Time stamping inputs and commands

Katie Knowles — Mon, 26 Jul 2021 12:23:32 -0000

Hi Eric,

I hope you are well.

I understand that you have not had an enquiry on here in a while, so I hope this reaches you.

I am hoping to create a bespoke environment within 42 for Attitude and Orbital Control System (AOCS) research over the course of my summer internship. My aims include adding specific visualisations of a 3-unit CubeSat as part of a student-led project, and defining the interfaces to define properties for:
Position sensors (e.g. sun/star trackers)
Reaction wheels
Magnetorquers
Propulsions systems
* Field of view pointing

My first question is: How are we able to command the spacecraft to complete manoeuvres at specific times? In other words, how may we time stamp inputs and commands? I initially believed that this would be achieved via the use of a command script, but I now believe it is much more complex than that.

My second question is: Is it possible to specify desired outputs into 42, (such as a certain FOV or the output torques), with a certain level of precision, have 42 run the simulation and determine what the AOCS needs to do in order to achieve this, and then 42 tells us what the essential inputs would need to be to achieve those outputs we specified?

Once again, I hope this query reaches you in good health, and please do get in touch if you wish me to elaborate further.

Kind regards,

Katie Knowles
MPhys Physics with Space Science
University of Leicester

installation on Mac

Roma Hladky — Tue, 08 Jun 2021 20:33:08 -0000

Hi,
I am trying to open and run 42 on my mac, but I am having trouble. I keep getting errors when i try to run the make file. This is the error I get when I do not change any of the code:

Loaner205849-18:~ loaner$ /Users/loaner/Downloads/42\ 2/Makefile ; exit;: command not foundoads/42 2/Makefile: line 2:
/Users/loaner/Downloads/42 2/Makefile: line 5: AUTOPLATFORM: command not found
/Users/loaner/Downloads/42 2/Makefile: line 6: syntax error near unexpected token $(MSYSTEM),MINGW32' 'Users/loaner/Downloads/42 2/Makefile: line 6:ifeq ($(MSYSTEM),MINGW32)
logout
Saving session...
...copying shared history...
...saving history...truncating history files...
...completed.

[Process completed]

I have tried commenting out the if statements and just setting 42Platform to apple but I get different errors when that happens. Can anyone help me?

Magnetic Field Measurements and External Torque Output File

Sebastian Green — Wed, 01 Jul 2020 12:20:08 -0000

Hi Eric,

I hope you are well. I realise you have not had an enquiry on here in a while, so I hope this reaches you.

I'm creating a simulation within 42 to find the torque outputs, and therefore slew rates, of a magnetorquer board onboard a 3U Cubesat platform. For now, this is just a basic simulation to advise mission concept of operations. I am learning 42 as a valuable part of a Masters major project.

My first question is: How do you output the IGRF magnetic field vector into an output (.42) file? This could then be used to find the magnetorquer torque outputs and therefore the slew rates, creating a more accurate simulation than my basic MATLAB models.

My second question is: When modelling the environmental torques acting on the spacecraft, are the outputs within the EnvTrq.42 file the torques (Nm) in 6DOF in the inertial frame (1st 6 columns) and body frame (final 6 columns)?

Once again, I hope this query reaches you in good health.

Kind regards,

Sebastian Green
MSc Space Exploration Systems
University of Leicester

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Yu Tso — Mon, 09 Dec 2019 06:15:52 -0000

The 4th one.

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Yu Tso — Mon, 09 Dec 2019 06:15:20 -0000

The 3rd one.

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Yu Tso — Mon, 09 Dec 2019 06:14:35 -0000

The 2nd one.

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Yu Tso — Mon, 09 Dec 2019 06:13:49 -0000

It seems that the video is so large that I failed to attached as a piece. I just cut it into four clips.

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Yu Tso — Mon, 09 Dec 2019 05:41:59 -0000

Hello Dr. Stoneking,
I'm Yu Tso. It's nice to meet you.

I'm working on making 42 a GUI like those of STK, GMAT, or FreeFlyer. The attached video describes what I have done so far.

I have two questions (listed as the title of this topic).

My friend any I are wondering whether we can send commands to 42 through sockets through a terminal as a control end and 42 as a receiving end.

Our goal is to use linux command "nc -l 42042" and the commands like "0.0 SC[0] qrl = [0.0 0.0 0.0 1.0]" in "Inp_Cmd.txt" when 42 is running.

However, even we modified the file "Inp_IPC.txt" file, set up a mission to be a receiver, and opened a terminal to send sockets to 42 through "nc -l 42042", 42 only crashed or showed messages like "Ack", "Imsg exceeded".
Is it possible to do what we plan to ?
If so, could you please show us examples about how to run it?

The second question is about my own project indicated by the attached video.

Before I go one step furher, I'd love to know how to do interplanetary orbit transfer like that from the Earth orbit to the Moon orbit in 42.

In the docs "Flight Regimes.pdf" you explained that 42 can do this by transfer from body-central motion(Earth) to 3-body motion then to body-central motion (Moon) again. I figure that I need three
Orbit files for each state, but I don't know how to combine them in the Inp_Sim.txt file or anything like that.
Also, I noticed that the seeming relevant code seems to be commented out in the source code.
Could you show me an example mission file for doing this kind of simulation?

Any suggestion or help is appreciated.

Regards,

Yu Tso (You can call me Roy. That's my nickname in USA) , Sent from Space Science Center, Morehead State University.

Interface with Matlab and Simulink

Eric Stoneking — Tue, 14 May 2019 15:17:58 -0000

Hi Javier,

Sorry about the belated response. I don't monitor this page, and somehow your message didn't get forwarded to my email.

To your question. I recommend that you download the latest version, and read "Docs/Using Standalone AcApp/Using Standalone AcApp.txt". To give away the ending, 42 can talk over sockets. If you can get Simulink to talk over a socket (and I suspect you can), then you can set up exactly the architecture you describe.

Regards,
-Eric

Interface with Matlab and Simulink

Javier Sanz Lobo — Fri, 15 Feb 2019 16:44:06 -0000

Hi Eric,

I'm designing an attitude control model in Simulink and I wonder if it is possible to create an interface with 42 to validate it. The idea is that Simulink recieves the dynamics from 42, then applies the control laws and finally sends the information back to 42.

Thanks in advance.

Best regards,

Javier

Recent posts to Discussion

Time stamping inputs and commands

installation on Mac

Magnetic Field Measurements and External Torque Output File

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

Two Questions: 1. Sockets 2. Interplanetary Orbit Transfer

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