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Re-add qetting started

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Samuel Sadok
2018-04-14 16:07:36 -07:00
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docs/developer-guide.md
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cd docs
gem install bundler
bundle install --path ruby-bundle
bundle exec jekyll serve
bundle exec jekyll serve --host=0.0.0.0
```
## Releases
docs/getting-started.md
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# Quick Start Guide
### Table of contents
<!-- MarkdownTOC depth=2 autolink=true bracket=round -->
- [Wiring up the ODrive](#wiring-up-the-odrive)
- [Downloading and Installing Tools](#downloading-and-installing-tools)
- [Start `odrivetool`](#start-odrivetool)
- [Configure M0](#configure-m0)
- [Position control of M0](#position-control-of-m0)
- [What's next?](#whats-next)
<!-- /MarkdownTOC -->
## Wiring up the ODrive
<div class="alert">
Make sure you have a good mechanical connection between the encoder and the motor, slip can cause disasterous oscillations.
</div>
All non-power I/O is 3.3V output and 5V tolerant on input, except:
<div class="alert" markdown="span"> __ODrive v3.2__: GPIO 3 and GPIO 4 are __not__ 5V tolerant.</div>
You will need:
* One or two [brushless motors](https://hackaday.io/project/11583-odrive-high-performance-motor-control/log/37666-hobby-motors-in-your-robots). It is fine, even recommended, to start testing with just a single motor and encoder.
* One or two [quadrature incremental encoder(s)](https://discourse.odriverobotics.com/t/which-encoders-to-choose/63/2)
* A power resistor. A good starting point would be a [0.47 ohm, 50W resistor](https://www.digikey.com/product-detail/en/te-connectivity-passive-product/HSA50R47J/A102181-ND/2056131)
<details><summary markdown="span">Do I really need a power resistor? What values to choose?</summary><div markdown="block">
If you don't have a brake resistor, the ODrive will pump excess power back into the power supply during deceleration to achieve the desired deceleration torque. If your power supply doesn't eat that power (which it won't if it's not a battery), the bus voltage will inevitebly rise. If you're unlucky this will break the power supply.
At some point, the ODrive's overvoltage protection will trip, after which both motors will be allowed to spin freely. Depending on your machine, this may or may not be a problem.
The power resistor values you need depends on your motor setup, and peak/average deceleration power.
To be on the safe side, think about what speed and current limits you want to set for the motor.
When braking at max speed and with maximum motor current, the power that is dissipated in the power resistor can be calulated as: `P_brake = V_emf * I_motor` where `V_emf = motor_kv * V_bus`.
</div></details>
* A power supply (12V-24V for the 24V board variant, 12V-48V for the 48V board variant). A battery is also fine.
1. Wire up the motor phases into the 3-phase screw terminals, and the power resistor to the AUX terminal. Wire up the power source to the DC terminal, make sure to pay attention to the polarity. Do not apply power just yet.
2. Wire up the encoder(s) to J4. The A,B phases are required, and the Z (index pulse) is optional. The A,B and Z lines have 3.3k pull up resistors, for use with open-drain encoder outputs. For single ended push-pull signals with weak drive current (\<4mA), you may want to desolder the pull-ups.
![Image of ODrive all hooked up](https://docs.google.com/drawings/d/e/2PACX-1vTCD0P40Cd-wvD7Fl8UYEaxp3_UL81oI4qUVqrrCJPi6tkJeSs2rsffIXQRpdu6rNZs6-2mRKKYtILG/pub?w=1716&h=1281)
## Downloading and Installing Tools
Most instructions in this guide refer to a utility called `odrivetool`, so you should install that first.
### Windows
1. Install Python 3. We recommend the Anaconda distribution because it packs a lot of useful scientific tools, however you can also install the standalone python.
* __Anaconda__: Download the installer from [here](https://www.anaconda.com/download/#windows). Execute the downloaded file and follow the instructions.
* __Standalone Python__: Download the installer from [here](https://www.python.org/downloads/). Execute the downloaded file and follow the instructions.
