Initial Poses

By default, the robot starts each episode in a fixed rest pose with small noise. The pose system lets you configure more diverse starting configurations, which is useful for training policies that generalize across different initial arm positions.

How Poses Work

A Pose defines 6 joint angles, one per joint. Each joint can be:

• Fixed (float): the same angle every episode (e.g., shoulder_lift_deg=-90.0)
• Free (tuple[float, float]): sampled uniformly from a range each episode (e.g., shoulder_pan_deg=(-110.0, 110.0))

This lets you keep some joints in known-good configurations while varying others for diversity.

Built-in Poses

Using Poses

Set a pose in config

from so101_nexus import RobotConfig, PickConfig

# Use a built-in pose by name
robot = RobotConfig(init_pose="rest")
config = PickConfig(robot=robot)

Create a custom pose

from so101_nexus import Pose, RobotConfig, PickConfig

my_pose = Pose(
    name="looking_left",
    shoulder_pan_deg=90.0,          # fixed: rotated left
    shoulder_lift_deg=-90.0,        # fixed
    elbow_flex_deg=90.0,            # fixed
    wrist_flex_deg=37.8,            # fixed
    wrist_roll_deg=(-157.0, 163.0), # free: full range
    gripper_deg=(-10.0, 100.0),     # free: full range
)

robot = RobotConfig(init_pose=my_pose)
config = PickConfig(robot=robot)

Default behavior (no pose)

When init_pose is None (the default), the robot uses the legacy behavior: rest_qpos_deg plus Gaussian noise scaled by robot_init_qpos_noise. This is fully backward compatible.

Joint Reference

All angles are in degrees.