An Introduction Into the Benefits Of

An Introduction into the Benefits of Fully Mechanical Governors Over Their Electromechanical SystemsCounterparts

Brian J. Katerberg, Senior Mechanical Engineering Student, Calvin College Andrew J. Vander Moren, Senior Mechanical Engineering Student, Calvin College Engr 315, Control Systems, Prof. Ribeiro

Abstract— Due to the lack of electricity electrical hookups II. TECHNICAL DETAILS and electrical know-howexperience found in many third world settings, a system designed for operation in the third world will With most systems used in the states in which a given be best suited for the culture if it does not include electrical shaft is required to spin at a certain speed, electronics are components. This year a group of four seniors including used to not only monitor the speed but also make myself the two authors of this paper are designing a kit style adjustments to it. This can be done in several ways one of mill to be designed and built in the United States then which is through the use of a tachometer which measures converted into a mobile kit that will be able to easily be the speed of a spinning shaft. Often this is done with an delivered to such places as Kenya where they will be unpacked optical reader thus not adding any extra resistance to the and assembled. The mill referred to earlier is a mill designed system. A processor hooked up to the tachometer to remove the seed and chaff from the amaranth plant and determines whether the shaft is moving too slow, too fast, or then separate the seed from the chaff in order to provide high quality grain. One of the primary areas of concern lies in the just right, in relation to some reference speed. In response separation of the grain from the chaff as there is not much size to this reading, the governor processor then sends a signal to difference and not an extreme weight difference thus setting bring about the necessary changes to pull the system to the tight tolerances on the fan speed. desired speed. A system like this one requires only asome fairly simple circuitry, with a motor, tachometer, Index Terms— amaranth, fan speed, fanning mill, potentiometer, a series of transformers, and some sort of mechanical governor, speed-control, speed regulation voltage source (see Figure 1). While this system is not very complex by our standards, we must remember that what we I. INTRODUCTION design is rarely done for people with the same level of n the United States we are so used to having electricity experience that we havethis is not being built for us, and in that we sometimes forget don’t realize what it would be this case, but rather the system is being designed for those a Ilike to live without it. It seems that the lack of people group that are is unfamiliar with electricity in general experience toward a life without electricity causes engineers and are almost guaranteed to not have any ability to fix a in the United States to design things that don’t integrate system of this nature when something goes wrong with it. adequately into the culture that they are intended for. My Our senior design team is trying to keep this in mind as we work on developing a mill to help process grain in the third world country of Kenya. While in the United States it would be very easy to use an electric powered, or even gas powered, system with complex moving parts to perform every step of a particular process without anyone needing to be involved; the samethis is not true in other portions of the world. While a breakdown of complex components will cause some delays in the United States as the new part gets made and shipped to the plant, other countries fully relying on that part will have to wait much longer as someone travels to assess the problem, then gets the equipment to Figure 1 Sample Tachometer Circuit 20 make the part, and then some time later provides the farmer operator with a the replacement part. Though it is possible to go through this series of steps, it is much more of a hindrance in other countries then it is here where we can get With electrical components being nearly impossible to fix things shipped ‘same next day’ many timesquite easily. in these third world settings especially with the level of electrical know-how that the locals are likely to have, it is

© B. Katerberg, A. Vander Moren 16 December 2004 important not to includeto avoid these in our design. Instead of using these electrically based systemsdoing it might be wiser to use this,some sort of mechanical systems are used in there place, , however even this can be dangerous. In order to make a mechanical system function in the same way that the electrical system would have functioned would require very complex components most likely taking up a lot more space then the electrical components would have inhabited. This in itself will add a good deal of weight to the system making it cost more and be harder to distribute. While the mechanical components could be built smaller that to reduce shipping costs it could increase the cost of machining them as they parts would have higher tolerances and then would be more fragile. This High levels of complexity, like electrical circuits, is also something that should be avoided when designing something for these third world settings. While we are often quite used to the idea that people from third world countries are likely to not have electrical know-howaxcess, we often assume that they have no mechanical background as well, which is not true. While they don’t have a vast mechanical background they still have a higher mechanical background then some people credit them with. don’t tend to think about the fact that they often don’t have a vast mechanical background either. Based on what we have been told by some missionaries to Kenya, it is our teams understanding that the mechanical abilities of the Kenyans we are hoping to design these mills for is also quite low 3, 4. While they might be able to repair Figure 2 Threshing Amaranth simple basic wooden parts it is quite certain that they would not know how to, or have the equipment to repair any sort of complex system, wood or metal.

