The motion of the device is carried out by two hacked servomotors, two regular wheels and a castor wheel.
The robot has two infrared distance sensors facing the ground in order to detect a significant change in the distance between the robot and the ground.
By using two distance sensors with enough separation between them, the robot can align itself in order to have both sensors parallel to the gap.
The bridge is grabbed by an electromagnet placed on the arm, and a servomotor attached to the arm allows its motion.
When the arm is correctly placed in the bridge, the electromagnet is turned on and the bridge is lifted back to its rest position.
The arm has two pyramid-shaped annexes that go inside two holes in the bridge to make sure that the relative position between the arm and the bridge is the right one.
All parts are made as small as possible, but big enough to place all the components and to support the efforts in the structure. An aditional metal piece is on the back of the robot for weight balancing.
The control of the system is made with an Arduino UNO device and a custom-made PCB.
The robot should have a cost ceiling of 200€.