M.J. van Wezel
De aandrijving van een robottrailer.
Report 96.3.TT.4782, Transport Engineering and Logistics.
An important issue for improvement of logistic properties of container terminals
is the optimization of logistic properties of vehicles that are used at those
terminals. Two of those vehicles are the Automatic Guided Vehicle (AGV) and the
The AGV is an automatic vehicle which saves the expenses of wages. Because
the top speed of the vehicle is very low, it is improper for covering long
distances. The MT is pulled in a train by a special tractor that has a higher
top speed than the AGV, through which the distances can be covered in a shorter
time. However using the MT, the expenses of wages cannot be saved.
Delft University of Technology Delft in the Netherlands has a research project
in bringing the advantages of the AGV and MT together in one vehicle, the so
called robottrailer (RT). The RT can also be used on public roads.
The RT can only be more economical than the AGV and the MT, if the purchase
costs are much lower than those of the AGV. However, the requirements with
regard to the velocity and the accuracy of the drive train when positioning
are the same as those of the AGV.
Because a main part of the costs of the RT are determined by the costs of the
drive train, it is being studied if the RT can cope with the operational
requirements of the AGV at lower costs. Especially the accuracy and
controllability of the drive train are important issues of the research
From the requirements that are used for the AGV's of the container terminal
of Europe Combined Terminals (ECT) in Rotterdam, the requirements for the RT
are specified. According to calculations and simulations, the RT needs a power
source of 130-150 kW. The drive train exists among others of an engergy source,
an energy converter and a transmission.
An external energy source, for example by conductor, is inconvenient and
therefore can not be used. The need for power is too high for the use of
hydraulic or electric batteries. Therefore, a internal combustion engine
must be used. Comparing the costs of fuels and the properties of the engines,
the dieselengine turned out to be the most useful powersource.
The transmission must be controllable within a long range, because the RT
must be able to drive with a constant 'crawling' velocity of 0,1 m/s. The
transmissions that are applied to comparable vehicles are the hydrostatic
drive of the AGV and the electric drive of the straddle carrier (SC).
Of five transmissions that are useful for the RT the properties were compared
with each other. It concerned two hydrostatic drives, a dieselelectric dive
and two drives with a automatic transmission and an electric drive for the
lowest speed. The dieselelectic drive turned out to be unsuitable, because
of the high dimensions. Ranked by usefulness the following four drive
trains were selected:
- A drive train wit a conventional automatic transmission and an
electric drive for the lowest speed (positioning);
- A drive train with a continuous variable transmission and an electric
drive for the lowest speed (positioning);
- A hydrostatic drive, combined with a synchronized automatic transmission;
- The hvdrostatic drive, which is used for the AGV at ECT.a
Reports on Transport Engineering and Logistics (in Dutch)
, TU Delft