Brainstorming: Platform Design

The stability and functionality of a Rov depends on the platform upon which it is built. A common idea is to build a frame out of PVC tubing which all components can be mounted too. Since water flows through the rov there is little resistance but very high speeds are impossible to obtain due to the friction causing body shape. A hydrodynamic body may be formed using sheeting or fiberglass. This will increase the overall speed of the Rov and make it more stable in the water, although it can also lessen the amount of room left to mount equipment. On Appendix II, which is shown below, I have sketched multiple designs which will be considered.

Design number one uses a long and skinny body to help increase the speed of the Rov. This design uses three motors to propel it through the water. The two forward motors swivel up and down to change the rov's depth in the water. The rear motor turns left and right to steer the Rov. This rov is very good at moving quickly since it may turn at full power. When operating at slow speeds the Rov may become difficult to handle and keep in one place. An arm can easily be mounted to the front of the platform although care must be taken to evenly balance the Rov.

In figure two a round design is considered. This rov will resemble a saucer and is capable of making precise movements at slow speeds. This Rov also employs three motors to work. Two are mounted on the left and right side which propel the Rov forward and turn it. A third is mounted vertically and is used to change the Rov’s depth. This design uses a closed body and is capable of moving quickly. Care must be taken when changing depth as the rotary movement of the vertical motor may cause the Rov to spin. If this becomes apparent it can be fixed by adjusting the trim on one of the motors to produce slight propulsion which will cancel out the movement from the vertical motor.

Figure three is designed as an all purpose Rov frame and makes use of less motors. Only two are used and they are mounted horizontally on the roof of the Rov. This makes sure that they will not be blocked by any of the other components. One problem that could arise is if the motors float above the water and are unable to propel the Rov. This is why a variable ballast tank is used instead of a third motor. The box in the middle will contain a variable ballast tank. When empty the Rov will have negative buoyancy and sink below the surface. When inflated the Rov will have positive buoyancy and float to the surface. If inflated fully the Rov will rise out of the water which can be helpful in retrieving items from the bottom of the test tank. Like all the designs an arm may be mounted although care must be taken to not throw off the balance of the Rov.

The fourth and final design is a larger Rov. It is meant to be very thin and should not weigh too much. Two motors are used on the left and right wings of the Rov. These can be operated independently to steer the rov left and right. A large paddle is built near the tail which can be adjusted to change the dive plane of the Rov. To change depth the Rov will also employ a variable ballast tank which will give it stability when operating in a stationary spot. This Rov will have less propulsive force due to the need to shut a motor off to turn, but will make up for it with its aerodynamic shape. The hull will be constructed of a fiberglass and a large hole will be left in the front to accommodate any type of robotic arm. This hole can also be used as a storage compartment if the tasks require one.While all these designs are possible and have been used to compete in the past the ultimate decision will come from the team and their decision on the attributes required of the Rov. It is important to keep in mind the electronic usage of motors and how this can be avoided by using pneumatic and hydraulic power. The size of the Rov must also be carefully decided as the larger and heavier it is the slower it will move due to the restricted amount of energy.