During week 3 of build season, the ‘Dox made a lot of progress: we finished robot CAD and drive assembly!
By Desiree Wang
By Nathan Sevilla
By Nathan Lee
By Nathan Sevilla
The 'Dox have completed a successful second day of build season. Now that the game has began to sink in a little bit, and the large influx of people attending our kickoff has diminished, we were able to accomplish our objectives in a reasonably straightforward manner. Today, we reached three major milestones.
Before lunch, subsystem leads worked with their respective design groups on potential designs to determine pros and cons of different systems before we decided which to prototype. However, we realized soon afterwards that, as a result of dividing into different subsystems, our derived and driven requirements were not communicated effectively to other subsystems. To rectify this, we held a subsystem lead meeting to flush out several unknowns.
The first unknown we discussed regarded strategy. After researching ideas from other teams, we considered the possibility of climbing while carrying one or more additional robots. We determined that there were essentially three different methods to climb while leaving opportunities for other robots. Firstly, a climbing mechanism could only contact a small proportion of the rung, leaving space for other robots to climb. We determined that it would be unreasonable to expect an alliance of three robots to have two which could both fit on the rung, and soon discounted this option. Secondly, a robot could deploy ramps or other rigid plates, allowing other robots to drive onto itself, before lifting all or two of them above the twelve inch climb height. Due to our ambitious requirements as driven from our prior day's strategic decisions, we felt as though we would not have sufficient student experience to lead a separate system capable of lifting two other robots from a drive perspective. The third option we considered was to mount a copy of the rung onto our robot, allowing other teams on our alliance to climb on a uniform standard. Despite depending on the mechanisms of other robots to secure a ranking point, we decided to utilize this strategy due to the relative simplicity of this method compared to the other two, as well as providing the option to utilize the full rung on the field.
The second decision we faced was to select a mechanism to deliver power cubes to the scale. Prior brainstorming conducted on kickoff narrowed our linear lift to two general categories; a single-jointed arm, and a multi-stage linear elevator. In our design review meeting after lunch, we compared and contrasted the qualities of both mechanisms. A single jointed arm is considerably less complex than a multi-stage elevator, but comes with several risks which were difficult to ignore, such as the possibility of violating the maximum volume during the game, or unpredictably changing the robot's center of gravity while lifted to nearly seven feet tall, allowing other robots to potentially knock us over. A multi-stage elevator would be effective due to its increased repeatability in software, rigidity in climbing, ease of allowing other robots to climb from our own, and predictable constant center of gravity. This will allow our programming team to develop more robust and dependable code to control the major subsystems of this robot, and we ultimately decided to pursue this design.
The third and final significant design decision we faced today was among the last facing our drivetrain. At the culmination of the kickoff meeting, we were undecided as to the benefits of using pneumatics on this robot, due to weight concerns and the relatively low-defense nature we predict for this game. Initially, we were unable to see other mechanisms which might utilize them, however, for the benefits pneumatics could provide for augmenting the intake and outtake systems of the cube manipulator, in addition to serving as a static lock for the elevator, we decided ultimately to implement pneumatics into our robot.
As you can see, today was extremely productive, and we left K2 with a clear idea of what our robot will eventually look like and how it will perform in-game. Tomorrow, we will present our decisions to the team as a whole, opening our discussion to a wider audience to find flaws before they may occur. Additionally, we will continue fabricating tomorrow, including beginning the structural members of the chassis.
Kickoff: the day in which the next season's FIRST Robotics Competition game is released, allowing a team to begin the arduous and extraordinary process of game and rule analysis, strategy, design, fabrication, electronics, and programming. Today marks the first day of this six week period, for many students the last one we'll ever experience.
Today was packed- nearly sixty individuals crowded into K2 this morning at around 6:30 PST to decide our 2018 Robot name and attend kickoff. The team decided to name this year's robot Emma, the Embryologist.
