Robotics Toolbox for Python

Robotics without the cruft
A high-productivity framework for robotics research and education.

GitHub • Wiki • Changelog • Installation

Status & Project Health

Ecosystem & Dependencies

Contents

• Synopsis
• Getting going
• Tutorials
• Code Examples
• Toolbox Research Applications
• References
• Using the Toolbox in your Open Source Code?
• Common Issues and Solutions
• Build a JupyterLite/Pyodide Wasm wheel

Synopsis

This toolbox brings robotics-specific functionality to Python, and leverages Python's advantages of portability, ubiquity and support, and the capability of the open-source ecosystem for linear algebra (numpy, scipy), graphics (matplotlib, three.js, WebGL), interactive development (Jupyter, JupyterLab, mybinder.org), and documentation (sphinx).

The Toolbox provides tools for representing the kinematics and dynamics of serial-link manipulators - you can easily create your own in Denavit-Hartenberg form, import a URDF file, or use over 50 supplied models for well-known contemporary robots from Franka-Emika, Kinova, Universal Robotics, Rethink as well as classical robots such as the Puma 560 and the Stanford arm.

The Toolbox contains fast implementations of kinematic operations. The forward kinematics and the manipulator Jacobian can be computed in less than 1 microsecond while numerical inverse kinematics can be solved in as little as 4 microseconds.

The toolbox also supports mobile robots with functions for robot motion models (unicycle, bicycle), path planning algorithms (bug, distance transform, D*, PRM), kinodynamic planning (lattice, RRT), localization (EKF, particle filter), map building (EKF) and simultaneous localization and mapping (EKF).

The Toolbox provides:

• code that is mature and provides a point of comparison for other implementations of the same algorithms;
• routines which are generally written in a straightforward manner which allows for easy understanding, perhaps at the expense of computational efficiency;
• source code which can be read for learning and teaching;
• backward compatability with the Robotics Toolbox for MATLAB

The Toolbox leverages the Spatial Maths Toolbox for Python to provide support for data types such as SO(n) and SE(n) matrices, quaternions, twists and spatial vectors.

Getting going

You will need Python >= 3.10

Using pip

Install a snapshot from PyPI

pip install roboticstoolbox-python

Available options are:

• swift install Swift, a web-based visualizer
• qp install quadratic-programming IK dependencies (qpsolvers, quadprog)
• collision install collision checking with coal and trimesh
• tool install IPython and pygments, needed to run the rtbtool interactive shell
• ik install SymPy and python-flint, to derive analytic inverse kinematics (robot.analytic_ik())
• all install swift, qp, collision, and tool. It does not include ik, since SymPy is large and only needed to derive an analytic solver

Windows note: coal does not publish Windows wheels on PyPI, so the collision/all extras skip it there and collision checking is unavailable via pip on Windows. It's available via conda install -c conda-forge coal-python if needed. Everything else in the Toolbox works normally.

Put the options in a comma separated list like

pip install roboticstoolbox-python[optionlist]

If you want the Swift visualizer, install the swift extra.

Install matrix:

• Core only

pip install roboticstoolbox-python

• Swift visualizer only

pip install roboticstoolbox-python[swift]

• QP solver dependencies only

pip install roboticstoolbox-python[qp]

• Collision checking dependencies only

pip install roboticstoolbox-python[collision]

• rtbtool interactive shell dependencies only

pip install roboticstoolbox-python[tool]

• Analytic inverse kinematics dependencies only (SymPy, python-flint)

pip install roboticstoolbox-python[ik]

• Everything except ik (swift + qp + collision + tool)

pip install roboticstoolbox-python[all]

• Multiple extras explicitly

pip install roboticstoolbox-python[swift,qp,collision]

From GitHub

To install the bleeding-edge version from GitHub

git clone https://github.com/petercorke/robotics-toolbox-python.git
cd robotics-toolbox-python
pip install -e .

To generate a Wasm wheel that will run in the browser see the instructions here.

Tutorials

Do you want to learn about manipulator kinematics, differential kinematics, inverse-kinematics and motion control? Have a look at our tutorial. This tutorial comes with two articles to cover the theory and 12 Jupyter Notebooks providing full code implementations and examples. Most of the Notebooks are also Google Colab compatible allowing them to run online.

