A Novel Real-Time Center of Gravity Estimation Method for Wheel Loaders with Front/Rear-Axle-Independent Electric Driving

Abstract

Estimation of the center of gravity (CG) is the basis for intelligent control of the front-and-rear-axis-independent electric driving wheel loaders (FREWLs). This paper presents a novel real-time method for estimating the CG of FREWLs, which is suitable for driving and spading conditions on bumpy roads. A FREWL dynamical model is proposed to set up the state-space model. The CG estimator is used to estimate the longitudinal tire force using the state-space model and the improved square-root unscented Kalman filter (ISR-UKF) algorithm. The simulation and experimental results indicate that this method is suitable for FREWL dynamics and operational characteristics, and the estimated value of CG basically converges to the reference value. Finally, the probable reasons for error occurring in two experiments and the practical challenges of this method are discussed. The research in this paper establishes a partial theoretical basis for intelligent control of construction machinery.

Hybird Nonlinear Control for Fighter With Center of Gravity Perturbation and Aerodynamic Parameter Uncertainty

“…4. The estimated value of the center of gravity 𝑥 ̂cgr is very close to its actual value 𝑥̅ cgr , and the estimation error is less than 1%, while the error of the traditional method is about 3-4% [10] . The RBF neural network algorithm can realize the online estimation of the perturbation center of gravity, which is also more accurate and faster than the traditional observer estimation method.…”

“…s e K e (10) where state error is e1 = x1-x1d, x1d is the reference instruction, provided by the output of the outer loop subsystem, K1 = diag(k11, k12, k13) is the diagonal gain matrix, and k1i > 0, i = 1, 2, 3.…”

“…This simplified method is robust to small changes in the center of gravity (e.g., fuel consumption, landing gear retraction, etc.). However, when the center of gravity encounters a wide range of changes, such as heavy airdrops (or in-flight structural damage to the fighters), it can severely affect the dynamics of the fighters and reduce the maneuverability [8][9][10]. The center of gravity perturbation has varying degrees of influence on the stability and maneuverability of the fighter, which manifests as the rise or fall of the flight trajectory, the sudden change of the flight speed, and the fighter maneuvering overdrive [11], where the fighters may deviate from its nominal dynamics.…”

Design and Testing of Innovative Type of Dual-Motor Drive Electric Wheel Loader

“…The EWL has become a prominent research topic in recent years [7][8][9][10]; researchers need to be aware of structural changes not only in the powertrain but also in the hydraulic system. Figure 1 shows the comparison of engine-drive WLs and electric-drive WLs in subsystems.…”

A Model of an Extending Front Loader

“…Due to the nature of the front loader's work, an important parameter of work safety is the location of the temporary center of gravity. The location of the center of gravity determines the stability of the loader's movement during the loading and unloading of materials as well as during transport [19]. The conditions used for the analysis of the longitudinal stability of the tractor-front loader and tractor-forklift systems in the most difficult working situations are as follows: descending a slope, braking in translational motion, and acceleration of the forks when lifting the load [20].…”