternative to lithium‐ion batteries (LIBs) due to the abundant natural reserves and low price of sodium resources. Nevertheless, Na+ ions possess a larger radius than Li+, resulting in slow diffusion dynamics in electrode materials, and thus seeking appropriate anode materials to meet high performance standards has become a trend in the field of SIBs. In this context, owing to the advantages of high theoretical capacity and proper redox potential, metal phosphides (MPs) are considered to be the promising materials to make up for the gap of SIBs anode materials. In this review, the recent development of MPs anode materials for SIBs is reviewed and analyzed comprehensively and deeply, including the synthesis method, advanced modification strategy, electrochemical performance, and Na storage mechanism. In addition, to promote the wide application of the emerging MPs anodes for SIBs, several research emphases in the future are pointed out to overcome challenges toward the commercial application. Metal phosphides (MPs, M = Sn, Fe, Ni, Cu, Co, Ge, V, Zn, Mo, et al.), possessing the advantages of high electrical conductivities, and high gravimetric and volumetric specific capacities, are considered to be the potential anode materials for sodium‐ion batteries (SIBs). This review comprehensively presents the recent development of MP anodes for sodium storage, including the synthesis methods, electrochemical mechanisms, and advanced modification strategies. In addition, to promote the wide application of the emerging MP anodes for SIBs, several research emphases in the future are pointed out to overcome challenges toward the commercial application.