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20 changes: 10 additions & 10 deletions
20
content/sdk/development/_index.md → content/sdk/advanced/_index.md
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,10 +1,10 @@ | ||
| --- | ||
| title : "Developing with Python SDK" | ||
| description: "Use Reachy 2 Python SDK." | ||
| lead: "" | ||
| date: 2023-07-25T17:37:16+02:00 | ||
| lastmod: 2023-07-25T17:37:16+02:00 | ||
| draft: false | ||
| images: [] | ||
| type: docs | ||
| --- | ||
| --- | ||
| title : "Advanced Python SDK features" | ||
| description: "Use Reachy 2 Python SDK, advanced features." | ||
| lead: "" | ||
| date: 2023-07-25T17:37:16+02:00 | ||
| lastmod: 2023-07-25T17:37:16+02:00 | ||
| draft: false | ||
| images: [] | ||
| type: docs | ||
| --- |
138 changes: 69 additions & 69 deletions
138
...nt/sdk/mobile-base/drive-control-modes.md → content/sdk/advanced/mobile-base.md
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,70 +1,70 @@ | ||
| --- | ||
| title: "Advanced" | ||
| description: "Drive modes and control modes description for the mobile base." | ||
| date: 2023-07-26T08:32:17+02:00 | ||
| lastmod: 2023-07-26T08:32:17+02:00 | ||
| draft: false | ||
| images: [] | ||
| type: docs | ||
| toc: true | ||
| weight: "160" | ||
| --- | ||
| ## Drive modes | ||
| ### Overview | ||
| The drive mode impacts the way the mobile base accepts commands. We could say it's the current state of the mobile base. | ||
|
|
||
| In most cases, there is no need to think about these modes or to handle them in your code. Below are the most common use cases. | ||
| * If you want to use the set_speed method to spam speed commands (e.g. pilot the robot with a controller), the mode has to be manually changed to 'cmd_vel': | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'cmd_vel' | ||
| ``` | ||
| * If you want to push the robot easily, this will set the wheels in a compliancy state: | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'free_wheel' | ||
| ``` | ||
| * On the contrary, if you want the robot to apply a passive resistance to movement, use: | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'brake' | ||
| ``` | ||
|
|
||
| You can use this [Jupyter Notebook](https://github.com/pollen-robotics/mobile-base-sdk/blob/main/mobile_base_sdk/examples/notebooks/drive-modes.ipynb) to explore the drive modes with your mobile base. | ||
|
|
||
| ### Detailed behaviour | ||
| This section is only useful if you intend to interact directly with the Hardware Abstraction Layer (HAL). | ||
|
|
||
| Six drive modes are available for the mobile base: | ||
| * **cmd_vel**: in this mode, speed instructions can be spammed to the wheels controllers. This mode is used for the *set_speed* method. | ||
| * **brake**: in this mode, the wheels will be stiff. | ||
| * **free_wheel**: in this mode, the wheels will be as compliant as possible. | ||
| * **emergency_stop**: in this mode, the wheels will stop receiving mobility commands. Switching to this mode will also stop the mobile base hal code. This is a safety mode. | ||
| * **speed**: another mode to send speed instructions, but less frequently than with the cmd_vel mode. This mode is actually not used at this level (python SDK level), but is implemented at the ROS level, in case one might need it. | ||
| * **goto**: this mode is used for the *goto* method. | ||
|
|
||
| *note: the 'speed' and 'goto' modes can't be changed by hand. The drive mode is handled automagically when requesting a set_speed or a goto.* | ||
|
|
||
| The code for the [HAL can be found here](https://github.com/pollen-robotics/zuuu_hal) | ||
|
|
||
| ## Control modes | ||
| ### Overview | ||
| The control mode dictates the low level control strategy used by the mobile bases's HAL. | ||
|
|
||
| Two control modes are possible: | ||
| * ***open_loop*** (default mode): in this mode, the wheels are compliant and the control is smoother. | ||
| ```python | ||
| reachy_mobile.mobile_base.control_mode = 'open_loop' | ||
| ``` | ||
|
|
||
| * ***pid***: in this mode, the wheels are stiff and the control is more precise. | ||
| ```python | ||
| reachy_mobile.mobile_base.control_mode = 'pid' | ||
| ``` | ||
| :bulb: We recommend that you run the following [Jupyter Notebook](https://github.com/pollen-robotics/mobile-base-sdk/blob/main/mobile_base_sdk/examples/notebooks/control-modes.ipynb) to get a feel of what the control mode does. | ||
|
|
||
| ### Detailed behaviour | ||
| Regardless of how the mobile base is piloted (goto, set_speed, controller), the HAL always ends up calculating a goal rotational speed for each wheel. | ||
| The control mode only changes the used strategy to reach that rotational speed. | ||
