These Planetary Gearboxes are nominally 32mm in diameter with permanent magnet reversible DC motors. We carry 12VDC and 24VDC motors and range from 8 to 265 RPM. Several right angle gearboxes. Several motors have encoders.
The InvenSense MPU-6050 sensor contains an accelerometer and a gyroscope in a single chip. It is very accurate, this sensor is used in self balancing robots, drones, smartphones, etc. The sensor uses the I2C-bus to interface with microcontroller.