MoonBots 2.0 Team Moonwalk: Robot CAD Design: Phase Two
Below is our robot , as designed in Lego Digital Designer. To read about how we ended up at this design
and to see pictures of the actual robot, visit this link!
The arm to pick up Helium-3 and Water Ice is designed as a trident. Similar to a human arm, it not only turns at the motor, but can swivel in the middle as well. When the motor goes up, the arm continues swinging and throws the loops straight into the basket. When the motor goes down, the arm moves until the hinged trident moves down as well. Two bendy axles are also attached to the trident and ends of the axles to prevent the arm from getting stuck.
The basket is designed to be as lightweight as possible, with a boundary of axles around a base. The back is slightly curved at the top to prevent loops from bouncing out of the basket.
The front of our robot, including the camera cage.
Side view of our robot, including gyroscopic sensor (LDD does not have gyroscopic sensors available for modeling, so we used a light sensor in the design instead).
Back view of our robot
MoonBots 2.0 Team Moonwalk: Robot Proposal: Phase One
We began designing the robot by identifying the challenges and obstacles it would face, both in this MOONBOTS challenge as well as on the actual lunar surface. Our design is worth sponsoring, as our focus is on solving these problems in both an efficient and cost-effective manner. By cutting out redundant pieces and designing the robot as a single unit instead of disparate modules attached together, we have designed our robot to be a compact, cheap, and classy craft. Easy to build, easy to troubleshoot, and easy to fund with its basic components, our robot is designed with the needs of modern space agencies in mind.
As the first issue that any lunar rover would encounter is locomotion, we wanted to design a mechanically simple drive train that would accomplish several major tasks: climb small terrain, turn smoothly without becoming stuck, provide maximum contact with the ground when climbing at an angle, and keep the main body of the robot safe. We believe that the optimal rover drive train should accomplish all of this with one mechanism, for which we chose a tread-based system of propulsion that lofts the robot off the ground. Two powered wheels will also be located at the front and back of the robot slightly above ground level, providing support in climbing. By choosing a drive train that can circumvent multiple issues encountered on the lunar surface, we avoid extraneous costs, integrate multiple necessities of design in an elegant fashion, and show our ability to engineer complex solutions within the simple body of the robot itself.
Once the robot can move effectively on the lunar surface, it needs to navigate in a manner that minimizes error, and the best way to do this is for the rover to observe its own movements. The most crucial motion to correct is a turn, as even a small error in angular position can cause a great error in the displacement of a rover after it travels the large distances necessary. While a compass sensor would allow us to achieve absolute position, it runs on the magnetic field of the planet, which varies greatly even across that planet’s own surface. Even more dangerously, since electric current generates magnetic fields, the compass sensor would have to be recalibrated whenever an electronic robot component stopped working. Without prior knowledge of the field variation both at home and on the Moon, and especially considering the impossibility of human intervention in those situations, we decided to investigate other sensors. As of now, we believe that we have found a solution in the gyroscopic sensor. Since it functions mechanically, the only way for it to fail is to be destroyed by a physical impact that would probably take the robot with it, meaning that it is very reliable. In addition, it could also check if the robot was swerving off-course while driving straight and correct the anomaly as soon as it is detected, minimizing error. Placing the sensor deep inside our robot it reduces the chance of physical damage as well as error due to swaying motion.
Finally, to actually collect the valuable resources, we decided on a simple and reliable mechanism. Our arm would essentially sweep the resources onto a receptor which would elevate them above ground level. By choosing a sweeping motion over a grabbing motion, we eliminate the need to manually input the specifics of the resource model. In real life, this would be comparable to commanding the robot to harvest resources in highly specific ways once it locates them, which creates unnecessary human concern and adds additional time and risk to the mission. With this wide-reaching solution, we hope to circumvent the accuracy issue entirely.In short, our team believes in achieving maximum results with minimal expenditure. Our robot design embodies this definition of efficiency, which has been our personal credo for the five successful years we have participated in FIRST Robotics. We also drew upon experience from last year’s lunar expedition with the first MoonBots challenge, in which we placed third. With a robot that achieves success without extraneous parts and only basic sensors, we believe we have circumvented one of the most common arguments against funding more space exploration: that it’s too expensive and difficult to ensure success. Our streamlined, yet effective design could be an excellent prototype for future cost-effective, easy-to-troubleshoot space vehicles. Thank you for considering our prototype for the 2011 MoonBots Challenge.
To view our proposal from last year's competition, follow this link.