BRAT Biped SEQ Tutorial v2.01XE

<td valign="top" align="left">Biped BRAT SEQ Tutorial.

Updated 03/27/2008<!--webbot

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bot="Timestamp" i-checksum="12626" endspan -->.

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Safety first! Wear eye protection and never touch a powered robot!

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Note: This tutorial applies to the SSC-32 v2 with Register Support.

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Software:

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- BRAT Projects

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> <a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-bipeds/brat-biped-seq/WebHome/minibipd.zip">minibipd.zip</a></td>

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Image of Biped BRAT.</td>

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I. BRAT Configuration: SSC-32 Registers

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<td valign="top" align="left">Step 1.

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Download and install <a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/view/ses-software/lynxterm/" target="_blank">LynxTerm</a>. Connect the

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SSC-32 to the serial port and apply power. The green LED should light and stay on until it receives a valid serial command. Run the LynxTerm

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program.

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Step 2.

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Type "ver" and press "enter". You should see "SSC32-V2.01XE" or higher returned. However, if you have the firmware

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v2.01XE, there is still one more test you have to do. Due to an error on our part, the early v2.01XE firmware did not include register support,

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and will need to be updated.

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To test for register support on your 2.01XE firmware, click on "Reg.", then "Read", and

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enable "Initial Pulse Offset". Click on "Write", then click "Read".

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- If the option is still enabled, you have the proper version and can move on to Step 4.

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- If the option is now disabled, you need to update your firmware.

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Figure 2.</td>

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<td valign="top" align="left">Step 3.

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Download the 2.01XE firmware. Remove power from the

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SSC-32, and make sure the baud rate is set to 115.2k. Refer to the manual if you need more information regarding baud rate.

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Apply power to the SSC-32 again, make sure it's connected to the PC, and click on "Firmware" along

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the bottom of the LynxTerm screen.

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Click on "Open" and browse to the firmware file you just downloaded.

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Click on "Begin Update".

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Figure 3.</td>

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<td valign="top" align="left">Step 4.

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When the firmware has been successfully updated, click "Ok" then "Exit".

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Now repeat the ver test: type "ver" then press "Enter". You should see the proper firmware

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version returned.</td>

Figure 4.</td>

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<td valign="top" align="left">Step 5.

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Place the robot in a position as close to neutral as possible. Click on "All=1500" in the bottom right portion of the screen. Your

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robot should go to and hold the neutral position, and should resemble figures 5-2 and 5-3. If the joints are off by more than 15° you may have

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made an error in assembly. To correct this, remove the center screw from the round servo horn, pull the servo horn off the servo, rotate until

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it's aligned, then reattach the servo horn.</td>

Figure 5.</td>

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Figure 5-2.

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Figure 5-3.</td>

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<td valign="top" align="left">Step 6.

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From the main screen, click on "Reg" to open the Registers page.

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Click on "Default" to initialize default values.</td>

Figure 6.</td>

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<td valign="top" align="left">Step 7.

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You'll want to start with the robot's right hip. Select servo #2, then adjust the "Offset" slider until the joint is a perfect 90°

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angle.

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Note, the mouse's scrollwheel or keyboard's arrow keys can be used to make fine adjustments.

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Figure 7.</td>

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<td valign="top" align="left">Step 8.

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Now adjust the robot's right knee servo. Select servo #1, then adjust the "Offset" slider until the robot's leg is perpendicular to

the ground.</td>

Figure 8.</td>

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<td valign="top" align="left">Step 9.

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Now adjust the robot's right ankle servo. Select servo #0, then adjust the "Offset" slider until the robot's foot is perpendicular to

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the leg.

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Do the same for the robot's left side (servos 16, 17, and 18).</td>

Figure 9.</td>

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<td valign="top" align="left">Step 10.

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Click "Write" and exit LynxTerm when the write process is finished.

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Note, you can also check "Initial Pulse Width" to automatically enable the servos on power-up as an

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option. If you do, make sure you "Write" to save the changes. The next section of this tutorial allows Sequencer to enable the servos

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instead.

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This completes the BRAT configuration process for the SSC-32 registers. Now, whenever the robot is turned on,

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the servos will automatically be aligned and/or enabled.

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Figure 10.</td>

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II. BRAT Configuration: Sequencer

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<td valign="top" align="left">Step 1.

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Install the SSC-32 Visual Sequencer. Read the Sequencer's manual. This tutorial is not meant to replace the manual! Run the Visual Sequencer

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program.

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Click on "SSC-32" in the upper left corner. This process configures the software to the servos in

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your robotic assembly. To do this, the servos' min and max positions are defined and the actual angles each joint can achieve are entered.

