Voyager 2.0 Angle Sensor for Wingsail

Voyager 2.0 Bluetooth Controller for Wingsail Servo

Voyager 2.0 Bluetooth Controller for Wingsail Servo

Voyager 2.0 Trials Under Motor

Voyager 2.0 Trials Under Motor - November 2018

Navigating a Sailing vessel is more complicated than navigating a motor vessel.

So start with motoring first.

The boat was fitted with motor pod on a stubby fin, instead of the full size sailing fin.

Additional battery power and an Electronic speed controller were added in order to commence trials of the boat and the software under motor.

This proved to be a valuable approach to addressing some of the software design issues, before heading into the complexity sailing.

It allowed trialling of many of the systems in a more controlled environment than sailing would have allowed.:

• Steering and course keeping
• Executing a mission
• Loitering
• Telemetry and SD Card Logging
• Magnetic compass accuracy

Setting up the motor

Typical scene before commencing

Realtime Telemetry Display - This image highlights compass accuracy problems

Heading off under motor on a mission

Going well

Note: This is part of the ongoing development of a low cost autonomous oceangoing sailing drones, utilising a self-trimming wingsail. This is the Voyager series of sailing drones.

Voyager 2.0 Wingsail with Bluetooth Controller

Voyager 2.0 Wingsail with Bluetooth Controller

Voyager 1.5 - Build, Launch and Voyage

Voyager 1.5 - Build, Launch, Voyage and Loss.

Following the voyage of Voyager 1 out near Lord Howe Island, I was provided with another unwanted model yacht hull, that I could send offshore.

This time I could employ some the lessons learned from Voyager 1 in the preparation of Voyager 1.5.

The main change was the use of closed cell construction foam to pack the hull and ensure that it is intrinsically buoyant. I want to ensure it doesn't sink.


Another change was the use of larger batteries for the Satellite Transmitter, changing from AA Cells to C Cells. This should yield an estimated 6 months of operating time. 

Voyager 1.5 was launched from Woodside Beach in Gippsland Victoria, as per Voyager 1. 
Once a suitable weather window arrived, it was launched on 13/6/2018.

The position reports were logged on this page http://ww2.acaciacs.com.au/voyager1.5/.



Progress was slow and after about 2 weeks, Voyager 1.5 hadn't entered the Tasman Sea.

Finally, a big Westerly gale arrived on July 7. This started to push Voyager 1.5 out into the Tasman Sea. 
However, at 4am the next morning. the last satellite transmission was received.

What had happened ?
The signal was lost during a gale with winds approaching 50 knots from the West.
That implies that the signal lost due to some sort of breakage.

Possible reasons why it is no longer transmitting:

• There has been electrical failure
• The has been a breach of the water tight container holding the SPOT GPS, and it has been damaged by the salt water.
• The Hull has broken up or been damaged in the gale, and the SPOT GPS does not have a clear view of the sky

.
We may never know....

Voyager 2.0 Controller Evolution

Voyager 2.0 Controller Evolution

This series of photo illustrates the evolution of the Voyager Controller design so far.

November 2016 - They're not called "Breadboards" for nothing

October 2018 - Veroboard Design

January 2019 - More compact and robust 3D Printed Chassis

January 2019

March 2019 - New PCBs  !!

April 2019 - The first dedicated PCB Design

Voyager 2.0 Hull

Voyager 2.0 Hull

The hull was design using Freeship.
This is very powerful free hull design software.
The hull design was not intended to be sophisticated, just a simple balanced hull providing good buoyancy fore and aft.

Once the design was settled, lines were exported and transcribed on the 3mm marine ply to be used as stringers, glued between the closed cell construction foam.

The foam board used was available in 50mm sheets, 1200mm long. This was the main parameter for determining the hull dimensions for Voyager 2.0. 
Six pieces of foam were cut to shape to follow the lines from hull design.
They were all to be glued together with the plywood stringers in between using one part polyurethane glue.

It was found that the stringers were not needed, except for the central one incorporating the mast bearing tube and centreboard casing. The use of plywood stingers between the foam board would have made the hull far heavy than desired, and unnecessarily solid.

Screen shot of the hull lines in the Freeship program.

Central Plywood stringer part way through construction. It will incorporate the Centreboard Casing and Mast Bearing Tube

Closed Cell Foam Construction Board 1200mm long by 50mm thick

Shaped Hull being weighed, prior to Fibreglassing

The fibreglass cloth used was rated at 2 ounces.

Epoxy resin was used. (Polyester dissolves the foam. A lesson I stupidly learnt the hard way!)

Preparing to Layup the Fibreglass

First float test

Note: This is part of the ongoing development of a low cost autonomous oceangoing sailing drones, utilising a self-trimming wingsail. This is the Voyager series of sailing drones.

Voyager 2.0 - Design Principals and Construction Methods

Design and Construction Principals to be applied to Voyager 2

Hull Construction

The vessel should be intrinsically buoyant and unsinkable.
It was decided to build the hull using surfboard construction methods of glass fibre coth with epoxy resin over a closed cell foam.
The hull will be built using sheets of construction foam sandwich glued with plywood stringers. The stringers would be cut to match the appropriate offset lines from the hull design drawings. Then the foam could be carved down to match plywood stringers and sanded and then glassed.

Hull Design

The hull would designed using Freeship. This is powerful, free, hull design software. It has reasonable export capabilities extracting lines and offset information.

