China
Africa
Explore chapters and articles related to this topic
Safe moving and storing of materials
Published in Mike Tooley, Engineering Technologies Level 3, 2017
Forklift trucks have two forks (similar to a pallet truck) a motor drive with rear wheel steering and seating for an operator. The rear wheel drive helps to improve manoeuvrability, particularly in tight cornering situations. However, since the centre of gravity of a forklift varies with the load mass and its position, forklift trucks are inherently unstable. Because of this it is important to avoid making turns at speed or with raised loads.
A coupled force predictive control of vehicle stability using front/rear torque allocation with experimental verification
Published in Vehicle System Dynamics, 2022
Reza Hajiloo, Amir Khajepour, Halit Zengin, Alireza Kasaiezadeh, Shih-Ken Chen
While torque vectoring and differential braking have been studied extensively in the literature, fewer studies have investigated the contribution of the torque distribution between the front and rear axles in vehicle handling performance. The front/rear torque distribution has been investigated in both feedforward and feedback control schemes. In [8], a feedforward strategy is presented for front/rear torque distribution to improve the vehicles lateral grip at handling limits. A quasi steady-state vehicle dynamic is used to saturate the front and rear axles at the same time by properly adjusting the torque distribution. The study uses the dynamic square method for evaluating the effect of front/rear torque distribution on the lateral grip margin. In [9,10], a yaw moment analysis is performed to identify the contributions of the longitudinal and lateral forces on the vehicles handling characteristics for front-wheel-drive, rear-wheel-drive, and all-wheel-drive architectures. It is shown that the handling characteristics vary with the vehicle speed and front-to-rear wheel torque distribution. In [11], the capability of front/rear torque shifting in producing the vehicle body yaw moment is investigated. The effectiveness and the capacity of the yaw moment produced for different values of longitudinal acceleration are also examined in the study.
A three-dimensional free-trajectory quasi-steady-state optimal-control method for minimum-lap-time of race vehicles
Published in Vehicle System Dynamics, 2022
The total driving force is split between the rear and front axle according to the distribution factor , under the open-differential assumption In acceleration for rear-wheel-drive (RWD) vehicles, for front-wheel-drive (FWD) vehicles, and for all-wheel-drive (AWD) vehicles. In braking where γ is the brake ratio, which is here defined as the ratio between the front and rear longitudinal tyre forces. A standard roll stiffness balance equation is included to solve the lateral load transfer from the roll stiffness ratio ξ In order to obtain the g–g–g maps of the car semi-analytically, the steer angle is neglected, as in the case of the motorcycle in Section 3.1. In addition, the following relationships between lateral and normal forces are included In practice, enforcing (38) means including the main assumption of the standard single-track car model in the double-track model (same cornering stiffness and slip on the tyres of the same axle). Yet the double-track model retains the lateral load transfer, which will in turn affect significantly the limit lateral accelerations.
Minimum-lap-time optimisation and simulation
Published in Vehicle System Dynamics, 2021
Some early examples of MLTS solved as minimum-time OCP appeared in the 1990s. A hairpin curve at the Fuji Speedway (Japan) is considered in [11]; the cost function is the manoeuvre time. Unlike earlier studies, no pre-assigned reference trajectory is provided – the trajectory is determined by the optimiser. A single-track three DOF car model is employed (the well-known ‘bicycle model’); the longitudinal and lateral tyre forces are constrained by friction circles. The lateral forces are modelled as linearly saturating: they grow linearly with slip (at fixed cornering stiffness) until saturation is reached. The side-forces remain constant thereafter; load transfer effects are not considered. Both front-wheel-drive (FWD) and rear-wheel-drive (RWD) configurations are considered, together with front- and rear-wheel steering variants. The solution of the OCP is obtained using a sequential conjugate-gradient-restoration algorithm [12,13].