The AH sidecar design addresses higher taxel density and model-side mapping complexity compared to 2F.

Goals:

• keep a stable sidecar service/topic contract while adding AH mapping/pattern semantics
• decouple bridge mode switching from optional viz-node mode service availability
• preserve compatibility with std_xela_taxel_viz_ahv4 namespace-local TF conventions

This enables incremental AH web visualization improvements without forcing changes in tactile producer or std-viz packages.

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xela_taxel_sidecar_ah¶

1. Overview and design objective¶

The AH sidecar design addresses higher taxel density and model-side mapping complexity compared to 2F.

Design intent:

• keep a stable sidecar service/topic contract while adding AH mapping/pattern semantics
• decouple bridge mode switching from optional viz-node mode service availability
• preserve compatibility with std_xela_taxel_viz_ahv4 namespace-local TF conventions

This enables incremental AH web visualization improvements without forcing changes in tactile producer or std-viz packages.

2. Bridge design¶

2.1 Mapping model¶

• mapping file provides flat index and frame-name contract
• pattern file provides 2D grid projection
• hand-side auto resolution switches prefix conversion and default pattern

2.2 Signal model¶

• force-first rendering with taxel fallback
• baseline/deadband for force and taxel paths
• optional group/module filtering (show_thumb, show_module_XX)

2.3 URDF point model¶

• enabled by emit_urdf_points
• TF lookup with cache (tf_cache_ttl_sec)
• optional frozen coordinates (freeze_urdf_positions)

3. Mode manager design¶

• service endpoint: /xela_viz_mode_manager/set_mode
• always updates bridge params
• viz service call controlled by:
  • use_viz_set_mode
  • require_viz_set_mode_service

This avoids hard failure when target viz node has no set_mode.

4. Launch design¶

xela_taxel_sidecar_cpp.launch.py:

• resolves hand/mapping/pattern at launch time (OpaqueFunction)
• configures transport + mode manager options
• supports namespace-local TF remap

xela_taxel_sidecar.launch.py: thin wrapper to cpp launch.

5. Risks¶

• wrong mapping/pattern combination for selected model
• optional viz service disabled while user expects viz-side mode switch
• TF frame mismatch in URDF mode

6. Validation¶

• launch left/right models
• verify output topic and web updates
• verify mode toggling with use_viz_set_mode off/on
• verify URDF points in bridge payload

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