* If you have Python 2 installed alongside Python 3, replace `pip` by `C:\Users\YOUR_USERNAME\AppData\Local\Programs\Python\Python36-32\Scripts\pip`. If you have trouble with this step then refer to [this walkthrough](https://www.youtube.com/watch?v=jnpC_Ib_lbc).
2. Launch the command prompt.
* __Anaconda__: In the start menu, type `Anaconda Prompt` <kbd>Enter</kbd>
* __Standalone Python__: In the start menu, type `cmd` <kbd>Enter</kbd>
3. Install the ODrive tools by typing `pip install odrive` <kbd>Enter</kbd>
4. Plug in a USB cable into the microUSB connector on ODrive, and connect it to your PC.
5. Use the [Zadig](http://zadig.akeo.ie/) utility to set ODrive driver to libusb-win32.
* If 'Odrive version 3.x' is not in the list of devices upon opening Zadig, check 'List All Devices' from the options menu. With the Odrive selected in the device list choose 'libusb-win32' from the target driver list and select the large 'install driver' button.
### Linux/macOS
1. [Install Python 3](https://www.python.org/downloads/).
2. Install the ODrive tools by opening a terminal and typing `pip install odrive` <kbd>Enter</kbd>
3. __Linux__: set up USB permissions
```bash
echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="1209", ATTR{idProduct}=="0d[0-9][0-9]", MODE="0666"' | sudo tee /etc/udev/rules.d/50-odrive.rules
sudo udevadm control --reload-rules
sudo udevadm trigger # until you reboot you may need to do this everytime you reset the ODrive
```
## Start `odrivetool`
<div class="note" markdown="span">__ODrive v3.4 and earlier:__ Your board does not come preflashed with any firmware. Follow the instructions [here](odrivetool#device-firmware-update) before you continue.</div>
To launch the main interactive ODrive tool, type `odrivetool` <kbd>Enter</kbd>. Connect your ODrive and wait for the tool to find it. Now you can for instance type `odrv0.vbus_voltage` <kbd>Enter</kbd> to inpect the boards main supply voltage.
It should look something like this:
```python
ODrive control utility v0.4.0
Please connect your ODrive.
Type help() for help.
Connected to ODrive 306A396A3235 as odrv0
In [1]: odrv0.vbus_voltage
Out[1]: 11.97055721282959
```
The tool you're looking at is a fully capable Python command prompt, so you can type any valid python code.
## Configure M0
<div class="alert">Read this section carefully, else you risk breaking something.</div>
1. Set the limits:
<details><summary markdown="span">Wait, how do I set these?</summary><div markdown="block">
In the previous step we started `odrivetool`. In there, you can assign variables directly by name.
For instance, to set the current limit of M0 to 10A you would type: `odrv0.axis0.motor.config.current_lim = 10` <kbd>Enter</kbd>
</div></details>
* The current limit: `odrv0.axis0.motor.config.current_lim` [A]. The default current limit, for safety reasons, is set to 10A. This is quite weak, and good for making sure the drive is stable. Once you have tuned the drive, you can increase this to 75A to get some performance. Note that above 75A, you must change the current amplifier gains.
* Note: The motor current and the current drawn from the power supply is not the same in general. You should not look at the power supply current to see what is going on with the motor current.
* The velocity limit: `odrv0.axis0.motor.config.vel_limit` [counts/s]. The motor will be limited to this speed; again the default value is quite slow.
* You can change `odrv0.axis0.motor.config.calibration_current` [A] to the largest value you feel comfortable leaving running through the motor continously when the motor is stationary.
2. Set other hardware parameters:
* `odrv0.config.brake_resistance` [Ohm]: This is the resistance of the brake resistor. If you are not using it, you may set it to `0`.
* `odrv0.axis0.motor.config.pole_pairs`: This is the number of **magnet poles** in the rotor, **divided by two**. You can simply count the number of permanent magnets in the rotor, if you can see them. _Note: this is not the same as the number of coils in the stator._
* `odrv0.axis0.motor.config.motor_type`: This is the type of motor being used. Currently two types of motors are supported: High-current motors (`MOTOR_TYPE_HIGH_CURRENT`) and Gimbal motors (`MOTOR_TYPE_GIMBAL`).