III. THE INCENTIVE It is important that steps be taken to not simply provide the Kenyans with up-to-date equipment, but rather to help fuel their own ability to build up their own economy. One way that this is can be done is through helping them develop their agriculture. By helping the Kenyan people grow and harvest a cash crop such as amaranth more effectively we are able to help the Kenyans develop themselves. When people go into third world countries and simply provide the people living there with what they think is needed to help them improve their quality of life, it doesn’t usually solve their problems. A combination of resources, time, and Figure 3 Winnowing By Hand patient guidance are what will help put a country back on its Because of the setback that these people have endured feet. because of being neglected for so long it is important that steps be taken to not simply provide them with up-to-date equipment, but rather to help fuel their own ability to grow. One way that this is can be done is through helping out in developing their agriculture. By helping the Kenyan people grow and harvest a cash crop such as amaranth more effectively and efficiently, we are able to help the Kenyans develop themselves. When people go into third world countries and simply provide them with stuff it doesn’t solve problems it often just temporarily reduces them. In order to develop a country, however, one can not expect that simply dumping more stuff into the country will solve the problems; instead it is often time, patients, and love that

© B. Katerberg, A. Vander Moren 16 December 2004 help put a country back on its feet. cultures are not as willing. By fully automating these mills, the farmers are less likely to feel that they have contributed as much and thus do not feel they have the same level of ownership that they used to have when they did everything by hand. So, while we feel it is nice to have things more or less run themselves, others do not feel the same way. One other reason that makes it harder for the Kenyans to accept the fully automated systems is that the farming is such a large part of their life and taking away their mills would take away a large part of their life. If these automated systems were all implemented at once, the things that the farmers used to spend their time with would be taken from them, By fully automating these mills, the farmers don’t feel like they have contributed as much and thus to not feel they have the same level of ownership that they used to have when they did everything by hand. So, while we feel it is nice to have things more or less run themselves, others don’t feel the same way. One other reason that makes it harder for the Kenyans to accept the fully automated systems is that the farming is such a large part of their life. Additionally, if these automated systems were all implemented at one moment all the things that the farmers used to spend their time with would be taken from them, leaving them with the decision of what to do with their time.

IV. THE CONCERNS As pointed out in Section IIusing an electrically based Figure 4 Harvesting Amaranth in Kenya system would add levels of complexity that can not easily be resolved by the Kenyan people; in the same way, complex mechanical systems would require a higher level of At the present time missionaries working in Kenya with maintenance then would easily be provided by people with such organizations as CRWRC (Christian Reformed World little machining background. With these two options being Relief CoalitionCommittee) and PCD (Partners for Christian blocked, we are left with needing a very simplistic system Development) have helped prove the feasibility of growing that is light weight, easy to use, low cost, and does a good large amounts of amaranth in Kenya. One Now that the job at processing the grain. As I already pointed out, using feasibility of growing the amaranth has been proven the next an electrically based system would add levels of detail that problem that is presently faced is how to handle all of the can not easily be resolved by the Kenyan people; grain being harvested. Currently the grain is harvested and additionally, complex mechanical systems also provide for a cleaned by hand in a very labor intensive and time system that would be hard for the recipients to care for as it consuming process. The current cleaning method for really needs. With these two options being blocked, we are example requires that the grain heads be beaten on the left with needing a very simplistic system that is light ground with a stick in order to knock the seed and chaff off weight, easy to use, and does a good job at processing the of the head. After this has been done, the seed/chaff mixture grain. Unfortunately this combination of things ideals does is tossed in the air on little screens allowing the chaff to be not come together easily. For example, a system that is caught by the wind and blown away. This cleaning takes a cheap and simplistic is not likely not going to do an large amount of time and even then does not provide the adequate job at processing the grain while a complex system quality that is desired. In order to make this process more that can adequately process the grain will not be light weight feasible, it would be ideal to replace the slow seed cleaning or easy to repair. In order to make a good design we have to process with a more automated one that works more make some value judgments. For example, is it more effectively. While this is the most time consuming portion important for the mill the work effectively or be simplistic; of the entire harvesting process, improving the threshing is it better to be small or to be capable of handling high process would also be very beneficial to the Kenyans that volumes? For these two issues we felt that while neither are towill receive these mills. extreme was completely ideal a mix that leaned towards being effective and capable of high volumes seemed to be a While it would be nice in the eyes of most Americans to more favorable goal. have a fully automated system, this can be lessis less then One thing that these old mills did was provide multiple desirable in to many in third world settings. Many in Kenya gear ratios to help provide greater ease in achieving are very willing to do physical work while some other consistent fan speeds, however the operator was the one

