Key Words Interdisciplinary Approaches, Other: capstone senior design projects

Transcription

1 A Kicking Mechanism for an Autonomous Mobile Robot Yanfei Liu, Indiana - Purdue University Fort Wayne Jiaxin Zhao, Indiana - Purdue University Fort Wayne Abstract In August 2007, the College of Engineering, Technology and Computer Science at Indiana University - Purdue University Fort Wayne and Raytheon Co., Fort Wayne initiated a 5-year project to promote robotics, artificial intelligence, and software engineering in the college curricula. The main goal is to build a robot team to compete in the Robocup competition ( This project also aims at introducing robotics into a variety of computer science and engineering courses. As part of the first year plan, a Pioneer 3-DX robot equipped with a Canon VC-C50 Pan-tilt-zoom (PTZ) camera has been purchased. Using this robot as a development platform, the first task is to design and build a kicker. In order to accomplish this task, a team of senior engineering students have been asked to design and build a kicking mechanism that is seamlessly connected and interfaced with this Pioneer 3-DX robot. This is a two-semester multidisciplinary capstone senior design project conducted by one computer engineering student, two electrical engineering students, and two mechanical engineering students. In the fall of 2007, the students started with the formulation of the problem and then the generation of conceptual designs. After evaluating the conceptual designs, they completed a detailed design of the best conceptual design. In the spring of 2008, the students will first build the kicking system, and then conduct experimental testing. The kicking system is composed of a kicker, a microprocessor based control and driving unit, and software design. The Pioneer 3-DX robot and its attached kicking system shall be able to locate a soccer ball, approach the ball, and control it. It should also be able to kick the ball in a particular direction for a minimum of 5 meters through preprogrammed kicking strategies. The kicking mechanism should be designed to work under the limitations and rules specified by the Robocup organization. Robocup provides rules regarding the size limitations of the robot for specific leagues. These size restrictions together with the given dimensions of the Pioneer robot will determine the allowable size and weight of the kicking system. The microprocessor based control and driving unit shall be able to provide enough power to drive the actuators of the kicker. Other than the technical aspects of the kicking mechanism, this paper also describes several different assessment approaches used throughout the project. The faculty members from the Department of Engineering and the local sponsors conduct the assessment. These assessments are based on either written reports or oral presentations by each design team. This paper also presents the ongoing and future effects in the curricula development brought by the Robocup project. Key Words Interdisciplinary Approaches, Other: capstone senior design projects

2 A Kicking Mechanism for an Autonomous Mobile Robot Yanfei Liu Assistant Professor of Electrical and Computer Engineering, Indiana University -Purdue University, Fort Wayne, Indiana 46805, Jiaxin Zhao Assistant Professor of Mechanical Engineering, Indiana University -Purdue University, Fort Wayne, Indiana 46805, I. INTRODUCTION This paper introduces a multidisciplinary capstone senior design project in Department of Engineering at Indiana University - Purdue University Fort Wayne (IPFW), which involves the design, build and test stages 1. The project is to design and build a kicking mechanism seamlessly connected and interfaced with a Pioneer 3-DX robot (shown in Figure 1). When the project is completed, the Pioneer 3-DX robot and kicker combination will be able to locate a soccer ball, approach and control it and finally kick it in a desired determined direction a minimum of 5 meters, through preprogrammed kicking strategies. Figure 1: Pioneer 3-DX robot with a Pan-Tilt-Zoom (PTZ) camera The kicking system is composed of a kicker, a microprocessor based control and driving unit, and software design. The kicking mechanism should be designed to work under the limitations and rules specified by the Robocup organization 2. RoboCup provides rules regarding the size limitations of the robot for specific leagues. These size restrictions together with the given dimensions of the Pioneer robot will determine the allowable size and weight of the kicking system. The microprocessor based control and driving unit shall be able to provide enough power to drive the actuators of the kicker. The remainder of this paper is organized as follows. In Section II, we introduce about the background of this multidisciplinary capstone project. In Section III and IV, we present the mechanical and electrical designs of this kicking mechanism. In Section V and VI, we describe