| * In the open_loop mode, a simple affine model was identified to match a PWM to a goal rotational speed. The VESC controllers then apply the PWM directly to the motors of the wheels, without any other low level control. The measures can be found [here](https://github.com/pollen-robotics/zuuu_hal/tree/main/measures). While the model is simple, it does account for the static friction and the experimental data shows a good fit when the mobile base is on a flat surface. | ||
|
|
||
| {{< img-center "images/sdk/mobile-base/affine_pwm_model.png" 400x "" >}} | ||
|
|
||
| --- | ||
| title: "Mobile base drive and control modes" | ||
| description: "Drive modes and control modes description for the mobile base." | ||
| date: 2023-07-26T08:32:17+02:00 | ||
| lastmod: 2023-07-26T08:32:17+02:00 | ||
| draft: false | ||
| images: [] | ||
| type: docs | ||
| toc: true | ||
| weight: "160" | ||
| --- | ||
| ## Drive modes | ||
| ### Overview | ||
| The drive mode impacts the way the mobile base accepts commands. We could say it's the current state of the mobile base. | ||
|
|
||
| In most cases, there is no need to think about these modes or to handle them in your code. Below are the most common use cases. | ||
| * If you want to use the set_speed method to spam speed commands (e.g. pilot the robot with a controller), the mode has to be manually changed to 'cmd_vel': | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'cmd_vel' | ||
| ``` | ||
| * If you want to push the robot easily, this will set the wheels in a compliancy state: | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'free_wheel' | ||
| ``` | ||
| * On the contrary, if you want the robot to apply a passive resistance to movement, use: | ||
| ```python | ||
| reachy_mobile.mobile_base.drive_mode = 'brake' | ||
| ``` | ||
|
|
||
| You can use this [Jupyter Notebook](https://github.com/pollen-robotics/mobile-base-sdk/blob/main/mobile_base_sdk/examples/notebooks/drive-modes.ipynb) to explore the drive modes with your mobile base. | ||
|
|
||
| ### Detailed behaviour | ||
| This section is only useful if you intend to interact directly with the Hardware Abstraction Layer (HAL). | ||
|
|
||
| Six drive modes are available for the mobile base: | ||
| * **cmd_vel**: in this mode, speed instructions can be spammed to the wheels controllers. This mode is used for the *set_speed* method. | ||
| * **brake**: in this mode, the wheels will be stiff. | ||
| * **free_wheel**: in this mode, the wheels will be as compliant as possible. | ||
| * **emergency_stop**: in this mode, the wheels will stop receiving mobility commands. Switching to this mode will also stop the mobile base hal code. This is a safety mode. | ||
| * **speed**: another mode to send speed instructions, but less frequently than with the cmd_vel mode. This mode is actually not used at this level (python SDK level), but is implemented at the ROS level, in case one might need it. | ||
| * **goto**: this mode is used for the *goto* method. | ||
|
|
||
| *note: the 'speed' and 'goto' modes can't be changed by hand. The drive mode is handled automagically when requesting a set_speed or a goto.* | ||
|
|
||
| The code for the [HAL can be found here](https://github.com/pollen-robotics/zuuu_hal) | ||
|
|
||
| ## Control modes | ||
| ### Overview | ||
| The control mode dictates the low level control strategy used by the mobile bases's HAL. | ||
|
|
||
| Two control modes are possible: | ||
| * ***open_loop*** (default mode): in this mode, the wheels are compliant and the control is smoother. | ||
| ```python | ||
| reachy_mobile.mobile_base.control_mode = 'open_loop' | ||
| ``` | ||
|
|
||
| * ***pid***: in this mode, the wheels are stiff and the control is more precise. | ||
| ```python | ||
| reachy_mobile.mobile_base.control_mode = 'pid' | ||
| ``` | ||
| :bulb: We recommend that you run the following [Jupyter Notebook](https://github.com/pollen-robotics/mobile-base-sdk/blob/main/mobile_base_sdk/examples/notebooks/control-modes.ipynb) to get a feel of what the control mode does. | ||
|
|
||
| ### Detailed behaviour | ||
| Regardless of how the mobile base is piloted (goto, set_speed, controller), the HAL always ends up calculating a goal rotational speed for each wheel. | ||
| The control mode only changes the used strategy to reach that rotational speed. | ||
| * In the open_loop mode, a simple affine model was identified to match a PWM to a goal rotational speed. The VESC controllers then apply the PWM directly to the motors of the wheels, without any other low level control. The measures can be found [here](https://github.com/pollen-robotics/zuuu_hal/tree/main/measures). While the model is simple, it does account for the static friction and the experimental data shows a good fit when the mobile base is on a flat surface. | ||
|
|
||
| {{< img-center "images/sdk/mobile-base/affine_pwm_model.png" 400x "" >}} | ||
|
|
||
| * In the pid mode, the HAL gives the goal rotational speeds directly to the VESC controllers of each wheel. The VESC will use a PID controller to control the speeds. |
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