© B. Katerberg, A. Vander Moren 16 December 2004 determining how fast to spin the crank. With the operator sifting tossing the seed in the air, but due to the high cost of acting as the closed loop portion of this system there is quite the screens and the cost of shipping something so large and a bit of variation in quality that will get better with heavy, these mills do not work well for being built in the US experience. It would be very nice if consistently good and then shipped overseas as several organizations are results could be achieved by different people no matter what hoping to do. Additionally the current mills are made out of their experience level is. plastic wood causing them to have a much more limited life seemed like the ideal mix. as boards wear or even rot. Another thing plaguing these mills is that there is a lot of back and forth motion. Because of all of this vibration, the mills wear down much more quickly then if all of the motion was cyclical. In order to V. THE CURRENT MILL make milling more simplistic, another thing that was done While many villages still winnow seed by hand, some was to use wooden pulleys instead or real gears. These have received Clipper Fanning Mills like the one seen in wooden gears do make the mills cheaper but they are also Figure 5. These millscurrently being used for processing less precise and require more maintenance. amaranth seed in Kenya have two layers of precisely sized screen, the first allowing anything the size of the seed and VI. HISTORY OF GOVERNORS chaff and other smaller things through while sending the The Scottish inventor James Watt is credited with larger stuff out a waste chute. The second screen keeps the inventing the first device that adjusted the input to a system seed and chaff on top while letting the fine dust through. relative to the system’s output 2. This device is called the After this sorting is done, the seed and chaff falls into a flyball governor. This invention stems from Watt’s interest vertical shaft that has a flow of air running up and out the in the newest invention of his time, the steam engine. One top. of the major causes of steam engine failure was due to over working/over revving an the engine. Watt’s’ flyball governor addressed this problem and enabled the steam engine to adjust its speed automatically regardless ofin response to the load applied to the system.

Figure 5 Clipper Fanning Mill

This air stream lifts the chaff and sends it out the upper chute while the seeds themselves fall

Figure 7 Watt’s Flyball Governor 2

A flyball governor is comprised of a shaft that is driven by the device in that is intended to be controlled. The shaft is spinning at the speed of the shaft that is to be monitored. This shaft is positioned vertically and has two weights that hang down from the shaft via small rods. As the speed of the shaft increases, the weights connected to the shaft move outward due to centrifugal force. The faster the shaft moves; the farther out the weights move. A special linkage is connected to the top ends of the shafts holding the weights. This linkage moves relative to the position of the Figure 6 Current Fanning Mill weights. This linkage can be connected to the throttle of the engine that is spinning the shaft the governor is attached to. When the engine is at rest, the throttle of the engine is wide down and are collected at the bottom. These mills work open. As the engine begins to speed up, the weights move quite a bit better faster then the manual traditional process of outward which causes the throttle to close slightly. If a load

© B. Katerberg, A. Vander Moren 16 December 2004 is suddenly applied to the engine, the speed of the engine slows down which causes the weights to fall down closer to their rest position. The movement of the weights supplies more fuel to the engine therefore allowing the engine to speed back up to the desired speed. Once the load on the engine is removed, the engine begins operating at higher speeds than it should. The weights then move even higher. This movement of the weights decreases the amount of fuel supplied to the engine. Less fuel being provided to the engine limits the amount of power the engine can make produce and therefore slows down the speed of the engine until the equilibrium speed is achieved once again.

