Qbkit edu

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qbkit hardware

qbkit edu emulates the mechanical and electrical interfaces of a nanosatellite mission: power and data interfaces, flexible mechanical interfaces and an Open Source computing platform running Linux OS.

The main components of the qbkit edu are:

  • qbkit edu electronics
    • Beaglebone Open Source computer.
    • qbkit power and data interfaces shield for Beaglebone.
  • 3d printed structure

qbkit edu electronics

Power buses

Qbkit edu electronics contain:

  • Converter 1 and converter 2 step down converters with manually configurable voltage and up to 3A current rating. Factory configuration is the following one:
    • Converter 1: 3.3V
    • Converter 2: 5V
  • Converter 3: step up converter with manually configurable voltage. Range: from Vin (12V with adaptor supplied) to 28V. Current rating is limited by the qbkit edu power supply (12V at 2A max).

Each power bus contains a current sensor.

qbkit edu electronics contains another step down converter currently not being used.

Adjustment of power buses voltage

Voltage in each of the 3 power buses can be adjusted

Data buses

qbkit edu electronics contain the following data buses:

  • CAN
  • I2C
  • SPI
  • UART
  • 2x GPIO

qbkit edu PL interface pinout

The following table shows the pin out of the payload connector on the qbkit edu electronics.

Header Pin number Pin name Comment
Payload_power_P 1 DGN Ground
Payload_power_P 2 O3.3 Converter 1 V+ 3V3
Payload_power_P 3 DGN Ground
Payload_power_P 4 O5 Converter 2 V+ 5V
Payload_power_P 5 DGN Ground
Payload_power_P 6 OH Converter 3 V+ high power
Payload_data_P 1 CAN_H CAN bus high line
Payload_data_P 2 CAN_L CAN bus low line
Payload_data_P 3 I2C_SCL I2C bus clock
Payload_data_P 4 I2C_SDA I2C bus data
Payload_data_P 5 SPI_CS0 SPI chip select
Payload_data_P 6 SPI_SCLK SPI clock
Payload_data_P 7 SPI_D0 SPI master MISO
Payload_data_P 8 SPI_D1 SPI master MOSI
Payload_data_P 9 UART1_TXD UART transmit
Payload_data_P 10 UART1_RXD UART receive
Payload_data_P 11 GPIO1_12 General purpose input/output
Payload_data_P 12 GPIO1_13 General purpose input/output
Electronics1.png


qbkit 3D printed structure

This section explains the 3d printed structure that acts as baseline for your creations. The parts has been designed to be printed in ABS or PLA and takes into account the tolerances of 3d printing non-professional machines. Test prints might be needed and CAD models adjusted depending on your printer, settings and materials. The 3d printed structure is composed of two main parts:

  • qbkit edu electronics box
  • qbkit edu structure

Most of qbkit edu structure parts join together without fasteners by using a pin to hole approach. The flexibility of the 3d printed material allows the assembly of the structure.

The CAD step files can be visualised and downloaded here.

A video showing the assembly can be seen here.

qbkit edu electronics box

qbkit electronics are fixed inside a 3D printed box consisting of two parts. This electronics box protects the qbkit edu electronics and allows them to be integrated into the qbkit edu structure.

3Dprint1.png

The lower part of the box contains holes were M2.5 nuts can be inserted. The upper part of the box contains countersunk through holes for M2.5 fasteners with a length of 20mm.


qbkit edu structure

qbkit edu structure is formed of three main elements:

  • Vertical elements: act as the main link for the elements inside the structure
  • Horizontal elements: link vertical elements. They also contain a feature that allows to insert an M2.5 nut in it to provide a mechanical interface to closure panels or exterior elements.
  • Closure panels / exterior elements: They mechanically interface with the horizontal elements with M2.5 fasteners.
3Dprint2.png


3Dprint3.png


MSD Tutorial example

This section presents a tutorial example to familiarise the customer with the features that are contained within MSD.


Scenario: Deployment from ISS

In this scenario, it is assumed that the satellite is released from the International Space Station (ISS) at a specific date and time, T: 01/01/2001 at 16:30:00Z, with the following payload configuration:

  • Average P/L Consumption: 1.3 W
  • P/L Operation: Uninterrupted
  • P/L database generation: 2000 bps

The ground segment supporting this scenario includes TRS and KIR. The scenario will be studied over 1 sidereal day.

The ground segment supporting this scenario includes TRS and KIR. The scenario will be studied over 1 sidereal day.


Input of initial parameters

Within the System tab in the Inputs section of the MSD tool, introduce the following values:

  • Average P/L Power Consumption: 1.3
  • P/L Operation: Uninterrupted (sunlight + eclipse)
  • P/L datarate generation: 2000


Example1.png


Within the Mission tab, ensure the following options are selected:

  • Orbit Configuration: ISS
  • Ground Station(s): TRS and KIR

The MSD offers the option to define the ISS orbit by only selecting ISS in the Orbit Configuration. This will lock all the orbital elements by default.

The Ground Stations selected for this scenario have been chosen so that one has visibility of the spacecraft while the other does not. This will be reflected later on in the results of the simulation.


Example2.png


In the right hand side of the Inputs section, ensure the start time is written down in the following ISO 8601 format standard for dates: 2001-01-01T16:30:00Z and the simulation time is expressed in seconds: 86164 s.


Example3.png


Press the Simulate Mission button to obtain the results of the simulation.

Analysis of output results

As it can be seen in the ground track plot, the ISS orbit has a relatively low inclination (51.6321 deg, as per parameter values defined in the input section). Due to this reason, KIR station does not perceive robust passes with a minimum elevation higher than 5 deg. This can be cross-checked in the Ground Station Passes list of the Mission Events window.


Example4.png
Example5.png


In the Eclipses list of the Mission Events window, it can be observed an initial eclipse that is shorter than the rest of the eclipses. This can be explained by the fact that the simulation starts in the middle of one of them.

Example6.png

Since this early version of the MSD is not attitude sensitive, the result patterns shown in Battery Energy and Generated Power correspond to the patterns to be seen in a constant attitude law. The variation in the sunlight part of each cycle of these graphs is due to the natural transition of the sun vector between the spacecraft faces. The times when both graphs experience a decrease are associated to the times when the satellite is in eclipse.


Example7.png


The implications of selecting P/L Operation: Uninterrupted (sunlight + eclipse) can be seen in the Consumed Power and Generated Data plots. In these plots, constant values for the PL parameters are seen due to the fact payload operations and, therefore, payload power consumption, remain constant regardless of whether they are in eclipse or sunlight.

In the plots below, it is possible to see a deconstruction of the total power consumption of the spacecraft and the total spacecraft generated data into two parts: PL, which stands to payload, and PF, which stands for platform. It is possible to see that, in any point in time, the values of PL and PF always sum the total value of the spacecraft, SC.


Example8.png


Finally, it can be observed how the data within the memory onboard the spacecraft accumulates over time and only reduces when there is a pass over a ground station. Hence, times where the Memory Status graph decreases coincide with the Ground Station passes.


Example9.png