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====== How To Move Gantry Using Visual Studio C++ ======

**Author:** Yunki Hong and Myong Geon Kim Email: m.geon.kim@gmail.com
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**Date:** Last modified on <06/20/19>
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**Keywords:** Tutorial, how to, step-by-step, gantry, CPP, intern
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{{ mgkim:gantry_1.jpg?600 |}}

===== Motivation and Audience =====
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This tutorial offers you the step-by-step method to control DASL Gantry crane with modifying Dynamixel SDK in Windows environment. 
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Readers of this tutorial assumes the reader has the following background and interests: 
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<fc blue>  
  * Basic background of CPP \\
  * Full understanding of Dynamixel tutorial : [[dynamixel_set_up|Dynamixel tutorial]] \\
  * Full understanding of Modifying Dynamixel SDK code : [[dynamixel_modification|Modifying Dynamixel SDK code]]
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</fc>
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The rest of this tutorial is presented as follows:
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  * [[how_to_move_gantry#gantry_set_up|Gantry Set Up]] \\
  * [[how_to_move_gantry#moving_x_axis|Moving X axis]] \\
  * [[how_to_move_gantry#moving_backward|Moving Backward]] \\
  * [[how_to_move_gantry#moving_all_axis|Moving All axis]] \\
  * [[how_to_move_gantry#go_home|How to go back home]] \\
  * [[how_to_move_gantry#accuracy|Accuracy]] \\
  * Final Words
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==== Gantry Set Up ====
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First of all, Dynamixels installed in DASL Gantry are MX-106 model. You should check control table for MX-106. 
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Here is the link. http://emanual.robotis.com/docs/en/dxl/mx/mx-106/
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You would find that there is no address or parameter difference between MX-28, Fortunately.
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We are going to use this power supply for Gantry because we can switch off the power when we need an emergency stop.
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{{ mgkim:ds_18.jpg?200 |}}
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<fc blue>
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Just turn the switch backward for an emergency stop
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</fc>
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The photo below is the basic structure of gantry system. 
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{{ mgkim:ds_16.jpg?200 |}}
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You need to measure some dimensions of this system for distance control.
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{{ mgkim:ds_17.jpg?200 |}}
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This photo will help you to understand the system.

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==== Moving X axis ====
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For moving gantry to x axis, we will use Dynanixel #1,2
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In gantry system, rotation angle of Dynamixel during sleep time will be changed to displacement of belt.
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So we need to do measurement and calculation to move gantry.
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If we know exact distance between each teeth in the belt and gear, 
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we can calculate displacement of belt accurately.
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- Measurement
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G1 = 28 teeth , G2 = 14 teeth, G3 = 24 teeth
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Distance between teeth = 5mm = 0.5 cm
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1 dynamixel speed unit = 0.11445 rpm
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- Calculation
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{{ mgkim:ds_19.jpg?600 |}}
{{ mgkim:ds_20.jpg?600 |}}
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Now we know sleep time we need.
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<fc blue>
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=======================================================================================================
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Exercise. Using only Gantry Dynamixel #1 and #2, make Dynamixels actuate until they reach to desired distance. 
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Set the moving speed value as 200 (Gantry will not work if the moving speed is too high). 
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Here is an {{https://drive.google.com/file/d/1fj95C_-Pr8NK6m9B8G-3SAEY4oNIW3Ph/view?usp=sharing|answer}}
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=======================================================================================================
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</fc>
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==== Moving Backward ====
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Problem of previous code is that gantry can not move backward.
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How can we modify code to move backward?
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Discover the method in this code. 
{{https://drive.google.com/file/d/1_2MN9d0GRw5eQWwrcQUP9LzIKec4Tt1c/view?usp=sharing|Moving backward}}
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==== Moving All axis ====
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Now you know everything to move all axis.
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<fc blue>
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=======================================================================================================
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Exercise. Move gantry along all axis.(X,Y,Z axis)
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Here is an {{https://drive.google.com/file/d/1NNSCatAnJ9nLW2lZw1tIvLvpOPigcs57/view?usp=sharing|answer}}
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=======================================================================================================
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</fc>
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==== How to go back home ====
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After moving it, gantry need to go back to home position for next use.
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If we know current position of gantry, going back to home position is easy.
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<fc blue>
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=======================================================================================================
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Exercise. Lets make it go back to home location after we move gantry.
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Here is an {{https://drive.google.com/file/d/1lJ9_IZ4xCaNBoBDNQAfajQw0aeIAMgSX/view?usp=sharing|answer}}
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=======================================================================================================
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</fc>
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==== Accuracy ====
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Now you are ready to check the accuracy of your code.
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{{ mgkim:ds_21.jpg?600 |}}
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There is a plate where the 10cm by 10cm grid is drawn.
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Try setting the origin at any intersecting point and run your code at 10cm resolution.
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If it is accurate enough, try narrowing down the resolution at 5cm. 
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If not, find out the problems by yourself. 
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The reason would be poor measurement or hardware out of work.
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Checking the tension of the threads would help you finding problems.
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==== Final Words ====


For questions, clarifications, etc, Email: m.geon.kim@gmail.com