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Take time to do an accurate configuration! Your robot will only perform as well as the accuracy of the

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configuration file it's using. In other words, sloppy configuration will make a sloppy robot when sharing projects.

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Figure 1.</td>

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<td valign="top" align="left">Step 2.

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Each servo you configure must first be enabled. You simply click on the Enable checkbox. You can move the servo by adjusting the slider bar.

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You will enable the servos one at a time as you configure them.

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Figure 2.</td>

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<td valign="top" align="left">Step 3.

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Move the slider for servo 0 until the servo is at a 45° angle as shown.

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Right click on the slider and select "Set position as min" from the menu as shown in Figure 3-2.

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Adjust the "Min Deg" box to say "-45°" as shown in Figure 3-3.

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Figure 3-1.</td>

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Figure 3-2.

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Figure 3-3.</td>

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<td valign="top" align="left">Step 4.

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Move the slider for servo 0 until the servo is at an 84° angle as shown.

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Right click on the slider and select "Set position as max" from the menu as shown in Figure 4-2.

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Adjust the "Max Deg" box to say "84°" as shown in Figure 4-3.

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Move the slider back to 0° before going on to the next servo.

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Figure 4-1.</td>

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Figure 4-2.

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Figure 4-3.</td>

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<td valign="top" align="left" colspan="2">Step 5.

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Channel 1 is for the BRAT's right knee. Adjust and set the min and max positions as shown in Figure 5-1 and 5-2. Note, you do not have to change

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the angles because the knee can reach +/-90°.

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Move the slider back to 0° before going on to the next servo.

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Figure 5-1.

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Figure 5-2.</td>

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<td valign="top" align="left" colspan="2">Step 6.

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Channel 2 is for the BRAT's right hip. Adjust the hip as in Figure 6-1 and set the minimum (-90°) position. Adjust the hip as in Figure 16-2

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and set the maximum (45°) position. For clarity, the knees were bent in Figure 6-2.

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Move the slider back to 0° before going on to the next servo.

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Figure 6-1.

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Figure 6-2.</td>

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<td valign="top" align="left">Step 7.

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The robot's right side is now configured. You can now configure the robot's left side. Click on the "Bank 3" button to gain access to

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channels 16-23. Channel 16 is the right ankle, 17 is the right knee, and 18 is the right hip. Configuring these channels is identical to

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configuring channels 0-2 with one exception: After you are done with the normal configuration, you must click on the "Reverse"

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checkbox for these three channels! Make sure all servos are set to 0° (home) and save your work. For this robot, "home" position is

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with all the servos set to their 0° position. However, any position you leave the sliders in when you save the configuration is how the robot

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will look when you start Sequencer. In other words, "home" position does not have to be the 0° position, that's just what we used.</td>

Figure 7.</td>

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<td valign="top" align="left" colspan="2">Save your work! The .cfg file will need to be loaded

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each time you run the program. If you only have one robot to set up, save over the "ConfigSSC32.cfg" file. However, if you plan on

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using the sequencer with more than one robot, then input a new file name, such as "BipedBRAT.cfg" It's important that you save these

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files in the install directory, default C:\Program Files\Sequencer_SSC-32\</td>

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<td valign="top" align="left">Step 8.

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Now we're going to import a pre-made project. This will enable you to use other people's projects on your robot.

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Download <a href="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-bipeds/brat-biped-seq/WebHome/minibipd.zip">this zip file</a>. It contains several projects. Unzip it into the

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SEQ install directory. By default, it is C:\Program Files\Sequencer_SSC-32\

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Click on "Project" in the upper left corner.</td>

Figure 8.</td>

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<td valign="top" align="left">Step 9.

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Click on "Import," then select "biped6-long stride.csv" and click "Open," then "OK."

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Enter a project name or leave the default, then click "OK." You should see an "Import

success" message.

Click "Exit."

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Figure 9.</td>

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<td valign="top" align="left">Step 10.

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Now for some fun! Let's make that robot walk!

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Click on "Sequencer" as shown in Figure 10-1.

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From the drop down menu in the project section, select "biped6-long stride."

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In the Play menu, click on "Project Loop" as shown in Figure 10-3. Caution, the robot will start

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moving immediately. To stop the robot, click on the black "stop" or "pause" buttons.

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If everything went well, your robot should have walked across the table. If it appears that the legs are moving

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in the same positions, you may have forgotten to reverse the servos on the robot's left side.

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Figure 10-1.</td>

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Figure 10-2.</td>

Figure 10-3.</td>

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<td valign="top" align="left">Step 11.

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Refer to Table 11 for a list of the projects included in the zip file and a video link when available.

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After you're comfortable with playing projects, you can consult the Sequencer manual for more information on

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how to create your own. Remember to send us images and videos of your cool projects so we can publish them online!

