Space Docking mechanism
Rutuja Jadhav | Jason Cui
Prototyping is an important process to gauge your ideas and realize design challenges in their initial phases. It can be achieved in low-fidelity versions through sketches, paper models to high fidelity as 3D-printing.
The article summarizes my work on iterating through different fidelity prototypes to implement a space dock.
Introduction
Space Dock demonstration is inspired by the team members’ space-enthusiasm and the real-world space docking mechanism which refers to joining of two separate free-flying space vehicles.
For more on space docking: https://www.youtube.com/watch?v=srsiLZLPiv0
Space Dock is an electronic desktop demonstration of space docking between two space stations. Both space stations perform routines (constant-on LEDs) independently before docking, and changes behavior through light and sound feedback during docking, and maintain consistent behavior after completion of docking successfully at a required angle.
To read about the work on the complementing space station by Jason Cui:
- System Diagram: The illustration of our interacting components is as depicted below
- Implementation: Two processes constitute the docking — Approaching Phase(AP) & Locking Phase(LP). During AP, the user manually moves one space station towards the other. Contact of both stations marks the end of AP and start of LP; for LP, once the two satellites are docked, there is a change in the LED light patterns for both the satellites and sound to indicate successful docking.
- Process:
Prototype 1 (Paper model):
The paper model of the space dock was a low-fidelity prototype. It was made by stacking sheets of cardboard for both the components.
The paper model was useful to anticipate the challenges we will have in long run as the appropriate dimensions for friction fits, design for enclosing all components in the case, etc.
It also gave us a good idea about making the aesthetics better by integrating solar panels externally.
Before proceeding with our designs we felt it important to test our friction fits for the docking components.
Our docking design included an alternating set of 60-degree protruding part of bigger diameter attached to a cylinder of smaller diameter. The base station to get docked included a depression of complementary design with a locking mechanism to restrict further motion after an ideal fit.
To improve our fit the docking part had its surface leveled height on the outer circumference which ensured that the connection was in-tact on achieving an ideal fit.
Prototype 2:
Base station B:
It was important to understand the different components that will go together and the initial prototypes gave us a clear idea of the same.
Reflection on the prototype:
The prototype gave us a clear idea of what the station could look like and helped us understand how the design could be improved. The fit had to be improved for all stacked components shown in the picture. The solar panels did not print well and were integrated separately later on as different components.
The fits were not accurate and needed to be adjusted to ensure proper fits. To experiment with the fits, it is a good practice to trial and error with laser cut dimensions and then use them for 3D-printing to save time.
Prototype 3 (Proceeding to integrate the components and integrate light guide):
The base component had a battery, battery charger, switch and circuit playground enclosed.
Light guide: The light emitted from the playground had to be projected on a bigger diameter and hence a loft-shaped light-guide was needed. I used stacked sheets of acrylic with an increasing diameter to achieve the same. Every C-shaped transparent acrylic sheet was enclosed with a translucent sheet to improve the diffusion. The last plate was used to increase the diffusion effect with the translucent acrylic sheet.
Solar panels: The solar panels were independently designed and printed to fit with the base component. The friction fit was sturdier than the initial integration and added to the aesthetics of the satellite.
A loft-shaped enclosure was designed taking into account the dimensions of the light guide for achieving a friction fit and hold the light-guide in-place.
Reflection on the prototype:
The switch didn't fit in properly at first but was well-fitted with screws and polishing the hole with sand-paper.
It is important to take the wires and their anticipated connections in-account from very initial phases. My light-guide design had no holes for the connection to be made from the circuit playground to the connector but was resolved and modified to C-shape as soon as I realized it.
On attempting to dock, the external component still protuded out and didn’t look completely aligned. Since the friction was good enough to hold the two satellites, we decided to remove the locking component.
The base station looked very smaller in comparison to the other station and hence needed a taller enclosing structure.
Prototype 4 (Final version):
The slits top white enclosure in design were added to enable soldering the connector to the circuit-playground.
The white-enclosure helped in further diffusion of light adding more to the aesthetics.
To demonstrate docking we integrated a different and analogous light pattern for both the space stations. Sound was also added to indicate the docking has been successful.
Schematics for the circuit connections
Software
Code for the base space station:
/**
Coded for the base station for the project ‘Docking of Satellite Space Stations’- TECHIN 511A
Library reference- Adafruit_circuitplayground library: http://adafruit.github.io/Adafruit_CircuitPlayground/html/class_adafruit___circuit_playground.html
Coded By: Rutuja Jadhav*/#include <Adafruit_CircuitPlayground.h>
uint8_t pixeln = 0; //used for circuitplayground colorwheel light pattern
void setup() {
//while (!Serial);
pinMode(A6, INPUT_PULLDOWN); // central pin receiving the signal from other part for interaction
Serial.begin(9600);
CircuitPlayground.begin();
}void loop() {
//int val;
val = analogRead(A6); // reading input value from A6- connected to other device
Serial.println(val);//Pattern at rest
if (val<900)// 900 is the threshold to detect successful docking. Blinking red pattern is executed when the objects are not interacting{
CircuitPlayground.setPixelColor(1, 255,0,0);
CircuitPlayground.setPixelColor(5, 255,0,0);
CircuitPlayground.setPixelColor(3, 255,0,0);
CircuitPlayground.setPixelColor(7, 255,0,0);
CircuitPlayground.setPixelColor(9, 255,0,0);
CircuitPlayground.setBrightness(255);
delay(2000);
CircuitPlayground.clearPixels();
}
else
{
//Color wheel pattern is xecuted when docked
CircuitPlayground.setPixelColor(pixeln++, CircuitPlayground.colorWheel(50 * pixeln));
CircuitPlayground.playTone(500 + pixeln * 500, 100);// tone
CircuitPlayground.setBrightness(255);
if (pixeln == 11) {
pixeln = 0;
CircuitPlayground.clearPixels();
}}}
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