Development of a 3D Printable Robot for use in Education Alexander Renken Bachelor of Science in Mechanical Engineering University of Nebraska – Lincoln December 7, 2015 Abstract This project analyzes the current field of educational robotics available for teach- ing science, technology, engineering, and mathematics (STEM) to middle and high school students. It then proceeds to purpose an original system with the target demographics in Africa. This target demographic brings a unique challenge to de- signing a product for education. Such challenges include feasibility of replacement parts, access to tools, and availability of lesson materials. The final robot design has taken into account all of these challenges. All of the parts are designed to be 3D printable. 3D printer technology is becoming cheaper and more ubiquitous in schools. By making the robots 3D printable, if a part breaks, the school can simply print a new one; no worry to buy a part from overseas and wait for it to be shipped. The project resulted in the development of the AZIBOt. The name is a play on the words azibo and bot; the word azibo meaning youth and bot being short for robot. The robots are also completely Arduino compatible, making replacement electronics available from many sources. The robot was designed to be completely assembled with just one wrench and one screwdriver, both are included in the kit. Finally, lesson plans have been made available online, free to use by anyone who wants to learn about robotics. i Contents 1 Introduction 1 1.1 Benefits of Robotics . .1 1.2 Current Work by SenEcole . .3 2 Framework 4 2.1 Infrastructure . .5 2.2 Other Systems . .5 2.2.1 Makeblock mBot . .5 2.2.2 AFRON . .7 2.2.3 Sparki . .9 3 Proposed Concept 10 3.1 Design Features . 10 3.2 Design Restraints . 11 3.3 Assumptions . 12 3.4 Applications . 13 4 Design Approach 14 4.1 Electronics Selection . 14 4.1.1 Main Control Board . 15 4.1.2 Arm Servos . 18 4.1.3 Drive Motors . 18 4.1.4 Sensors . 20 ii 5 Prototyping and Analysis 21 5.1 Chassis . 22 5.2 Tracks . 24 5.3 Battery Lid . 24 5.4 Servo Lid . 26 5.5 Arm . 26 5.6 Full Assembly . 27 6 Future Work 28 7 Conclusion 29 8 Appendix 30 8.1 Bill Of Materials . 30 References 31 List of Figures 1 Participants in the SenEcole 2015 Robotics Camp competing with their robots . .2 2 Participants in the SenEcole 2015 Robotics Camp in Dakar, Senegal .4 3 Assembled mBot made by Makeblock, image from Makeblock website6 4 Assembled MIT printable robot . .7 5 Assembled AERobot from Harvard . .8 iii 6 Educational Sparki robot made by ArcBotics . .9 7 Romeo BLE board produced by DFRobot [9] . 15 8 SB-GVS shield by Solarbotics [10] . 16 9 Grove shield produced by Seeed Studio [11] . 17 10 Freaduino Uno produced by ElecFreaks [12] . 17 11 SpringRC servo used as the drive servos from Pololu . 19 12 Left: Top of the hunt sensor. Right: Bottom of the hunt sensor [14] . 20 13 Octopus push button from ElecFreak [15] . 21 14 Ultrasonic range finder from ElecFreak [16] . 22 15 Rendering of the chassis subassembly . 23 16 Left: Rendering of a single link Right: A full track of 34 links . 25 17 Rendering of the battery lid subassembly . 25 18 Rendering of the servo lid subassembly . 26 19 Rendering of the arm subassembly . 27 20 Rendering of the fully assembled robot . 28 iv 1 Introduction SenEcole is the outreach branch of the Nano & Micro Systems Research Lab at the University of Nebraska – Lincoln led by Dr. Sidy Ndao. Dr. Sidy Ndao has done extensive outreach both locally and internationally. His main focus is teaching science, technology, engineering, and mathematics (STEM) throughout Africa [1]. To expand SenEcole’s capabilities in Africa, the Nano & Micro Systems Research Lab has undertaken developing a robot for use in African classrooms. While African classrooms are the target demographic for this project, the same robot platform could be used to teach robotics in any classroom in the world that has access to a computer and the internet. 