/py-scurve

Planning s-curve trajectories with python

Primary LanguagePythonMIT LicenseMIT

PyScurve

Small library for planning scurve velocity profiles. The crucial part of implementaion is based on "Trajectory Planning for Automatic Machines and Robots-Springer (2008)" by Luigi Biagiotti, Claudio Melchiorri.

Installation

Installation is pretty simple. Firstly clone repository:

git clone https://github.com/nameofuser1/py-scurve.git
cd py-scurve

and then run installation script:

python setup.py install

Examples

  • Plan 1-DOF trajectory
from pyscurve import ScurvePlanner, plot_trajectory

if __name__ == "__main__":
    q0 = [-2.]
    q1 = [20.]
    v0 = [1.]
    v1 = [5.]
    v_max = 20.
    a_max = 15.
    j_max = 100.

    p = ScurvePlanner()
    tr = p.plan_trajectory(q0, q1, v0, v1, v_max, a_max, j_max)
    plot_trajectory(tr, 0.01)

Result

  • Trajectories for several DOFs are automatically synchronized. Assuming that constraints on jerk, acceleration and speed are the same for each DOF:
from pyscurve import ScurvePlanner
from pyscurve import plot_trajectory

if __name__ == "__main__":
    q0 = [-2., 0., 10.]
    q1 = [20., 15., -10.]
    v0 = [0., 5., 0.]
    v1 = [2, 4., 0.]
    v_max = 30.
    a_max = 30.
    j_max = 100.
    T = None

    p = ScurvePlanner()

    tr = p.plan_trajectory(q0, q1, v0, v1, v_max, a_max, j_max, t=T)
    plot_trajectory(tr, dt=0.01)

Synchronized trajectories

  • Specify parameter T in order to fit all the trajectories in the same execution time:
from pyscurve import ScurvePlanner
from pyscurve import plot_trajectory

if __name__ == "__main__":
    q0 = [-2., 0., 10.]
    q1 = [20., 15., -10.]
    v0 = [0., 5., 0.]
    v1 = [2, 4., 0.]
    v_max = 30.
    a_max = 30.
    j_max = 100.
    T = 3.0

    p = ScurvePlanner()

    tr = p.plan_trajectory(q0, q1, v0, v1, v_max, a_max, j_max, t=T)
    plot_trajectory(tr, dt=0.01)

Trajectories fitted in time

Synchronization

Just to make it clear. If trajectory final speed is 0 then it is NOT synchronized in time with others and minimum time trajectory is computed. all trajectories with non-zero final velocities are fitted in the same time because non-zero final speed will introduce unwanted displacement if trajectories are not synchronized. Same is true for constant time trajectories(possibly not a good approach for constant time trajectory, will fix it in future builds).

License

Copyright (c) 2017 Kamnev Iurii

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.