IK solvability

[shengyangzhuang]

I tried to configure curobo with PiPER from AgileX Robotics company, but it seems that the solvability sucks. I have tried to increase significantly max_attempts and enable_graph_attempt in MotionGenPlanConfig but it doesn't make much difference. Can anyone share your experience about IK solvability? Is it because the configuration file I created?

Here is the video of reachability example:

reachability.example.PiPER.mp4

[balakumar-s]

Does it improve if you set self_collision_check=False, self_collision_opt=False here:

curobo/examples/isaac_sim/ik_reachability.py

Line 196 in 2fbffc3

self_collision_check=True,

If yes, then it's an issue with how the robot self collision ignore list was created.

[shengyangzhuang]

Hi!

Thanks for your reply. I tried to disable it and it seems that there is no change in solvability. I adjusted the orientation to be in a more "reachable way" as attached, and the solver still doesn't work very well. There are clearly a dozen of poses that have solutions but appear to be not solvable with cuRobo. What else can I do? I would appreciate any help you might provide!

2025-04-29.14-38-41.mp4

for your information, here is the created file:

##
## Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
##
## NVIDIA CORPORATION, its affiliates and licensors retain all intellectual
## property and proprietary rights in and to this material, related
## documentation and any modifications thereto. Any use, reproduction,
## disclosure or distribution of this material and related documentation
## without an express license agreement from NVIDIA CORPORATION or
## its affiliates is strictly prohibited.
##

robot_cfg:
  kinematics:
    use_usd_kinematics: False
    usd_path: "/home/szhuang/piper_ros_ws/src/piper_ros/src/piper_description/urdf/piper_no_gripper_description/piper_no_gripper_description.usd"
    usd_robot_root: "/home/szhuang/piper_ros_ws/src/piper_ros/src/piper_description/urdf/piper_no_gripper_description"
    isaac_usd_path: ""
    usd_flip_joints: {}
    usd_flip_joint_limits: []

    urdf_path: "/home/szhuang/curobo/src/curobo/content/assets/robot/piper/piper_no_gripper_description.urdf"
    asset_root_path: "/home/szhuang/curobo/src/curobo/content/assets/robot/piper"
    
    base_link: "base_link"
    ee_link: "link6"
    link_names: null
    lock_joints: null
    extra_links: null

    
    collision_link_names: ['link1','link2','link3','link4','link5']
    collision_spheres: 
      link1:
        - "center": [-0.002, 0.0, -0.007]
          "radius": 0.04
      link2:
        - "center": [0.052, -0.011, -0.0]
          "radius": 0.03
        - "center": [0.223, -0.04, -0.0]
          "radius": 0.03
        - "center": [0.095, -0.018, -0.0]
          "radius": 0.03
        - "center": [0.137, -0.025, -0.0]
          "radius": 0.03
        - "center": [0.18, -0.033, -0.0]
          "radius": 0.03
        - "center": [0.263, -0.034, 0.0]
          "radius": 0.03
        - "center": [0.285, -0.002, -0.0]
          "radius": 0.04
      link3:
        - "center": [-0.021, -0.044, -0.0]
          "radius": 0.03
        - "center": [-0.023, -0.08, -0.0]
          "radius": 0.02
        - "center": [-0.021, -0.108, -0.0]
          "radius": 0.02
        - "center": [-0.02, -0.137, -0.0]
          "radius": 0.02
        - "center": [-0.022, -0.172, -0.0]
          "radius": 0.025
        - "center": [-0.021, -0.205, -0.0]
          "radius": 0.025
      link4:
        - "center": [0.0, 0.0, 0.0]
          "radius": 0.025
      link5:
        - "center": [0.0, -0.04, -0.0]
          "radius": 0.025
        - "center": [0.0, -0.072, -0.0]
          "radius": 0.025


    collision_sphere_buffer: 0.01 # float or Dict[str, float]
    extra_collision_spheres: {}
    self_collision_ignore: {
      "base_link": ["link1"],
      "link1": ["link2", "link3"],
      "link2": ["link3", "link4", "link5"],
      "link3": ["link4", "link5"],
      "link4": ["link5", "link6"],
      "link5": ["link6"],
      }
    self_collision_buffer: {'link1': 0.01,
      'link2': 0.01,
      'link3': 0.01,
      'link4': 0.01,
      'link5': 0.01,
      'link6': 0.01,
      } # Dict[str, float]

    use_global_cumul: True
    mesh_link_names: null

    cspace:
      joint_names: ['joint1', 'joint2', 'joint3', 'joint4', 'joint5', 'joint6'] # List[str]
      retract_config: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
      null_space_weight: [1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
      cspace_distance_weight: [1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
      max_jerk: 500.0
      max_acceleration: 10.0

Here is the collision sphere visualization: