Joint calibration is vital for the robot to work properly.
The pre-assembled robot should have the legs installed, but you can further improve its performance by fine-tuning the joints' calibration.
- 1.You don't know where the servos are pointing before they are powered and calibrated. So if you attach the legs, the legs will rotate to random angles and may collide with the robot's body or other legs and get stuck. If a servo is stuck for a long time, it may break.
- 2.The robot has a posture called "calib" with all joints set at zero degrees. You can put the robot to the calib posture so that you know all the joints should be rotated to their zero points (though you cannot see because the legs are not attached to the servos yet). Then you can attach the legs to the servos one joint by one joint, perpendicular to their nearby references on the body frame.
- 3.Because the servo's gear teeth are discrete, it's impossible to align the legs to the right angles perfectly. So you will need to fine-tune the offsets within the software.
The principles are the same for Nybble and Bittle.
Entering calibration mode requires the following preparations:
1. All servo circuits are connected to the motherboard
2. The battery is plugged into the controller board and is turned on (long-press the button on the battery to turn on/off the power)
If you build the robot from an unassembled kit, do not install the head and leg components before entering the calibration state.
The robot's legs may point to unknown angles when booting up. When entering the calibration state, the joints will be moved to their zero positions. You can see the output gears of the servos rotate and then stop. Then you can attach the legs and fine-tune the joint offsets in the software interface. There are 3 software interfaces to enter the calibration state and fine-tune the joints.
You can also enter the calibration state by booting up the robot with one side up. This method doesn't require any computer, remote, or smartphone app, so it's convenient when you are focused on assembling the robot from the kit.