forge3d.robot

Robot arm loading, FK, IK, and Jacobian.

Robot

Kinematic robot arm.

Holds joint angles, computes FK, and exposes link poses for rendering. Physics (dynamics) is NOT simulated — the arm is kinematically controlled.

Parameters

model : RigidBodyModel (n revolute joints, serial chain). link_radii : Visual cylinder radius per link (m). Default: 0.04 m. name : Display name. material : Snapshot material ID for link boxes. base_position : World-frame position of the robot base.

q property writable

q: ndarray

Current joint angles (rad), shape (n,).

set_joint

set_joint(idx: int, angle: float) -> None

Set joint idx to angle (radians).

set_joints

set_joints(q: Any) -> None

Set all joint angles at once.

link_world_poses

link_world_poses() -> list[tuple[np.ndarray, np.ndarray]]

FK for all links.

Returns

List of (pos, R) pairs (one per link), world frame. pos : (3,) float64 — joint origin position. R : (3,3) float64 — link frame orientation.

ee_pose

ee_pose() -> tuple[np.ndarray, np.ndarray]

End-effector pose (last link): (pos, R) in world frame.

link_visual_boxes

link_visual_boxes() -> list[tuple[np.ndarray, np.ndarray, np.ndarray]]

Compute (center, R, half_extents) for each link visual box.

Each box connects the joint-i origin to the joint-(i+1) origin. Box z-axis is aligned along the segment direction.

Returns

List of (center, R, half_extents) tuples.

---

Loading a preset

import forge3d.robot as f3r

arm = f3r.load("ur5", base_position=(0, 0, 0))

Available presets: "ur5" (UR5 6-DOF)