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HyMAR devices creased in chronological order of development
Logger V1
Two boards make up the initial logger. One board to sample torque, shaft speed, shaft
direction and thrust. This board also formed the main power supply for the logger
which ran from the onboard mains inverter. This style of PSU was chosen due to the
current loop chips requiring a +/-15V DC supply (Figure 1). The second board was
designed to measure fuel, interface to the first board, log data and pass it onto a PC
asynchronously for processing (Figure 2).
Figure 1
Figure 2
Logger diagnostics
To test the accuracy of the logger before it was installed on the boat, a small device
was designed to simulate the current loops and pulses found on the sensors boat
(Figure 3).
Figure 3
Wi-Fi router PSU
Using the boat inverter to power devices turned out to be quite inefficient and
laborious to make sure everything was turned on. One of the critical systems was a
Wi-Fi router which interfaced to the logging PC (notebook). This had to be a smooth
supply from a noisy 24V source so a board was designed (Figure 4)
Figure 4
200A current and voltage sensor V1
The initial current sensors where hall effect devices that went inline with the
conductor they were measuring. A voltage tap was built in for voltage measurement
and a common ground was assumed. It was a simple device designed to test the
accuracy of a hall effect device over traditional shunts (Figure 5).
Figure 5
Current sensor interface board
The current sensors output a 0-5V signal which had to be converted into real life amps
and volts. An interface board was designed to sample and send this data to a PC either
via RS232 serial or USB (Figure 6).
Figure 6
200A current and voltage sensor V2
Due to voltage drops over the cable runs between current sensors it proved too
inaccurate to remotely sample the data. It was decided to swap to sensors with
onboard sampling logic and then communicate back to the interface board digitally.
The board was double sided to keep the size compact (Figure 7).
Figure 7
Logger V2
The first logger was combined, reduced in size and alterations where made to improve
accuracy. The mains power supply was also done away with in favour of a DC/DC
converter to produce the +/-15V needed for the current loop chips (Figure 8).
Figure 8
200A current and voltage sensor V3 experiment 1
It became apparent that even though we'd chosen a hall effect device to measure
current, the inline nature caused a small resistance which translated to heat. This was
unacceptable and unsafe at high currents so a non-intrusive method was devised. A
coil would be wrapped around the conductor current was to be measured. The
experiment formed essentially a metal detector that changed frequency with current
flowing through a conductor. The frequency could be measured and the current could
be derived (Figure 9).
Figure 9
200A current and voltage sensor V3 experiment 2
More accuracy was required to measure the frequency fluctuations. A phase locked
loop design was tried (Figure 10).
Figure 10
200A current and voltage sensor V3 experiment 3
The accuracy of the frequency shift design proved untenable in the time available.
The hall effect design was re-visited but this time with a non invasive device, a
doughnut that slipped over the conductor (Figure 11).
Figure 11
200A current and voltage sensor V3 prototype 1
The results of the non intrusive hall effect device were encouraging and we needed to
try it as part of a complete system for further tests. A sensor board was designed to
measure current and voltage and send it to the logger via RS485. RS485 can be daisy
chained and is also good for long distances. Cheap, readily available RJ45 connectors
and network cable could then be used. Rudimentary electrical isolation was added as a
precaution with an onboard DC/DC design. The actual sensor was moved off-board
and onto a short fly lead for ease of fitting. (Figure 12 and 13).
Figure 12
Figure 13
200A current and voltage sensor V3 prototype 2
Electrical isolation became a very real problem especially when measuring across
battery banks as a common 0V could no longer be used. The zero offset of the hall
effect sensor was problematic so a second hall effect sensor was added in parallel and
inverted to the first to increase the zero offset accuracy. A more accurate ADC was
added and multiplexed to keep the cost down (Figure 14 and 15).
Figure 14
Figure 15
200A current and voltage sensor V3 prototype 3
Multiplexing the ADC caused measurement anomalies so two separate ADC's where
employed instead (Figure 16).
Figure 16
400A current and voltage sensor V3 prototype (final)
Even greater electrical isolation was implemented and accuracy was increased with
higher bit ADC's, a new hall effect sensor with offset compensation and the DC/DC
PSU was greatly stabilised. A new carrier board was designed for the updated sensor,
the current range was increased and accuracy was +/30mA (Figure 17 and 18).
Figure 17
Figure 18
400A current interface board
So we could still use the existing logger an interface board was designed to connect
directly to it. The RS485 data was harvested, collated and then sent via RS232 on
request. The daisy chain nature of the RS485 interface was kept so the board could be
placed anywhere in the chain (Figure 19).
Figure 19
EMM (Jason) prototype experiment 1
Now we had real data from the system the energy management device could be
started. Initially we interfaced a WiFi module to the logger so that an Android
application could process the data (Figure 20).
Figure 20
EMM (Jason) prototype 2
We had the data and now we needed a controller to deal with the data and provide a
platform to start building algorithms. RS232 communication with the old logger was
left in and USB support was added for a new logger. The RS485 interface to the
existing current sensors was left in but a new CAN network was added ready for the
next sensor revision. Basic relay control was added. An 8bit DAC and digital
potentiometer provided potential helm control. Provision for an LCD display and
daughter board expansion was integrated along with onboard RAM for logging.
Finally the wi-fi interface was added so an Android tablet could run a monitoring app
and provide a way to handle the complex calculations that may be needed (Figure 21).
Figure 21
400A current and voltage sensor V3.5
Current sensors were the key to a decent control and efficiency strategy so there were
increasing numbers installed on the boat. Each sensors current draw became a very
real problem with over 1A needed to run the sensors alone. Their efficiency had to be
improved along with an accuracy tweak to a 24bit ADC (Figure 22).