<details><summary markdown="span">Which `motor_type` to choose?</summary><div markdown="block">
If you're using a regular hobby brushless motor like [this](https://hobbyking.com/en_us/turnigy-aerodrive-sk3-5065-236kv-brushless-outrunner-motor.html) one, you should set `motor_mode` to `MOTOR_TYPE_HIGH_CURRENT`. For low-current gimbal motors like [this](https://hobbyking.com/en_us/turnigy-hd-5208-brushless-gimbal-motor-bldc.html) one, you should choose `MOTOR_TYPE_GIMBAL`. Do not use `MOTOR_TYPE_GIMBAL` on a motor that is not a gimbal motor, as it may overheat the motor or the ODrive.
**Further detail:**
If 100's of mA of current noise is "small" for you, you can choose `MOTOR_TYPE_HIGH_CURRENT`.
If 100's of mA of current noise is "large" for you, and you do not intend to spin the motor very fast (omega * L << R), and the motor is fairly large resistance (1 ohm or larger), you can chose `MOTOR_TYPE_GIMBAL`.
If 100's of mA current noise is "large" for you, _and_ you intend to spin the motor fast, then you need to replace the shunt resistors on the ODrive.
</div></details>
* `odrv0.axis0.encoder.config.cpr`: Encoder Count Per Revolution (CPR). This is 4x the Pulse Per Revolution (PPR) value. Usually this is indicated in the datasheet of your encoder.
## Position control of M0
Let's get motor 0 up and running. The procedure for motor 1 is exactly the same, so feel free to replace read "axis1" wherever it says "axis0".
1. Type `odrv0.axis0.requested_state = AXIS_STATE_FULL_CALIBRATION_SEQUENCE` <kbd>Enter</kbd>. After about 2 seconds should hear a beep. Then the motor will turn slowly in one direction for a few seconds, then back in the other direction.
<details><summary markdown="span">What's the point of this?</summary><div markdown="block">
This procedure first measures your motor's electrical properties (namely phase resistance and phase inductance) and then the offset between the motor's electrical phase and the encoder position.
</div></details>
The startup procedure is demonstrated [here](https://www.youtube.com/watch?v=VCX1bA2xnuY).
Note: the rotor must be allowed to rotate without any biased load during startup. That means mass and weak friction loads are fine, but gravity or spring loads are not okay. Also note that in the video, the motors spin after initalisation, but in the current software the default behaviour is to do position control to position 0 (i.e. the position at startup)
<details><summary markdown="span">My motor doesn't beep or doesn't turn</summary><div markdown="block">
Make sure the motor wires are connected firmly. Check the value of `odrv0.axis0.error` and then refer to the [error code documentation](troubleshooting.md#error-codes) for details.
Once you have understood the error and fixed its cause, you may clear the error state (`odrv0.axis0.error = 0` <kbd>Enter</kbd>) and retry. You may also need to clear the error state of other subcomponents (e.g. `odrv0.axis0.motor.error`).
</div></details>
3. Type `odrv0.axis0.motor.config.pre_calibrated = True` <kbd>Enter</kbd> and then `odrv0.save_configuration()` <kbd>Enter</kbd>. This will save all the configuration and calibration you just did so the next time you start the device it's already ready to go. Except for one thing: you need to run the encoder offset calibration after every power cycle.
4. Type `odrv0.axis0.requested_state = AXIS_STATE_CLOSED_CONTROL_LOOP` <kbd>Enter</kbd>. From now on the ODrive will try to hold the motor's position. If you try to turn it by hand, it will fight you gently. That is unless you bump up `odrv0.axis0.motor.config.current_lim`, in which case it will fight you more fiercely.
## What's next?
You can now:
* Set the [tuning parameters](commands#tuning-parameters) for better performance
* Control the ODrive from your own program or hook it up to an existing system through one of it's [interfaces](interfaces)
If you have any issues or any questions please get in touch. The [ODrive Community](https://discourse.odriverobotics.com/) warmly welcomes you.