Inspiring Creative Fun Ysbrydoledig Creadigol Hwyl. Microbots Workbook

Transcription

1 Inspiring Creative Fun Ysbrydoledig Creadigol Hwyl Microbots Workbook

2 Challenge 3 Nations competing against one another on the Moon! Each racing PICAXE robots to sample lunar rocks and follow a given course. The nation who reaches the sample area first wins! 1) Teams Divide yourselves into 3 teams. Pick which nation your team wishes to represent you can choose from the following: United States of America China Russia Once you have chosen your team and your nation, you are ready to proceed. 2) Creating a course If attending a workshop, your course may be pre-built. But if you are working through this at home or at school, this is where you can become very creative! You can use a variety of paper mache, paints and crafty accessories to customise your lunar racecourse. But most importantly, don t forget to add a thick black line for your robot PICAXE Microbots to follow and race one another. A PICAXE is a micro-controller, it tells connected components what to do and how to do it once a program is uploaded onto it. It is considered the brain of an electronic project or kit. These are cheap to buy and can be bought as kits, or as separate components. The PICAXE can be programmed, given instructions so it knows what to do, when. You can program the micro-controller using a programming language called BASIC or through the use of flowcharts. 1

3 3) PICAXE Before you begin coding your PICAXE and getting it to move around your lunar racecourse, you should become more familiar with the Microbots components - what they do and how they work. See if you can identify the following on the PICAXE? Motor A (Hint: this turns the robot to the right). Motor B (Hint: this turns the robot to the left). Line Tracker Bumper Switch To program your Micro-controller, you can use a variety of different programming environments. The main one is PICAXE Programming Editor, it is free but currently only runs on Windows. For Mac or Linux machines, you can download AXEpad, this also runs on Windows and is free. To begin, let s start by introducing labels. Labels are used as markers in order for programmers to refer back to segments of code by using the goto command followed by the name of the label. Labels can be up to 40 characters long and can contain any combination of letters and numbers, however there cannot be any spaces. To ensure the editor recognises it is a label, make sure to add a colon at the end. For example: outputtext: goto outputtext 4) Label Make your own label, don t forget the colon. It is key to remember to make this meaningful, there is no point in giving the label gobbledegook as anybody looking at your code (or even when you look at your code later on) won t have any understanding of the content of that segment of code. Note: For the PICAXE you will require a USB download cable. This will enable you to plug your Microbot into the computer and download your program. Your Microbot will remember the last downloaded program, even if it gets turned off! To make sure it gets downloaded correctly, turn your Microbot on and plug it in making sure the USB end is fully inserted to the port. 2

4 Now you can begin adding content to your label. Here we can start telling our robot to move, but as you have seen there are 2 separate motors. One motor is Motor A and one motor is Motor B. Let s start which basic instructions, programming each motor individually. To get our Motor A to move forward add the following code: movement: forward A 5) Forward Tell the other motor to move forward also. You can add that to the movement label. 6) Backward Similar to above, see if you can tell the PICAXE to move backward in the same label. Don t forget to do this movement for both of the Motors so the robot moves straight. As explained on the previous page, there is a command you can use that lets us refer back to a particular segment of code for the environment to continue running the code from that point on. 7) Goto Implement your own goto command at the end of this program. When you run this on your PICAXE can you see what is happening and how the microbot is reading the instructions? You now understand how to perform basic movements, but what about having a break in between them? You can use a variety of commands to get the robot to stop, this can be done for a specified length of time or indefinitely if desired. The options are as follows: wait pause halt This command will delay the program for a specified number of seconds. This command will delay the program for a specified number of milliseconds. This command will halt the specified Motor (either A or B). 3

5 7) Movement 1.0 See if you can program your robot to make a SQUARE. For the first go, do not use the goto command, give the robot instructions line by line and run the program on the PICAXE. 8) Movement 2.0 Now have a look at your code again. There will be some repetition within the instructions. See if you can reduce the length of your code by removing the repetitions and replacing them with a goto command instructing the program to go back to the described label name. For example: movement: goto movement Note: As the PICAXE Microbots have been built by hand separately, there may be some slight variation from robot to robot. This may be reflected when getting your Microbots to turn corners. For instance a 180 degree turn may be slightly more or slightly less to get your robot to face the other way. Be aware of these variations when giving your Microbot code. 4

6 9) Movement 3.0 Now that you have mastered the square, see if you can program your robot to create a figure of 8 shape. Once you have mastered this, try putting 2 obstacles in the way, with sufficient space between. Now see if you can program your robot to make the figure of 8 around the 2 obstacles, avoid any collisions! The PICAXE comes equipped with a Line Tracker. This shines a red LED line down towards the surface the PICAXE is moving on, there is a phototransistor next to the LED that detects how much light is reflected back. It is used as an analogue sensor on Pin C.2, also channel 8 to see how much light is reflected back at the PICAXE Microbot. How much light is reflected back will tell us more about the surface, for instance if there is a low reading (which also means there is a lot of reflected light) then the surface may be quite light, such as white paper! If the reading is high (which means there is not a lot of reflected light) then the surface may be quite dark, such as black paper! When light reaches a surface, the surface can absorb some of the light and not reflect it. Black surfaces absorb all of the light whereas white surfaces reflect the light. Black surface White surface The command readadc can be used with the Tracker to read the Line Tracker sensor, where a value will be returned, however how will you know what that value is? You can also use the debug command which will display the value. 5

7 Hint: For the read command, don t forget to set the channel and the pin mentioned on the previous page. You can do this similar to below: readadc 8,b0 10) Reading light sensors Create a new program that read the value sensed by the Line Tracker sensor, debug and then repeat. Conditional statements are regularly used within programming as a means of declaring an outcome if a particular circumstance occurs. For instance, if you were creating a game you could use a conditional statement for the following example pseudocode: IF *the main character gets caught by the enemy* THEN deduct 100 points from the overall score return main character to the start of the game END IF You can expand the basic IF statement to become an IF ELSE statement, which is if a particular circumstance occurs then do something, if anything else occurs then do something else. For example: IF *the student gets the answer right* THEN the student gets a PASS grade ELSE the student gets a FAIL grade END IF 11) Line Tracker Algorithm Use an IF ELSE statement to get your PICAXE Microbot to follow the a black line. Remember, you do not need to repeat the instructions, you can just use the goto command to refer back to a label in your code. Note: You may begin your IF ELSE statement by using the following command if b8 >...* then * this is a number closest to either the black or white value. 6

8 APPROPRIATE_IMAGE REPRESENTING_WORKSHOP (REMOVE BORDER) APPROPRIATE_IMAGE REPRESENTING_WORKSHOP (REMOVE BORDER) APPROPRIATE_IMAGE REPRESENTING_WORKSHOP (REMOVE BORDER) Inspiring Creative Fun Ysbrydoledig Creadigol Hwyl