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COST-EFFECTIVE AND INNOVATIVE TEST JIG FOR
FISHING-BAIT RELEASE MECHANISMS ATTACHED TO
DRONES
Pierre Eduard Hertzog
Department of Electrical, Electronics and Computer Engineering
Central University of Technology, Bloemfontein, (South Africa).
E-mail: phertzog@cut.ac.za ORCID: http://orcid.org/0000-0002-3396-6050
Arthur James Swart
Department of Electrical, Electronics and Computer Engineering
Central University of Technology, Bloemfontein, (South Africa).
E-mail: aswart@cut.ac.za ORCID: http://orcid.org/0000-0001-5906-2896
Recepción:
26/12/2019
Aceptación:
23/03/2020
Publicación:
30/04/2020
Citación sugerida Suggested citation
Hertzog, P. E., y Swart, J. (2020). Cost-eective and innovative test jig for shing-bait release
mechanisms attached to drones. 3C Tecnología. Glosas de innovación aplicadas a la pyme. Edición Especial,
Abril 2020, 119-135. http://doi.org/10.17993/3ctecno.2020.specialissue5.119-135
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ABSTRACT
Fishing-bait release mechanisms are used in conjunction with drones to drop bait at a specic
shing location. It is really a revolutionary technology to many shermen. However, many
of these release mechanisms have no real technical data associated with them. Therefore,
the purpose of this paper is to present a cost-eective and innovative test jig that may
be used to determine the reliability and consistency of operation of various shing-bait
release mechanisms. The main components of the system are a HX711 instrumentation
amplier, a load cell and an Arduino Mega microcontroller. The accuracy of the system
was determined to be 99,879%. Reliability values for a Gannet Sport mechanism with a
0.55 mm Kingsher line ranged from 599 g to 642 g, giving a maximum deviation of 43 g.
The results provide evidence that the system is both reliable and valid. It is recommended
to use it to clarify technical data regarding the weights at which dierent shing-bait release
mechanisms operate.
KEYWORDS
Arduino, Load-cell, Electronic measurements.
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1. INTRODUCTION
“A few years ago, the city council of Monza, Italy, barred pet owners from keeping goldsh
in curved bowls... saying that it is cruel to keep a sh in a bowl with curved sides because
gazing out, the sh would have a distorted view of reality. But how do we know we have
the true, undistorted picture of reality?” (“Brainy Quote”, 2019). These words by the late
world-renowned physicist, Stephen Hawking, illustrates that our perception of reality may
be distorted, just as the viewpoint of a sh may be distorted in a curved glass bowl. To
correct this distortion would require that we obtain accurate knowledge based on facts.
However, we would rst need to de-construct our erroneous knowledge and then re-
construct it with the accurate knowledge that we have received. De-constructing knowledge
must be preceded by an acknowledgement that our knowledge, or perceptions, may be
erroneous, or even biased. This is true even of simply things in life, such as shing.
Fishing is as old as the hills, yet as new as today when it comes to new and innovative
equipment and technologies. For example, drones have been used in shing to identify
good sh spots and for bait release purposes. The Internet of Things and shing drones
using an integrated remote camera have been used to target specic shing spots to enable
easier catching of sh (Maksimovic, 2018). Fishing for large sh beyond the breakers by rst
looking for them and then dropping the bait and a hook in front of them is quite popular
in South Africa and can be achieved by using a shing line dropping drone (SUAS News,
2019). This may also be termed a shing-bait release mechanism that is attached to the
bottom of a drone, which is really a revolutionary technology to many shermen.
However, with so many dierent models available for this type of technology, the question
may arise “Which release mechanism is more reliable and consistent in operation? Some
shermen may prefer the old tradition of casting the shing line, while others may have
strong opinions about a preferred modernized technology that makes use of a shing-bait
release mechanism. De-constructing erroneous perceptions of which model is best, and
then re-constructing knowledge of which model is reliable and consistent would require the
use of one or other scientically accepted test.
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The purpose of this paper is to present a cost-eective and innovative test jig that may
be used to determine the reliability and consistency of operation of various shing-bait
release mechanisms. The paper starts with a brief history of drone technology and presents
some of its many applications. Previous research in the eld of release mechanisms are also
presented. The design of the jig is then given, followed by the methodology employed to
obtain the scientic empirical results. Conclusions end the paper.
2. LITERATURE
Some believe that the rst type of drone was used in July 15, 1849 when the Habsburg
Austrian Empire launched 200 pilotless balloons armed with bombs against the revolution-
minded citizens of Venice (Ferrao, 2016). However, others view this as an erroneous belief,
especially when considering the ocial denition given by The Oxford Dictionary. It denes
a drone as “a remote-controlled pilotless aircraft or missile” (“Oxford Dictionary”, n.d.).
The aspect of remote-control and ight must be factored into the discussion. The Federal
Aviation Administration (FAA) of the USA further denes a drone as a small unmanned
aircraft system weighing under 55 lb (or 24,9 kg) (Federal Aviation Administration, 2016 ).
