Driving in Circles

I am designing a live “planetarium” using 9 Sphero Bolts. I want the Bolts to go in perfect circles so that they can all orbit my “sun”. This is my code thus far (obviously for just one of the Bolts, the parameters will change for each one due to the varying orbit radii):

The sensor data shows the Bolt traveling more elliptical that perfectly round (I couldn’t upload that image because I am a new user limited to one embed per post at this time). Does anyone have any idea how I can get the Bolt to travel in a perfect circle? All input appreciated folks. Thank you!

SPHERO Email Marketing -