This page outlines some of the alternate pieces that can be used for building.

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1 Artbotics Exploring Mechanisms with Lego Mindstorms EV3 This packet contains information on each mechanism you will be using, including a to-scale image of all of the pieces needed to build each one and a short programming exercise to make each mechanism move. This page outlines some of the alternate pieces that can be used for building. Color Changes All of the pieces needed to build each mechanism are available in the EV3 kit, but the color of each piece may be different than what is depicted in the Lego Digital Designer model. Technic bars with many holes may be white instead of gray. Technic bars with three holes may be red, green, blue, or yellow. Shafts and crank connectors may be black or gray. Connector pegs may be black, blue, or beige. Similar Sized Pieces Some pieces in this guide are labeled, meaning that a piece of that exact length or size does not need to be used; a piece of similar size can be used in place of it. Long technic bars labeled as can vary by a couple of units and still be used for building the mechanism. The same goes for shafts labeled as.

2 Exploring Mechanisms with Lego Mindstorms EV3 There are three mechanisms we will focus on: cranks, gears, and cams. All three take a single rotary movement and convert it into a new form of motion. For each one below there is a corresponding Lego Digital Designer file that you can open on your computer; it will instruct you on how to build each mechanism. Starting up the Lego Digital Designer Software Double-click the icon on the desktop labeled Lego Digital Designer. Once the program opens, click the Free build icon in the middle window. Crank The crank converts a single rotary movement into a smooth waving motion. To build the crank: In Lego Digital Designer click File > Open and navigate to the folder on the Desktop labeled Lego Models. Open the file Artbotics_Crank_EV3.lxf In the top-right click the Building guide mode icon. This will instruct you on how to build the crank. Follow the steps by clicking the left and right arrows at the top of the screen. This is just one of many ways to build a waving crank. Many qualities of the crank can be adjusted to change the kind of waving motion it will produce: The connector and end bar can vary in size The connector and end bar joint placement can vary The end bar to ground bar joint placement can vary

3 Waving Crank Parts List Refer to Artbotics_Crank_EV3.lxf in Lego Digital Designer for building instructions. 1/10 2/10 3/10 4/10 5/10 6/10 (motor not to scale) 7/10 8/10 9/10 artbotics.org

4 Crank Programming Exercise How to control motors Now that the crank is built we will write a short program to make it move. Plug the motor into port B on the EV3 brick. Before continuing to the next exercise, you should always click File > Save Project. Then, click File > Add Program to start a new program within that project. 1. Drag a Large Motor block and drop it to the right of the sequence beam. 2. Ensure the port on this block is set to B, and adjust the power to 50 and duration to 3 rotations. 3. Add another Large Motor block and set it s port to B. Adjust its power to -75 and duration to 3 rotations. 4. Make sure the EV3 brick is turned on and connect the USB to both your computer and the EV3. 5. Locate the download controller in the lower right of your work area and click the center (play) button. (Download and run) Action: Your crank should rotate 3 times in one direction, then 3 times in the opposite direction at a faster speed. Final sequence beam

5 Gears A set of gears converts a single rotary movement into multiple rotary movements with different speeds. To start you can build a set of gears that makes the motor movement faster or slower: In Lego Digital Designer click File > Open and navigate to the folder on the Desktop labeled Lego Models. Open the file Artbotics_Gears_Faster_EV3.lxf or Artbotics_Gears_Slower_EV3.lxf In the top-right click the Building guide mode icon. This will instruct you on how to build the crank. Follow the steps by clicking the left and right arrows at the top of the screen. This is the gear mechanism built to produce a slower motion than the initial motor movement. There are many ways to build a set of gears to change motor speeds, and within one set of gears both fast and slow movements can be achieved. In short, a gear with more teeth will move slower than a gear with less teeth, and a gear with less teeth will move faster than a gear with more teeth. This is because the number of teeth and size of the gear change how long it takes to complete one full revolution. There are three sizes of gears we can use: A large gear against a medium gear would have a ratio of 40:24, or reduced to 5:3. A medium gear against a small gear would have a ratio of 24:8, or reduced to 3:1. A large gear against a small gear would have a ratio of 40:8, or reduced to 5:1.

