Joint axis orientation specified as Euler angles.

The axis defines the direction of rotation (for revolute joints) or translation (for prismatic joints). By default, the axis points along the Z direction. Use roll, pitch, and yaw to rotate it to the desired orientation.

Examples

# Default Z-axis (no rotation needed)
axis do
end

# Y-axis (pitch by 90°)
axis do
  pitch(~u(90 degree))
end

# X-axis (pitch by 90°, then roll by 90°)
axis do
  pitch(~u(90 degree))
  roll(~u(90 degree))
end