Figure 22
Sensor simulator board
Back in the lab it was becoming increasingly difficult to recreate large current loads
so a simulator was designed to aid Jason development (Figure 23).
Figure 23
EMM (Jason) prototype 3
The Android app approach was working but it was decided a roaming tablet could be
lost and it forms a critical part of the system so an RJ45 Ethernet connector was added
to Jason. This provided a dedicated hard wired tablet whilst keeping the roaming one
(Figure 24).
Figure 24
Battery monitor unit V1
To keep track of state of charge a current sensor needs to be on constantly. A 400A
current sensor was re-tasked for this job and new firmware was added (Figure 25).
Figure 25
14 way battery voltage and temperature monitor V1
Each battery in the 144V bank needed to be monitored to detect equalisation issues
during discharge and charging. Individual current/voltage sensors would have been
impractical for this job as current was not required and the total power consumption
would be prohibitive. A new board was designed to measure all 14 batteries along
with their temperature (Figure 26).
Figure 26
V2 sensor prototype 1
The 14 way board failed catastrophically due to the multiplexed nature of the sensors.
The batteries were accidentally wired in the incorrect order and electrical isolation
broke down. It was time to swap to something smaller, less power hungry and CAN
based. The V2 was born which measured voltage and temperature at the stud of each
battery. The device had to draw less than 10mA, be totally isolated and interface to
the new CAN bus which we called the ARGO bus. Two boards were designed that
stacked to keep the foot print small. For the first time onboard programming was
integrated (Figure 27).
Figure 27
V2 sensor prototype 2
The initial design worked well and the design was refined to include even better
isolation and increased efficiency (8mA). The size was also tweaked to allow easier
assembly. A final pass for size tweaks finished the design (Figure 28 and 29).
Figure 28
Figure 29
E2 sensor prototype 1
Now that the voltage sensors were CAN based (ARGO bus) we had to update the
current sensors. The old design consumed too much power and the ADC noise floor
caused drifting accuracy issues. The E2 sensor was designed to also integrate the hall
effect sensor to lower any noise that could have crept onto the old fly lead design. A
new self calibrating 16bit ADC was chosen for the design. Once again electrical
isolation was important and this time conductor temperature sensing was added. The
device has a super capacitor which is used to backup SoC and iBC data on the event
of a power failure. Once again onboard programming was added so the devices could
be upgraded in situ (Figure 30).
Figure 30
E2 sensor prototype 2
The final revision of the E2 sensor was smaller. Power failure detection was
enhanced. The current sensor ADC was upgraded to an 18bit device and the power
requirements where dropped to below 20mA (Figure 31).
Figure 31
EMM (Jason MD) modular experiment 1
Jason was going to be radically redesigned and one of the changes was to use a web
server as the human interface. A board was created to test the suitability for this idea.
It incorporated a web server, ARGO bus and a serial output for monitoring the
validity of the data from the web server (Figure 32).
Figure 32
EMM (Jason MD) modular prototype 1
The android app and multiple tablet approach was dropped and it was decided that the
human interface would be totally web browser based to allow any web enabled device
to be used. The main MCU of Jason was upgraded to be more powerful and use a C
based language as opposed to assembly. This meant Jason could deal with complex
algorithms without the need for external devices to do hard work. We also stepped
away from a global board and adopted a modular approach. If Jason needed to do
something specific then a box could be added to the ARGO network to carry out that
specific function under Jason's supervision. This reduced the need for board
redesigns. So a new board was created with 4 CAN interfaces (ARGO CAN,
NMEA2000, J1939 and a spare), a web server and serial output. Jason would now
functioned as the logger as well (Figure 33).
Figure 33
NMEA0183 to ARGO CAN module V1
Many instruments use the NMEA0183 protocol or provide an NMEA0183 gateway.
Raymarine navigation data is an example of this and we needed to get that
information filtered and placed on the ARGO CAN. This is where the new modular
design of Jason comes into it's own because a simple board adds a lot of functionality
to Jason with a minimum of fuss (Figure 34).
Figure 34
Wiring replacement boards
With the modular devices new being built into boxes the internal wiring became a
time issue and so circuit boards were designed to connect together internal connectors
(Figure 35 and 36).
Figure 35
Figure 36
Generator control module experiment
To implement re-gen we needed to be able to control the generator load and that was
the aim of this board. It's a high power FET with driver, protection and links to the
PWM output found on Jason MD (Figure 37).
Figure 37
Universal modular board V1
It quickly became apparent that many of the external functions Jason needed such as
engine cooling control, data translation, addressable switching and remote control
could be done with one single board. Much of the hardware design was coming up
again and again and becoming more like building blocks. With a universal board you
place all those building blocks together and then all you needed to create a new device
is different firmware. Not every design uses all the hardware so that hardware is
simply not populated (Figure 38).
Figure 38
Watchdog MD V1
With all the data flowing around the boat and the ability to view this on a local web
browser device it was the next logical step to offer the data over the internet. A board
was designed to power the ARGO bus if needed, sample the data flowing on the
ARGO bus and report that data back at a set interval over the GPRS mobile network.
This gives the users near real time data that they can view from anywhere in the
world. The first board used a real time clock onboard the processor and a Maestro
GSM modem (Figure 39).
Figure 39
Watchdog MD V2
The real time clock built into the MCU proved unworkable due to the configuration
we'd chosen for the chip itself. Instead a dedicated real time clock chip was added
along with provision to fit various GSM modems from different manufacturers. We
were going through the process of selecting the best modem for the job and it seemed
prudent to have a board that would support any (Figure 40).
Figure 40