Turobot 4WD Bluetooth Arduino Robot Smart Car Kit Smart Programmable Robot ULTRASONIC OBSTACLE-AVOIDANCE: Use rudder machine and ultrasonic module. The car measure distance constantly through ultrasonic when its move forward, If the obstacles is in the set range of alarm distance the car will stop, Then adjust the direction through the rudder machine led ultrasonic module to move away. INFRARED OBSTACLE AVOIDANCE: Using two-way infrared obstacle avoidance module, identification obstacle in front left and front right, in order to achieve intelligent obstacle avoidance. INFRARED TRACKING: Using two infrared tracking module, intelligent identify the black line when car move on a white ground, so as to achieve the effect of track. INFRARED REMOTE CONTROL: Using matching remote control, After programming you can use the remote control to move forward, backward, turn left, turn right and stop. BLUETOOTH MODULE:Can be controlled by APP on the Android Phone