Launching Balls with the Petoi Bittle X + ARM gripper
Bittle's ARM gripper makes way for interesting projects
A short post and project post for the Thanksgiving weekend. We had written about the new Robotic ARM gripper for the Petoi BittleX some time back. The ARM is a 2 degrees-of-freedom (DoF) accessory which fits at the same slot as Bittle’s head, thereby making BittleX a 11 DoF robot. The gripper opens possibilities for a lot of interesting projects… and this weekend we have been having a family contest on who can use the BittleX + ARM to have the best trajectory of launching toy balls.
Here is a short video of how this looks like. The ask is to program the ARM movements so that it can launch the ball in the coolest trajectory.. the challenge being that the ball should reach the maximum possible height. You are allowed to place the ball on the ARM gripper in the best convenient way. Let’s look at the video.
Code
The open source code for the launch movement is documented here. The code is as follows:
const int8_t launch[] PROGMEM = {
-5, 0, 0, 2,
0, 0, 0,
0, 23, 0, 0, 0, 0, 0, 0, 16, 16, 15, 15, -8, -8, 15, 15, 8, 0, 0, 0,
0, 90, 0, 0, -3, -3, 10, 10, 21, 21, 60, 60, 35, 35, -34, -34, 64, 4, 1,-50,
0, 0, 25, 0, -3, -3, 10, 10, -3, -3, 32, 32, 12, 12, 15, 15, 75, 1, 0, 0,
0, 10, 0, 0, 0, 0, 0, 0, -5, -5, 25, 25, 15, 15, -9, -9, 8, 0, 0, 0,
0, -1, 0, 0, 0, 0, 0, 0, 6, 6, 17, 17, 15, 15, 13, 13, 8, 0, 0, 0,
};We made some small variations in the above code to have the two BittleX robots deployed with different firmware. You will see some subtle differences in the way the two robots launch the ball. The two balls are also a bit different… the red ball held by the BittleX on your left is a ping-pong ball, while the white ball held by the BittleX on your right is a rubber ball. The release motion coupled with different weights of the ball make the launch trajectory very different. Do you have an opinion on which motion looks cleaner? Please post in the comments.
We will keep posting our findings and the best code. Meanwhile, our Thanksgiving Sale is on for another 3 days, and you might want to use the following link to get an annual membership and also sponsor our work. You can also find a lot of our content and Bittle videos on our YouTube channel.. please join us there as well.