feat(vo): visual odometry fallback — CUDA optical flow + EKF fusion + slip failover (Issue #157) #164

Merged
sl-jetson merged 1 commits from sl-perception/issue-157-visual-odom into main 2026-03-02 10:26:10 -05:00

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Author SHA1 Message Date
572e578069 feat(vo): visual odometry fallback — CUDA optical flow + EKF fusion + slip failover (Issue #157)
New package: saltybot_visual_odom (13 files, ~900 lines)

Nodes:
  visual_odom_node    — D435i IR1 stereo VO at 30 Hz
                        CUDA: SparsePyrLKOpticalFlow + FastFeatureDetector (GPU)
                        CPU fallback: calcOpticalFlowPyrLK + goodFeaturesToTrack
                        Essential matrix (5-pt RANSAC) + depth-aided metric scale
                        forward-backward consistency check on tracked points
                        Publishes /saltybot/visual_odom (Odometry)

  odom_fusion_node    — 5-state EKF [px, py, θ, v, ω] (unicycle model)
                        Fuses: wheel odom (/saltybot/rover_odom or tank_odom)
                               + visual odom (/saltybot/visual_odom)
                        Slip failover: /saltybot/terrain JSON → 10× wheel noise on slip
                        Loop closure: /rtabmap/odom jump > 0.3m → EKF soft-correct
                        TF: publishes odom → base_link at 30 Hz
                        Publishes /saltybot/odom_fused + /saltybot/visual_odom_status

Modules:
  optical_flow_tracker.py — CUDA/CPU sparse LK tracker with re-detection,
                            forward-backward consistency, ROI masking
  stereo_vo.py            — Essential matrix decomposition, camera→base_link
                            frame rotation, depth median scale recovery,
                            loop closure soft-correct, accumulated SE(3) pose
  kalman_odom_filter.py   — 5-state EKF: predict (unicycle), update_wheel,
                            update_visual, update_rtabmap (absolute pose);
                            Joseph-form covariance for numerical stability

Tests:
  test/test_kalman_odom.py — 8 unit tests for EKF + StereoVO (no ROS deps)

Topic/TF map:
  /camera/infra1/image_rect_raw  → visual_odom_node
  /camera/depth/image_rect_raw   → visual_odom_node
  /saltybot/visual_odom          ← visual_odom_node  (30 Hz)
  /saltybot/rover_odom           → odom_fusion_node
  /saltybot/terrain              → odom_fusion_node  (slip signal)
  /rtabmap/odom                  → odom_fusion_node  (loop closure)
  /saltybot/odom_fused           ← odom_fusion_node  (30 Hz)
  odom → base_link TF            ← odom_fusion_node  (30 Hz)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-02 10:15:32 -05:00