VII. MODERN MECHANICAL GOVERNORS Figure 9 Mechanical Governor 2 Most modern mechanical governors operate is in a fashion very similar to the flyball governor invented by James Watt The problem of droop is compounded when hunting 200 years ago (see Figure 7Figure 8). occurs. Hunting refers to overshoot/undershot of the system as it attempts to come backreturn to its equilibrium position after a load has been applied or removed. For example, if a load is applied to an engine, the mechanical governor causes the engine to speed up to offset the increased load. However, often times the governor causes the engine to run slightly faster than what is desired. This in part happens because the engine gets the system running and in turn increases the momentum of the system which helps carry it beyond the equilibrium point. The governor then compensates for this and decreases the fuel to the engine. This often slows the engine to just slower than the desired speed. This oscillation above and below the desired speed is hard on the engine and can make for undesirable results. To compensate for this “underdamped” situation, an external hydraulic linkage can be attached to the governor. This linkage is often referred to as the primary compensation. This setup anticipates the Figure 8 Flyball Governor 2 where the throttle should be set to compensate for a Of course today our governors use better materials such particular load change. A relay valve is then used to open as ball bearings and a more compact setup but the basic and close oil supply ports before the final position is principle is the same (see Figure 9). With these new reached. This, in essence, causes the system to be slightly governors the axis of rotation does not need to be the underdamped. This setup gets rid of the hunting problem vertical axis as these governors rely on springs instead of and also allows the system to achieve equilibrium much just gravity. While Watt’s’ governor does a good job more quickly. An alternative way of achieving similar following the load applied to an engine, the governor does results is by way of a flywheel. Due to the large mass and not do a good job if loads are often applied and removed rotational inertia of the flywheel, small changes in input from the engine. When this occurs, the governor speed will not have any significant effect on the output experiences something referred to as “droop.” This is speed. refersring to the delay between when the load on the engine changes to and when the engine responds appropriately to the change. Sometimes this change does not affect the VIII. USING MATLAB WITH SIMULINK TO MODEL SETTLING performance of the system while other times the speed of TIME the engine is extremely important to the output of the system and thus the droop is unacceptable. The problem of hunting can be modeled using MatLAB in conjunction with Simulink. Using this program, we can simulate the response from any type of system. Simulink uses mathematical functions and calculates the response of a system over time. The following system was constructed to model the governor setup that could be utilized on our winnowing device:.

This block diagram mathematically shows a variety of mechanical components. The Hand Powered Input is in the form of a step input. This can be interpreted physically as the operator beginning to turn the handle on the winnower fan. In this model, we are not taking into account the fluctuations in handle speed rotation after the fan has Figure 11 Response with Relative Affect Equal to 1 achieved the desirable operating speed. The Speed Increaser can be interpreted as being a gear system that gears up the This graph shows the response when the affect of the input handle speed. This causes the fan to spin at a speed sensor signal is set to one. This means that the signal from that is fast enough to push enough air to separate the seed. the sensor goes straight to the governor without being The Fan Shaft Speed Governor is a device that limits the adjusted. This correlates with installing a linkage with no amount of air allowed into the intake of the fan. This would regard towards its affect on the performance. It is apparent most likely be a type of gate that adjusted the size of the from this graph that the percent overshoot is almost 70%. intake opening to the fan. The gate would be controlled by This means that when the winnowing fan is first started, it some sort of linkage from the Shaft Speed Sensor. This will operate 70% faster than its final speed for a short period Shaft Speed Sensor would be mounted to the output shaft of of time. The speed of the fan will continue to stabilize as the Fan Shaft Speed Governor. This sensor would take time progresses. It looks as if it takes about 20 seconds for readings of the speed of the shaft after the governor has the fan to begin operating at a constant speed. altered the speed. Similar to the Fan Shaft Speed Governor, This model does a great job of showing the droop this sensor would be governed in a way that would by a type associated with a mechanical governor. It shows that the of transfer function to simulate the conversion of the speed governor is able to do a good job of governing the fan speed, reading to a mechanical action. Finally, one of the most however, the amount of time it takes for the system to important parts of the system is the Relative Affect of the perform this governing is rather large and often Sensor Signal. This can be interpreted physically as the unacceptable for most applications. There are several ways affect the sensor feedback loop has on the input to the Fan to work around this problem of slow response times. that Shaft Speed Governor. When this concept is applied to our this problem of slow response can be accounted for. One of winnowing device, it could be seen as the amount the air these ways would be to begin turning the fan and allow the intake gate moves relative to the size of the fluctuation in speed fluctuations to take place before sending any seed speed. The amount the gate moves would be affected through the wind tunnel. This would be very effective only mostly by the geometry of the linkage that operates the gate. if the hand crank was able to be turned at a constant speed Depending on how this gate is set up, the function driving throughout its entire operation. If there are any fluctuations, the Relative Affect of the Sensor Signal could be rather a new disturbance will be created which will cause there to complicated. By this, I mean that there is a possibility that be more speed fluctuations. the signal can not always be modeled linearly. This The same system can be simulated with the effect of the correlates physically to the possibility of the intake orifice sensor signal on the system having a smaller affect on the being circular in shape rather than rectangular. A circular response of the system. The following graph shows the shape means that for every increment that the gate opens, a response of the system when the feedback signal from the different amount of area is open for air to pass through. sensor is only half of what it was in the previous example. However, a rectangular shape provides that for every increment the gate opens, the same amount of intake area is available for air to pass through. The following graphs show the response predicted by Simulink. Notice the amount of oscillations that occur before stability is achieved and the amount of time passed before becoming stable.