The game is FIRST Power Up, an arcade-themed challenge in which robots attempt to gain control of their alliance's Switch, a central Scale, and their opposing alliance's Switch in order to incrementally score points during a match. Robots can gain control of their alliance's switch by placing Power Cubes, thirteen inch square milk crates, onto each side. Power cubes can also be given to an alliance's Human Player on their respective alliance station wall by entering the cube into the Exchange Zone, where it is entered into that alliance's Vault to score points and earn Power Ups. At the end of the match, robots may climb onto the central scale to score additional points, and may also hang from/climb on other team's robots.
Today, we began with an intensive rule analysis to ensure all members know the game thoroughly. We conducted a game simulation, as well-after tracing a 1:1 scale model of the Arcade onto asphalt, humans pretended to be robots in order to learn how to play the game. This allowed our strategists to develop insight into the role the Vault, Scales, and Switches will play during the match, and how Power Ups could be utilized to most effectively score points.
We calculated the absolute maximum score an alliance could earn in one match for comparison purposes (in green) , and a projected week one score bracket (in orange): https://i.imgur.com/aFuD1yC.jpg
After the team fully understood the game, we worked to develop a general robot requirements list. In order to be highly competitive, our robot must:
- Score Power Cubes onto the Switch
- Score Power Cubes into the Exchange and Vault
- Climb to earn ranking points
- Score Power Cubes onto the Scale
- Intake Power Cubes from the floor
We determined that leaving out any of these objectives could be problematic if no robots on our alliance are able to complete these tasks. For example, if no robot on our alliance can manipulate the scale, then as long as the other alliance has at least one robot which can, the match is essentially decided based on the 125 points the scale could possibly award (considering the usage of a Force Power Up)
Using these fundamental robot requirements, we were able to begin setting derived and driven requirements for our other systems, currently divided into three rough areas.
- Linear Lifting Structure: concerned with housing the Cube Manipulator and Climb subassemblies. Must be able to:
- tentatively reach a maximum height of seven feet,
- structurally support the weight of the robot in tension
- structurally support the weight of the gamepiece in addition to it's own structure in compression.
- compact to a minimum height of 55 inches
- vary in height continuously
- Climb: concerned with lifting the robot at the end of the match to climb the scale. Must be able to:
- lift our robot one foot above the platform zone
- hook onto the rung or another robot with similar lifting style
- complete a climb in seven seconds or less
- Cube Manipulator: concerned with manipulating the Power Cube game elements. Must be able to:
- intake Power Cubes from the floor
- mount to the Linear Lifting Structure
- outtake Power Cubes to the Switch
- outtake Power Cubes to the Scale
- outtake Power Cubes to the Exchange
- handle cubes from all directions
We decided to use our standard 6WD WCD drivetrain for this game due to the relatively flat and familiar surfaces. However, CAD analysis of the drivetrain ground clearance profile suggests that the bottom of the chassis would have less than one eighth inch of clearance from the platform zone ramp at the closest point. For this reason, we decided to use six inch wheels to refrain from concerns which might arise from driving onto the platform zone at an angle. We have not yet decided an objective floor speed or if we plan to use pneumatics in this robot for a shifting gearbox.
Tomorrow, our objectives are to take the rules test, resume discussion, research existing mechanisms, begin fabricating game elements, and begin prototyping for potential designs.
Hello, and welcome to the first Robodox blog post for the 2018 season! We've had an extremely busy week of meetings and organization, and are excited to attend kickoff in less than nine hours.
Here are our objectives for the 2018 season:
- Bring home our first blue banner
- Practice driving for two weeks prior to bag & tag
- Build a second robot
- Improve documentation
Accomplishing all of these will require maximum effort on our part. Due to our large student experience base and the large number of seniors on the team this year, we have chosen to build two robots--one for competition and one for drive/programming practice--pushing our fabrication and design capabilities to the limit.
To assist with this, we have finished CAD models of off-season robot chassis models, available on the CADs page of this website. These CAD models are special, however; they parametrically update in response to user-driven variables, such as width and length. The result is that the chassis CAD is projected for completion by the end of the first weekend at the latest. Students can begin fabricating parts as soon as the drivetrain is decided, and we will hopefully hit the ground running to begin a successful season.
Good luck to all, and try to get some sleep!
2018 Chief Engineer