Robot Design Proposal - Phase 1

Pick Us!  Pick Us! - Introduction

Team 2011 - Lego Odyssey feels that our robot design should be funded by the Moonbots administration because we drew on our research of previous NASA missions as well as our own robotics experiences to aid us in our unique design.  The chassis utilizes the rocker-bogie suspension in combination with treads and wheels to maximize the maneuverability and traction of our robot, which is perfect to traverse the harsh terrain rather than avoid it.  Our navigation system with the Compass and Ultrasonic sensors allows our robot to know its XY Coordinate on the field.  This, in conjunction with our system of waypoints, allows our robot to efficiently move around the field in a timely manner.  The arrangement of our forklift arm will be based on that of the elements it will retrieve, so multiple can be lifted in one motion.  Finally, unnecessary friction will be avoided as our parallel linkage technique serves to prevent stored items from dragging on the ground.  We are confident in our design proposal, and feel that for these reasons, the Moonbots judges should fund our robot design. We will test our designs ideas and change them as necessary to improve robot performance, and we will document our progress to learn from both successes and failures.


Getting Places - Propulsion

Each mode of transportation has its own faults, so we plan to use a hybrid tread/wheel design that can cover for those failings.  The wheels will be placed in front to allow our robot to turn quicker, while the treads in the back, with their ability to conform to the shape of obstacles, will give our robot the traction it needs to traverse the field. Guards will be installed to prevent objects from clogging our treads.

 

Getting to the Body – Chassis Design

Our team performed research on previous NASA rover missions (Pathfinder, Spirit/Odyssey), and we realized that NASA favors an articulated and compact chassis.  The articulated chassis, such as the rocker-bogie design, utilizes a series of hinges to provide independent suspension to the robot and allow it to climb over obstacles without impacting its overall movement.  We plan to use a differential drive system with articulation hinges between each tread and the front and the back of the robot.

 

Can You Find Me Now? – Navigation/Sensors

We will definitely utilize a Compass Sensor, as well as enough Ultrasonic Sensors to map out the field.  We will mount the Compass Sensor vertically to prevent magnetic interference from the electronics. We plan to use multiple readings from the Ultrasonic Sensor(s) to gauge our robot’s distance from the field boundaries by creating an XY coordinate plane that will be refined with our Compass Sensor.  We will also use the concepts of waypoints, or digital landmarks, that take the form of preprogrammed XY coordinate calculated through the NXT’s VIEW mode.

 

I Want to Hold Your Hand – Peripherals

Our robot will incorporate an arm driven by a single NXT motor.  Parallel linkage will be used to keep the lifted payload perpendicular to the ground in order to prevent the objects picked up from dragging on the ground and impeding the progress of our robot.  We will first try a forklift design because not only is it compact, but will also allow us to pick up and store multiple objects at a time.  


So Many Design Choices, So Little Time! - Selecting the Best Design

Even though we created a set of general guidelines for our robot, there is the possibility that they may not be well-suited for the challenge field.  In such a situation, our team will take into account the following factors in picking alternative designs:

Time LimitWe feel that the time limit requires the greatest changes to our robot design.  After all, what good is a robot that can perform all missions but cannot do so within the time limit?  

Terrain/Obstacles: The terrain and the obstacles on the field also merit high priority for obvious reasons.  We will favor design characteristics that enable our robot to traverse the field and deal with any obstacles in the most efficient manner.

Hardware/Software Complexities: As for the hardware and the software, our team will apply the K.I.S.S. - Keep it Simple, Stupid principle.  While a complex robot or program is indeed impressive to watch, if there is a simpler solution to a given problem, we will select that design.

Sensor InaccuraciesWhile Lego Mindstorms gives a powerful set of electronics to work with, the sensors are not as accurate as industrial-grade sensors are. Therefore, our team will select a design that minimizes sensor inaccuracies.


The Software Deep Inside - Programming Techniques

One of the things that we plan to program into our robot is that of Error Handling.  To prevent motor stalls, critical actions can be programmed in time, rather than rotations.  Alternatively, LabVIEW has a programming block that is able to detect motor stalls. One possible feature for Error Handling during navigation utilizes our waypoint system; we can program our robot to find the closest known waypoint in the event that it becomes lost on the field.  


Conclusion

2011 - Lego Odyssey feels that our robot design should be funded because not only have we come up with a general guideline for our robot, we are still open in terms of trying out various ideas for our robot.  We also follow different design/programming testing techniques such as the K.I.S.S. principle, as well as utilizing a division of labor to create an effective team.

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