bam.testbench
=============

.. py:module:: bam.testbench


Classes
-------

.. autoapisummary::

   bam.testbench.Testbench
   bam.testbench.Pendulum


Module Contents
---------------

.. py:class:: Testbench

   Abstract base class for identification testbenches.

   A testbench defines the rigid-body dynamics of the physical setup:

   .. math::

       \tau_m + \tau_e(q) = M(q)\ddot{q}

   where :math:`\tau_m` is the motor torque, :math:`\tau_e` the external
   (bias) torque, and :math:`M(q)` the effective inertia.


   .. py:method:: compute_mass(q: float, dq: float) -> float
      :abstractmethod:


      Return the effective inertia at the current state [kg·m²].

      :param q: Joint angle [rad].
      :param dq: Joint velocity [rad/s].



   .. py:method:: compute_bias(q: float, dq: float) -> float
      :abstractmethod:


      Return the external (bias) torque at the current state [Nm].

      :param q: Joint angle [rad].
      :param dq: Joint velocity [rad/s].



.. py:class:: Pendulum(log: dict)

   Bases: :py:obj:`Testbench`


   Single-axis pendulum testbench.

   A point mass at the tip of a uniform rod driven by the actuator output
   shaft.  The zero angle is the arm pointing downward; positive angles are
   counter-clockwise.

   :param log: Log dict containing ``"mass"`` [kg], ``"arm_mass"`` [kg], and
       ``"length"`` [m] keys.


   .. py:attribute:: mass


   .. py:attribute:: arm_mass


   .. py:attribute:: length


   .. py:method:: compute_mass(q: float, dq: float) -> float

      Return the pendulum's rotational inertia about the pivot [kg·m²].

      :param q: Joint angle [rad] (unused — inertia is constant here).
      :param dq: Joint velocity [rad/s] (unused).



   .. py:method:: compute_bias(q: float, dq: float) -> float

      Return the gravity torque at the current angle [Nm].

      :param q: Joint angle [rad].
      :param dq: Joint velocity [rad/s] (unused).