Figure 12 Response with Relative Affect Equal to .5

This graph shows that the equilibrium value for the system is larger than that for the original system. This is because the feedback loop is a negative feedback loop and the signal due to the sensor is subtracted from the input from the hand crank. The percent overshoot of the system is also much less than the original system- only about 40%. This means that the size of the fluctuations when the system is first started are not as large as they were for the original Figure 14 System Response of Mechanical Model system. The amount of time that must pass before the system reaches equilibrium looks to be about 13 seconds. This is a seven second improvement over the original IX. TYPES OF GOVERNORS system. However, before someone can use the winnowing When choosing which type of governor to use for our machine, they must still run the fan for 13 seconds before specific application, it is important to understand the they can begin processing the seed. different types of available governors and the advantages No matter how much tweaking is done to the system, and disadvantages of each. there will always be a delay in the response time. The only There are three main types of governors. They are way to create a mechanical system that has little to no velocity, mechanical, and electrical governors. Each type of response time is to design a system that can anticipate a governor has specific types of applications where they are change in load or speed and prepare the system to make the best used. The following discussion highlights these appropriate adjustments as soon as the load or speed different types of governors and the advantages and actually changes. This requires an additional control system disadvantages of each. to detect future changes in the system dynamics. A. Velocity Much more complicated governor systems can be Velocity governors are relatively simple devices which modeled using Simulink. Every system can be tailored to operate by measuring the vacuum created by an engine. the specific application. The following figure shows a more These devices are very complicated governor system that can be modeled using easy to install and are Simulink. compact. These governors operate by measuring the revolutions per minute of the engine. Linking the measurement of the speed of the air into the Figure 15 Velocity Governor engine to the main 13 engine control device gives the engine controller designer the ability to write indesign a safety device to limit the maximum speed of the engine. B. Mechanical

© B. Katerberg, A. Vander Moren 16 December 2004 Within the mechanical governor category, there are electronic governors is that the hunting problem can be three different types of governors. First, there is the belt avoided completely if care is taken in writing the program driven governor. This type of governor works well with to control the speed. However, if any problem is an engine that was not originally outfitted with a encountered in the speed controlling process, it may be governor. The governor itself is not mounted directly to more difficult to locate and fix when an electronic speed the engine but instead and pulley is mounted to the output governor is used. A mechanical governor is very of the engine crankshaft and a belt from this pulley drives transparent. Any problems encountered during use can the belt of the governor. When choosing a type of usually be identified by watching the governor perform its governor, it is equally important to carefully choose the function. size of the pulleys that will be used to drive the governor. Much like the velocity governor, this governor is able to limit the top speed of the system. Additionally, this There are still other variations between governors. For device is also able to quickly react to load changes. This example, a governor could be used avoid or focus in on is especially useful in machines such as wood chippers certain rotational speeds kind ofmuch like a band-pass where loads are constantly changing in what are usually filter., or to focus in on other desired speeds. The band- very large magnitudes. pass style governor could be used to keep a system from Gear drive governors are another example of atype of operating atstaying near resonant frequency as shown by mechanical governor. These are usually included in the the ‘Unstable’ curve in Figure 18. The governor can initial design of an engine. otherwise be setup to always focus the system to a They are most often mounted specific speed as shown by the ‘Stable’ curve. inside the timing gear chain cover and are run off one of the timing gears. The timing gear of an engine is connected 0.8 directly to the crankshaft of an engine therefore giving a direct 0.6 Stable() measurement of the speed of Unstable() the engine. This type of a Figure 16 Mechanical 0.4 governor would be difficult to Governor 13 add after the initial design 0.2 because it is likely that the parts surrounding the timing gear chain area would not allow for enough space for the 0 governor to be installed. 0 50 100 150 As stated before, a flyball governor is also another form  type of mechanical governor. One way of using the deg Figure 18 Stability of Governors concept of the flyball governor is to mount a race to the camshaft with ball bearings enclosed inside the race. When the speed of the engine is increased, the camshaft X. APPLICATIONS FOR MECHANICAL GOVERNORS rotates faster and the ball bearings inside the race are thrown to the outside of the race. An arm inside the race Mechanical governors have various useful advantages is then engaged due to the force from the ball bearings. over electronic governors. One of these advantages is that This arm indicates to the engine controller that the engine mechanical governors can operate in wet conditions without has reached excessive speeds and must be slowed down to any difficulty. This is especially useful on ships which are avoid damage to the components. constantly exposed to sea conditions. If an electronic C. Electronic governor were used for this application, the circuits would Most governors that are installed on devices that most likely eventually short out due to the water coming in involve electronics and computing software use electronic contact with the electrical components. In water related governors. These governors often get a reading for the applications, Iit is common to find things components such speed of the device in question directly from the output; as speedometers transmitting readings by way of a flexible but unlike mechanical and cable or other similar techniques.techniques. velocity governors, the Some applications which call for a governing device data is turned into an require that the device have the ability to operate under electrical signal. This extremely high temperatures. Electronic devices can not be signal is then transferred to subjected to high temperatures without some sort of the central computer protective shield surrounding the wires and components. (controller) for the device. This extra cost due to shielding can be avoided by using The computer then makes Figure 17 Electronic mechanical governors when possible. However, Tthis is not the appropriate adjustments Governor 13 always a possibility because mechanical governors might to compensate for any not fit in the space available or may not provide accurate differences from the desired speed. An advantage of enough governing. It is important to carefully measure the

