TERRAMARTIAN MINING ROBOT Rafael Gonzalez, Joel Hernandez, Alex Muller-Poitevien, Michael Montan, Melissa Morris, Sabri Tosunoglu Florida International University Department of Mechanical and Materials Engineering 10555 West Flagler Street Miami, Florida 33174
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The mission defined by NASA for this project is to design and build a mining robot that would help NASA scientists and researchers develop clever solutions for future Martian mining applications. By accepting this challenge, the FIU team was put to the test on various engineering elements needed to accomplish the mission. These include mechanical, electrical and software engineering aspects. Once the design was completed, and computer simulation results were satisfactory, full manufacturing of the robot and testing stages of the project were addressed.
weight for their payloads. Creating a robot that can do everything that NASA would like, but that exceeds the weight limit of the rocket, would be useless since there would be no possible way of transporting the robot. Another objective is to create a robot with a very efficient movement system. For our design, the team decided to use a track system which, theoretically, would benefit many aspects of mobility including maneuverability/turning radius, weight distribution, and traction in rough terrain which would result in a more efficient overall system. This would be further discussed in the following report.
Keywords
3. CHASSIS STRUCTURE
NASA, Regolith, BP-1, Robotic Platform, Mining Robot, Mars.
3.1 Chassis Selection
1. INTRODUCTION
Before we started coming up with ideas on what the robot would look like, we decided to use a chassis already available to us. This would dramatically lower the cost of the robot since the chassis is one of the more expensive and crucial parts of any robot. Other teams had started working on this chassis, but scrapped it as it was too compact. We thought of this as an advantage. It would help with saving space and weight. But in order to begin building the robot, various modifications to the chassis had to be completed.
ABSTRACT
NASA is always looking for innovative ideas to implement for their various projects across the agency. NASA’s plans for the future are to create a human presence on Mars. In order to make this feasible, there will be a need to utilize the regolith from the surface of the planet. A teleoperated mining robot, where the robot will obtain the regolith and transport it to the collection site, would do this. The NASA Robotic Mining Competition was created to encourage universities from around the world to come up with innovative robotic excavation concepts that may eventually lead to clever ideas or solutions for an actual excavation device. The challenge of the competition is to create a mining robot that can excavate a ballistic regolith stimulant, called Black Point-1 (BP-1) and transport the material and drop it into a bin. The team that can collect the most BP-1 in a 10-minute period will win that part of the competition. The regolith used is a flour-like dirt substance, similar to that found on the surface of Mars. The excavation robot will be judged on a variety of topics, which include weight and dimension, as well as design, and efficiency of said design. [1] Simplicity will be key in developing an effective robot, while still trying to create innovative ways that NASA is constantly looking for.
3.2 Construction The first modification we made was to remove the third cross beam, which would allow space for the collecting system. This can be seen in Figure 1.
2. OBJECTIVE
Figure 1: Bottom View of Chassis
Our objective for the project is to create a robot that can efficiently collect the regolith, while making it light and cost effective. One of the major problems that NASA faces everyday with their designs is the cost and weight of their projects. The rockets that will ultimately send these robots to the Moon and Mars, such as the SLS, are only allowed a certain amount of
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In order to create a support for the dumping mechanism, two beams were welded on to the chassis which can be seen as the gray bars in Figure 2. These provided the necessary support to allow the bucket system to be mounted. Bearing slots were drilled into these beams allowing the bucket system to have less radial friction, providing more power towards the bucket. Next, bearing
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holes were drilled on the sides to allow the gearboxes to connect to the front chain rollers. Additional holes were drilled in order to install the suspension brackets as well as the gearbox for the mobility system.
increase the angle of the scooper which can be also be seen in Figure 4.
Figure 4: Design 2 Modification Figure 2: Side View of Chassis The last study in the final concept design was how to implement the motors. For example, how would the loading hopper elevate in order to drop the load into the unloading bucket? Two different motor types were compared, a linear actuator and a rotational actuator. In the end, the linear actuator proved more useful and easier to implement than the rotational actuator. No gearbox would need to be developed to provide the needed torque to lift the loading scooper. The design we chose can be seen in Figure 5. There are two actuators that perform the actual lifting of the scooper, which are the actuators labeled “lift.” While the other actuator labeled ”tilt” will just move the pitch of the scooper.