The aspect of weight thus needs to be factored into the discussion. Considering the words
remote-controlled, ight and weight leads one to conclude that drones were rst used
towards the end of the 20
th
century, when newer technologies allowed for the inclusion of
these factors into their design and development.
Moreover, the decline in cost due to these technological advancements has allowed drones to
become viable options for a diverse range of services, including health services (Wulfovich,
Rivas, & Matabuena, 2018), agriculture (Parihar, Bhawsar, & Hargod, 2016), sports (Park,
Kim, & Suh, 2018), conservation (Sandbrook, 2015) and in monitoring solar farms (Benatto
et al., 2019). Drones have also been used in border patrol, disaster relief, law enforcement,
and in the original use of military missions and training (Upchurch, 2015).
A specic research paper, published in 2019, described a novel way to reliably deliver
packages using a drone. For years, companies such as Amazon and Google have been
hard at work developing a safe and practical way of utilizing the potential of unmanned
aerial vehicles to improve upon their current network of delivery services. Transportation
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of even large packages has become feasible due to the advances in drone-based robotics.
The biggest problem left unanswered is how to best release the package once the drone has
arrived at the drop o location. A possible solution details a basket that can hold onto the
package until the drone is rapidly ipped upside down in an aerial maneuver (oftentimes
called a roll) and the centrifugal force ejects the payload from the basket (Burke et al., 2019).
However, this may prove draining to the battery.
Another option that overcomes this challenge involves a mechanism attached to the bottom
of a drone that can deploy a payload from air to land using a parachute method. The study
that reported on this release mechanism made use of an Arduino UNO microcontroller
(Wan, Azrie, & Shuib, 2018). This type of Arduino microcontroller can also be used in a
practical test system to determine the reliability and consistency of operation of various
release mechanisms relating to shing-bait.
3. INNOVATIVE TEST JIG DESIGN
The practical test system of the innovative test jig is given in this section. Firstly, an overview
of the complete test system is given, where after the load cell, instrumentation amplier
and the 24-bit analogue-to-digital converter is explained. The next step explains the
Arduino software as well as the communication between the microcontroller, the SD card
and the Nextion touch screen display. The complete block diagram of the tension release
measurement system is shown in Figure 1.
The rst block is a load cell that is rated for 5 kg. The load cell has a safe overload of 6 kg
and will be damaged if the load exceeds 7.5 kg. The load cell has a measurement precision
of 0.05%. It is mounted with two x 5 mm bolts onto a xed structure, while two x 4 mm
bolts are used to connect to the load. One of the reasons why this load cell was selected is
because of its ease of mounting. The load cell is constructed of four strain gauges that is
coupled in a Wheatstone Bridge conguration. As the innovative test jig is custom made for
release mechanisms for sh-bait, a 5 kg load cell is adequate. In order to perform accurate
weight measurements, an instrumentation amplier and higher resolution analogue to
digital converter is necessary.
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The second and third blocks shows the instrumentation amplier and the high precision
24-bit analogue to digital converter that is part of the HX711 load cell sensor interface
module. The HX711 module was chosen for this project and is specially designed to work
with strain gauges that is coupled in a Wheatstone Bridge conguration. It was used in load
cell project involving a garbage alert system that was developed by the National Institute of
Technology in India (Paavan, Sai, & Naga, 2019). The HX711 module can be programmed
for a gain of 32, 64 or 128 and it has an input voltage range of 4.8 to 5.5 V DC. The refresh
frequency is selectable between 10 and 80 Hz and it has a low operating current of 1.6 mA.
The center block in the diagram is the Arduino Mega microcontroller. It is used to obtain
the high-resolution 24-bit data from the HX711 module and to do necessary processing.
This process will be explained in the following section with the use of ow charts.
5 kg Load cell
Intrumentation
amplifier
24 bit Analog to
Digital converter
Arduino Mega
Microcontroller
7 inch Nextion
Touch screen
display
SD card module
Figure 1. System block diagram.
The Arduino Mega microcontroller also saves the recorded data to a micro SD card that
is situated on an SD module that ts as a shield on the Arduino. The microcontroller also
connects to a 7-inch Nextion touchscreen display. This display is used as a user interface
that shows recorded data while providing a number of push-button functions.
The Arduino program is presented in the form of a simplied owchart as can be seen in
Figure 2. Because of limitations in space, the owchart only shows the major functions in
the Arduino program to give the reader an idea of the general ow of data. After startup,
the rst block is the initialization bock where the necessary libraries for the display, the SD
card and the HX711 module is loaded. After initialization, the weight measurements start
and is displayed on the Nextion display. There are three push-button functions that can be
selected by the user.