Code Examples

We will load a model of the Franka-Emika Panda robot defined by a URDF file

import roboticstoolbox as rtb
robot = rtb.models.Panda()
print(robot)

	URDFRobot.Panda: panda (by Franka Emika), 7 joints (RRRRRRR), 1 gripper, geometry, collision
	┌─────┬──────────────┬───────┬─────────────┬────────────────────────────────────────────────┐
	│link │     link     │ joint │   parent    │              ETS: parent to link               │
	├─────┼──────────────┼───────┼─────────────┼────────────────────────────────────────────────┤
	│   0 │ panda_link0  │       │ BASE        │                                                │
	│   1 │ panda_link1  │     0 │ panda_link0 │ SE3(0, 0, 0.333) ⊕ Rz(q0)                      │
	│   2 │ panda_link2  │     1 │ panda_link1 │ SE3(-90°, -0°, 0°) ⊕ Rz(q1)                    │
	│   3 │ panda_link3  │     2 │ panda_link2 │ SE3(0, -0.316, 0; 90°, -0°, 0°) ⊕ Rz(q2)       │
	│   4 │ panda_link4  │     3 │ panda_link3 │ SE3(0.0825, 0, 0; 90°, -0°, 0°) ⊕ Rz(q3)       │
	│   5 │ panda_link5  │     4 │ panda_link4 │ SE3(-0.0825, 0.384, 0; -90°, -0°, 0°) ⊕ Rz(q4) │
	│   6 │ panda_link6  │     5 │ panda_link5 │ SE3(90°, -0°, 0°) ⊕ Rz(q5)                     │
	│   7 │ panda_link7  │     6 │ panda_link6 │ SE3(0.088, 0, 0; 90°, -0°, 0°) ⊕ Rz(q6)        │
	│   8 │ @panda_link8 │       │ panda_link7 │ SE3(0, 0, 0.107)                               │
	└─────┴──────────────┴───────┴─────────────┴────────────────────────────────────────────────┘

	┌─────┬─────┬────────┬─────┬───────┬─────┬───────┬──────┐
	│name │ q0  │ q1     │ q2  │ q3    │ q4  │ q5    │ q6   │
	├─────┼─────┼────────┼─────┼───────┼─────┼───────┼──────┤
	│  qr │  0° │ -17.2° │  0° │ -126° │  0° │  115° │  45° │
	│  qz │  0° │  0°    │  0° │  0°   │  0° │  0°   │  0°  │
	└─────┴─────┴────────┴─────┴───────┴─────┴───────┴──────┘

The symbol @ indicates the link as an end-effector, a leaf node in the rigid-body tree (Python prompts are not shown to make it easy to copy+paste the code, console output is indented). We will compute the forward kinematics next

Te = robot.fkine(robot.qr)  # forward kinematics
print(Te)

	0.995     0         0.09983   0.484
	0        -1         0         0
	0.09983   0        -0.995     0.4126
	0         0         0         1

We can solve inverse kinematics very easily. We first choose an SE(3) pose defined in terms of position and orientation (end-effector z-axis down (A=-Z) and finger orientation parallel to y-axis (O=+Y)).

from spatialmath import SE3

Tep = SE3.Trans(0.6, -0.3, 0.1) * SE3.OA([0, 1, 0], [0, 0, -1])
sol = robot.ik_LM(Tep)         # solve IK, with the fast C++ solver (ikine_LM is the Python one)
print(sol)

	IKSolution: q=[-2.709, -1.176, 1.961, -1.642, 1.173, 1.958, 2.876], success=True, iterations=6, searches=1, residual=1.06e-07

q_pickup = sol.q
print(robot.fkine(q_pickup))    # FK shows that desired end-effector pose was achieved

	-1          0.0002931   0.0003122   0.5999
	 0.0002931  1           7.601e-05  -0.2999
	-0.0003121  7.611e-05  -1           0.1001
	 0          0           0           1

We can animate a path from the ready pose qr configuration to this pickup configuration

qt = rtb.jtraj(robot.qr, q_pickup, 50)
robot.plot(qt.q, backend='pyplot', movie='panda1.gif')

where we have specified the matplotlib pyplot backend. Blue arrows show the joint axes and the coloured frame shows the end-effector pose.

