Wheel loader optimal transients in the short loading cycle
A nonlinear wheel loader model with nine states and four control inputs is utilized
to study the fuel and time ecient optimal control of wheel loader operation in the short loading
cycle. The wheel loader model consists of lifting, steering and powertrain subsystems where the
nonlinearity originates from the torque converter in the drivetrain. The short loading cycle, from
loading point to a load receiver and back to the loading point, for a fork lifting application is
described in terms of boundary conditions of the optimization problem while the operation is
divided into several phases with constant gearbox gear ratios in order to avoid discontinuities
due to discrete gear ratios. The e ect of load receiver standing orientation on the wheel loader
trajectory, fuel consumption and cycle time is studied showing that a small deviation from the
optimal orientation ( 20 [deg]) results in up to 18 % higher fuel consumption in the minimum
time cycles. Also, an alternative lifting strategy where for operation safety load is lifted only
when wheel loaders moves forward is studied showing that this increases the fuel consumption
of a typical 25 [sec] cycle only less than 2 %. The wheel loader path between loading point and
load receiver is also calculated by optimization and analyzed for di erent cases. It is shown that
when the load receiver orientation is not optimized and is set manually, the time or fuel optimal
paths will di er from the shortest distance path, however when the load receiver orientation is
calculated by optimization the fuel, time and shortest distance paths become identical.
Vaheed Nezhadali and Lars Eriksson
2014
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Senast uppdaterad: 2021-11-10
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