3 the project assessment and curricula development. Finally, we conclude the paper in Section VII. II. Background In August 2007, the College of Engineering, Technology and Computer Science at IPFW and Raytheon Co., Fort Wayne initiated a 5-year project to promote robotics, artificial intelligence, and software engineering in the college curricula. The main goal is to build a robot team to compete in the Middle Size League (MSL) Robocup competition 2. This project also aims at introducing robotics into a variety of computer science and engineering courses. As part of the first year plan, a Pioneer 3-DX robot equipped with a Canon VC-C50 Pan-tilt-zoom (PTZ) camera has been purchased (shown in Figure 1). Using this robot as a development platform, the first task is to design and build a kicker. In order to accomplish this task, a team of senior engineering students have been asked to design and build a kicking mechanism that is to be seamlessly connected and interfaced with this Pioneer 3- DX robot. This is a two-semester multidisciplinary project 1 conducted by one computer engineering student, two electrical engineering students, and two mechanical engineering students. Electrical and mechanical engineering students work separately on the electrical and mechanical design and together on the electrical and mechanical interfacing. In the fall of 2007, the students started with the formulation of the problem and then the generation of conceptual designs. After evaluating the conceptual designs, they completed a detailed design of the best conceptual design. In the spring of 2008, the students will first build the kicking system, and then conduct experimental testing. III. Mechanical design Figure 2: CAD Drawing of Final Design

4 Figure 2 shows the final design of the kicking mechanism mounted on the Pioneer 3-DX robot 3. The students successfully used their knowledge learned in a kinematics and dynamics of machinery course to design a linkage system with two degrees of freedom, one for kicking the ball and the other for controlling the direction of the kick. After comparing pros and cons of the conceptual designs, the team settled on implementing a pneumatic system. A dual cylinder system was designed that can not only kick the ball forward, in order to score, but also kick it at an angle, perhaps to pass to a teammate. The two pneumatic cylinders can be fired individually or as a synchronized pair. The kicking plate will be attached via a pin to one of the cylinder and via a slider to the other cylinder as shown in Figure 3. The simple linkage shown, allows for a left kick when the right cylinder fires and a right kick when, alternatively, the left cylinder fires. The figure gives the approximate positions of the linkage before a kick and then after the left cylinder has been activated. The cylinders will be controlled via 3/2 solenoid valves. 3/2 solenoid valves have 3 ports. One port comes from the supply line, one port goes to the cylinder and one goes to exhaust. 3/2 solenoid valves allow air to pass between one pair of ports chosen from the three ports, which creates two operating positions. The two positions determine which output line is active. When kicking, the output to the cylinder is active, when idle the position is switched and air is allowed to exhaust. Figure 3: Cylinders and kicking plate. Right diagram shows side kick. Figure 4 shows the pneumatic circuits with a pair of 3/2 solenoid valves to control the pneumatic cylinders.

5 Figure 4: Pneumatic Circuit IV. Electrical design The electrical design of the kick mechanism is mainly a microprocessor based control and driving unit 3. This unit will enable the main controller of the Pioneer 3-DX robot to drive the kicker as well as utilize possible sensors to determine short range robot motions. The team chose the PIC18F458 as the microcontroller for their design. The PIC microcontroller communicates with the main controller of the Pioneer 3-DX robot through the serial connections. The PIC microcontroller pins operate mostly at a TTL, as oppose to the serial connectors that is RS232 level compatible; thus, a transceiver or driver is needed to be interfaced with the PIC microcontroller and convert the voltage levels between the serial connectors and the microcontroller. The team chose the driver chip, MAX232 from Maxim Inc, for their design. Figure 5 shows the interfacing circuit. VCC 5V C8 PIC18F458 C5 1uF C4 1uF C1+ C1- C2+ C2- T1IN T2IN R1OUT R2OUT VCC V- V+ T1OUT T2OUT R1IN R2IN U2 C7 1uF C6 1uF 1 10uF GND 6 GND RX/RC7 25 TX/RC6 26 GND MAX232E 5 9 DB9 SERIAL/FEMALE

6 Figure 5: RS232/Serial Interface circuit Two of the DRV104 manufactured by Texas Instruments will be used to drive the solenoids of the pneumatic valves actuated system. The input voltage signal of the DRV104 driver chip is the output PWM signal from the PIC18F458 microcontroller. The duty cycle of the PWM voltage signals from the PIC18F458 microcontroller, which can be programmed and adjusted as desired, is used for the DRV104 to generate a modulated current needed to actuate the kicker with various speed. In order for the kicking mechanism to perform a more powerful kick, we want to avoid the situation where the ball is in contact with the pedal. Thus, the team decides to use two proximity sensors to alert the robot when the ball gets too close to the robot. The proximity sensor selected is CT1-AP-1A, manufactured by AutomationDirect. The sensing range of the CT1-AP-1A is 2-15mm. V. Project assessment As mention above in Section II, the senior design project in Department of Engineering at IPFW is a two-semester project 1. In the end of each semester, the students will give an oral presentation about what they have accomplished throughout that semester. The presentation is open to the public. After the presentation, the faculty members from the department and the local sponsors will conduct the course outcome assessment for each individual project. The evaluators are asked to rate each outcome from 1 to 4. The five outcomes evaluated for the project are listed below. The results presented in Table 1 shows that those outcomes are well achieved. 1. The ability of the students to formulate a problem statement. 2. The ability of the students to generate solutions. 3. The ability of the students to evaluated the generated solutions. 4. The ability of the students to obtain a final design including safety, economic and ethical considerations. 5. The ability of the students to communicate effectively. Table 1: The assessment results Outcome Evaluator average There are also three other assessment activities related to the senior design project. The faculty members from the department and the project advisor assess the problem statement and the generated conceptual designs. The written problem statement is evaluated by the project advisor and another faculty member in the department. The assessment of the generated conceptual