4. REGOLITH COLLECTING In order to determine what kind of systems we would be using for our design, we first had to research the type of terrain our robot must traverse and collect. The regolith simulant BP-1 is made from the Black Point basalt flow from the San Francisco Volcanic Field, in northern Arizona. [2] The regolith also contains gravel 30 cm underneath the regolith to simulate the icy layer buried in the Martian regolith. With this information we were then be able to choose the appropriate type of systems used for our robot.
4.1 Design Alternatives The first concept design was inspired by implementing a combination of a road cleaning vehicle with a crop harvesting vehicle. The chassis being used, however, could not be used for the design; it would require the construction of a new chassis. This design also proved inefficient, as multiple loading stages would be required. Figure 3 shows the first stage of the design. It was to sweep up the regolith stimulant, where it would be placed in a small temporary hopper. Then a screw conveyer would move the soil up an incline and dump the regolith into a larger bucket. The concept was taken from corn harvesting combines. This posed a problem because the design Figure 3: Scooper Alternative 1 was for large grain material and not for the powder-like regolith simulant. The simulant would create friction and possibly jam the mechanism, a risk the team was not willing to take. For those reasons, a new, simpler and more efficient design had to be conceived. That is when we decided to go with a more tried and true method of a simple scooper. There are two key aspects in the design of the scooper: The digging phase and the unloading phase. If you look at Figure 4, in its digging phase, the angle of penetration by the lower jaw of the scooper appears adequate. However, when it is moved to its upright phase, to transfer its load into the unloading hopper, the sharp angle of this scooper would prove useless, as the regolith will be trapped in the corner. This is why we decided to
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Figure 5: Scooper Actuator Layout
4.2 Force Analysis For the loading scooper, the forces on the joints and on the actual bucket must be calculated in order to determine the amount of regolith the robot can hold before it fails. Through simple calculations, we were able to determine that the max load the scooper can handle is 84.28 lbs. This is much higher than we would need during the competition. In order to qualify, we must only collect around 22 lbs of regolith within a 10 minute period. [3] The load diagram can be seen below.
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performed it was determined that the bucket was to carry a total of 50 lbs for its maximum volume. That meant that the bucket needed to be a bit sturdier than originally anticipated. Fortifying its structure redesigned the bucket. Figure 9: Bucket Design 2 L beams were added to each edge to support the corners, removing the possibility of the sheet metal tearing on the sides. Two-inch flat plates were bolted together with the Lbeams, strengthening each face of the bucket. This can be seen in our final design in Figure 9.
Figure 6: Scooper Force Analysis
4.3 Construction The scooper generates a large torque on the forward arms. The weight of the structure was critical in order to have larger loads. For this reason, we decided to use a thin aluminum sheet to construct the scooper. The aluminum sheet sealed the scooper and provided a guide for the regolith. The support structure was then cut and built around the CAD drawings we created on SolidWorks. The supports consist of aluminum L-beams and flat beams which were chosen for their lightweight properties and manufacturability.
5.2 Force Analysis In order to determine the max load the bucket can handle, force analysis was completed. The first analysis done was to see the volume of the bucket and determine the weight of the regolith if the bucket is indeed filled to capacity. Using the density of the BP-1 regolith we determined that the total weight of the regolith would be 180 lbs. After figuring out the max capacity, we had to determine the max load the bucket structure can handle without collapsing. According to the forces that can be seen in the Figure 10, the max payload for the unloading bucket is 98.91 lbs.
