Robot Band Neo
The robot band Neo is a musical band of self-playing robots composed of 3-4 communication robots.

Communication robot, named "Buddy-kun(朋友)" is a robot that talks with everyone, instructs and guides singing and gymnastics, and plays musical instruments in kindergartens and nursing homes.
It can't have very advanced conversations, but it takes advantage of AI and use speech recognition and speech synthesis to join the chat circle.
It can also play musical instruments, such as bells and drums.
Multiple robots can work together to play tunes with a wider note range.
The three robots work together to ring the 24 bells from lower G to upper G.
When the four robots work together, one of them would play drums.

Buddy-kun has a mechanism for communicating with people and playing music on multiple units.
Devices such as a 3D camera, microphone array, and speakers are connected to a small PC carried on the back.
It also has nine servo motors to move its head and arms.
It can express emotions by devising the lighting pattern of the LEDs.
Realsense has the function of measuring the distance to an object in addition to the function of a normal camera, and is used to recognize objects and faces.
A re-speaker is a microphone array that can identify the direction of sound and remove ambient noise and self-generated sound.
A field of AI called machine learning is used for object recognition and programs that compose conversations.
Programs that control sensors and motors are integrated on the OS for robots called ROS.
Normally, Buddy-kun works independently, but If multiple units perform an ensemble, they must be connected to one PC and synchronized.
It uses software developed specifically to send commands to each robot connected by a cable.
When the program loads a music file in MIDI format, it is converted into motion data for each robot and sent out at the right time.
They can play chords by letting two robots hit the bell at the same time.
Acrylic is used as the material for the frame of the robot.
Parts are designed with CAD software and cut with a laser cutter.
Cube-shaped metal fittings are used for assembly.
Power is supplied from a mobile battery using a USB cable.