Petoi Bittle Manual
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6 📐 Calibration

"A miss is as good as a mile." 🎯
You should NOT attach the legs to the servos before the first-time calibration.
When powered off, the servos' output shafts can be rotated to random angles. If you attach the legs, the robot won't know where the legs are pointing. When the robot is powered, the legs could run into each other or collide with the body. The servos may be damaged after getting stuck for a long time.

Enter the calibration mode

The joints of Bittle have to be calibrated before use. Make sure all the servos are connected to the correct sockets on the circuit board in the correct orientation. Long-press and power on the battery (blue LED for Bittle indicates powered-on, whereas yellow LED for Nybble indicates powered-on). Make sure all the legs and head are NOT attached to the servos so that the servos can rotate freely.
There are three methods to calibrate Bittle:
Our calibration routine will send a calibration signal to the main board and rotate all the joints to their neutral positions. (Once Bittle is in the calibration mode and all servos are at their neutral positions, you can now proceed to install the head and the legs onto the body. You will be able to fine-tune the joints using our app/software.)

Install the head

In the calibrated neutral state, place the head as close to the central axis as possible and insert its servo shaft into the servo arm of the neck.
Press down on the head so it is firmly attached to the neck.

Install the legs

Insert the upper legs and the lower legs into the output teeth of the servos while Bittle is powered on and in the neutral position. When inserting, try to keep the torso, upper leg, and lower leg at right angles with each other as much as possible. Pay attention not to install the lower leg backward (the correct orientation is shown in the picture below).

Calibrate the head and the legs

To calibrate the head, adjust the neck servo angle in the app until the head is straightly forward. If the servo angle reaches the limit but the head is still not straight, you should return the servo to the neutral position, and reattach the head closer to the forward position.
To calibrate the legs, place the L-shaped ruler included in the kit next to a leg, as shown in the picture below. (Note: the picture below shows the screws in the joints. You may put on the screws, but you should NOT tighten them before the calibration is finished.) Adjust the servo angles of the corresponding servo in the app until the reference features on the leg (i.e., the screw holes on the joints, the "muscle line" on the upper leg, and the triangular hollow space on the lower leg) are all aligned with the openings on the L-shaped ruler. Repeat this process for all four legs.
Once calibration is finished, use the provided flat-head screws to secure all the shoulder and elbow joints.
For more details, you can also read the calibration guides below:
For more details, please refer to the Joint Calibration in the Doc Center.