Rudders

Standard RC Servos will be used for the rudder (or rudders). These have a limited life, mostly constrained by the wear of the feedback potentiometer. It seems that low cost servos have a single wiper within the potentiometer whereas longer life servos use potentiometers with multiple wipers (typically 3).

One way of doubling the life of a servo is to use it half the time.

Voyager 2 will only have a single rudder, but a later version of voyager will use two rudders, operated by two servos. The steering will be performed by the leeward rudder, while the windward rudder will remain centred. 

Sail

The sail will be self trimming wing sail.

This type of sail is particularly good for low powered autonomous vessels, because it  takes very little power to operate the trim tab to set the sail.

Traditional soft sails or a traditional solid sail typically require a fairly powerful winch or machinery to control.

Keel

One of the hazards to vessels is floating weed.

It is critical that the design of the keel and rudder will shed weed, rather than catch it.

This generally involves using profile with a gentle rake on the leading edge of the keel and rudder skeg to allow the weed slide off.

This also tends to lead to a the use of a unbalanced rudder attached to the sloping rudder skeg.

Equipment Housing and Equipment Bay

The Sistema plastic containers are reasonable for use as equipment housings.

They are reasonably waterproof for short term usage, but can be sealed using a non-corrosive silicone sealer if a completely water tight compartment is required.

It was decided that Voyager 2 would have an equipment bay located aft of the keel assembly, all the way to the back of the vessel with an open transomn.

Servo Endurance - Test Results

Hextronik HXT900

Two model HXT900 servos were tested. Both failed at approximately 40,000 cycles.
The component that failed was the potentiometer, which developed dead spots.
The Servo could continue to be used if the operating region was changed to a different position on the potentiometer.

The image below shows the potentiometer removed from one of the failed servos, showing the worn area. This potentiometer has two wipers.

Hextronik HXT900

HXT900 Potentiometer showing Wear

 

Arduino Servo Endurance Tester

How long do RC servos last ?

The RC servo manufacturers don't seem to publish any information about the operational life span of their servos. The life span of a servo will be influenced by the amount of loading, both static and dynamic. But there'is a fundamental limit which is the number of cycles with no load.
It seems that the quality of feedback potentiometer, rather than the drive train or motor is the limiting factor for the maximum number of cycles an RC servo can perform.

This is a design for a very simple RC Servo exerciser to cycle a servo 20 degrees either side of neutral about once per second. It includes an I2C LCD 2 line by 16 character display to display a count of cycles.

Servo Test Rig showing Arduino Nano, I2C LCD and Test Servo

The code for the Arduino is provided below:


#include "LiquidCrystal_I2C.h"
#include <Wire.h>
#include <Servo.h>

Servo myservo; // create servo object to control a servo
int pos = 0; // variable to store the servo position

// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

long CycleCounter = 0;
int BasePosition = 90;

void setup()
{
  // attach the servo on pin 9 to the servo object
  myservo.attach(9);

  // initialize the LCD
  lcd.begin();

  // Turn on the blacklight
  lcd.backlight();
  lcd.clear();
}

 void loop()
{
  myservo.write(BasePosition); // tell servo to go to Base Position
  delay(400);
 
  myservo.write(BasePosition+20); // move + 20 degrees
  delay(300);

  myservo.write(BasePosition-20); // move - 20 degrees
  delay(300);

  CycleCounter++;
  lcd.setCursor(0, 0);
  lcd.print(CycleCounter);
} 


The YouTube clip below shows the test rig in operation with an initial test using a low cost servo. It lasted for about 40,000 cycles before failure. I'll discuss the results of servo tests in another post.

Voyager 1 - Why did it disappear ? Conclusions. or A Study of the Water Take-up Rates with Different Foam Types.

Voyager 1 - Why did it disappear ? Conclusions.

A Study of the Water Take-up Rates with Different Foam Types.

I suspect Voyager 1 sank off Lord Howe Island due to the take-up of water into the spray foam, which was used as primary buoyancy.

The test this hypothesis, I set up a test using samples of foam with a standardised size of 10cm x 10 cm x 10cm (1litre). These were held in water for several weeks. The foam samples were weighed daily and the results were plotted.

Two Foam Samples created from Spray Foam (Open Cell). 

Sample of Construction Foam (Closed Cell).

Test Rig - Two Buckets of Water and Bricks.

Weight Gain of the Foam while held in water over 42 days.

The Construction Foam (closed cell) gained a couple of grams of water in the first day or two, and then its weight did not noticeably change for the next 40 days.

The Spray Foam (open cell) gained weight through out the 40 day test.  The samples of Spray Foam gained between 150g and 190g of water during the test. This represents 15% to 19% by volume of the foam.

---

I suspect that this take-up of water into the spray foam buoyancy caused the vessel to sink; and this was the most likely reason for the loss of signal.

Voyager 1 - The Last Signal

Voyager 1 - The Last Signal

The Last Signal was received on May 28, 2016 at 1:38am.

http://ww2.acaciacs.com.au/voyager1

The boat was approaching Lord Howe Island at approximately 2 knots at a distance of 110km, when it sent its last transmission.

It had travelled about 1200km from the launch point in Gippsland, Victoria, over 28 days.

Approaching Lord Howe Island when the last signal was received.

What happened ?
We will probably never know what happened to the boat, because we will probably never see it again.

Possible reasons why it is no longer transmitting:

• It has sunk
• The batteries are flat
• There has been electrical failure
• The has been a breach of the water tight container holding the SPOT GPS, and it has been damaged by the salt water.
• The SPOT GPS does not have a clear view of the sky.