The first morphological chart, shown in Table 2.1 shows the options for controlling material in the system.
In the function structure, we have identified the materials sub-functions as collect wind, drive forward and execute turn. The three options to accomplish this which our team has discussed are a wind turbine, a Peltier device, and a kite on a string. When wind blows across a wind turbine, it causes the blades to spin, which in turn cranks a generator and creates electricity from wind. A Peltier device uses a temperature difference to create electricity using the thermoelectric effect (also known as the Seebeck effect). Finally, if the fan were to blow a kite on a string connected to the device, the potential of the air pressure drives the kite away to produce electricity. While this option came up during brainstorming, it is the least effective solution for the sub-function because it is hardest to control; what if the fan blows it out of the airstream and it fails to push the kite? The Peltier device is feasible; our team could lay a damp paper towel or similar item over one side, and the fan blowing across would create a temperature difference and thus electricity. However, a wind turbine is the most common means of converting wind energy to electricity.
The next sub-function under the material section which must be completed is to drive forward. Options for completing this task include an electric motor, falling weight, pressure differential, or a compressed spring. Once the wind energy is converted to electrical energy, it is possible to use an electric motor to power the wheels and propel the vehicle. This is ultimately the most common practice and probably the most effective solution. The next solution, a falling weight, is possible. In this case, the wind energy would be converted to potential energy as the wind caused an item to rise. Then, at the beginning of the run the weight would be released, and it is gradually fell the potential energy would be converted to kinetic energy using gears. The practice of using potential energy as power has been used to power electric lamps for up to 6 hours at a time. A pressure differential can be used to drive a body towards the area of lower pressure. While this principle guides many natural phenomena such as weather patterns and blood circulation, it is not feasible to create a useful pressure differential in the testing area. A compressed spring would work in a similar fashion as the falling object; the spring would be somehow compressed by the air flow, and the spring would slowly decompress releasing its potential energy and converting it to kinetic energy.
Finally, the last sub-function in the materials section is to navigate the track. Possible solutions include a turn wheel, a pivot axle, differential braking, multiple motors, gearbox, or castors. The next function that the robot must perform from the function structure is to navigate the track. Due to the shape of the track, the only navigation which needs to occur (other than driving forward) is to turn. One of the simplest and most feasible method of doing so is to use turning wheels; wheels which have the ability to pivot to allow turning. Another solution is to use a pivoting axle, which has the same end-result as the pivoting wheel, but the entire back end of the vehicle will pivot as one unit, as opposed to the turning wheel where the wheels turn individually, and the frame stays in place. Differential braking is also a valid option to turn the vehicle. Differential braking is where one side of the vehicle brakes and the other side does not, thus causing the faster side to rotate and turn the vehicle. The counterpart to differential braking is using multiple motors. Using multiple motors allows to control each wheel individually, and if the motors on one side are spinning faster than the motors on the other side then turning will occur. A gearbox can alternatively be used to cause one motor to affect wheels on opposite sides differently to induce turning. Lastly is castors, which are essentially the wheels found on rolling chairs. These wheels have a very free range of motion, but are more difficult to control, and are a less than excellent solution for the requirements.
Table 2.2 below shows different possibilities for managing energy within the system.
In the function structure, we have identified the energy sub-functions as convert energy (from wind to a storable form), store energy, convert energy (from a storable form to a useful form), convert motion, transfer motion.
To convert energy, we have discussed using an alternator, a generator, a winding drum, a pump, and a compressor. The alternator, generator, and winding drum would be used to convert the mechanical energy of a spinning axle to AC electrical energy, DC electrical energy, and potential energy respectively. The pump and compressor would be used to convert the mechanical energy of a spinning axle to fluid and gas pressure, respectively.
To store the converted energy, we have discussed using a battery, a capacitor, a spring, a rubber band, and a pressure vessel. The battery and capacitor would both be used to store electrical energy. The spring and rubber would store energy as elastic potential energy. Gravity would be used to store energy as gravitational potential energy, such as a suspended weight or elevated fluid. A pressure vessel would be used to store energy in pressurized gas.
To convert the stored energy into motion, we have discussed using a motor, a solenoid, a released spring, a falling weight, and a small engine. The motor would be used to convert electrical energy to torque. The solenoid would be used to electrical energy to linear motion. The released spring could convert elastic potential energy into either linear motion, or into torque, depending on the type of spring used. The falling weight would be used to convert gravitational potential energy into torque. The small engine would be used to convert gas or fluid pressure into torque.
To convert the motion into force, and to make the force more useable, such as adjusting the strength or direction of the force, we discussed using a lever, a gear system, and pulleys. A lever allows us to turn rotational motion into linear motion and will also allow us to adjust the force output by changing the input and output arm lengths. A gear system allows us to adjust the force by changing the number of teeth on the input and output gears, as well as changing the direction by utilizing beveled gears. Pulleys allow us to adjust the force by going through more or fewer sets of pulleys and allows us to change the direction that the force is acting.
To transfer the force into forward motion of the vehicle, we have discussed using wheels, legs, and tank tracks. The wheels and tank tracks will both transfer rotational force into forward motion. Legs will transfer rotational or linear force into forward motion.
The final morphological chart is shown in Table 2.3 and expresses different means of controlling information within the system.
In the information section within the function structure, we defined three sub-functions as activate device, read data, (from the surroundings for use in decision making), and determine executable (what the device should do in response).
To activate the device, we decided a switch or button could be used to make an electrical connection which would allow the device to turn on. A lever could also be used to release or impinge on a mechanical system to activate something like a gear system. Voice activation, Bluetooth, a proximity sensor, or a remote start button could also be used for a touchless means of activating the main system programming or initiating an electrical protocol.
To read data from the surroundings for the device to navigate the course, we came up with five possible options. A switch or a button could be used such that when the device comes into contact with the wall, the switch or button is triggered to send a signal to a control board. Similarly, an infrared or sonar sensor could be used to sense the distance from the wall and send this information to a control board for navigation. I lever could be used as a completely passive device to steer the vehicle by following the border and directing the wheels where to turn.
To determine the executable, we found that there were four possible options. The first was the device could be programmed to take in live data from the surroundings and use that information to navigate the course. The device could also use a mechanical linkage which impinges on its surroundings to steer the device. Alternatively, the device could randomly select which direction to move and the movement would be based on chance. Further, the device could be programmed either mechanically or electronically to have a pre-defined path such that it continuously drives ovals or rectangles of a specified dimension.