Gripcanical| Let's Connect
Let's Connect
Gripcanical: Let's Connect
Summary
Precision is something vital during the space docking process if we want a soft and accurate maneuver. In order to achieve such a goal, Gripcanical proposes a powerful and effective solution. If we split our final spaceship approach into three stages, we may identify a first rough modules axis alignment (for which we will use a vision system); a 2 final meters approach (using a pair of robotic arms); and a final fine axis alignment during the last step of the process (to provide the required precision, we will use a laser system plus an iteration algorithm). This is the way we consider space docking may reach a new level of security during mankind's future missions.
How We Addressed This Challenge
Our project focuses on optimizing the precision when docking two space modules, mainly during the final meters of the approach. The artificial vision system together with a group of 3 visual beacons to triangulate the relative position of the modules, gives the approaching module a first good approximation of how it should connect. Once the vision system has aligned the two modules, it's time for the robotic arms to engage the module. Then, the servos located on each articulation of the arms will start the final maneuver, regulating its velocity through the automated control system. During this final maneuver, the laser position system is working along the robotic arms, providing information about the position of the modules, and thus participating in the feedback signal that regulates the output velocity of the arms servos. This laser assures a soft and highly precise docking of the modules.
How We Developed This Project
We love space-related things, real and sci-fi ones. So, when we had a look at the challenges, we couldn't resist signing up for Let's Connect, even though we found interesting many others.
When we started our research stage, we found out many details about how actual spaceships are connected and how these modules interact with each other. Our first idea was to redesign the way the modules make and strengthen their connection, using a rail-based system. This first iteration of our work had its focus on using many pneumatic actuators to grab the modules and hold them tight, but after a few hours of thoughts and sketching, we assumed that it wasn't going to work as we expected. So, we came with a new idea, inspired after watching a video about how Canadarm2 was being used to help in some ISS experiments.
Our idea was to design a pair of robotic arms with 3 DoF that allowed the bigger modules (such as the ISS) to grab the new module and perform a highly precise maneuver minimizing the possibility of an error during the final steps of the docking process. Even though this could mean displacement of the bigger module due to the principle of action-reaction, we compared the ISS with the standards of the modules that are sent to space and came with a mass relation of about 2%-7%, meaning that this displacement could be neglected due to how little the acceleration of the servos would be. Apart from that, ISS may use the propellers to balance this force and avoid any subtle displacement.
In order to assist the arms, we came with the idea of using a vision system with 3 beacons to align the axis of the modules and make the arms movement much easier. Once the entring module has been grabbed by the robotic arms, they control the approach velocity, and when close enough, the low-frequency laser system gives the arms information about the position of the module, and if some corrections are needed before proceeding to dock.
How We Used Space Agency Data in This Project
One of the motivations behind the project came after we read a document about Risk and Reliability (https://www.nasa.gov/pdf/140639main_ESAS_08.pdf). Here we found information about the percentage of errors during space docking maneuvers and eventhough it was really low it motivated us to try to lower that error percentage down to 0 with our solution.
Project Demo
Here´s a link to a Google Drive Cloud:
https://drive.google.com/drive/folders/1BI8nxCAUi1K7-2K_WpjTtFKiClCGUkoT?usp=sharing
Here you will find our slides presentation as well as a folder with the code of our web page.
Data & Resources
Risk and Reliability data (NASA): https://www.nasa.gov/pdf/140639main_ESAS_08.pdf