We can also plot the trajectory in the Swift simulator (a browser-based 3d-simulation environment built to work with the Toolbox)

robot.plot(qt.q)

We can also experiment with velocity controllers in Swift. Here is a resolved-rate motion control example

import swift
import roboticstoolbox as rtb
import spatialmath as sm
import numpy as np

env = swift.Swift()
env.launch(realtime=True)

panda = rtb.models.Panda()
handle = env.add(panda)
handle.q = panda.qr

Tep = panda.fkine(handle.q) * sm.SE3.Trans(0.2, 0.2, 0.45)

arrived = False

dt = 0.05

while not arrived:

    v, arrived = rtb.p_servo(panda.fkine(handle.q), Tep, 1)
    handle.qd = np.linalg.pinv(panda.jacobe(handle.q)) @ v
    env.step(dt)

# Uncomment to stop the browser tab from closing
# env.hold()

env.add(panda) returns a handle owning this instance's live joint state -- drive the simulation via handle.q/handle.qd, not panda.q/panda.qd directly. panda itself stays a plain, shareable kinematic model, so the same panda object can back several independent handles/instances at once.

Loading models from robot_descriptions

The Panda example above uses one of the ~50 models shipped with the Toolbox, but many more robots are available on demand via the robot_descriptions package, which is installed automatically as a dependency. Passing a bare name (no file suffix) to URDFRobot fetches and loads it from there:

from roboticstoolbox.models.URDF.URDFRobot import URDFRobot
ur5 = URDFRobot("ur5")

rtb.models.catalog() lists everything available — the models built into the Toolbox as well as those it can load from robot_descriptions — with filtering by keyword/DoF/model type and column sorting:

rtb.models.catalog(mtype="URDF", sorton="name")

Run some examples

The notebooks folder contains some tutorial Jupyter notebooks which you can browse on GitHub. Additionally, have a look in the examples folder for many ready to run examples.

References

Key papers

• P. Corke, "A computer tool for simulation and analysis: the Robotics Toolbox for MATLAB," Proc. National Conf. Australian Robot Association, pp. 319–330, Melbourne, July 1995. [PDF]
• P. Corke, "A robotics toolbox for MATLAB," IEEE Robotics and Automation Magazine, 3(1):24–32, Sept. 1996. [IEEE Xplore]
• P. Corke, "A simple and systematic approach to assigning Denavit-Hartenberg parameters," IEEE Transactions on Robotics, 23(3):590–594, 2007. [IEEE Xplore] — introduces the Elementary Transform Sequence (ETS) notation used throughout the Toolbox.
• J. Haviland and P. Corke, "A systematic approach to computing the manipulator Jacobian and Hessian using the elementary transform sequence," arXiv preprint, 2020. [arXiv]
• P. Corke and J. Haviland, "Not your grandmother's toolbox – the Robotics Toolbox reinvented for Python," Proc. ICRA 2021. [IEEE Xplore] [PDF]

Talks

• Peter Corke – The Robotics Toolbox: 30 Years Old and Still Going Strong — a retrospective on the Toolbox's history and motivation, a good starting point before diving into the API.

Related book

The Toolbox is a companion to Peter Corke's textbook Robotics, Vision & Control (Springer) — many docstrings and examples reference specific figures/sections from the book.

Citing the Toolbox

If the toolbox helped you in your research, please cite

@inproceedings{rtb,
  title={Not your grandmother’s toolbox--the Robotics Toolbox reinvented for Python},
  author={Corke, Peter and Haviland, Jesse},
  booktitle={2021 IEEE International Conference on Robotics and Automation (ICRA)},
  pages={11357--11363},
  year={2021},
  organization={IEEE}
}

Using the Toolbox in your Open Source Code?

If you are using the Toolbox in your open source code, feel free to add our badge to your readme!

For the powered by robotics toolbox badge

copy the following

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For the powered by python robotics badge

copy the following

[![Powered by Python Robotics](https://raw.githubusercontent.com/petercorke/robotics-toolbox-python/main/.github/svg/pr_powered.min.svg)](https://github.com/petercorke/robotics-toolbox-python)

Common Issues and Solutions

See the common issues with fixes here.

Using the Toolbox with Windows?

Graphical visualisation via Swift is currently not supported under Windows. However there is a hotfix, by changing in SwiftRoute.py

self.path[9:] to self.path[10:]

Toolbox Research Applications

The toolbox is incredibly useful for developing and prototyping algorithms for research, thanks to the exhaustive set of well documented and mature robotic functions exposed through clean and painless APIs. Additionally, the ease at which a user can visualize their algorithm supports a rapid prototyping paradigm.

It's been the implementation substrate for several published reactive-control papers, and its kinematics are a direct implementation of a two-part differential-kinematics tutorial — see the wiki's Reactive control and Inverse kinematics pages.