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1
Ballooning Considerations / High Altitude ball bearings
« Last post by Cosmoneer on November 20, 2017, 05:04:32 PM »
Bearing grease may play a factor at high altitudes, so low friction grease-less bearings will be a better option.


http://www.vxb.com/608-Si3N4-Ceramic-High-Clearance-Bearing-4-balls-p/608-C4-SI3N4-PTFE.htm?gclid=EAIaIQobChMI_N7YkpHO1wIVjiWBCh2aKQOlEAYYASABEgI7pvD_BwE

Also, for our purposes of CMG design, since we may not run the drive motor the entire flight, we will need a clutch system that only engages when we need it to.

http://www.vxb.com/CSK8-One-way-Sprag-Freewheel-Backstop-Clutch-p/kit8176.htm
2
Ballooning Considerations / Battery selection
« Last post by Cosmoneer on November 20, 2017, 04:40:01 PM »
Unless you insulate your project and protect it from the extreme cold encountered at high altitude, you will need to use a power source (read battery) that can handle the temperature.


Good sources for flight heritage HAB power sources can be found below:

https://ukhas.org.uk/ideas:power_supply
https://www.sparkfun.com/tutorials/188
3
Inertial Guidance / Using CMGs for model rocket guidance
« Last post by Cosmoneer on November 08, 2017, 01:18:11 PM »
A question regarding usage of Cosmoneer CMGs (or larger versions) for model rocket guidance was submitted.  This led to further emails and some questions on my part as to the legality and safety regarding guided rockets.  Given the high-powered nature of the top end of the hobby, I expect safety to be paramount.

My fears aside, I continued to look around the internet for others who had attempted guided rockets.  Most solutions are fin-based, followed by gimbaled motors or reaction control thrusters.  At the bottom end you may have reaction wheels to control spin, but I have not yet found where a CMG design was used to control a rocket's attitude.

This forum section was create to give those who are curious or want to participate in the design of a hobby sized vertical stabilization system a place to share their ideas and struggles.


Below is a list of links to other projects for guided hobby rockets.  If you have a link that is not listed, please let me know!



http://www.ibiblio.org/pub/archives/rec.models.rockets/ARTICLES/guidanceFAQ.txt

Quote
2nd Gyro torquing

    Finally, there is a technique for controlling rocket attitude without fins,
    gimballed motors or any outher external affectations. In fact, it's very
    close to the presumed ideal of a gyro that "resists" external forces all by
    itself. The technique was originally used to stabilize ocean liners along
    their roll axis but is now used in some spacecraft to do attitude control
    without the use of gas jets.

    The first thing you need is a reference platform to tell you which way is
    "up". This can be a small mechanical gyro with encoders on the gimbal axes
    like we've been discussing, or even a non-gyro system like horizon sensors
    (this is the way satellites do it) or a "target" sensor like sun guidance.

    The second part is the control gyro. It must be fairly massive and positioned
    somewhere around the rocket's CG. Actuators are placed on the gimbal axes so
    that when the reference platform detects an error, say on the yaw axis, the
    actuator twists the gyro's pitch axis which forces it to precess in yaw. If
    you've got the signs hooked up right, this will counter the disturbing yaw
    and put you back on track.

    While the theory is good and has been proven out on real spacecraft (such as
    the "Magellan" Venus orbiter) it all seems quite involved for a hobby rocket.
    I'm sure someone out there will try it for just that reason :^)


http://psas.pdx.edu/
http://linuxdevices.linuxgizmos.com/ldfiles/article039/psas.html
https://www.scribd.com/document/118511360/lv2-avionics-design-pdf

http://www.ukrocketman.com/rocketry/gimbal.shtml



Forum threads where the topic was discussed:
https://forum.ausrocketry.com/viewtopic.php?t=1185
http://www.rocketryforum.com/showthread.php?132881-Blackbird-Project-Arduino-controlled-high-power-carbon-fiber-rocket


4
Remote Telemetry & Control Module / Re: Telemote Unit
« Last post by Cosmoneer on August 24, 2017, 12:32:41 PM »
I'll post pictures soon of the progress made on the unit.  The case has been designed around easily obtainable break-out boards and parts.  All that is needed is some soldering to connect everything and programming the microcontroller.

One change has occurred though, Serial Bluetooth will be used for direct linked communications between the Cosmoneer and the Telemote unit.
As always, Thingiverse models will be posted and an Instructable for building/assembly, too.
5
Mods / The Proto is Evolving!
« Last post by Cosmoneer on August 24, 2017, 12:25:49 PM »
The Cosmoneer Proto is going through an evolution.  The next version is receiving a second CMG for a total of two, making it a scissored pair.  It is also receiving a full 9DoF sensor board, versus the previous 3DoF magnetometer.  The PCB is underwent minor changes to support the 9DoF board with several minor components getting shuffled around.

