1301 CS Summer 2009
Homework 4 Avoiding Obstacles / Binary Conversion Due: Friday, June 5th, before 6 PM
(10% late penalty if turned in before Monday, June 8th, before 6 pm)
Scored out of 100 points Files to submit: hw4.py This is a PAIR PROGRAMMING Assignment: Work with your partner!
For pair programming assignments, you and your partner should turn in identical assignments. Your submission must not be substantially similar to another pairs submission. Collaboration at a reasonable level will not result in substantially similar code. Students may only collaborate with fellow students currently taking CS 1301, the TA's and the lecturer. Collaboration means talking through problems, assisting with debugging, explaining a concept, etc. You should not exchange code or write code for others. For Help: - TA Helpdesk Schedule posted on class website. - Email TAs Notes: Don't forget to include the required comments and collaboration statement (as outlined on the course syllabus). Do not wait until the last minute to do this assignment in case you run into problems. If you find a significant error in the homework assignment, please let a TA know immediately. Part one --- Avoid Walls 65 points There are five kinds of sensors on the robot: light sensor (detect the how bright the light is), proximity sensor (see whether there is anything around the robot), stall sensor, the camera, and the battery voltage. We are going to use the robot's proximity sensors for this homework. Be sure to read all of the information below. It explains many functions that are vital to the successful completion of this assignment. Mission: Your robot will be randomly placed in an arena of size 5 x 3 (Unit: 11 in). You need to write a function called avoidWalls() to move your robot around for one minute (+/- 5 seconds) without hitting walls. The robot needs to be moving at a minimum of 1/3 of it's maximum speed. (Your robot may drive "backwards" if you want to use the getIR() sensors instead of the getObstacle() sensors.) The robot should also celebrate after finishing the mission successfully. How it is going to celebrate is up to you, although it must be recognizable. We suggest moving around and beeping at a minimum. For more information on the arena, see the posted file.
--- What's on the robot? --Proximity Sensors: Proximity sensors are used to detect objects that are close to the robot. The robot has two sets of proximity sensors: one set is on the robot and the other set is on the fluke. The IR sensors on the robot: There are two infrared (IR) sensors on the back of the robot (Assuming the fluke is facing forwards). You use the sensors by calling the getIR(<position>) function. Examples: >>> getIR() [1, 0] >>> getIR('left') 1 >>> getIR(0) 1 >>> getIR('right') 0 >>> getIR(1) 0 getIR(<POSITION>) Returns a integer value in the <POSITION> IR sensor. <POSITION> can either be 'left' or 'right' or one of the numbers 0, 1, which correspond to "left", and "right". IR sensors return either a 1 or a 0. A value of 1 implies that there is nothing in close proximity of the front of the sensor and a 0 implies that there is something right in front of it. The proximity sensors on the Fluke: There are three proximity sensors on the fluke: one front sensor and two side sensors. They give different values than the ones on the robot. To use this set of sensors, you need to call getObstacle(<position>). getObstacle() return a list that contains the values from all three sensors. To get a value from a specific sensor, you can call getObstacle(<position>). <position> can be "left", "right" or "center". <position> can also be number 0, 1, or 2, which correspond to "left", "center", and "right". Examples: >>> getObstacle() [1703, 1128, 142] >>> getObstacle('left') 1703 >>> getObstacle(0)
1703 >>> getObstacle('center') 1128 >>> getObstacle(1) 1128 >>> getObstacle('right') 142 >>> getObstacle(2) 142 getObstacle(<position>) returns a integer value between 0 and 7000. A zero (0) indicates there is nothing in close proximity of the sensor. Higher value implies the presence of objects in front of the sensor(s). Note that the center sensor is the most accurate. The side sensors will detect objects located at about a 45 degree angle, but not those directly to the sides of the robot. More details about the sensors can found: be <http://wiki.roboteducation.org/Learning_Computing_With_Robots Chapter 5 Sensing the World> Reminder: Robot needs to be moving at a minimum of 1/3 speed. Internal Clock function: To keep track of time, you can use the myro internal clock function. To get the current time, call currentTime() function. The function returns the number of seconds past since sometime in the past. [Epoch or Unix time if you're interested.] Example: >>> currentTime() 1222374008.360949 To keep track of time, you need to call currentTime() and save the time to a variable (e.g. time). You can get the time that has passed since you last called currentTime() by subtracting time from currentTime(). Example: time = currentTime() doing something..... doing something..... timePast = currentTime() - time More detail about the internal clock function:
http://wiki.roboteducation.org/Learning_Computing_With_Robots Chapter 4 Sensing From Within
If you want, you may use the timeRemaining() function and a while loop instead of the currentTime() function to time your robots motion. If you need help with the move functions, go to
http://wiki.roboteducation.org/Learning_Computing_With_Robots Chapter 2 Personal Robots
Turning it in, and Demo. Be sure to put the lines from myro import * and initialize() or init() at the beginning of the file (after the required comments). Be sure not to specify the port parameter in your initialize command, such as initialize("com4"). This makes it very time consuming to grade if we have to go into your code and change the com port to the one that works on our specific system. The TA will type avoidWalls() to start your robot moving, so you don't need to include a call to that function in your hw4.py file. Reminder on collaboration statement: This is a group assignment. Each group member need to turn in the identical hw4.py to T-square before the deadline. Please include your name, and all your group members' name in the header and collaboration statement. Demo: Each group (All members) needs to come to the recitation (tues/wed) the week following the due date to demo your robot to your grading TA. If that is not possible, you may demo to a different TA at the TA helpdesk at some other time, but this may delay your grade slightly as that TA will have to give the grading sheet to your grading TA. All group members will be asked questions about your code at the demo. The TA you demo to will fill out the (attached) grading sheet and give it to your grading TA (if they are not the same person). Be sure your program works as you want before you do the demo, because your grade will be based upon the Demo! The TA observing your demo may give you an extra chance if the robot hits a wall, at their discretion. Print out the attached grading sheet and bring it to your TA when you do your demo. Part 1 Avoid Walls Grading Criteria: Demo (See attached grading sheet) File named correctly Uses iteration correctly Uses IR sensors to detect obstacles (Walls) Celebration in the end 30pt 5 pt 10pt 10pt 10pt
Part 2 Binary Conversion
Your group will write a function dec2binary( decNum ) that will return a string made up of 1's and 0's corresponding to the (positive) decimal number that is the argument. For example: dec2binary(255) should return the string "11111111", dec2binary(0) should return the string "0", and dec2binary(5) should return the string "101". Your function must work for decimal numbers of any size! You may assume that only positive integers will be used as input. Include this function in your hw4.py file. When you demo your robot and the avoidWall() code, your TA may also ask any group member questions about this binary conversion code, so all group members should understand how it works.
Part 2 Binary Conversion Grading Criteria: Produces correct results for all inputs Function named correctly & returns a string (instead of printing) Randomly chosen group member could explain (see attached demo sheet) 20pt 5 pt 10pt
Robot Avoiding Walls / Binary Conversion TA Demonstration Grading Sheet Group Members: ___________________ ___________________ ___________________ Demo TA:
Grading TA (if different)
:
___________________ ___________________
10 pts ________
Robot moved for aprox 60 seconds, without hitting obstacles!
20 pts ________ All group members understood and could explain the code.
Part 2 Binary Conversion: 10 pts ________ A randomly chosen group member can successfully explain how the dec2binary function works.
Total: ________ / 40