© B. Katerberg, A. Vander Moren 16 December 2004 advantages and disadvantages of each system before to most other gears of equivalent sizes. While I we had deciding which type is best for each a particular application. considered implementing an automatic shifting bike Cost is another issue that may affect the decision of what derailleur in mind that it would be nice if we could type of governor should be used for a particular application. implement one of the automatic shifting bike derailleur (see If an application requiring a governor does not already have Figure 19) into the design, so that the gearing would any electrical components, the expense to electronically automatically change to provide a consistent fan speed we govern the system would be much larger than it would be if began to feel that this would remove some of the simplicity electrical controls were already a part of the system. This is that we were hoping for and also would also add a great deal because electrical components are easily regulated using an of cost to the system. While most automatically shifting electronic interface. However, mechanical components can bikes work by providing a consistent torque to the operator not be controlled without some sort of electronic actuation. pedaling, the goal for implementing one of these shifters It is situations such as these that necessitate the need for into our design would be to provide a consistent torque to mechanical governors. Our senior design project falls into the fan no matter who is providing the power to the system. this “all mechanical” category. Implementing an electronic While this seems to be a good idea, there are several things control system would not only add complexity to our design, that need to be looked into such as whether or not the but it would also add a large additional cost. For example, Kenyans have variable speed bikes such as we are used to. an electronic sensor would need to be purchased to monitor It doesn’t make a whole lot of sense to throw in this the speed of the fan. This signal would then need to be complex of a system when they do not have the range of transferred to the processing unit (another expense) to be gearing that it would take to replace a system of this nature. analyzed. A new signal would then be sent from the Additionally these automatic gear shifters can be rather processing unit to another expensive device that controls the pricy thus making it less ideal for a project that is being speed of the device fan such as a power regulator. There is funded solely by a small church in the area (Hillcrest CRC a good possibility that this device would be small and in Hudsonville, MI). While it is not only important for us to lightweight (two goals for our project), but the sheer cost of do as much to cut the cost of our system because the all of the equipment would far outweigh any size and weight the kits are being provided by a small church, it is an extra benefit. incentive that is helping to drive our design. Implementing a mechanical governor on our winnowing device has the potential of being simpler and also much cheaper. The most difficult part would be to find a way to mechanically measure the speed of the air through the wind tunnel or the speed of the fan. Assuming this could be accomplished, a simple linkage could be set up that could meter the amount of air intake to the fan. It is this metering device that makes the question of governing a difficult one.