Figure 7: Loading Scooper
5. REGOLITH DUMPING With the system we designed, a dumping system must be built. The scooper in the front of the robot is used to excavate, but it is not suitable for transportation of the regolith. The rough terrain will cause a large amount of regolith to be lost during travel. This is the reason we decided to implement a storage unit. This storage unit must be able to hold a large amount of regolith and then dump it into the collection bin. Figure 8: Bucket Force Analysis
5.1 Design Alternatives The design for the unloading bucket was inspired by the dump trucks that are used to pick up the garbage. Seeing the trucks in person allowed for a brief analysis on how they operate as well as the way it might be applied in our situation. Originally we had the actual bucket supported by two beams on the left, right, and underneath (as shown in Figure 8). However, once the weight analysis was Figure 8: Bucket Design 1
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This means that the bucket would only be able to carry around half the bucket’s total capacity of regolith. Although this may seem like a failure, as previously stated, the competition only requires a total collection of around 22 lbs of regolith in a 10 minute period. This shows that the 98.91 lbs max payload, far exceeds our needs for the competition.
5.3 Construction This system required the ability to hold as much content as possible while maintaining complete rigidity as to not obstruct the processes of the other systems. Plexiglas was a good option, but aluminum sheet found locally was easier to acquire. Once all the materials were gathered, we decided that in order to construct the
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bucket, the design must be separated into three separate pieces. One for each side of the bucket and one that ran along the entire bottom of the bucket. Rectangles were drawn on the edges of the selected pieces that were used to hold the corners of the shape together. The pieces were cut to the specifications of the SolidWorks model created. The malleability of the aluminum allowed the team to use simple industrial scissors to slice through sketches drawn on the sheets. Once the pieces of sheet metal were cut to the desired shape, it was assembled and bolted together on the frame to complete our bucket that can be seen in Figure 12.
the ground is spread over a larger surface area, which translates to less digging into the sand. This feature allows the robot to carry a much heavier load. Some of the disadvantages of using this system are that there are more moving parts which lead to more repairs and lower speed. Even with these disadvantages, we decided to implement a track system for our robot. We felt that the advantages of the track system Figure 11: Tractor with far outweighed the Track System disadvantages.
6.2 Track Design Alternatives While observing the tread system found in last year’s FIU mining robot, it was noticed that the robot could not make a zero-point turn, at least not without the treads coming off their rails. This was because of the lack of a sturdy sprocket for the treads to travel around. Another detail noted was the lack of a suspension that would absorb the shocks and impacts from the ground. Both of these issues could inevitably lead to structural damage and overall failure of the robot. Since it needs to traverse a field with many obstacles, a suspension would be crucial in absorbing shock and preventing the robot from shaking itself apart. [6] This is why a suspension system that also acted as a belt tensioner was designed. The three proposed designs can be seen in Figure 15.
Figure 9: Unloading Bucket
6. MOVEMENT SYSTEM The way the robot travels across the simulated Mars terrain is one of the most important parts of the competition. The debate on whether to use a wheeled robot vs. a tracked one is constantly taking place. Each system has its advantages and disadvantages. The goal was to determine which movement system best fits our goals.
6.1 FORMS OF MOVEMENT 6.1.1 Wheels Some of the ways that wheels have an advantage over treads is their simplicity and maneuverability. Wheels have much less moving parts, which means fewer things that can go wrong. Wheels are also much Figure 10: Wheeled Tractor lighter than using a continuous track system, which is a great advantage to have in space exploration. One of the disadvantages in using wheels is the amount of traction to the ground. During excavation, when the scoop is being forced into the ground, or being lifted, one runs the risk of having their robot tilt forwards. [4]
6.1.2 Tracks One of the biggest advantages in using a tracked system is being able to travel across uneven terrain with greater ease. [5] During the competition, the robot will need to maneuver over a simulated Mars surface that contains many obstacles and ditches to drive through. This requires higher traction, which is what you get with a continuous band of treads. Another advantage is the pressure on
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Figure 12: Movement Design Alternatives
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chassis, but rather are confined to a critical point on the pivot rods and the chassis.
6.3 Force Analysis In order to determine which suspension system would be most suitable for our application, several simulations were completed in SolidWorks. As you can see in the Figure 16, the first two designs would fail under the given load. This can be noted by the red spots near the joints. It was then that we determined which suspension system would be viable for our robot, as there were no failures.