While the PCB still boasts the plated holes for soldering the front prototype PCBs, this board is receiving a full 3D printed support structure.  This structure is easier to assemble and easier to print.

This upgrade is also receiving a full 1 Amp wireless inductive power coil set. This is more than ample to supply power for the main board, two 5g servos and the two gyro motors.  It is also sufficient to supply additional power for a Bluetooth radio and a 25mW 5.8gHz FPV mini camera.

These upgrades are the first step towards a full 3DoF Evolution Cosmoneer!
6
Hardware / Step 9 - OLED Display troubleshooting
« Last post by Cosmoneer on July 17, 2017, 01:53:07 AM »
If you have been directed to this step then your Cosmoneer's OLED Display is not functioning properly.


Things that will need to be checked are:

  • Connector is fully seated
  • Wires are not pinched or broken
  • I2C solderable jumper setting on back of board is connected
  • Confirm voltage at OLED
  • Confirm other I2C devices are working as expected


7
Hardware / Step 8 - SuperBurst troubleshooting
« Last post by Cosmoneer on July 17, 2017, 01:52:31 AM »
If you have been directed to this step then your Cosmoneer's SuperBurst board is not functioning properly.

Things that will need to be checked are:
  • Connector is orientated correctly
  • Voltage level to the SuperBurst board is sufficient
  • Confirm voltage switch trip point


This first check is to confirm all the connectors are orientated correctly. The SuperBurst + ESC connector is adjacent to the Gimbal servo connector that is next to the white power connector on the back corner of the Cosmoneer mainboard.





For the second check, you'll need your voltmeter/multimeter.  With your Cosmoneer temporarily attached to the hanger coil via scotch tape and the power adapter plugged in, touch the positive probe to the "+" point and the negative probe to the "-" point indicated in the image below.  You should measure between 4.8v and 5.1v.




All SuperBurst boards are equipped with a voltage detector ic (and sometimes trip point adjustment resistors.)  This voltage detector is marked as "U1" om the board and is located at 2 o'clock from the open hardware logo.  The purpose of U1 is to hold the Mosfets closed via the NPN transistors, which are pulled low and kept deactivated during the charging cycle, thus allowing voltage to flow to the Mosfet gates and closing them.  Once the 2.7v threshold is reached, the detector goes high, turning on the transistors and pulling the Mosfet gates low and opening them.

The dual power path of the board enables normal current to initially flow freely to the ESC via a single Mosfet, Schottky diode and then the final output Mosfet gate.  The Mosfet prior to the diode along this path is kept off during the supercap charging cycle so the charging energy flows solely through the 20ohm 1Amp resistor.

The supercap powerpath is allowed to pre-charge before the energy is exposed to downstream circuitry.  A pair of back-to-back Mosfets act as a bi-directio0nal switch, capable of blocking voltage and current in both directions.  The gates of these Mosfets could be broken out and controlled, if the need arose to do so, which would allow the supercap to be exposed to the ESC ONLY during motor start-up periods.



The Schottky diodes are excellent places to troubleshoot the voltage, as they will tell you if power is flowing through the first stage mosfets and will also tell you if they have dropped the voltage after the diode.

Q4, the 1st stage direct power Mosfet is also an excellent test point to determine if the main powerpath is being provided energy after charging is completed.  If ~5v is not being read between the Mosfet and the diode, then the Mosfet has gone bad and needs to be replaced.

Q5, the final stage Mosfet and its transistor driver can be tested when the board indicates it is charged (the LED is illuminated) but no power is being allowed through the Mosfet.  If the transistor is being powered and is driving the gate low, but the Mosfet is still closed then the Mosfet is bad.  If the transistor is being powered but is not pulling the Mosfet's gate low, then the transistor is bad.  This will manifest itself (when the Cosmoneer is placed in the sphere and a 2mm gap is observed between the bottom of the sphere and the hanger coil) as a slow drop in voltage to the motor, which can be heard as the whine of the motor decreases until the SuperBurst's voltage detector briefly turns off, restarting the ESC and stopping the motor completely.

(The SuperBurst spec sheet can be found here:
http://cosmospioneering.com/wp-content/uploads/2017/06/SuperBurst-SpecSheet.pdf)
8
Hardware / Step 7 - Gimbal Servo troubleshooting
« Last post by Cosmoneer on July 17, 2017, 01:51:48 AM »
If you have been directed to this step then your Cosmoneer's servo is not functioning properly.

Things that will need to be checked are:
  • Connector is orientated correctly
  • Voltage level to the gimbal servo is sufficient
  • The Servo responds to a non-pulsewidth modulated signal


This first check is to confirm all the connectors are orientated correctly. The gimbal servo connector attached to the Cosmoneer mainboard should have its yellow signal wire facing outboard of the Cosmoneer, with the gimbal servo wire being the closest to the (white) power receiver connector at the corner of the mainboard.

