ECE 417/598: TF trees

TF tree

Denavit-Hartenberg convention

https://www.youtube.com/watch?v=rA9tm0gTln8

Denavit-Hartenberg convention

\[ R_x(\alpha) = \begin{bmatrix} 1 & 0 & 0 \\ 0 & \cos(\alpha) & - \sin(\alpha) \\ 0 & \sin(\alpha) & \cos(\alpha) \end{bmatrix} \]

\[ T_x(\alpha, r) = \begin{bmatrix} 1 & 0 & 0 & r\\ 0 & \cos(\alpha) & - \sin(\alpha) & 0\\ 0 & \sin(\alpha) & \cos(\alpha) & 0 \\ 0 & 0 & 0 & 1 \end{bmatrix} \]

Denavit-Hartenberg convention

\[ R_z(\theta) = \begin{bmatrix} \cos(\theta) & - \sin(\theta) & 0\\ \sin(\theta) & \cos(\theta) & 0 \\ 0 & 0 & 1 \end{bmatrix} \]

\[ T_z(\theta, d) = \begin{bmatrix} \cos(\theta) & - \sin(\theta) & 0 & 0\\ \sin(\theta) & \cos(\theta) & 0 & 0\\ 0 & 0 & 1 & d \\ 0 & 0 & 0 & 1 \end{bmatrix} \]

Denavit-Hartenberg convention

\[ {}^{i}T_{i+1} = T_z(\theta_i, d_i) T_x(\alpha_i, a_i); \quad a_i = r \]

TF trees in ROS

  • tf2
  • sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 10