6.4.1 Suspension As shown in Figure 17, the aluminum case was a simple design utilizing an L-beam with channels cut to allow a certain degree of freedom on the suspension. Springs connected the two levers, allowing for the robot to bounce. One of the malfunctions of the system involved was the lever arm reaching and passing the vertical position. This would make the suspension lock up and cease to work. This was fixed by implementing a stronger spring, as well as adding a bolt to where the arms can no longer pass that angle.
Figure 15: Suspension System While working on the suspension system, it became obvious that sprockets would work best with the chains rather than the initial design that used skateboard wheels rolling directly on the pins that supported the chain threads. The suspension system only needs to keep the chain on track and in contact with the ground. That means that the sprockets need to be light and strong. With that in mind, the group decided to go with 3D printing. In order to 3D print the sprocket, an understanding of gears and how they work was needed. Because the 3D sprocket needed to move freely with the chain with the least amount of interference and friction, it was necessary to draw the sprocket with the same pitch as the chain. The team researched #40 chains to find the required pitch, teeth width, and roller diameter. Figure 13: 3D Printed Sprocket Since the team decided to keep the conformity, it was decided to print sprockets with 15 teeth. The sprockets were printed with 30% fill and tested by applying 15 lbs of force on the teeth. 15 lbs is three times the load that the sprockets will receive on the robot. The 3D printed sprockets, as seen in Figure 18 were attached to the bottom ends of the lever arm. The 3D printed sprockets saved the team several hundred dollars as custom steel sprockets are very expensive. We were also able to save a large amount of weight as well.
Figure 14: Stress Analysis of Suspension
6.4 Construction Once we saw the results of the simulations, we decided to build the third option, as it had no failures. Having simulated various force distributions using multiple materials, stainless steel proved to be the most successful and passed the rigorous tests. Unfortunately, during construction the heavy weight from the stainless steel bracket of the suspension forced us to remove the bracket all together. Although the system had to be modified, the suspension system works the same without it. However, the forces are no longer distributed through the bracket and into the
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6.4.2 Chain System The chain treads were designed to create a strong and durable tread that could be easily operated. It is made up of two hollow pin roller bicycle chains, connected by 4inch bolts. Once the bolts were connected, rubber panels were attached to give the movement system more surface area, increasing the grip. We sewed the rubber panels with threaded nylon to create a sturdier mechanism. As slipping is one of the main issues with using a track system, sprockets connected to the output shafts keep the track in line.
7. ELECTRICAL SYSTEM 7.1 Electrical Components 7.1.1 Battery The main power source of our robot is four LiFePo4 batteries connected in series. Each battery supplies 3.2 V and 2300 mAh. So the entire battery pack will supply 12.8 V and 9200 mAh that is an ample amount of energy to supply energy to all the processes. A 5 V voltage regulator is connected between the battery pack and the camera in order to power the robot. The Arduino is powered on its own with a 6 V battery.
7.1.2 Motor Controller The motors used include four brushless DC motors that will be used to control the movement system. Two motors are on each side of the treads, working in the same gearbox to help increase the power into the system. Two linear actuators control the unloading bucket, and three more linear actuators control the movement of the loading scooper. All of these motors run with 12 VDC. In order to control the speed and direction of these motors, a Vex Victor 888 motor controller is used. This allows us to completely control the motors.
Figure 16: Chain System
6.4.3 Gearbox Dismantling the robot built last year allowed the team to scavenge all the needed pieces for the gearbox. Two gearboxes were designed with an input of two motors and a single output shaft. The gearboxes were also designed to pick up the torque required to excavate the Martian regolith. As shown in Figure 20 (left hand side), the gear train assembly consists of two stages. Stage 1 takes the input from the two motors and distributes it on the center gear.
