EVcrane Construction

The EVcrane is constructed entirely using Lego apart from one servo motor due to a shortage of motors ports on the shield.

The Crane is created with three modules in mind.

First Module (Tank Treads)

The tank treads are the first module. They consist of two treads powered by a separate motor. I used tank treads as they felt as the best way to create traction and avoid slippage especially since I knew they would have to carry quite a load with the other two modules; the tower and the arm. Tank treads also allowed the weight to be more evenly dispersed and because of the chain like nature of them I would have the back "wheel clamp" also because as it was connected with the forward "wheel" which was powered by the motor, whereas in the case of a simple wheel only the forward two wheels directly connected would be powered while the two back wheels would not. Tanks treads also provide greater ease in turning the body of the robot as it rotates on its centre point. A Ultrasonic sensor is placed here as well for obstacle and object detection.

Second Module (The Tower)

The Tower is essentially designed with the idea of being able to attach the third module, the arm to the top. With that in mind I used one EV3 motors and two power gear ratios to create the running mechanism. A lot of power was needed to make sure that the motor was able to rotate the arm. Fiction between the tower and arm would be a lot when the crane would be carrying weight so in order to fight that I used two power gear ratios. The tower also holds the gyro controller when not in use. It also house the Arduino and the EVshield

Third Module (The arm)

The arm is what is doing the actual lifting and consists of two EV3 motors and one continuous rotation servo. One is attached to a cart that is on one end of the Arm to and is able to move about a third of the arms length. Below the arm is the actual "hook" which does the lifting and is able to touch the floor from a tables height. The third motors is on the opposite end of the arm and has two functions. The first being to move the cart along the arm back and forth, the second to act as a counterweight to the cart and whatever the crane would be picking up. This motor uses a pulley mechanism with a string to which the cart is attached allowing the cart to move back and forth. There is also a ultrasonic sensor on the end of the crane facing the floor. This also for object detection as well as if the crane is about to fall off the table.