XI. OUR DESIGN IDEAS We have been told that there are not many people in Kenya who have an extensive mechanical background. However, the Kenyans do have considerable experience with bicycles. Bicycles are the leading form of transportation in Kenya. While we have been informed that Figure 19 Automatic Derailleur 11 there is not a lot of know-how in terms of machining parts or using electronics, we have been informed that one of the leading forms of transportation in Kenyan villages is XII. COMPONENTS THAT WOULD BENEFIT bicycles. With this in mind we know that it is likely that While the primary component that would require some sort there are some in the Kenyan villages there are at least some of mechanical governor is the fan or winnower, the thresher in the village that have the knowledge of how to perform would also be benefited by the governor. In many ways this general maintenance to bikes. Because of this it seems that could be done with more simplicity by running the thresher it would make sense to try to use bike parts in the design of directly off of the governor used to regulate the fan speed. the mill whenever possible. seemed that one nice way of The thresher would benefit from a governor because it providing good quality parts in the mill that we design seems that there would be some operating speed that would would be to use bike parts. For example, if we were to use a provide the highest quality threshing. This could also be regular gear and chain for translating the motion from the linked in with some sort of flow regulator to make certain inlet input crank to the fan, the repair cost and time needed that the volume of ‘dirty’ seed placed onto the belt would to fix the gear would be quite high in comparison to if we never be too high preventing the good separation that we were to use bicycle gears and a bike chain to carry out the need. same process. Not only are these parts readily accessible but they are also very durable and quite light in comparison

© B. Katerberg, A. Vander Moren 16 December 2004 XIII. OUR DESIGN IDEAS but instead could be run directly off of the governor used to We have been told that there are not many people in regulate the fan speed. The thresher would benefit from a Kenya who have an extensive mechanical background. governor because it seems that there would be a certain However, the Kenyans do have considerable experience operating speed that would provide the highest quality with bicycles. Bicycles are the leading form of threshing. This governor could also be linked with some transportation in Kenya. With this in mind we know that it sort of flow regulator to make certain that the volume of is likely that there are some in the Kenyan villages that have ‘dirty’ seed placed onto the belt would never be too high the knowledge of how to perform general maintenance to preventing the good separation that we need. bikes. Because of this it seems that it would make sense to try to use bike parts in the design of the mill whenever XV. MATHEMATICAL CALCULATIONS possible. For example, if we were to use a regular gear and In order to get an idea of how fast we need to have the fan chain for translating the motion from the input crank to the spinning to provide adequate lift to separate the seed and fan, the repair cost and time needed to fix the gear would be chaff, mathematical calculations were performed using quite high in comparison to if we were to use bicycle gears general values for the size, weight, and drag coefficient of and a bike chain to carry out the same process. Not only are the seed, as well as the density of the air through which the these parts readily accessible but they are also very durable seed is falling. and quite light in comparison to most other gears of equivalent sizes. While we had considered implementing an automatic shifting bike derailleur (see Figure 19) into the design, we began to feel that this would remove some of the simplicity that we were hoping for and also would add a great deal of cost to the system. While most automatically shifting bikes work by providing a consistent opposing torque to the rider of the bike, the goal for implementing one of these shifters into our design would be to provide a consistent torque to the fan no matter what the input to the system is. While this seems to be a good idea, there are several things that need to be looked into such as whether or not the Kenyans have variable speed bikes such as the ones we are used to. It doesn’t make much sense to use a complex system such as this when they do not have the range of gearing that it would take to replace a system of Equation 1 Wind Speed Calculations this nature. Additionally these automatic gear shifters can be rather expensive thus making it less ideal for a project The technique used here was to calculate the terminal that is being funded solely by a small local church (Hillcrest velocity of the seed. At this wind speed, a seed could be CRC in Hudsonville, MI). placed into the column of air and theoretically stay at that same elevation. Because the seed would be falling into the column of air it would have some momentum that would help it carry all the way through to the outlet. However, even with this momentum it would probably be wise to set this wind speed as the limit and actually try to maintain a speed slightly slower than this to be sure that the good seed will not be blown out of the winnower. In addition to calculating the desired air speed, the active response of the mechanical governor also became something of interest. In order to accurately set up a mechanical governor, one must know the point at which the governor begins to affect the output of the system. In order for the governor to respond most effectively one would generally want to have the flyballs at an angle between about 45° and Figure 20 Automatic Derailleur 11 70° (see Figure 21) 4. The reason for this is that this is where the rotational speed has the greatest impact on the stable angle θ. What follows here is a series of calculations used to calculate the response of an ideal mechanical XIV. COMPONENTS THAT WOULD BENEFIT governor. While the primary component that would require some sort of mechanical governor is the fan or winnower, the thresher would also benefit from the use of a governor. The thresher would not necessarily require a separate governor;

