Around the distribution cone, linear feeders (LF)
are arranged in a circle towards the outside. Feed
buckets (FB) are located below the LF, followed
below by weighing buckets (WB), both buckets in
red. Finally, chutes and a funnel are attached below.
The piece goods are fed from above and supplied
to the WB via distribution cone, LF, and FB. The
weight of the partial quantity is determined when the
product is in the WB. Each WB is connected to a
load cell (Profe and Ament, 2022).
1.2 Challenges and Application of
Product Model
A detailed model description of the weighing pro-
cess is of high relevance for the development and
improvement of weighing systems. A model can be
used for example for digital twins, virtual experi-
ments to understand the cause-effect relationship,
control systems (e.g. as an observer), and, in general,
to generate virtual data (Profe and Ament, 2022).
Figure 1 shows the block diagram of the system
weighing station. The output is the weighing signal
from the associated load cell. The system weighing
station includes WB, which is connected to a load
cell. The system input corresponds to the product
impact force (PIF).
The PIF is the force created by the partial quan-
tity falling out of the FB and hitting the WB (weigh-
ing station). A detailed knowledge of the PIF is
important for fast and accurate weighing.
Figure 2: System Weighing station with product impact
force as input and weighing signal as output.
For this purpose, a model approach for a so-
called Product Model will be presented in this paper.
Models of weighing stations were presented in the
publications of Eckstein and Ament (2019) and
Profe and Ament (2022). However, these models
work without a product model although this could
increase the weight acquisition speed or the accuracy
of results. Wente (1992) and Gilman and Bailey
(2005) presented force curve models of weighing
stations, but in these models, there is no specific link
to the weighing goods of a CS. A product model has
not yet been used because the impact force does not
exist as a sensor quantity. PIF is even difficult to
measure directly. Only the system response (weigh-
ing signal) is available. Another complicating factor
in developing a product model is the large variety of
products to be weighed and the varying fall behav-
iour of the product. Even with identical product
properties, falling comprises strong stochastic influ-
ence. In this work the PIF is determined with the
help of the Discrete Element Method (DEM).
2 DEM SIMULATION MODEL
A direct measurement of the PIF was not carried out
on a real test setup, due to the challenges to generate
controlled and reproducible data. Instead, a virtual
model was created (see Figure 2). The model con-
sists of LF, FB and WB. It is a section of a CS.
There is product in LF, FB and WB. In contrast to
the real scale, the product falls directly into LF (see
product input in Figure 2) instead of the distribution
cone. The flaps of FB and WB are able to open and
close the respective buckets.
Figure 3: Virtual simulation model of a weighing station.
Table 1: Timing of LF, FB and WB within a weighing
cycle.
Table 1 depicts the sequence of the processes
running in parallel in the virtual model. The pro-
cesses start in the third row with opening and closing
of WB. Shortly after the WB flaps are closed again,
new product falls into WB. Parallel to WB, FB
opens with a time delay. The flaps of FB start to
open at the moment when WB flaps are fully open.
After the FB flaps are closed, new product can be
added. Therefore LF starts to vibrate. FB is filled