A Flat!


A turn of bad luck on the road to the completion of my entry in the Servo City #AHA Challenge–a flat tire! First some background:

Lately, my leaf grinder robot has been undergoing field tests. Most of these tests are mundane verification of the original proof of concept–namely, that this bot can hack a leaf to smithereens. Similarly, these tests involve a lot of driving around. On tile, on concrete, on bricks, and, most importantly, on grass: this robot has put a lot of feet/yards on its odometer.

During these tests the only negative feature that I discovered was the minuscule lowering of the shredding/grinding/mulching box towards the ground. What!?! Yup, over the course of a several days the front panel opening on the box has dropped over 1/4-inch. While it doesn’t sound like much of a drop, this small amount is enough for occasionally digging the box into the ground and overloading the drive system.

It only took a brief examination of the robot’s front chassis to discover the culprit for this drop–a flat tire. Actually, this isn’t so much as a flat tire as it is a separation of the tire from the wheel.

Now I had been warned about the weakness of the #Actobotics foam-filled tires by fellow robot writer Jeff Cicolani. Jeff had reviewed the Acotobtics Nomad robot kit for SERVO Magazine (March 2015) and he described the tire separating from the wheel. His solution was to add wheel “pants” built from channel brackets which prevented the tire/wheel separation.

Rather than using Jeff’s solution, I discovered that with a little more aggressive steering control I was able to prevent the tire from separating from the wheel. In my case, the separation was caused by one motor driving while the other motor remained OFF. The skidding action from the stationary tire resulted in wheel separation.

Now all tests are complete and there is time for one more entry in this construction process.


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