motion_system.md

🏁 Motion state controller

The motion controller is a finite state machine that allows for static and dynamic posing, 8-phase crawl, bezier-based trot gait, and choreographed animation.

Controller Input Mapping

The controller input is interpreted differently between the modes. For walking, it looks like this:

Controller Input	Mapped to Gait Step	Range
Left x joystick	Step x	-1 to 1
Left y joystick	Step z	-1 to 1
Right x joystick	Step angle	-1 to 1
Right y joystick	Body pitch angle	-1 to 1
Height slider	Body height	0 to 1
Speed slider	Step velocity	0 to 1
S1 slider	Step height	0 to 1
Stop button	E stop command	0 or 1

Walking gait

General description of walking gait.

Time step

Phase condition

Stance and swing controller

8-phase crawl gait

The 8-phase crawl gait works by lifting one leg at a time while shifting the body weight away from that leg.

As the name implies, the gait consists of 8 discrete phases, which represent which feet should be in contact with the ground or in swing.

At each time step the phase time $t\in [0,1]$ is updated. When $t\geq 1$ the phase index is updated and phase time is reset.

Is derived from mike4192 spotMicro

Trot gait (12 point bezier curve)

The trot gait implements a phase time $t\in[0,1]$, but instead of using contact phases we define a swing/stance ratio of phase time offset for each leg.

The stance controller implements a sin curve to control the depth of steps.

The swing controller implements a bezier curve using 12 control points centered around the robot leg.

Rotation is calulated using the same curve