7.1.3 Micro-Controller The brain of any robot is the microcontroller. The microcontroller selected must be able to run all the processes including processing the information from the wireless router and sending signals to the motors. The most popular microcontrollers used in robotic applications are the Rasberry Pi and the Arduino. Although the Rasberry Pi has a faster processor, the Arduino’s ease of use was considered a more valuable trait for our team. The Rasberry Pi requires code to be written for Linux. The Figure 19: Arduino Mega 2560 Arduino can be programmed on Windows, which was the operating system more readily available. After we decided to go with an Arduino, we then had to decide which model to use. The most common models are shown below. Included are the values most important to our team. [8]
Figure 17: Top and Front View of Gear Box Diagram During this transfer, speed is reduced due gear ratios, but the torque is increased. [7] The second stage, seen on the right, then repeats the first stage and increases the torque once more. Finally, the last gear takes the power and distributes it to the output shaft. Figure 21 shows the finished mobility system. The output shaft of the gearbox is then connected to the rightmost sprocket using a chain. That is the sprocket that would drive the entire track system.
Table 1: Arduino Comparison
As one can see, all three models have many similarities. Where they differ the most is in the amount of digital IO/PWM pins and the amount of flash memory. Since our robot runs several processes through the Arduino, the amount of pins is very important. The amount of flash is much greater in in the Mega 2560, meaning that it can handle more tasks. All this data made our decision easy, so we chose the Arduino Mega 2560. Figure 18: Finished Mobility System
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7.1.3 Router The router that is used for receiving and sending the data to our robot is a Netgear WNR1000 wireless router. This router fulfills competition rules of USA IEEE 802.11n wireless connection standards. [9] The router will be placed in an area immediately outside the competition field. It will receive the wireless signal from our team’s robot and Figure 20: Netgear Router then send it to the WiFi shield attached to the Arduino.
7.1.4 Wi-Fi Camera
Figure 21: Wi-Fi Camera
Figure 23: Arduino-Relay Connection
The camera we decided to choose was a TENVIS Wireless IP camera. This camera has a built-in wireless router which makes communication with the user simpler. Through a computer program, we will be able to view the images from the camera and determine the robot’s position in the competition field. It also has the ability to turn 360 degrees horizontally as well as tilt vertically for optimal view of the robot and the course.
One side of the relay is connected to 12 V, while the other goes to the collector of the 22N2222 transistor with a diode in between the two coil wire connections. The emitter of the transistor is connected to ground and the base is connected to the desired pin of the Arduino with a 1kOhm resistor in between. This setup was done for all five relays used on the robot. Once the relay coils are connected to the Arduino, power must be run through the common and normally open ports of the relay. The Vex Victor 888 motor controllers must then be connected to the normally open ports. This causes all the motors to be off until the Arduino tells them to turn on. These Figure 24: Relays connections can be seen as the red cables in Figure 26. The motors are then connected to the motor terminal of the motor controllers. 40 A and 20 A circuit breakers are applied according to the type of motor the motor controller it’s running; 40 A for the CIM motors, and 20 A for the linear motors. In order to control the motor controllers, the PWM wire must be connected to the desired pin of the Arduino. The ground of the PWM wire must also be connected to the ground of the Arduino. This is shown as the thin white and black cables going from the motor Figure 22: Vex Victor 888 Motor controllers to the Controllers breadboard.
7.2 Programming In order to ultimately send data from the computer to the robot, a program had to be developed to send data to the wireless receiver of the Arduino. A PlayStation 3 controller was used to control the robot. This makes operating the robot much easier as it is a very common controller that many people are accustomed to. The number of buttons and joysticks on the controller make the process of simultaneously controlling several motors easier. It is connected straight to the computer via a USB cable. A C++ program was then created in Visual Studio to receive the commands from the controller and send it to the wireless router. The program uses User Datagram Protocol (UDP), which works by sending a series of bytes across a wireless connection. Once the data is sent to the wireless router, the Wi-Fi receiver on the Arduino must retrieve the data stored and apply the code to the motor. This code was created using the Arduino IDE. When certain buttons or joysticks are moved on the PS3 controller, the Arduino then sends individual commands to motors.
7.3 Assembly One of the most important parts of a robot is its brain. In this case, as stated before it is an Arduino Mega. Once the Arduino with the Wi-Fi shield is installed, it must be wired to the breadboard. The relays used on the robot that control all the motors must be turned on and off by the Arduino. Two coil connections of the relays must be connected to the Arduino through the breadboard. This diagram can be seen in the following figure.
