Multidisciplinary Design Optimization of Robotic Football Players by Undergraduate Students from Multiple Science and Engineering Programs

This paper presents the multidisciplinary design optimization (MDO) and fabrication of four robotic football players: quarterback, center, and two receivers. Each robot has a footprint of up to 16 square inches and is up to 24 inches high. The game of American football is played in an enclosed arena similar to a basketball court and each robot is remotely controlled. The design, fabrication, and operation of the robots involves Indiana University-Purdue University Indianapolis (IUPUI) undergraduates majoring in STEM disciplines, including mechanical, electrical, and computer engineering. The students are exposed to numerous engineering design challenges, such as shock absorbent structure design, fast and dexterous robot maneuvering, development of robust and reliable control hardware and software, and ball transfer between robots in a highly unpredictable game environment. To address these challenges, we adopted a collaborative optimization (CO) approach. CO is a multi-level MDO method that incorporates system-level and subsystem-level optimization. Five disciplines emerged in the course of this project, namely: structures, mechanisms, electronics, software, and manufacturing. CO’s advantage over other MDO methods is that it allows disciplinary autonomy while achieving interdisciplinary compatibility. The effectiveness of this experience is demonstrated with the multidisciplinary design, fabrication, and operation of the IUPUI-Butler robotic football team in a game environment. Introduction Indiana University-Purdue University Indianapolis (IUPUI) was invited to participate in the 2013 intercollegiate mechatronic football competition organized by the University of Notre Dame. IUPUI was scheduled to play Indiana University-Purdue University Fort Wayne (IPFW) at the end of the spring semester. The goal was to design and manufacture four remotely controlled robotic football players (quarterback, center, and two receivers) in about 20 weeks. At the game day, the robotic football team was completed with Notre Dame robotic players with a kicker and linemen. The design and manufacturing project was carried out by a group of 25 IUPUI undergraduate students (from freshmen to senior) from three different disciplines: mechanical (eleven students), electrical (eight students), and computer engineering (six students). In our work, this challenge is systematically addressed following a multidisciplinary design optimization (MDO) strategy. MDO can be described as collection of design theories, computational tools, and practices developed in the applied mathematical community to improve the design process of engineering complex systems through the interaction of coupled discipline analyses. Its theory was formalized in the aerospace industry where designers recognized the need to decompose a system-level problem into a set of smaller tractable disciplinary problems. Depending on the level of complexity, an MDO problem may involve a large number of analysis and design variables and conflicting multidisciplinary requirements. The discipline coupling forces discipline interaction to arrive to a consistent system design. This work groups five disciplinary teams: (i) structures, (ii) mechanisms, (iii) electronics, (iv) software, and (v) manufacturing. Depending on preference, expertise, and availability, students P ge 24924.2 are assigned to one or more disciplinary teams. Each disciplinary team has a leader that interacts with the system-level project coordinator to define local objective targets, e.g., speed, weight, range. In order to integrate the disciplinary optimization problems in a system-level platform, this work incorporates a collaborative optimization (CO) strategy. CO allows the work in parallel of disciplinary teams in a way that the system-level problem has control over all the disciplines. The resulting designs are manufactured and used in the game. Learning outcomes The students at IUPUI gain exposure to systems engineering. Examples of skills that begin to develop within the members include project management practice for team leaders and discipline design decisions that impact adjacent disciplines for all team members. For example, the team designing the circuitry are able to employ the theory and analysis skills learned in their circuit’s class. Likewise, the team designing the linkage are able to employ the machinery design analysis tools learned in their respective class. The complexity of learning systems engineering in its entirety is not realistic given the format of the student club, however student learning is achieved through practice. Student learning include the following objectives; 1) team work and building effective meeting skills where tasks are clearly identified and assigned, 2) cross discipline involvement, 3) learn how to design, build, and test robots using knowledge gained from past/present courses, and 4) communication skills. Student learning is motivated by participation of the robotic football competition given the robots are functional. The students will be able to demonstrate the learning accomplishment by participating in the next football competition April of 2014. Design guidelines The game is played on a 94 ft × 50 ft field by two robotic teams identified as Blue and Gold (Figure 1). Each team is composed of a total of nine remotely controlled robotic players, but no more than eight are allowed on the playing field during a play; six robots were actually used by each team during the 2013 game. The game commissioners provide a miniature souvenir football for the game. In the 2013 scoring, a field goal is worth 3 points, a touchdown is worth 6 points, a kicked point after touchdown is worth 1 point, a short forward pass (5 to 15 feet) is worth 7 points, and a long forward pass (more than 15 feet) is worth 12 points! There is a 3-point penalty if the ball is damaged by a robot during the game. Figure 1—Playing field dimensions. The opposing teams are identified as Blue and Gold. Student players and additional hardware can be located in the designated areas around the field. All robots are operated by remote control using the controllers provided by the commissioners. If other remote controllers are used, they cannot interfere with the signals broadcast from the P ge 24924.3 opposing team. The robot locomotion must be DC powered with a 24V maximum circuit voltage. Each robot must have a kill-switch mounted externally to their top surface. When activated, the switch should disconnect the main power to the system. The weight of the each robot (except quarterback and kickers) is limited to 30 pounds. Quarterbacks are limited to 45 pounds. At the beginning of any play, all robotic players (except centers and kickers) must fit within a 16 inch ×16 inch footprint × 24 inch tall box. Centers may reach out from beyond this footprint before a play to deliver the ball to another player. The centerline of a player's base plate must be located 3.0 ±.1 inches above the playing surface and remain in that position at all times. Each robot is required to incorporate a digital accelerometer to sense upsetting events such as knockdown, fall down, or tackle. A single multi-color, highintensity LED is used to indicate robots status, e.g., red indicates an upsetting event. A student can remove a damaged robot from the field between plays, but once touched by a human, that robot cannot participate in the next play unless the team calls a time out. Robots other than the center can have up to two extensible arms consisting only of rotational joints. Each arm may extend no more than 18 inches in any direction from the center of the joint at which it connects to the player. However, the 2013 guidelines do not allow the deployment of any material beyond the perimeter of the robot’s base plate that impedes the ability of an opponent to contact a robot’s base plate. The base of each robotic must be solid and made of HDPE not thinner than 1⁄2 inch. A reasonable number of clearance holes for component mounts, component clearance, fasteners and wires are allowed. Tires must be mounted on rigid, solid wheels. Pneumatic tires are not allowed and suspensions and shock absorbing systems are not permitted. MDO approach In the fall semester of 2012, the project was presented to mechanical engineering undergraduate students of the course Design of Mechanisms (ME 37200). Following this presentation, a group of students from this class funded the IUPUI Robotics Club that later included students from electrical and computer engineering. Twenty-five students were involved in the development of the four robots. Instead of independently assigning the development of each robot to a group of students, say six students per robot, this project incorporated disciplinary teams based on preference, expertise, and availability. In this project, the robotic system is described as a nonhierarchical collection of five disciplines: • Structures: to design robot chassis and transmission for the robot displacement • Mechanisms: to design all moving components on the chassis • Electronics: to design, select, and fabricate electronic boards and peripherals • Software: to design and program control algorithms • Manufacturing: to fabricate and assemble final robot As the project evolves, the inter-disciplinary coupling changes so the design and communication tools should allow such natural evolution. The main challenges faced in this project are the organizational issues related with the data sharing and inter-disciplinary communication. Students quickly learn the need to coordinate the activities of a multidisciplinary team and keep Page 24924.4 everyone on board required the use of a systematic MDO approach such as collaborative optimization. Collaborative optimization is a bilevel design framework composed of system-level and disciplinelevel design problems (Figure 2). In CO, individual disciplinary teams are in charge of solving local optimi