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<td align="center" bordercolor="#808080" bgcolor="#C0C0C0">Project File</td>

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<td align="center" bordercolor="#808080" bgcolor="#C0C0C0">Video Link</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Balance on Ankle</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv04.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Balance</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv06.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv05.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Get up from Front</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv01.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Headbutt</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv07.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv03.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Long Stride</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv08.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv09.mpg">Video</a>></td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF"><<a href="http://www.lynxmotion.com/images/video/bp6srv02.mpg">Video</a>></td>

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Table 11

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III. Creating a Walking Sequence

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<td valign="top" align="left">Step 1.

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Run the Sequencer program.

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Select the "empty" project from the Project drop down menu, and click on the black "+" to

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make a new project. Enter a name for your project. As we are making the robot walk, a name such as "BRAT-Walk" might be applicable.</td>

Figure 1.</td>

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<td valign="top" align="left">Step 2.

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Now we're faced with an empty project and a screen full of servo blocks. To make the screen more manageable, click on "Swap" at the

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top. This will swap the selected servos with the unselected ones. Since no servos are unselected, this will clear the screen.

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Now just click on the servos that you need, which should be servos 0, 1, 2, 16, 17, and 18.</td>

Figure 2.</td>

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<td valign="top" align="left">Step 3.

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You can click and drag the servo boxes to arrange them so they resemble the robot's physical layout.</td>

Figure 3.</td>

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<td valign="top" align="left">Step 4.

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You can also name the servos by clicking on the number in the servo box. It will bring up the screen in Figure 4. In addition to naming the

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servo, you can change the color of the servo box.</td>

Figure 4.</td>

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<td valign="top" align="left">Step 5.

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Now we're almost ready to make the robot walk. First, here's an outline of the walking sequence. The last two steps are just mirror images of

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the first two steps.</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Shift weight to robot's right</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Step forward</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Shift weight to robot's left</td>

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<td align="center" bordercolor="#C0C0C0" bgcolor="#FFFFFF">Step forward</td>

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Table 5.</td>

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</center></div>

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<td valign="top" align="left">Step 6.

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To make this project even easier, click on the "A<img border="0" src="https://wiki.lynxmotion.com/info/wiki/lynxmotion/download/servo-erector-set-robots-kits/ses-v1-robots/ses-v1-bipeds/brat-biped-seq/WebHome/link.gif" >B"

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button in the lower left corner. This screen allows you to link servos together. Click on "Servo 1" on the left side and "Servo

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17" on the right, then click "Add." Do the same with Servos 2 and 18. This will allow you to switch the positions of the right

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and left legs with just a few clicks.</td>

Figure 6.</td>

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<td valign="top" align="left">Step 7.

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The first step in this walk is to get the robot into position to take a stride in the second step. Set your servos to the degrees shown in Table

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7. They don't have to be exact; close will do. When you're done, click on the red "=" in the Step section to overwrite Step 1.

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Table 7.</td>

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Figure 7.</td>

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<td valign="top" align="left">Step 8.

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Now, click on "A<=>B" and deselect the "Selected step" check box and click OK. Then click the green "+" in

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the Step section to add the current position as a new step.</td>

Figure 8.</td>

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<td valign="top" align="left">Step 9.

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To shift the robot's weight, just use the sliders and switch the degrees for Servos 0 and 16. Click on the green "+" in the Step

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section when you're done to add this as a new step.</td>

Figure 9.</td>

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<td valign="top" align="left">Step 10.

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Now all you have to do is take another step! Click on the "A<=>B" button again, deselect "Selected step" if it

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isn't already, and click OK. Click on the green "+" in the Step section when you're done.</td>

Figure 10.</td>

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<td valign="top" align="left">Step 11.

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To test the walk sequence, click on the sequence loop button on the right side of the screen under "Play." You can stop or pause the

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walking sequence from the Play menu.

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If you were successful, the robot should be walking now. If the robot doesn't walk in a straight line, try

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increasing the ankle degrees so that more weight is shifted.

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Figure 11.</td>

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<td valign="top" align="left">Step 12.

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To adjust the biped's walking speed, you can use the "Advanced Play" feature. Click on the Advanced Play button on the right side of

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Figure 12.</td>

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<td valign="top" align="left">Step 13.

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By moving the Time slider, you will adjust the speed of all the servos in the project to a percentage of the normal speed. 100% is the project's

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normal speed. Moving the slider below 100% causes the robot to move faster, while above 100% slows the robot down.

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Click on the Loop button to test your new speed. You can tweak the speed while the robot is moving to get it

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perfect.

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If you click on the Apply button, the new speed will be applied to the project. </td>

Figure 13.</td>

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