6 Gears Parts List Refer to Artbotics_Gears_Faster_EV3.lxf in Lego Digital Designer for building instructions. 1/9 2/9 3/9 4/9 5/9 6/9 7/9 8/9 9/9 (motor not to scale) artbotics.org

7 Gears programming exercise How to loop and repeat commands With a set of gears built we will write a short program to make it move. Plug the motor into port B on the EV3 brick. You can first try out your set of gears by running the crank program from the previous exercise. Before continuing to the next exercise, you should always click File > Save Project. Then, click File > Add Program to start a new program within that project. 1. Click on Flow Control (orange/2 nd tab) on the color palette located at the bottom of the screen. Drag and place a Loop block on the sequence beam. Any blocks placed inside of a Loop block will repeat for a specified number of times, forever, for a specific length of time, based on sensor input, or based on a true/false condition 2. After placing the Loop block on the sequence beam, adjust its duration by clicking the infinity icon. From the pop-up list, change it from Unlimited to Count, then change the count by clicking on the number 1. Once highlighted, type the number 4. This will set the loop to repeat 4 times. 3. Add a Large Motor block within the Loop block from the green/action tab in the programming palette. Change the port to B. Adjust the power to 25 and its duration to 4 rotations. 4. Add another Large Motor block within the Loop block, to the right of the first Large Motor block. Change its port to B, adjust its power to 75, and duration to 4 rotations. 5. Make sure the EV3 brick is turned on and connect the USB to both your computer and the EV3 6. At this point, you should save your program, and give it a filename. After saving, click the download button (the button on the bottom right of the screen), then disconnect the USB cable. Now your program is downloaded to the EV3 brick. Action: Your gears should rotate 4 times at a slow speed, 4 times at a faster speed, and then repeat 4 times.

8 Cams A cam converts rotary movement to linear motion. There is no Lego piece in the Mindstorms EV3 kit that will properly function as a cam, so one must be made out of foam core and electrical tape. To build the rest of the cam mechanism: In Lego Digital Designer click File > Open and navigate to the folder on the Desktop labeled Lego Models. Open the file Artbotics_Cam_EV3.lxf In the top-right click the Building guide mode icon. This will instruct you on how to build the crank. Follow the steps by clicking the left and right arrows at the top of the screen. A cam is a curved piece that rotates and moves its accompanying follower. There are many different types of cams that can be built: There are two Lego pieces that can be used as cams (shown above). You can also build your own. To build a cam, cut a shape out of foam core or cardboard using an exacto knife (only on a cutting mat or over another piece of foam core or cardboard not directly on a table!). Seal the outside of the cam using electrical tape; this will make the surface smoother.

9 Cam Parts List 1 Refer to Artbotics_Cam_EV3.lxf in Lego Digital Designer for building instructions. 1/18 2/18 3/18 (motor not to scale) 4/18 6/18 7/18 8/18 9/18 artbotics.org

10 Cam Parts List 2 Refer to Artbotics_Cam_EV3.lxf in Lego Digital Designer for building instructions. 10/18 12/18 13/18 14/18 (brick not to scale) 16/18 17/18 artbotics.org

11 Cams Programming Exercise With a cam shaft built we will write a short program to make it move. Plug the motor into port B on the EV3 brick. Keep in mind that a cam shaft may only function properly when rotating in a certain direction. Experiment with how your cam rotates before deciding on a direction. Before continuing to the next exercise, you should always click File > Save Project. Then, click File > Add Program to start a new program within that project. 1. Place a Loop block on the sequence beam. The default state of a Loop block s duration is Unlimited. That is the setting we need for this step, so we do not have to adjust it. 2. Add a Large Motor block inside of the Loop block. Change it to port B and click on the icon in the bottom left and choose On for Seconds. Adjust the power to 25 and the duration to 5 seconds. 3. Click on Flow Control (orange/2 nd tab) on the color palette located at the bottom of the screen. Drag and place a Wait block after the Large Motor block. Change the duration of the Wait block to 2 seconds. This will make your program pause for 2 seconds. Action: Your cam should rotate for 5 seconds, stop for 2 seconds, and then repeat forever. Final Sequence beam For more information on Artbotics see artbotics.org Please send any questions or comments to Adam Norton at anorton@cs.uml.edu