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The camera we installed is powered by the main power source. In order to do this, a voltage regulator was connected between the camera and the main power supply. This is because the camera runs with 5 V. The diagram can be seen in the picture below. A capacitor is connected near the camera helps filter out ripples and improves the image quality. [10]
skateboard wheels were scrapped and instead 3D printed sprockets replaced them as stated earlier in the report. Testing began the same way. Placing one hand on the back sprockets and another on the front sprockets, the chains were spun around. At first the springs seemed to not be strong enough for the suspension. After replacing the springs with ones of higher spring constants, the robot was able to successfully travel across the sand. Using a plier, the gearbox was rotated. This ensured that high pressure was applied to the gears and any slippage would be noticed. Other than noise from a spacer, everything worked great. Testing power had to come later after the treads were installed.
8.4 Electrical High amounts of debugging were conducted throughout the project. The first test simply required the Arduino to be connected via Wi-Fi. The next test was to be able to send and receive data from the Arduino to the computer and was verified both on screen via command prompt and via LED installed in a small board simulating the motor controllers. This type of debugging was conducted slowly adding to the complexity of the circuit. The final tests involved the final power source and ensuring that all relays were working properly on command via the PS3 controller. Loose wires caused much of the headaches. The entire system would need to be debugged in order to find misconnections.
Figure 25: Wi-Fi Camera Connection After all those components are connected, the only thing left is to install the battery. The battery pack we used supplies 13.2 V, which is enough to power all components except for the Arduino. The Arduino is being powered by its own 6 V battery and internal 5 V regulator. The main power source is connected to a 150 A circuit breaker, which is then spread across the five relays of the robot. The ground wire is connected with the rest of the robot’s ground onto the chassis.
8.5 Sandbox Once all the simple tests were complete, we took the robot to a nearby park where we placed the robot into a sandbox. We started the testing by lowering the scooper and moving the robot forward. This lead to the scooper being filled with sand, just like a shovel would if it were grazed on top of a pile of dirt. We then proceeding to lift the scooper with the excavated sand and dumped it into the unloading bucket. Very little sand was lost during this process which was greatly desired. After the sand was dumped into the unloading bucket, we then proceeded to unload its contents. The movement of the bucket as it moved upwards was very smooth. It unloaded the sand with great success. The only issue was some sand remained in the bucket. We fixed this by smoothing out some of the rough edges within the bucket. Once the previous tests were completed successfully, we then proceeded to test the mobility system. We drove the robot forwards, backwards, and made several zero-point turns. Although we were satisfied with the results, we did not test the limits of the robot. We thought it would be better to do that at the competition.
8. TESTING 8.1 Scooper Using similar testing methods conducted on the bucket, the scooper was analyzed. With our first test, we used two 35 lbf actuators to lift the scooper but it did not work as expected. The load on the scooper was far too great. We then replaced the actuators for a pair of 225 lbf actuators. We started the testing by adding a single weight at a time. The scooper was able to successfully lift and unload the desired amount of weight into the bucket. We were also able to test and unload through the back out of the scooper and into the bucket. In case overloading occurred, we could remove the load.
8.2 Unloading Bucket One of the first tests we developed was using 35 lbf linear actuators salvaged from last year’s robot. These only allowed for a maximum of 3 lbs of load, which was verified both in empirically and experimentally with a 5 lb bag of sand inside. As the sand was placed in various distances from the experimental center of gravity of the bucket, the linear actuators would hasten or stall. The team desired 50 lbs of load capacity, and therefore required stronger linear actuators. The 225 lbf linear actuators were then installed. Testing was conducted by lifting one bag of sand and progressed by adding more until the bucket was able to lift more than 50 lbs worth of sand bags. This is sufficient for the competition, which makes it a success.
