Sg90 servo motor: 5 pieces sg90 tower Pro micro servo motor. Ultrasonic: hc-sr04 ultrasonic sensor power supply :5v DC quiescent current : effectual angle: <15 degree ranging distance : 2 cm - 500 cm resolution : 0.3 cm mode of connection: vcc/ trig(T)/ echo(R)/ gnd (VCC supply 5V, and GND is ground wire. TRIG is trigger control signal input, ECHO is echo signal output.) quantity: 1 PC attention: the module should be inserted in the circuit before been powered to avoid producing high level of misoperation; if produced, power it again. The module is not suggested to connect directly to electric, if connected electric, the gnd terminal should be connected the module first, otherwise, it will affect the normal work of the module. When tested objects, the range of area is not less than 0.5 square meters and the plane requests as smooth as possible, otherwise, it will affect the results of measuring.