91 lines
5.7 KiB
Markdown
91 lines
5.7 KiB
Markdown
## Micro Manipulator Stepper
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This project contains an open source low-cost, easy-to-build motorized **XYZ Micro-Manipulator** motion control platform achieving sub micrometer precision.
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It's designed for applications such as optical alignment, probing electronic components, and microscopy.
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Check out the YouTube video for more information about the device and how it is built:
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[](https://youtu.be/MgQbPdiuUTw)
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Thanks to its parallel kinematic structure and miniature ball joints, it achieves good mechanical stiffness and a large range of motion.
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The motors are off the shelf stepper motors driven by a 30 kHz closed loop controller and a very precise PWM signal.
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A 'magnetic gearing' approach increases the resolution of the low-cost magnetic rotary encoders by a factor of 30 allowing for steps down to 50nm
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(**Please mind the difference between resolution and accuracy**. The absolute accuracy is much lower).
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The device can be controlled via simple G-Code commands over a USB serial interface and is thus easily integrated into other projects.
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The firmware implements a complete motion planning stack with look-ahead for smooth and accurate path following capabilities.
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### ⚙ CAD-Files
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All CAD models are made in **FreeCAD** to allow everyone to view and modify the design without subscribing or paying for a proprietary CAD solution.
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Note that most components are already designed with the goal to make them easily machinable on a 3-Axis CNC-Mill.
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You can also 3D-Print the parts but have to live with thermal drift (carbon filled filaments can reduce this problem).
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<div style="display: flex;">
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<img src="images/FreeCAD-Model.jpg" alt="FreeCAD Model" width="50%">
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</div>
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<br>
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The files can be found here: [CAD Models](construction).
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Please note that FreeCAD version **1.1.0dev** was used, and the files might not work with older versions.
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### ⚙ Kinematic Model
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The kinematic model is defined here: [kinematic_model_delta3d.cpp](firmware/MotionControllerRP/src/kinemtaic_models/kinematic_model_delta3d.cpp).
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Please check the dimensions of your build against the values set in the constructor. In particular, make sure the arm length matches.
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### ⚙ Electronics
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IMPORTANT: If you fabricated PCB verion v1.2 (see version label on the board) you need to drill out a misplaced via on diode D1 that shorts 5V rail to ground. The problem was fixed in v1.3.
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The electronics are designed in **KiCAD** and only commonly available modules (motor drivers and MCU boards) are used and connected by a simple PCB. No SMD soldering is required to populate the board to make the build extra accessible.
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For usual winding resistance of your motors, the device should be powered by $${\color{lightgreen} 5V-6V }$$ (2A) to keep current and heating to a reasonable level.
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<div style="display: flex; gap: 5%;">
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<img src="images/Kicad-Board.jpg" alt="Image 1" style="flex: 1; object-fit: contain; height: 10vw;">
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<img src="images/ControllerPCB.jpg" alt="Image 2" style="flex: 1; object-fit: contain; height: 10vw;">
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</div>
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### ⚙ Firmware
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The firmware is written in C++ and takes some inspiration from the 'SimpleFOC' project. It aims to be streamlined and readable without any extra fuss, focusing on the hardware used in this project.
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It implements path planning with look-ahead and, unlike many other motion controller projects, supports true 6DOF-Pose interpolation and planning, making it ready for driving hexapod motion platforms; that may or may not be the next step for this project.
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You may find configuration for pin numbers, motor type, and other parameters in [hw_config.h](firmware/MotionControllerRP/src/hw_config.h). Please check them before uploading the firmware.
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<div style="display: flex; gap: 5%;">
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<img src="documentation/firmware/firmware_overview.png" alt="Image 1" width="50%">
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<img src="documentation/firmware/path_planning.png" alt="Image 2" width="50%">
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</div>
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#### Building and Flashing the Firmware
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For building and flashing the firmware, Visual Studio Code (available for free on Windows and Linux) is recommended.
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Install the PlatformIO add-on and open the firmware folder. You can now build and flash the firmware like any other PlatformIO project.
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### ⚙ G-Code Interface
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The firmware supports only a small subset of G-Code commands listed below.
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Each command is acknowledged with either an **`ok`** or **`error`** response.
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If a command provides additional information (e.g., the *get position* command), that information is returned **before** the `ok` message.
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The client must wait for an acknowledgment from the previous command before sending the next one—otherwise, behavior is undefined.
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| Command | Description |
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|----------------|-----------------------------------------------------------------------------|
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| `G0 X Y Z F` | Move the end-effector in a straight line to the specified position. <br> • `X`: target position on X-axis <br> • `Y`: target position on Y-axis <br> • `Z`: target position on Z-axis <br> • `F`: feed rate (movement speed) |
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| `G1 X Y Z F` | Same as `G0`. |
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| `M204 L A` | Set current acceleration. <br> • `L`: linear acceleration (m/s²) <br> • `A`: angular acceleration (rad/s²) |
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| `M50` | Get current actuator pose (position). |
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| `M51` | Get motion controller and servo loop update frequency. |
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| `M52` | Get the number of items in the planner queue. |
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| `M53` | Check if all moves are finished. Returns `1` if finished, `0` otherwise. |
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# Youtube Video
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[](https://youtu.be/MgQbPdiuUTw)
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