© B. Katerberg, A. Vander Moren 16 December 2004 [1] A.F. Armer, S.A. Eweda, and M.A. Eweda. (2004, November 11). Speed Control of Marine Diesel Engine Using Fuzzy Approach Part (II). Available: http://iccta.aast.edu/cms/166/Speed.pdf [2] Carolina RR. (2004, November 11). Speed Regulation of Micro-Hydroelectric Power Plants. Available: http://home.carolina.rr.com/microhydro/governors.html [3] Post, Tom. (2004). Conversations with Tom Post of CRWRC on his experiences in Kenya. [4] Beute, Bob. (2004). Conversations with Bob Beute of Hillcrest CRC on his experiences with amaranth in Kenya. [5] Prof. David VanBaak (10 December 2004). Assistance with Mechanical Governor calculations [6] Speed Controlling Devices. (2004, November 8). Available: http://www.tpub.com/content/engine/14076/ css/14076_101.htm [7] Ribeiro, Paulo. (2004). Control Systems professor at Calvin College. [8] Video Demonstrations of Control Systemshttp://www.engr.colostate.edu/~dga/video_de mos/controls/ [9] Yin, Hwa-Yung, “Automatic Derailleur,” U.S. Patent 6,692,389, Feb. 17, 2004. [10] Wesling, Kevin F., “Semi-Automatic Shifting System,” U.S. Patent 6,352,486, March 5, 2002. [11] http://www.popularmechanics.com/outdoors/bicycles/2 002/3/bike_with_brains/index2.phtml Equation 2 Mechanical Governor Calculations [12] Speed Controlling Devices. (2004, November 8). Available: http://www.tpub.com/content/engine/14076/ css/14076_101.htm [13] Tech Tip #40 – Governors on Industrial Engines: A Brief Overview. (2004, November 8). Available: http://www.foleyengines.com/TechTips/TechTip40.htm l [14] Speed Regulation of Micro-Hydroelectric Power Plants. (2004, November 8). Available: http://home.carolina.rr.com/microhydro/govenors.html [15] http://www.elecdesign.com/Articles/ArticleID/6168/61 68.html [16] http://www.elecdesign.com/Files/29/6168/Figure_01.gif [17] http://www.engr.colostate.edu/~dga/video_demos/index .html [18] Patent Search Engine: Figure 21 Mechanical Governor Response http://www.uspto.gov/patft/index.html While Figure 21 shows the desired rotational governing [19] Ribeiro, Paulo. (2004). Control Systems professor at speed to be around 20Hz this could be changed by using a Calvin College. governor with different masses or by gearing the system [20] Trump, Bruce C. PWM Motor Speed Control Uses AC differently. Tachometer Feedback. Available: Because of the accuracy that could be built into a http://www.elecdesign.com/Globals/Pla mechanical governor it seems reasonable to believe that a netEE/Content/4937.html winnower could be built that will accept nearly any input speed (above a particular lower limit) and then provide a constant output. With more gearing this could carry out all Brian Katerberg (November 2004) the thrashing as well without any trouble. was born in Dayton, Ohio, August 11, 1983. He will be graduating in REFERENCES May of 2005 from Calvin College with a Bachelors of Science in

© B. Katerberg, A. Vander Moren 16 December 2004 Engineering with a Mechanical concentration. From here he intends to use his engineering experience and hands on skills to do third world development with a missions organization such as CRWRC or CAMA (Compassion and Mercy Associates), or possibly do disaster relief with someone like the Red Cross. Other interests that might lead Brian to a different job include such things as prosthetics and artificial joints which Brian says that he feels he would greatly enjoy working on as well due to the large impact it can have not only on an individual’s life but also on their whole family’s life.

Andy Vander Moren (December 2004) was born on May 30, 1983 in Visalia, California. He is currently attending Calvin College in Grand Rapids, Michigan and will be graduating in 2005 with a degree in Engineering and a concentration in Mechanical Engineering. His plans after graduation are to enter the work force. He would enjoy a hand-on job that is challenging and enjoyable. Andy enjoys working on automotive related projects and also enjoys woodworking projects. Andy is interested in the possibility of becoming a licensed contractor and owning a custom homebuilding business.