Walking Controller

Walking Controller#

The Walking Controller is a cascade optimal controller to make Kangaroo Walk.

A Model Predictive Controller based on the Linear Inverted Pendulum formulation proposed by Kajita, serves a planner for the PAL Whole Bpdy Control presented in the WBC Controller section with a different set of constraints.

The set of active constraints is:

  • Joint Limits

  • Feet Pose Constraints

  • Center of Mass Contraint

  • Base Link Orientation

  • Friction Cone Constraints

  • Contact Forces Regularization

  • Inverse Dynamics Constraint

This controller uses a different type of control in each joint.

The hip_z, hip_roll, hip_pitch, ankle_roll, ankle_pitch are controlled in POSITION mode.

The leg_length is controller in IMPEDANCE mode, where the feedforward torque and desired position is computed by the WBC. This allows to be more compliant and reduce the impacts with the ground.

CAUTION

During the initial transition from the double support phase to the single support phase, the robot becomes unstable and may fall. It is necessary to physically support the robot during this phase to prevent it from falling. This limitation will be addressed in a future release.

📹 Video Reference:#

The following video shows how to use Joystick to command Kangaroo Robot while walking.

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