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5 kg Load cell
Intrumentation
amplifier
24 bit Analog to
Digital converter
Arduino Mega
Microcontroller
7 inch Nextion
Touch screen
display
SD card module
System start
Zero
button
pressed
Start
button
pressed
Calibrate
button
pressed
Current
reading
<< than
previous
Initialize system and
start weight
measurement
Zero scale with
current tare weight
Record weight
measurement and
store in array
Guide user and do
calibration with
specific weight
Write recorded
values
to SD card
No
Yes
No
No
Yes
Yes
Yes
No
Figure 2. Simplied ow diagram of Arduino Mega program.
The rst button is the calibration button that is used to calibrate the scale with a specic
weight that is recorded in the program. If this button is pressed, the user must remove the
load bucket and dropping mechanism from the load cell and connect a calibrated weight
(333.2g) to the scale. The program will then do an automatic calibration to nd the best
calibration factor. There will also be a message on the screen that will notify the user when
the calibration process is completed. Calibration is discussed in more detail later in the
paper.
The zero button is used to zero the scale, with or without the tar weight, before the load
bucket is connected to the dropping mechanism. The zero button also sets the experiment
counter to zero that is used to identify the start of the recorded data that is sent to the SD
card.
The next button is the start button and is used to start a test session where all weight
measurements are recorded in an array. The weight is increased by allowing more water to
ow into the load bucket by means of a water-value. After each measurement, a test is done
to determine if the current measurement is smaller than the previous measurement. If not,
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then another measurement is done. As soon as the current measurement is smaller than the
previous measurement then the system will detect that the release mechanism has activated.
It will then display the maximum weight reading on the screen and write all the weight
measurements in the array to the SD card. The number and name of the experiment is
also recorded that species certain parameters about the shing line that is used with the
shing-bait. The time taken, in milliseconds, to complete a series of measurements for
each experiment is also recorded, along with the number of measurement samples and the
number of milliliters (ml) per sample. As 1 ml of water is equal 1 g, the number of grams
per sample can be used to calculate the accuracy of the measurement. For instance, if the
weight increases with 1 g per sample then the maximum accuracy of the measurement
cannot exceed 1 g. After all the data is written to the SD card, a message is displayed on the
Nextion display to inform the end user that the test system is ready for the next experiment
session.
Calibration is done by using a specic calibrated weight. In this test system, a stainless-steel
bar of 333.2 g is used. The exact weight of the bar was determined by using a calibrated
scale (ADAM 6031) with a resolution of 0.1 gram. Figure 3 shows the ow diagram of the
calibration sequence used in the Arduino program. When the zero button on the Nextion
display is pushed, the scale is set to zero with the current tar. The user is then required
to put the calibrated weight onto the scale, and the program executes a measurement
command. If the measured weight is too high, then the calibration factor is decreased, and
the measurement is repeated. If the measured weight is too low, then the calibration factor
is increased, and the measurement is repeated. As soon as the measured weight is equal to
the 333.2 g of the calibrated weight, then a completion message is communicated to the
user via the Nextion display.
The Nextion touch screen display is used as a user interface for the test system. A photo
of the display is shown in Figure 4. On the display, two measurements can be seen. The
rst measurement is the current reading from the load cell and the second reading is the
last maximum reading recorded by the test system. On the bottom, left-hand corner are
messages that have been communicated to the user. The three push-button functions can
be seen on the bottom right side of the gure.
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Calibration
Start
Measured
weight to high
Measured
weight to low
Zero scale with current
tare weight
Yes
Ask user to place
calibration weight on scale
Measure calibration
weight
Yes
Decrease calibration
factor
Increase calibration
factor
Calibration completed
Figure 3. Simplied ow diagram of calibration software.
The calibration button (CAL) is used to calibrate the test system. The zero button (ZERO)
is used to zero the scale with the tar weight. The start button (START) is used to start
the experiment session. When the start button is pressed, the experiment number will be
incremented by a value of 1 (the current value of 3 is shown in the top right-hand corner).
The top left-hand corner shows the description of the experiment that can be changed in
the Arduino software for each make of and model of the release mechanism. For instance,
in Figure 4 it shows that the Gannet Sport release mechanism was used with a dry shing
line having a 0.55 mm diameter. It also shows that the test was concluded at 525 g.
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Figure 4. Nextion touch screen display showing the user interface.
Figure 5 shows a typical circuit and internal block diagram of the HX711 microchip. The
HX711 load cell model has two analogue input channels (INA and INB). The dierential
inputs on the channel are coupled directly with the load cell Bridge sensor output. Channel
INA can be programmed with a gain of 128 or 64. These large gains are needed to
accommodate the very small output signals from the strain gauge sensors. An input voltage
of +- 20 mV will result in a full-scale output of 5 volt with the 128 gain setting. Channel
INB has a xed gain of 32 and the input V range is +-80mV for a full-scale output reading.
Figure 6 shows a photo of the completed practical test system. A two-liter water reservoir
is located at the top of the system, which is used to increase the weight of the load bucket.
The Nextion touch screen display, mounting bracket and dropping mechanism are also
visible. Calibration weights are shown at the bottom of the photo.
Figure 5. Typical circuit and internal block diagram of the HX711 microchip. Source: (Qian, Liu, & Wu, 2019).