A Preliminary Study on Ergonomic Contribution to the Engineering Design Approach of a Wheel Loader Control Lever System

Studies show that heavy machinery operators are exposed to risk factors of musculoskeletal diseases. However, there has yet to be a study investigating the grip analysis of heavy machinery control levers. This preliminary study aims to investigate the grip analysis of a system that emulates the push–pull operations, handle shapes, and resistance of wheel loader control lever systems. The system was designed, analysed, and optimised using Autodesk Inventor 2019 before fabrication and testing. It underwent usability testing for estimated and perceived grip force analysis (ergonomics analysis). The tests measured estimated force using a sensor glove, and perceived force using the Borg CR10 scale. The data were analysed using regression and paired t-tests. The findings suggested that pulling and high resistance factors required higher estimated force (339.50 N) and perceived force (5.625) than pushing and low resistance factors in manoeuvring the system (p < 0.05). The cylindrical handle required more estimated force (339.50 N) but less perceived force (4.5) than the spherical handle due to ergonomic design considerations (p < 0.05). Although there were inaccuracies in force measurement methods, the perceived method was still effective for data collection, since it is challenging to measure grip force in a real situation with heavy machinery. While this study was only a simulation, it provided researchers with ideas that may solve problems in the manipulation of heavy machinery control levers.

Probabilistic Analysis of Wheel Loader Failure under Rockfall Conditions Based on Bayesian Network

Rockfall is one of the most serious geological hazards in mountain regions. During the rescue situations after rockfall, the wheel loader, a vital type of modern engineering mechanism, plays an important role in relieving the obstruction of the catastrophic site. Increasing the reliability of the wheel loader during the rescue situation is quite important. This study aims to build a fault diagnosis model based on Bayesian network (BN) to diagnose the probability and path of the fault occurrence in the wheel loader during a rockfall disaster. Meanwhile, to reduce the influence of subjective factors, the fuzzy set theory is introduced into BN. The result showed that the probability of failure of the wheel loader under rockfall disaster is 13.11%. In addition, the key cause of the failure of the wheel loader under the rockfall disaster is the malfunction of mechanical parts. The probability of mechanical component failures in this case is as high as 88%, while the probability of human error is 6%. The research results not only show the ability of the BN to incorporate subjective judgment but also can provide a reference for fault diagnosis and risk assessment of wheel loaders under rockfall disaster conditions.

Vehicle Trajectory Test on Interlocking Pavement Made From No Fine Agregate Concrete

In rainy season, many cases of roads being submerged in water because of a lack of drainage capacity and low water absorption by the subgrade. This study makes no fine aggregate concrete as an interlocking pavement to increase water absorption to the drainage layer and subgrade. No fine aggregate concrete is made from mix of cement : coarse aggregate = 1 : 6 with water cement ratio 0,4. The results showed the value of specific gravity, water absorption, compressive strength, and Na2SO4 resistance are 1,703 gr/cm3, 2.57%, 10.8 MPa, and 0.79%. To see the level of interlocking pavement performance, no fine aggregate concrete is arranged above the drainage layer and the levelling layer, and then a trajectory and inundation test is performed. The result of inundation and trajectory tests shows that interlocking pavement can pass water to subgrade without inundation and can withstand the wheel loader that is equivalent to 13,000 kg so that it can be used for sidewalks, park lanes, and pavement with a maximum axle load of 8 tons.

Online optimization of Pontryagin’s minimum principle for a series hydraulic hybrid wheel loader

The hydraulic hybrid powertrain has great potential for reducing fuel consumption and emission of off-road vehicles. The energy management strategy is the key to hybrid powertrain and currently there are many well-developed strategies. Of which the Pontryagin’s minimum principle is of research interest since it is a global optimization method while less computational burden than dynamic programming. However, it requires full cycle information to calculate co-state value in the principle, making it not implementable. Therefore in this study an implementable Pontryagin’s minimum principle is proposed for a series hybrid wheel loader, where the optimal co-state value in the principle is trained through repetitive wheel loader duty cycle. The Pontryagin’s minimum principle formulations of hybrid wheel loader are developed. The online co-state training algorithm is presented. A dynamic simulation model of hybrid wheel loader is developed. The fuel consumption of hybrid wheel loader with proposed strategy is compared with dynamic programming strategy and rule-based strategy in wheel loader long and short loading cycles. Results show the fuel consumption with proposed strategy is close to dynamic programming result and is lower than rule-based strategy. Finally, the influence of pressure level of hybrid powertrain on vehicle fuel consumption is studied.

Performance analysis of hydrodynamic mechanical power-split transmissions

The objective of this study was to evaluate the performance of 24 basic hydrodynamic mechanical power-split (HMPS) transmission designs effectively based on their torque multiplication capacities (TMCs) and efficiencies. Firstly, four schemes were preliminarily selected. Secondly, the matching between the four schemes and a reference wheel loader was considered, and an expression for the TMC was developed based on the traditional transmission and a second reference transmission. Thirdly, two performance metrics in terms of the TMC and efficiency – the average torque multiplication capacity (ATMC) and average efficiency – were defined to eliminate the couplings of four transmission parameters with the vehicle speed and speed ratio. Finally, the performances of the two best schemes and traditional hydrodynamic mechanical (HM) transmission were carefully compared. The results show that a transmission with power recirculation cannot present energy savings potential regardless of the ATMC, whereas a transmission with a power split can achieve an ATMC of 0.255, an average efficiency increment of 0.0143 in the short loading cycle, and a miniscule efficiency increment in the long loading cycle compared with the HM transmission.

Variable universe fuzzy control of the wheel loader semi-active cab suspension with multimode switching shock absorber

The aim of this work is to design a variable universe fuzzy control of a wheel loader semi-active cab suspension with damping multimode switching shock absorber. Considering the cost and reliability, a new type of shock absorber, whose adjustable damping characteristics are achieved by just changing the on–off statuses of two solenoid valves, is applied to the wheel loader cab suspension. The vibration model of the wheel loader, which considers the vibration characteristics of the working device, the four-wheel correlated random road excitation, and the engine vibration excitation simultaneously, is established first. Based on the working principle of the target shock absorber, the damping multi-state switching model is also established to reflect the relationship between the damping coefficients and the on–off statuses of two solenoid valves. Then, a variable universe fuzzy damping control strategy, which can determine the optimal switching sequences of the damping modes according to the cab suspension performance indexes, is designed. Finally, simulation analyses were conducted to verify the effectiveness of the proposed control approach of the wheel loader semi-active cab suspension with multimode switching shock absorber.