The structure of the robot will be based on the form of a plastic can that has a spherical lid. The camera will be positioned on the lid and it will have the capability to spin 360°.
There are going to be two levels inside the structure. On those levels the battery and the robot control circuitry will be stored.
The traction system will be conformed by two DC motors of 12V. They will give traction to the robot with a crazy wheel to give stability and facility of movement to it.
The aproximated weight of the robot is 5.5 Kg and for this reason a reductive transmission will be located to reduce the motors revolutions and increase the torque that will be transmitted to the traction wheels of the robot.
At the beginning we propose to use a transmission made from polyethylene and composed by bands and pulleys to make the revolutions reduction, but we found that in some cases at the moment of taking the transmission to forced jobs and find break points or skid of the material, the robot stoped moving or the plastic bands blow out. This is why we decided to implement a transmission composed by gears to avoid shuffles between components inside it.
The first transmission tests were done with transmissions that contained three gears with the purpose of having one gear that was the product of the movement, which goes directly to the rotor´s DC motor. The second gear is conected to the rotation axis of the wheels. The third gear is located between the other two and it has the function of transmitting energy and it´s also a fuse gear which aviods that the motor overheating burns the motor or the circuitry.
Due to the complexity of this system we decided to make a simple two-gear transmission with a ratio of 3 to 1. The final system will be a gear on the rotation axis of the wheel and another on the DC motor´s rotor. This means that the gear that goes into the axle of the wheels is approximately 3 times bigger than the one that goes on the motor´s rotor.
The transmissions´ gears were molded with resistant plastic to prevent fractures caused by friction when the robot is moving. Since the gears will be interacting directly with each other, the rotor´s gear of the DC motor is made of heat resistant plastic, with a total of 19 teeth on its circumference, the gear that is placed on the axis of the rim is made of lightweight plastic to make it easier to spin the wheels with a total of 60 teeth on its circumference. The robot´s wheels diameter is 2.5 inches and they are made of hard plastic and coated with soft plastic to cushion the bounce that is caused by the irregularities of the terrain.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment