ASABE Robotics Student Design Competition 2011 Organized by P-127 Committee Challenge Subcommittee: Santosh Pitla (University of Kentucky) Aaron Franzen (Oklahoma State) Joe Dvorak (Kansas State) Seth Perkins (Kansas State) Wei Han (Kansas State) Xu Wang (Kansas State) Vince Schielack (Texas A&M) Yufeng Gu (Texas A&M) Advisor: Dr. Tony Grift, University of Illinois Figure 1. Drawing of the challenge (see Appendix 1 for a large drawing) 1
Challenge The premise behind the 2011 ASABE Student Robotics Design Competition is to develop an autonomous machine that is capable of following a crop edge. This type of tool is very helpful in harvesting operations, where a part of the crop has been cut and the machine follows the resulting crop edge in subsequent passes. The challenge is to optimize the travel speed, while at the same time, guide the machine maintaining a constant distance from the crop edge. The machine also has to leave a bread crumb trail, which consists of dropping visible particulates (in this case ground coffee) that allow the judges to see where the machine has gone out of bounds. Board construction The challenge will take place on a board that is 8 ft square, having a standard 2*1 border, which means that the border height is approx. 1.5 inch and the width approximately 0.75 inch. The borders are mounted on top of the challenge board, so the inside area is reduced by 0.75 inch around the circumference. The board will be made from two pieces of 4*8 ft, ¾ inch Medium Density Fiber board: which has a rather smooth surface. There will be a seam running from bottom to top in the center of the board, but we will use two-by-fours to pull the seams together. The surface and borders will be painted flat white. For the standing crop edge, we will use black bristles from a Libman 00800 broom. The brooms have 158 (5*30+8) bristles each containing about 80 strands, therefore your team will need three brooms. These brooms are widely available, for instance Menards offers them for $9,96 (before tax). However, some places on the web charge up to 70$! Try Sam s Club, Menards, Lowes/Home Depot or go to the Libman website, which shows you where to buy these brooms in your state. The length of the bristles will be at least 8 cm above the board surface, but some strands within the bristle will be shorter. To see how bristles are fixed into a broom, watch this video. We will drill holes with a diameter of 1/4 inch at a distance of 10mm apart and insert the strands into them using a similar method as the one shown in the video. Figure 2 shows the method. After the ¼ inch hole is drilled, a steel wire is pulled downward through it which encompasses one bristle. By pulling the strands into the board with the steel wire, the bristle will stand up straight. Bristle ¼ inch hole MDF (3/4 inch thick) Steel wire Figure 2. Method of attaching bristles into holes to create the crop edge. Here, a sequence of images is given that show how to produce the standing crop edge. It comes down to removing bristles from a broom, and placing them into holes that are drilled into the challenge board. Notice that to place the bristle into the board, only a pair of pliers and a steel wire are needed. 2
1) Grab one bristle with a pair of pliers and remove it from the broom. The staple will keep the bristle together. 2) Thread the steel wire around the bristle, remove the staple, and feed both wire ends through the board to the opposite side. 3
3) Pull the two steel wires taut against the board with the pliers. 4) Turn the pliers sideways and pull the steel wires through the hole, using the board itself as a base. 4
5) Turn the pliers until your fingers hit the board. This will pull the bristle into the hole by about ½ inch, leaving an 8 cm bristle standing. 6) Here is a picture of the completed bristle from the board side. 5
The total length of the crop edge is 360 cm, therefore 360 strands will make up the complete crop edge. There will be no material placed inside the wheat field, which means that your sensor may also see the edge on the opposite side of the board! Although the robots must follow the crop edge, there will be lines on the board that are used to monitor the path of the robot by the judges. These lines are made from yellow electrical tape and they form a 2- inch wide band. This band will allow the judges to monitor where the robot has traveled since it is required to drop coffee particles during the run. Therefore, the robot must drop a sufficient number of particles, that is at least two particles per cm traveled. If no coffee particles are found, this will be treated as particles falling out of bounds, which leads to penalties. IT IS ILLEGAL TO USE THE YELLOW LINES ON THE BOARD FOR GUIDANCE. TEAMS WILL HAVE TO RUN THEIR ROBOT ON A SEPARATE BOARD WITHOUT YELLOW LINES BEFORE TAKING PART IN THE COMPETITION. The challenge is to have the robot follow the crop edge as accurately as possible, and to circumnavigate the track as many times as possible within a three-minute time limit. This represents a trade-off between running fast and running accurately. The number of circumnavigations is counted to the nearest crop strand (1 cm resolution). The starting point of the run is in the center of the long straight line (see Appendix 1). The teams need to start dropping particles before that line, and continue until the end of the run. Teams are allowed to run either clockwise or counter-clockwise. Robot construction As in previous years, there are limitations to the robot layout. Firstly, the robot must fit within a 1 cubic foot volume at the start and end of the run. This means it is legal to extend sensors and arms during the run as long as they are retracted before the end of the run. It is legal to use any type of sensor you wish, including tactile sensors. It is also legal to use combinations of identical or different sensors. The robotic machine can be built based on any platform you wish (LEGOs, BOE-BOT, etc). Presentation /Report Each team will present their design in a 15-minute PowerPoint presentation discussing details of design (Sensing and Actuation mechanism), algorithms, and effectiveness of mechanical, electrical and software components. The presentation session will be held separately from the competition. In addition, teams are required to bring three hardcopies of their report to the meeting. Since time is limited for the judges, the size limit on the report is ten pages. Scoring The following actions result in deduction of points: Hitting either the crop edge or the edges of the challenge board Dropping coffee particles outside the guidance band Manually assisting the robot 6
There will be three judges and a separate timekeeper present during the competition. Scoring is as follows: 1) Performance: The total number of points P that is awarded for performance is a function of the completed distance (in cm) in the allotted 3-minute period. Therefore there is no maximum number of Performance points, but we envision P to have an approximate maximum of 5 completed runs*360 = 1800 points and all other points are given relative to this maximum. 2) Penalties: -25 Every time the team manually assists the robot -25 * Length in cm at which coffee particles fall outside the 2-inch yellow band or are absent 3) Elegance of design: This is a qualitative indicator that adds to the total score at the judges discretion (up to 1000 points). 4) Presentation/Report: The presentations will be scored by the judges based on the teams a) presentation performance, and b) written report. The total points available to the judges are 1500 for the presentation and 1500 for the report. Example scoring table: Circuit completion points Elegance of design Track deductions Assistance deductions Presentation Report Total (Max) P 1000-25 * Length -25 per violation 1500 1500 Max ~1800 1000 1500 1500 ~5800 Rules arbitration Although the rules presented here have been developed to be as encompassing and unambiguous as possible, it is possible that questions, the need for clarification and concerns arise up to and during the competition. Rules have been defined by the P-127 Challenge Subcommittee and they will make the final decision regarding any and all concerns as well as ruling when a team violates the rules. Unless otherwise specified, any rules violation or attempt to bend the rules will result in disqualification of the team. However, teams are very much encouraged to develop out of the box solutions as long as those solutions are within the rules. If the team is in doubt whether a proposed solution is legal, contact the Challenge Subcommittee with detailed explanation by emailing Dr. Tony Grift, grift@illinois.edu. We will maintain a Q&A page on the Website, where questions and answers are shown, unless the team instructs us not to post the question/answer, to prevent leaking good ideas. 7
Appendix 1. Complete drawing of the challenge board. 8