This week was a very productive week the mechanical side of Ballbot. I began this week by attaching a ramp between the two railings assembled last week. Below is a picture of the assembled ramp and runway ontop of the iRobot Create 2.
Before I continued with the assembly, I wanted to verify that the ramp was capable of raising tennis balls from the ground to the top of the iRobot Create 2. I rolled some tennis balls towards the ramp and observed the following:
As one can see, the ramp deflects tennis balls straight upwards instead of the up and towards the back of the robot as desired. This suggests that the ramp is too steep, so I went back to the designs and decreased the ramp’s angle from 45 degrees to 30 degrees.
With this new design, I recut and reassembled the ramp. After some additional testing, I was confident that the new ramp could deflect tennis balls towards the back of the robot, so I continued with the assembly. I attached the motor mounts to the railings and added our motor assembly. Now I was ready to test our tennis ball launching mechanism. Below are two videos of the mechanism in action:
After testing our launching mechanism, I added the arms and caster wheels to the motor mounts to complete the robot frame assembly.
For the rest of the week, I focused on developing a method for attaching the assembled frame to the iRobot Create 2. After some initial difficulties, I decided to screw together the Create 2 top plate, our acrylic top plate, and the wooden runway railings with six screws. The screws used to fasten the frame to the Create 2 are shown in the following video:
Using this method, we joined the frame to the iRobot Create 2 to complete the front side of Ballbot pictured below:
To end the week, I ran a mechanical integration test to see if the robot was able to pickup tennis balls when being controlled manually. Although we do not have a basket yet, Ballbot was to pick up all the balls and “shoot” them out its back. Take a look:
With the front side of Ballbot finished, we’re in a pretty good position for our demo next week. For next week, I plan on adding a roof (to help guide the tennis balls) and second layer to Ballbot (to house our battery, Jetson Nano, and camera). If I have time, I’ll begin prototyping our tennis ball basket.