In industry, the engineering design process is usually a formal series of steps. In competition robotics, the formality is usually discarded in favor of a faster turnaround time. There are about as many different implementations of the engineering design process as there are engineers. In this tutorial, the general process we will follow is illustrated in the opening picture. In the FIRST Robotics Competition, this circular process is accompanied by the mantra “design is iterative,” as popularized by John V-Neun of Innovation First International.
To fully adopt and successfully implement this iterative approach to design is challenging. Your team will need to have the motivation to continue working even when you face repeated failure. You will have to be willing to develop and re-develop a manipulator until you achieve excellence. Attaining it will not come naturally, only through hard work not just during the build season, but during the rest of the year as well.
Finally, the process you use to implement a manipulator heavily depends on an honest evaluation of your team’s resources. A team that has access to materials, work time, and experienced people will operate differently than a second year team that is still learning the ins and outs of building a robot and only has several hours per week to work. Failing to make adjustments appropriate to your team’s capabilities will inevitably result in failure.
The pictures in this tutorial are primarily from my team's (FRC Team 2374) design process for the 2012 FRC game, Rebound Rumble.
This tutorial was made through the Autodesk FIRST High School Intern program.
Step 1: Develop a Strategy
- The robot’s max speed is 8 ft/s – Demand
- The robot’s max speed is 12 ft/s – Desire
- The robot can shift with max speeds of 7 and 15 ft/s – Wish
The final part of developing a strategy is ensuring that it does not overshoot your team’s abilities. Your team must check that your goals are achievable with your given resources. If they are not, you must focus on fewer, higher priority objectives rather than spreading your team too thin.
Step 2: Brainstorm Solutions
Second, look at real world examples for inspiration. For example, a FRC team may have looked at a forklift if they were designing an elevator for 2011 game.
Finally, don’t reject ideas at this stage, as one crazy idea may inspire a brilliant one. In addition, if individuals see others’ ideas shot down, they may be afraid to share their own ideas.
Step 3: Choose Initial Prototypes
More information about Weighted Objective Tables (WOT):
A WOT is a tool used by designers to quickly and objectively evaluate possible solutions to a problem. You can learn more about how to use a WOT in this paper.
Step 4: Begin Prototyping
At this stage, your prototypes do not even have to be close to perfect. Instead, they should demonstrate that a concept will have potential if it were further developed. Because the prototypes should be very crude, they should be able to be completed in one or two meetings. It is also important that testing is done to see how the prototypes actually behave, particularly in relation to the field elements. It is not necessary to have field elements built to do this. Instead, your team can use a crude mockup of the important elements using common items such as garbage cans.
Continue trying different ideas until your team has found one that will work. However, remember that you have very limited time during the build season. This stage of the process should not take longer than one week for the majority of teams.
Step 5: Refine a Single Design
After selecting one design, your team can begin to refine your prototype. This is where the “design is iterative” mantra comes in. Only by iteratively improving a design will a team be able to meet their performance specifications. It is important to determine your team’s goal, or what it wants to learn, for each version of the prototype. This goal will guide the changes you make and help to indicate when to move on to the next iteration. If possible, measure the performance of your prototype at each stage. This will help your team determine how each iteration has improved (or diminished) the prototype’s performance. In addition, the measurements will help you determine if your improvements have helped you achieve your goal for the iteration.
Also during this stage, your design team should begin to figure out how each of the incomplete parts will interface together. Otherwise, you will have several different systems that do not function when assembled together.
Finally, you need to decide when you have refined the prototype enough begin final design. While the refined prototype does not need to work as well as the final version, your team does need to know how they can improve it. Knowing when you have reached this level of refinement is challenging. It requires knowledge, experience, and a fair amount of intuition.
Step 6: Design Final Manipulator
Step 7: Build and Test
The process of iterative improvement does not end on “Stop Build Day.” If your team builds a practice robot, they can continue to practice and find improvements until their first competition. These improvements can then be added to the competition robot on the first day of the tournament. If your team attends multiple competitions, you are often allowed to make improvements based on your robot’s performance at the first. However, be aware that it is difficult at best to drastically change your robot from one competition to the next. You will have much better luck refining your robot’s performance at this point in the design process.
Step 8: Final Thoughts
Hopefully this tutorial has given you the information you need to prototype and design manipulators more effectively. Though I tried to cover as many aspects of the design process as I could, I have inevitably missed important points. Listed below are several resources that you can use to learn more about the engineering design process and prototyping.