BB.Robot (bb v0.2.1)

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An optimised robot representation for kinematic computations.

This struct is built from the Spark DSL at compile-time and contains:

  • All physical values converted to SI base units (floats)
  • Flat maps for O(1) lookup of links, joints, sensors, and actuators by name
  • Pre-computed topology metadata for efficient traversal
  • Bidirectional parent/child references

Structure

The robot is organised as flat maps indexed by name:

  • links - all links in the robot, keyed by atom name
  • joints - all joints in the robot, keyed by atom name
  • sensors - all sensors (at any level), keyed by atom name
  • actuators - all actuators, keyed by atom name

Unit Conventions

All physical quantities are stored as native floats in SI base units:

  • Length: meters
  • Angle: radians
  • Mass: kilograms
  • Moment of inertia: kg·m²
  • Force: newtons
  • Torque: newton-meters
  • Linear velocity: m/s
  • Angular velocity: rad/s

Summary

Types

actuator_info()
sensor_info()
t()

Functions

child_joints(robot, link_name)

Get the child joints of a link.

get_joint(robot, name)

Get a joint by name.

get_link(robot, name)

Get a link by name.

joints_in_order(robot)

Get all joints in traversal order.

links_in_order(robot)

Get all links in topological order (root first).

parent_joint(robot, link_name)

Get the parent joint of a link (nil for root link).

path_to(robot, name)

Get the path from root to a given link or joint.

Types

actuator_info()

@type actuator_info() :: %{name: atom(), joint: atom()}

sensor_info()

@type sensor_info() :: %{
  name: atom(),
  attached_to: {:link, atom()} | {:joint, atom()} | :robot
}

t()

@type t() :: %BB.Robot{
  actuators: %{required(atom()) => actuator_info()},
  joints: %{required(atom()) => BB.Robot.Joint.t()},
  links: %{required(atom()) => BB.Robot.Link.t()},
  name: atom(),
  root_link: atom(),
  sensors: %{required(atom()) => sensor_info()},
  topology: BB.Robot.Topology.t()
}

Functions

child_joints(robot, link_name)

@spec child_joints(t(), atom()) :: [BB.Robot.Joint.t()]

Get the child joints of a link.

get_joint(robot, name)

@spec get_joint(t(), atom()) :: BB.Robot.Joint.t() | nil

Get a joint by name.

get_link(robot, name)

@spec get_link(t(), atom()) :: BB.Robot.Link.t() | nil

Get a link by name.

joints_in_order(robot)

@spec joints_in_order(t()) :: [BB.Robot.Joint.t()]

Get all joints in traversal order.

parent_joint(robot, link_name)

@spec parent_joint(t(), atom()) :: BB.Robot.Joint.t() | nil

Get the parent joint of a link (nil for root link).

path_to(robot, name)

@spec path_to(t(), atom()) :: [atom()] | nil

Get the path from root to a given link or joint.