Rustypot: a Rust package to communicate with Dynamixel/Feetech motors

Getting started

Rustypot is a communication library for Dynamixel/Feetech motors. It is notably used in the Reachy project. More types of servo can be added in the future.

Feature Overview

• Relies on serialport for serial communication
• Support for dynamixel protocol v1 and v2 (can also use both on the same bus)
• Support for sync read and sync write operations
• Easy support for new type of motors (register definition through macros). Currently support for dynamixel XL320, XL330, XL430, XM430, MX*, Orbita 2D & 3D.
• Pure Rust plus python bindings (using pyo3).

To add new servo, please refer to the Servo documentation.

APIs

It exposes two APIs:

• DynamixelProtocolHandler: low-level API. It handles the serial communication and the Dynamixel protocol parsing. It can be used for fine-grained control of the shared bus with other communication.
• Controller: high-level API for the Dynamixel protocol. Simpler and cleaner API but it takes full ownership of the io (it can still be shared if wrapped with a mutex for instance).

See the examples below for usage.

Examples

use rustypot::{DynamixelProtocolHandler, servo::dynamixel::mx};
use std::time::Duration;

fn main() {
    let mut serial_port = serialport::new("/dev/ttyACM0", 1_000_000)
        .timeout(Duration::from_millis(10))
        .open()
        .expect("Failed to open port");

    let dph = DynamixelProtocolHandler::v1();

    loop {
        let pos =
            mx::read_present_position(&dph, serial_port.as_mut(), 11).expect("Communication error");
        println!("Motor 11 present position: {:?}", pos);
    }
}

use rustypot::servo::feetech::sts3215::STS3215Controller;
use std::time::Duration;

fn main() {
    let serial_port = serialport::new("/dev/ttyUSB0", 1_000_000)
        .timeout(Duration::from_millis(1000))
        .open()
        .unwrap();

    let mut c = STS3215Controller::new()
            .with_protocol_v1()
            .with_serial_port(serial_port);

    let pos = c.sync_read_present_position(&vec![1, 2]).unwrap();
    println!("Motors present position: {:?}", pos);

    c.sync_write_goal_position(&vec![1, 2], &vec![1000, 2000]).unwrap();
}

Tools

Simple bus scanning tool:

cargo run --bin=scan -- --serialport=/dev/ttyUSB0 --baudrate=1000000 --protocol=v1

Documentation

See https://docs.rs/rustypot for more information on APIs and examples.

See python/README.md for information on how to use the python bindings.

Python bindings

The python bindings are generated using pyo3. They are available on pypi(https://pypi.org/project/rustypot/). You can install them using pip.

pip install rustypot

To build them locally, you can use maturin.

First, generate the type annotations for the python bindings, by running:

cargo run --release --bin stub_gen --features python

Then, you can build the python bindings using maturin. You can either build the wheel files to distribute them, or install them directly in your local python environment.

To build the wheel files, you can run:

maturin build --release --features python --features pyo3/extension-module

or, if you want to install them in your local python environment:

maturin develop --release --features python --features pyo3/extension-module

See maturin official documentation for more information on how to use it.

Using the Python bindings

The Python bindings exposes the same API as the Controller API in the rust crate.

You first need to create a Controller object. For instance, to communicate with a serial port to Feetech STS3215 motors, you can do the following:

from rustypot import Sts3215PyController

c = Sts3215PyController(serial_port='/dev/ttyUSB0', baudrate=100000, timeout=0.1)

Then, you can directly read/write any register of the motor. For instance, to read the present position of the motor with id 1, you can do:

pos = c.read_present_position(1)
print(pos)

You can also write to the motors. For instance, to set the goal position of the motors with id 1 to 90° you can do:

import numpy as np
c.write_goal_position(1, np.deg2rad(90.0))

Then, you can also sync_read any registers on multiple motors in a single operations. For instance, to read the present position of the motors with id 1 and 2, you can do:

pos = c.sync_read_present_position([1, 2])
print(pos)

Same with sync_write. For instance, to set the goal position of the motors with id 1 and 2 to 0.0 and 90° respectively, you can do:

import numpy as np
c.sync_write_goal_position([1, 2], [0.0, np.deg2rad(90.0)])

Contributing

If you want to contribute to Rustypot, please fork the repository and create a pull request. We welcome any contributions, including bug fixes, new features, and documentation improvements. We especially appreciate support for new servos. If you want to add support for a new servo, please follow the instructions in the Servo documentation.

License

This library is licensed under the Apache License 2.0.

Support

Rustypot is developed and maintained by Pollen-Robotics. They developed open-source hardware and tools for robotics. Visit https://pollen-robotics.com to learn more or join the Discord community if you have any questions or want to share your projects.