Servo - June 2008

FIGURE 10. The weapon assembly is installed in the frame and the drive motors are test fitted.

FIGURE 11. All of the components are mounted and wiring has begun.

• Tank steering

• Minimum drivetrain speed of 6 mph

• Minimum 1/4” ground clearance

• Five minute run time

• As small a size as possible in all dimensions

• Importance of subsystems

• 40% weapon

• 15% armor

high current draw the weapon would have. However, my drive required much less current so I used 12 gauge wire for it. Every connection was crimped and soldered for maximum strength and conductivity. I used Anderson power poles at each major connection point because of their high current carrying capacity and ease of use. After mounting all of the components and wiring the robot, it was finished! The completed robot — dubbed Papercut — can be seen in Figure 12.

• 20% drive train

• 25% reliability

• Comply to all of the Robot Fighting League’s and BotsIQ rules

Papercut met all of these requirements, and even with its high powered weapon system weighed in at 117 pounds — 3 lbs underweight. After testing, I found that Papercut could be improved in one area. The wheel configuration was very long and narrow; this led to the robot having a hard time turning unless it was already moving. To alleviate this problem, in future designs I need to ensure the robot’s wheel base is at a minimum as wide as it is long.

Testing and Analysis

In Conclusion

Part of building a robot is analyzing how well it meets its goals and design specifications. After comparing the completed robot against the design specifications from the first article of this series, I would say that we were successful in meeting all of our requirements. To refresh your memory, those requirements were:

• Combat robot for fighting in national competitions

• Middleweight weight class (120 pound maximum weight)

• Four-wheel drive

• Inboard wheels

In this four part series of articles, we have covered a lot of material! We have discussed every part of building a custom robot from scratch. Starting with a simple idea, we developed and quantified that idea. Next, we came up with a number of different options and analytically compared them, choosing the best one. We decided upon a frame type and components, along with the best way to lay them out. Taking all of this information, we designed the robot using CAD. Next, we discussed a number of tools and techniques that are useful when building a robot. Using this new construction knowledge, we applied it towards building a robot using the CAD as the instructions. We successfully built the robot and analyzed how well it matched the design specifications along with identifying its weaknesses. I hope you enjoyed this series of articles and that the information presented will be useful in your future robotic projects! For more information on myself or my robots, or if you have any questions, please visit www.robotic-hobbies.com. SV