7 designs is based on the oral presentation given by each design team. In the end of the first semester, the project advisors assess the ABET course outcomes a, c, d, e, and g 4. VI. Curricula development The majority of capstone design projects in Department of Engineering at IPFW are currently multidisciplinary due to the fact that we have Electrical Engineering, Computer Engineering and Mechanical Engineering in the same department. The project presented in this paper is similar to other projects in the multidisciplinary nature, but also goes beyond that scope because robotics is a field that not only attracts people from engineering but also from computer science. Other than this capstone design project, there is still another software engineering course that uses this Pioneer 3-DX robot. The software engineering course, offered by the computer science department, requires a class group project. The students first learn how to use the APIs in the software development package ARIA 5 (Advanced Robotics Interface for Applications) provided with the Pioneer 3-DX robot. ARIA is a powerful Object Oriented toolkit, usable under Linux or Windows Operating Systems. Then the students program the Pioneer 3-DX robot to accomplish certain interactive tasks utilizing the PTZ camera. One student in that software engineering project is also in this engineering capstone project. Therefore, the experience that he gained in software engineering course can be used in the engineering capstone project. As mentioned above the ongoing Robocup project that IPFW and Raytheon initiated together is a long-term project. It is planned that in the year one of the multidisciplinary capstone projects will be to design and build our own mobile robot base. The advantages of designing and building our own robot are twofold. First, the robot could be customized exactly for our application, Robocup competition. Second, it will be less expensive than buying a commercial robot. In order to make this project a success, it is very important to provide undergraduate students with sufficient knowledge to participate the Robocup project in their senior year. There are two courses offered by Department of Engineering which fulfill this goal. One of them is a junior level robotics course that introduces the students the basic knowledge in mechatronics. This robotics course is a multidisciplinary course required for all of the students in the three majors, Computer Engineering, Electrical Engineering, and Mechanical Engineering. The other is a newly developed course that is about embedded real-time operating system. VII. Conclusions In this paper, we discussed a kicking mechanism interfaced with the Pioneer 3-DX robot, which is a Capstone senior design project in Department of Engineering at Indiana University Purdue University Fort Wayne. The whole system design consists of a kicker and a microprocessor based control and driving unit. We described the design of each component in details in this paper. We also introduced the assessment methods used in the capstone design project as well as the curricula development based on the Robocup project. Bibliography

8 1. Abu-Mulaweh, H., Engineering capstone senior design, World Transactions on Engineering and Technology Education, Vol.5, No.1, pp , Robocup Official Site (2007), 3. Craft, C.; Macki, M.; Mikobi, F.; Nzudie, L. and Tostado, M., Kicking Mechanism for the Pioneer 3-DX, Capstone Senior Design Report, Department of Engineering, Indiana Purdue University Fort Wayne, Dec Engineering Accreditation Commission, Criteria for Accrediting Engineering Programs, page 2, March 18, Mobile Robots, Dr. Yanfei Liu received the B.S. in Electrical Engineering from Shandong Institute of Architecture and Engineering, Jinan, China in July She then received the M.S. degree from Institute of Automation, Chinese Academy of Sciences, Beijing, China in July 1999, and Ph.D. Degree from Clemson University in August Dr. Liu has been a member of the IPFW Department of Engineering since August Her current address is liu@engr.ipfw.edu Dr. Jiaxin Zhao is an Assistant Professor of Mechanical Engineering at Indiana University- Purdue University Fort Wayne. He received his BS from the University of Science and Technology of China, his MS from the University of Missouri-Rolla, and his PhD from Purdue University-West Lafayette. His research and teaching interests are tribology, machine design, solid mechanics and numerical methods including finite elements and parallel computing. His current address is zhaoj@ipfw.edu