CSU Electrical and Computer Engineering Department

Mechanics


For a good design of robot, the following design specifications are essential.

A few of the parameters given above conflict with each other. For an instance, if the robot has a strong chassis, it is difficult to have a light chassis at the same time. After extensive research, 1/4" HDPE material is used for platforms, which is strong and light in weight. Aluminum stand-offs are used to build three floors, because aluminum is one of the lightest and strongest metal element.

In order for each robot to work effectively, all the devices on the robot have to be performing well.  Each device on the robot has certain requirements that have to be satisfied for that device to work optimally. 

The three ultrasonic sensors on the robot have to be mounted perpendicular and about 6 to 8 cms above the ground to work properly.  One of the ultrasonic sensors had to be located on the front, center of the robot.  The second and third had to be located on the sides of the robot near the front.  The square design of our robot worked very well with these specifications.  We also decided to mount the ultrasonic sensors on the second floor at about 9 cms above the ground.

The radio receiver is located on the top floor.  The reasoning behind this is to optimize the radio transmission to the base station.

The PCB is also located on the third floor to allow easy access while debugging the robot.  In addition, the gyroscope (located on the PCB) must lie on the center of rotation of the robot chassis.

The LCD display is also located on the third floor so that it can be easily viewed. The LCD is used to display commands sent to the robot and facilitates debugging.

The battery packs are located on the bottom (first) floor.  Sixteen AA batteries power the robot.  The batteries are in two separate 8 battery holders that can easily be removed from the robot when the batteries need to be changed.  The batteries must be on the bottom floor because they are heavy and would cause the robot to be top heavy and unstable if they were too far above the ground.

The camera is mounted a few inches above the third floor of the robot.  It is positioned in the front of the robot to allow the base station to view images of objects in front of the robot.

Each robot has two wheels that are centered on either side of the chassis. Using physics principles the team decided that placing the wheels parallel to the center of rotation would facilitate the programming of directional calculations for our robot. Because of the centered location of the wheels, two casters were added onto the bottom of the chassis.  One caster is in the front of the robot and one caster in the back.  These casters allow the robot to sit at a slight angle to prevent the robot from losing traction.

The final design is a 16 cm x 16 cm square.  The design is three floors tall, though some of the robots have been modified slightly with a smaller top floor.  Each floor is separated by metal stand-offs.  Each floor has certain devices that are designated to it. From this information a prototype robot chassis was created.  This prototype chassis was created in the sense to be very flexible for changes. After all the devices were tested the final design of the chassis was built based on the prototype. Computer generated templates were created so that additional identical robots could be easily produced.