For the second check, you'll need your voltmeter/multimeter.  With your Cosmoneer temporarily attached to the hanger coil via scotch tape and the power adapter plugged in, touch the positive probe to the "+" point and the negative probe to the "-" point indicated in the image below.  You should measure between 4.8v and 5.1v.



For the third check, you will need three male jumper wires and a 5v power source.  You will be mimicking a PWM signels full on and full off state, which will drive the servo from one end to the other in one sudden jerk.  To do this, you'll need to insert two of your jumper wires into the servo cable's female header's brown and red wire positions.  The third wire will need to be inserted into the remaining yellow wire header position.  The other end will be what you touch to your GND and +5v power source leads.  Switch between +5v and ground a few times to make sure the servo responds by rotating the gyro motor 180 degrees one way, then the other.  If your servo fails to perform any motion during this test, then your servo will need to be replaced.

9
Hardware / Step 6 - Motor/ESC troubleshooting
« Last post by Cosmoneer on July 17, 2017, 12:54:18 AM »
If you have been directed to this step then your Cosmoneer's motor and/or ESC is not functioning properly.

For this step, you'll need the USB programmer and USB cable that came with your Cosmoneer.  We're not going to do any programming, instead we're using the stable power and connection it provides to make it easier to measure power levels at various points to the ESC and to the motor itself.

Things that will need to be checked are
  • Wiring connections are all correct
  • Voltage level at the ESC (from the SuperBurst board)
  • Solder joints at the flex circuit to connector junction (where the ESC connects to the gyro motor)
  • ESC microcontroller state (locked-up or in a wait-state)

This first check is to confirm all the connectors are orientated correctly.  Both the servo and SuperBurst connectors attached to the Cosmoneer mainboard should have their signal wires facing outboard of the Cosmoneer, with the servo wire being the closes to the power receiver (white) connector at the corner of the board.



The ESC connects to the SuperBurst board on the LED side, or the leaded side of the super capacitor, depending on which side of the board you are looking at.  The ESC signal wire is furthest away from the LED, while the ground wire (brown) is closest to the LED.

The SuperBurst board connects to the mainboard via the opposing header.  The signal/power/ground pins are in the same orientation as the ESC pins, with the signal wire on the same outside PCB edge as the ESC connector.


This second check assumes the SuperBurst board is functioning correctly and is passing power to the ESC.  With the programming cable connected and the SuperBurst's green LED illuminated, take the test probes from your meter (which is set for DC measurment) and touch the red (positive) probe to the red or "middle" wire on the ESC's input connector that is plugged in to the SuperBurst board and touch the black (negative) probe to the brown/black wire on the same plug.

With the Cosmoneer starting up, you should see the voltage rising to roughly 4.0 volts.  If the motor were to start, you would see the voltage slowly drop to 3.0 volts.

The third check is to confirm the solder joints on the flex circuit have not been stressed beyond their limit and have broken.


If all of the above appears to be working, then the final check is to confirm the ESC is working, and what state it is in.  For this complete step, you will need a servo tester.

If, during power-up or ESC start-up, you disturbed the Cosmoneer, the ESC may have become confused and is stuck in an "in-between" state, waiting for PWM input for a command it unintentionally is now waiting for.  Some ESCs may recover by removing their connection to the SuperBurst board and letting them sit for about ten minutes.  Other ESCs have responded to being connected to a Servo tester and following the ESC startup instructions (http://cosmospioneering.com/wp-content/uploads/2017/03/MX-3A_ESC_blhelimanualsilabsrev11.x.pdf).  Worst case, the ESC is bad and needs to be replaced with another MX-3A ESC.


The Gyro motor is a 5v brushless outrunner motor.  Worst case, magnetic material has become attracted to the inside of the motor and the motor no longer spins freely.  However, if the motor does not beep during the ESC power up sequence, then the ESC is most likely the culprit.  If you want to test the motor separately, you will the servo tester mentioned above and a fully charged 4.3v single LIPO cell.  Connect the suspect ESC (with motor attached) to the servo tester and follow the ESC's start-up instructions.
10
Hardware / Step 5 - Power troubleshooting
« Last post by Cosmoneer on July 17, 2017, 12:27:51 AM »
If you have been directed to this step then your Cosmoneer is receiving power but appears not to boot up.

For this step, you'll need the USB programmer and USB cable that came with your Cosmoneer and you'll need At least Arduino v1.6.2.  Plug the USB cable into your computer and plug the programmer into the Cosmoneer.  The Cosmoneer code ("Evolution_18_2... & Evolution_18_3...) have the serial port monitoring code commented out.  In order to see if the Atmega microcontroller is responding, you'll need to download "Evolution_16_8_MX_3A.ino" from GitHub and attempt to upload it to the Cosmoneer (a separate post will be provided to step you thought that process.)

If your computer fails to communicate with the Cosmoneer, troubleshooting the problems with the Cosmoneer mainboard are beyond the scope of this post step and will require you to contact us to arrange for return of your Cosmoneer for repair.
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