8.3 Mobility The treads went through various design changes as soon as testing began. The original skateboard wheels design were creating such high amounts of pressure on the 4-inch bolts that they were beginning to bend. The wheels were also were getting caught in between the bolts preventing the chains from moving. The
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Figure 26: Terramartian Robot
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9. CONCLUSION
12. REFERENCES
Building this robot has proved to be a difficult task to undertake. Manufacturing it required multiple people working together to ensure all goals are met. Despite insufficient funding and limited time, this robot still functions with all its desired fundamental qualities. There were significant gaps between the design phase and the prototype that had to be improvised. Many items did not work as intended in our original design. As in any design project, many iterations had to be made along the way to ensure that a successful robot was developed. The bucket and scooper system, once complete, created the first pieces to the puzzle. The successful tests completed in the sandbox has given the robot a lot of promise for the upcoming competition.
[1] Cannon, R. (2014, November 19th). 2014 NASA Robotic Mining Competition Scoring Correction [Information]. Retrieved from http://www.nasa.gov/offices/education/centers/kennedy/tech nology/nasarmc.html#.VEZqfvnF_1Y [2] Wilson, S.; Stoeser, D.B.; and Rickman, D.L. (2010, September). Preliminary Geological Findings on the BP-1 Simulant. [PDF Book]. Retrieved from http://isru.msfc.nasa.gov/lib/Documents/PDF%20Files/NAS A_TM_2010_216444_BP1.pdf [3] NASA’s Sixth Annual Robotics Mining Competition Rules & Rubrics 2015. (2014,August 20th). [Information]. Retrieved from http://www.nasa.gov/sites/default/files/robotics_mining_com petition_rules_2015.pdf
10. FUTURE IMPROVEMENTS There are a few items that could be improved if more funding for materials and labor was available. The team focused on simplicity and efficiency while creating the robot. The idea was to perform the task with the least amount of parts. However, the pieces that we manufactured could have been performed professionally for better precision and performance. The holes that were drilled for all the bearings could be more precise and would not have been filled with epoxy to hold them together. Another improvement that could have been implemented is material selection when constructing the unloading bucket. As we have shown earlier, the capacity of the bucket is about 180 lbs, but the strength of the bucket allows only a maximum of 60 lbs. The unloading bucket could have been constructed out of a higher grade aluminum or thicker sheet metal to hold more weight.
[4] Calin, D. (2013, November 11th). Wheels vs. Continuous Tracks: Advantages and Disadvantages. [Article]. Retrieved from http://www.intorobotics.com/wheels-vscontinuoustracks-advantages-disadvantages/ [5] “Wheels or Tracks,” Military Technology, Vol XVIII, Issue 7, Jul 1994, 14. [6] Hibbeler, R C. Engineering Mechanics: Statics & Dynamics. 12th ed. Upper SaddleRiver: Pearson Prentice Hall, 2010. Print.
11. ACKNOWLEDGEMENTS Without Mr. Zicarelli’s expertise and hands-on help, this robot could not have been constructed. With access to the Student Manufacturing Lab, we were able to mill, lathe, cut, grind, drill, tap, thread and weld the components needed. SAE members also played a large role in helping the team better understand manufacturing techniques in the manufacturing lab. We would like to thank Dr. El-Zahab for the guidance in power sources and useful input. We would also like to thank Dr. Boesl for the advice and input on the belt and suspension systems. We would like to thank Dr. Reding and Mr. Pradeep on the input on the material selection for the treads as well as methods in which to attach the rubber to the bolts. We would like to thank Dr. Tremante for access to the 3D printer, crucial in developing the suspension system. One author (RG) would also like to thank him for the job opportunity that helped earn the funds necessary to build this robot. We would also like to thank Dr. Tosunoglu and Mrs. Melissa Morris for their guidance and support throughout the entire project.
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[7] Budynas, Richard G., and J. Keith Nisbett. Shigley's Mechanical Engineering Design.9th ed. New York: McGraw-Hill, 2011. Print. [8] Arduino. 2015, March 18). Compare Board Specs. Retrieved March 18, 2015, from Arduino: http://arduino.cc/en/Products.Compare [9] NASA.(2015). NASA's Sixth Annual Robotic Mining Competition Rules & Rubrics 2015. Kennedy Space Center: NASA. [10] Dimension Engineering Switching Voltage Regulator Application https://www.dimensionengineering.com/appnotes/video/vide o_tutorial
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