RBT-225 Scorbot Lab #10 Repeatability November 28, 2016

RBT-225 ScorBot Lab #10 – Repeatability November 28, 2016

The objective of this experiment is to understand the repeatability error of the robot. The requirement of this experiment is to pick up a needle, go to another place with various speeds, and then put the needle back to its original position.

Experiment #1:

1. Read and study the explanation of Precision, Repeatability, and Accuracy that is explained on the following website: http://paladintechworks.com/index.php/home/blog/12-tech/14-understanding-the-terms-precision-repeatability- and-accuracy-in-the-cnc-world

Experiment #2:

Note: make sure that you calibrate the arm before you start this lab.

1. Place a piece of white paper on top of two layers of cardboard (or foam) on the table.

2. Let the robot grab a needle and record the following three positions: a) Manually move the robot to let the needle stab the paper in a perpendicular way while trying to make the hole on the paper as small as possible. Record this as the 1st position. b) Manually move the robot up along the Z axis a little to make the needle come out of the paper. Record this as the 2nd position. c) Manually move the robot to a third position as far as possible. Try to move all the joints using the joint control. The more movements, the better. Record this as the 3rd position. You may use a fourth position to allow the needle to safely clear the table/paper.

3. Write a program that will ask the robot to go to the same hole on the paper. The following is an example of one cycle: 3rd position2nd position1st position2nd position3rd position, etc.

4. Use five different speeds (1, 3, 5, 7, and 9) to ask the robot to repeat the sequence which will add five more holes in the paper.

5. Observe and measure the different insertion points on the paper, and explain the differences.

6. Summarize your conclusions about the precision, repeatability and accuracy. Include a copy of your program and the X,Y,Z coordinates of the positions.

Experiment #3:

1. Write a short explanation for Precision, Repeatability, and Accuracy. Use your own words; do not repeat/copy the website text.

Experiment #4: This class required a text book and a series of lab instructions. I am evaluating whether we should eliminate the textbook and instead rely on the reading of website material which would be required reading (from the web) and would be specified in each week’s lab instructions.

1. Answer the following survey questions: a) Do you think this new approach would work for you? 1=Yes 2=Most Likely 3=Not Sure 4=I Think So 5=No

b) Considering the price and the use of the textbook, how much value did you get out of the textbook? 1=A Lot 2=Pretty Good 3=Average 4=Some 5=None

Optionals:

1. Enhance as you wish.

Evaluation: 1. Create a (individual student) lab report summarizing your work. Include the following: a. 5 points: Title page with Course number, Lab#, Lab Title, your name, and the date. b. 25 points: Your task description for Experiments #1-4 (do not copy this lab description). c. 30 points: Detailed conclusions, measurements, and calculations for repeatability and accuracy. d. 10 points: Detailed list of arm positions. (X,Y,Z Positions). e. 10 points: Define accuracy, precision and repeatability (in your own words). f. 5 points: Detailed list of arm movements. I.e. the sequence flowchart or description. g. 5 points: List of program code. Explain any new program instructions. h. 10 points: A quick description of any optional work/assignments.