Guide for Lollybot Rollerbot Build & Programming

Transcription

1 PICAXE What you will learn? How to build a robot using lollipop sticks How to connect all the electronics How to write a program to control a robot How to download a program to a robot Safety and tools Glue guns get very hot, be careful Glue guns are very messy, make sure you have a suitable work area Clean up any mess as you go along Be careful when using snips to cut lollipop sticks Don t rush around Take your time when making Don t worry if you make a mistake Mistakes can be made right easily when working with lollipop sticks What You Need: (Tools) Lollybot Rollerbot Kit: Lollybot s servo control board kit Lollipop sticks 2 x Geared DC Motor Battery holder (3 x AA) or (4xAA) 3 batteries 4 x female to female header wire 1 x HC-SR04 Ultrasonic range finder 5 x wire 80mm (2x red, 2x black, 1x other) 2 x BCx38C Transistor 2 x Stripboard (4 x 2 row) Rubber matting Cardboard 2 x small screw Tools: Hot glue gun with glue sticks Sharp scissors or shears Ruler Pencil Solder iron and solder Blue tack PICAXE download cable What you need? (Software) You will need to download two programs from the PICAXE website. 1. PICAXE Editor 6: This software is used to write the program. It can be found on the PICAXE website: 2. AXE027 USB Cable Driver: This driver is needed if you are using the PICAXE USB cable for programming. These cables cost about 12. Normally needed if you use a laptop. It can be purchased from PICAXE and Rapid. Or use the RVFM PICAXE Download Cable. This cable costs about 3 from rapid. This is not suitable for some laptops. It can be purchased from rapidonline.com.

2 1 Solder the motor driver circuit shown here. The motor driver circuit is used because the PICAXE 08M2 microchip does not provide enough power to the motor. Here we use the transistor as an electronic switch to turn the motor on and off. You will need two of these circuits (one for each motor) 2 For the wires which will be attached to the circuit board (Pin out, GND, VCC), create connectors for the header pins on the servo circuit board. The connectors here are striped wire with heat shrink. For small circuits, blue tack can be used to hold while soldering. The final two wires are 3 connected to the motor terminals. It s not important which way round they go as the voltage direction can be changed by swapping the You may need to attach a 10nF capacitor to the two connections on the terminals of the motor circuit board.

3 4 Print a design of a wheel, or draw a wheel on some paper. The wheel for this design is 50mm in diameter but you can make it any size. The bigger the wheel, the faster you robot will move. 5 Glue the design to some card and cut it out using some scissors. Do this step 3 or more times. The more times you do this step, the thicker your wheel will be. For small circuits, blue tack can be used to hold while soldering. Using some rubber 6 matting, cut a strip and glue to the outside edge of your wheel. Put a screw through the middle and screw the wheel to the motor shaft. Use some glue on the motor shaft to stop the wheel from slipping on the motor shaft.

4 7 Glue the motor onto the batter holder at either an angle or straight up. The image below shows the alternate with motor straight up. 8 For small circuits, blue tack can be used to hold while soldering. Glue the second motor on level with the first. Make sure the battery connector is facing out the back as shown here. The front face is needed for the ultrasonic range finder. 9 Glue two lollipop sticks to the back of the back of the battery holder so the battery holder does not drag on the floor when moving.

5 10 Glue a lollipop stick to the ultrasonic range finder and stick this to the front of your robot. Connect the female to female header connectors to the range finder. 11 Connect all the wires to the following positions on the circuit board. C.0 to Trig (HC-SR04) C.1 to left motor C.3 to Echo (HC-SR04) C.4 to right motor Then VCC and GND C.3

6 10 Now we can start programming Lollybot 2L! Open PICAXE Editor 6 Connect your cable to the robot and PC Check you have the correct COM port selected (COM 1 Communication Port if you are not using USB cable & AXE027 if you are using USB) This button downloads the program to the robot This is the type of chip This shows the connection type from PC to robot This is where we type our code Green status bar will appear here when downloading program to robot Type this code into PICAXE Editor 6 Click Download Turn on robot within 5 seconds 11 This code is going to be used to test the circuit and motors are working. Once downloaded you should see the motors turning forward together for 1 second then stopping, on a loop. If motors aren't moving forward, swap the motor power connectors on the circuit board. Starts the main program Turns pin C.4 and C.1 on (High) Waits 1 second Turns pin C.4 and C.1 off (Low) Waits 0.2 of a second Loops back to start

7 12 Below is the full working code for this project. This code reads the ultrasonic range finder on a loop until one of the if statement conditions are met, then when they are met they activate the sub routines. Start main project Send a pulse out of C.0 Read a pulse in on C.3 Wait 0.01 of a second Equation to convert time to distance Wait 0.05 of a second If statement for robot decision If this is true go to right sub routine Then fwd sub routine If this is true go sub routine fwd Ends if statements Continuous loop Sub routine to move the robot forward Sub routine to turn the robot right

8 Potential problems The program is not downloading to the robot: If you get a syntax error, it means there is something wrong with the code you have written. Any other error means you either: Haven't installed the correct driver for the cable Don't have batteries charged or inserted the correct way Haven t switched the robot on for programming Damaged the wire leading to the circuit board or switch Have not pushed the download cable full into the download slot Servo motor not moving: The servo motors are not designed to be turned by hand. They are quite delicate. Check to see you have the connector on the correct pit and in the correct orientation. New servo s are cheap if you damaged one. For this project, I recommend Tower pro SG90 from ebay. You can also upgrade to metal geared servo, MG90S by tower pro from ebay. It may sound silly but most problems are either the robot not receiving power or connections not in the correct position/orientation. Add-ons There are lots of different add-ons you could test out on this robot. I m not going to go into too much detail how use these but a quick internet search and you'll be well on your way. Inputs: Infrared control See PICAXE website or search internet. You can control your robot with a TV style remote. Switches Check PICXE website for how these should be connected. Note: You have available 1 more pin which is C.3 which can be set as an input.