Add additional functions for goal analysis to the Xela Web UI interface.
Add tools to the Xela Web UI to monitor whether the robot's control based on sensor input is performing the desired motion at the appropriate time.
These functions are FollowCam and Analysis:

• FollowCam
• Analysis
  

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xela_taxel_sidecar_2f - FollowCam / Analysis¶

1. Overview and design objective¶

The 2F sidecar is designed as a non-invasive visualization adapter: it does not alter upstream tactile publishers or downstream control logic.

Design intent:

• transform ROS tactile payloads into browser-consumable state with low integration cost
• expose runtime mode switching as a stable ROS service contract
• support both global and namespaced TF transport models through launch remapping

This keeps web visualization evolvable independently of control-stack release cycles.

2. Node architecture¶

2.1 Bridge node (xela_taxel_web_bridge_node)¶

• subscribes tactile array topic
• optionally subscribes grasp telemetry/event topics and embeds recent JSON metadata
• normalizes/maps values
• publishes compact JSON payload
• optional TF lookups for URDF points

2.2 Mode manager (xela_viz_mode_manager_node)¶

• service facade: /xela_viz_mode_manager/set_mode
• writes bridge params: viz_mode, emit_urdf_points, freeze_urdf_positions
• forwards request to viz node service
• startup sync retry timer

2.3 Web transport¶

• static HTTP server for web/taxel_sidecar
• optional dedicated rosbridge instance
• browser websocket fallback order: :9090, :3201, /ros

2.4 Web UI runtime¶

• browser-side display modes are GridMode, XelaModel, and RobotModel
• GridMode/XelaModel/RobotModel are distinct from ROS-side grid/urdf
• RobotModel includes optional FollowCam logic and telemetry analysis rendering
• FollowCam / Analysis toolbar exposure can be toggled independently from the underlying code paths

2.4.1 FollowCam detailed design¶

• Scope:
  • available only in RobotModel
  • client-side camera controller only; does not change ROS-side viz mode
• Activation:
  • toggled by the FollowCam toolbar button
  • enabling resets filtered state and performs a one-shot snap to the first resolved camera goal
  • disabling returns RobotModel to normal fixed orbit framing
• Frame resolution policy:
  • anchor priority: grasp_link -> robotiq_base_link -> tool0 -> base_link
  • left tip priority: left_inner_finger -> left_outer_finger -> left_inner_finger_pad -> x_base_01_uSPr2F_link
  • right tip priority: right_inner_finger -> right_outer_finger -> right_inner_finger_pad -> x_base_02_uSPr2F_link
  • if tip frames are missing, the camera falls back to an anchor-forward estimate
• Camera placement policy:
  • target base is the midpoint of left/right tip frames when both are available
  • direction is reconstructed from fingertip geometry (tip span x finger axis) and protected against hemisphere flips
  • camera goal = targetBase + forward * forwardDistance + worldUp * heightOffset
  • look target = targetBase - forward * lookAhead + worldUp * lookUp
• Motion policy:
  • filtered anchor position, filtered target base, and filtered forward vector
  • lerp smoothing plus per-frame max step limits
  • one-shot TF jump rejection with later re-sync
• Manual override policy:
  • manual orbit pauses follow for 3s
  • automatic follow resumes after the pause window expires
• Diagnostics:
  • followDebug shows resolved anchor/tip frames, source branch, raw vector, filtered vector, and sign
  • debug output is throttled to reduce DOM churn

2.4.2 Analysis detailed design¶

• Scope:
  • client-side analysis panel for tactile/grasp telemetry inspection
  • independent of ROS-side grid/urdf mode
• UI surface:
  • controlled by the Analysis toolbar button
  • shows/hides statsRow (summary text, current-value strip, contact badge, sparkline, event tooltip)
• Data sources:
  • current sidecar payload from /x_taxel_2f/web_state
  • reads meta.grasp, meta.grasp_event, and derived current force values
• Timeline model:
  • rolling window presets: 10s, 30s, 60s
  • pause/resume support without dropping existing history
  • discrete event markers stored separately from continuous samples
• Render policy:
  • recomputes summary text (age, mode, force/sigma/phase/event fields)
  • draws sparkline history
  • overlays event markers and hover tooltip inspection
  • updates the contact badge on sparse/broad/slip-related event conditions
• Intended use:
  • operator/debug visibility for grasp phase changes
  • quick inspection of force trends, event timing, and slip/contact transitions
  • complements, but does not replace, external logging or ROS topic introspection

Analysis panel display items:

• statsText: top-level summary line showing age, active UI mode, source, force/sigma/phase/event fields
• statsCurrent: current-value strip for fz_total, left/right force, sigma peak, and phase
• contactBadge: short-lived badge for sparse, broad, or slip-related contact conditions
• sparkline: rolling history visualization over the selected window
• event markers: discrete meta.grasp_event points overlaid on the timeline
• event tooltip: detailed event inspection on mouse hover
• window buttons (10s, 30s, 60s): change the retained/rendered history window
• Pause: freezes timeline advancement without discarding collected samples

FollowCam tuning contract:

• follow_cam_forward_distance: forward camera offset from the resolved fingertip target (current built-in baseline: -0.2)
• follow_cam_height_offset: height offset above the target in world Z (current built-in baseline: 0.1)
• follow_cam_look_ahead: backward look offset toward the sensor area (current built-in baseline: 0.028)
• follow_cam_forward_sign: hemisphere flip for the resolved forward vector (current built-in baseline: -1.0)
• There is no separate follow_cam_profile selector in the current implementation; the effective preset is the combination of these follow_cam_* query values.

3. Launch architecture¶

• primary: xela_taxel_sidecar_cpp.launch.py
• compatibility: xela_taxel_sidecar.launch.py
• primary launch exposes bind hosts for the static web server and sidecar rosbridge (default 0.0.0.0)

4. Integration strategy¶

• default target: viz_node_name=/xela_taxel_viz_2f
• std-viz namespaced target via overrides:
  • viz_node_name:=/xviz2f/std_xela_taxel_viz_2f
  • bridge_tf_topic:=/xviz2f/tf
  • bridge_tf_static_topic:=/xviz2f/tf_static

5. Design risks¶

• target viz service unavailable
• TF remap mismatch in URDF mode
• duplicate transport nodes from multiple launch variants

6. Validation¶

• launch smoke test
• topic publish-rate observation
• service toggle test
• web render check on sidecar URL
• browser websocket fallback check (9090 -> 3201 -> /ros)
• verify URL query defaults are used when no follow_cam_* overrides are present