1.1 Benefits of Robotics There are many real world applications from what can be learned through robotics. The most obvious include programming and electronics, but there is much more to programming a robot then just code. Programming a robot is different than pro- gramming a program that just runs on a computer. Programs that run on a computer do the same thing every time. Programming a robot has unique challenges of work- ing with the real world. The robot may act a little differently based on different conditions. If its batteries are low, it will move a bit slower, if the lighting isn’t consistent, then the line sensors may read differently. These challenges of working with real world problems help programmers develop a host of valuable skills. These include skills specific to robotics such as sensor characterization along with 1 much broader skills such as problem solving and critical analysis. By learning to char- acterize a sensor, students learn the importance of working with real world products, products that are not perfect, and how to best utilize them. By programming sys- tems that have imperfect sensors, students are challenged to come up with ways to work reliably. Further, programming teaches critical analysis. Students must pro- gram their robot, test it to see what it does, and then modify the code to make the robot do exactly what they want. Looking at what the robot does and figuring out why it is doing what it is based on the code is a great way to learn critical analysis. Finally, basic electronics skills can also be taught with robotics such as the difference between an analog and digital signal. An example of students testing their robots can be seen in Figure 1. Figure 1: Participants in the SenEcole 2015 Robotics Camp competing with their robots 2 Technical skills are not the only thing learned through robotics. Students must learn to work in teams to program their robot. This skill is invaluable as nothing is designed in a vacuum. By challenging students to look at the world around them along with providing them the means to learn, these students can gain self confidence in their ability to change their world for the better. By working through the robotics lessons, then applying them to their own projects, we hope to instill an "I can do this" attitude in the students encouraging them to choose a career in STEM. 1.2 Current Work by SenEcole SenEcole has already been working with teaching STEM in Africa. This includes teaching robot camps and holding robotics competitions. Previously, Dr. Sidy Ndao has gone to Dakar, Senegal to show of robotics like a six wheels remote control robot along with a bi-pedal robot. While he was there, he also taught robotics camps teaching hands on experience with hardware and software. The goal of these camps is to help children develop critical thinking and problem solving skills, develop teamwork, understand physical concepts of science and math, and to encourage them to pursue a career in STEM. A group of participants from 2015 can be seen in Figure 2. Previous camps have used the Makeblock line of robots along with Lego Mind- storm to teach robotics. This includes the ongoing PARC or Pan Africa Robotics Competition, during which, kids are challenged to use STEM to solve real world problems [2]. This competition involves a research project portion where kids pre- pare a poster and give an oral presentation along with a programming portion where 3 Figure 2: Participants in the SenEcole 2015 Robotics Camp in Dakar, Senegal kids program robots to accomplish specified missions. 2 Framework This section reviews the scope of the project. It will outline the goal for both the robot’s capabilities along with the long term teaching goals. It will also outline any assumptions made regarding the end user. Competing systems will be identified to show current options for educational robotics. 4 2.1 Infrastructure Currently, some schools have access to computers and the internet, but lack funds to buy robots or software. The long term objective for this project would be to bring robotic education to all of Africa, but the initial tests will be in Senegal. As of June 2015, 22.9% of Senegal has access to the internet with 27% of Africa as a whole having internet access [3]. Assuming that a computer is prerequisite to internet access, then at least 22.9% of Senegal must have access to a computer. All programs for this project can also be loaded onto either a compact disk or a flash drive allowing for computers that do not have internet access to still participate in the program. 2.2 Other Systems There are current systems that are targeted to education generically and specifically to education in Africa. There is a wide variety in price, capabilities, lessons, and beginner friendliness. This section will look at a wide variety of systems that are currently available and rate them on the aforementioned characteristics along with commentary of other features that make each unique. 2.2.1 Makeblock mBot The mBot is a robot designed by Makeblock for STEM education for kids [4]. The robot uses a bent sheet metal chassis. It is driven by two DC motors. It comes with with a light sensor, button, infrared receiver, ultrasonic sensor, and line follower. For outputs, it has a buzzer, RGB LED, infrared emitter, and two motors.