AOI Yaw Tracking

Table of contents

1. AOI Yaw Tracking
   1. Summary
      1. What
      2. Inputs
      3. Processing
      4. Outputs
      5. Config
   2. Usage
      1. voxl-portal
      2. voxl-vtx

Summary

What

• voxl-nano-tracker is a headless object-tracking service for VOXL devices that uses the NanoTrack/NCNN tracker and OpenCV (with optional OpenCL GPU acceleration) available in SDK 1.6.3+.

Inputs

• subscribes to camera frames via MPA pipes (configurable camera pipe).

Processing

• pre-processes frames (undistort/resize/color convert)
• runs the NCNN-based tracker, computes object offset (yaw correction) and tracking ROI; supports calibration (use_cal) and OpenCL for speed.

Outputs

• publishes camera frames and metadata/ROIs via MPA pipes and sends object_tracking_data_t (yaw offset, timestamp, sequence) for downstream consumers.

Config

• runtime options live in /etc/modalai/voxl-nano-tracker.conf (camera pipe, ROI size, rates, debug, etc.).

Usage

In order to enable voxl-nano-tracker to run on boot, run the following:

voxl-configure-nano-tracker factory_enable

The generated config file lives at /etc/modalai/voxl-nano-tracker.conf and has the following default settings:

{
	"camera_pipe_name":	"hires_small_color",
	"yaw_rate":	0.20000000298023224,
	"yaw_accel":	1,
	"xy_rate":	1,
	"forward_vel":	0.5,
	"z_vel":	0.5,
	"min_track_size":	150,
	"roi_size_x":	150,
	"roi_size_y":	150,
	"neutral_border":	40,
	"min_sensitivity":	8,
	"dewarp_as_needed":	0,
	"en_debug":	false
}

Each setting can be tweaked to fit the user’s application.

In order to enable AOI yaw tracking in flight the user must be in VFC position mode (VIO) and it must be enabled in /etc/modalai/voxl-vision-hub.conf as a VFC (VOXL Flight Controller) sub-mode.

The relevant config options are below:

"tracking_trigger_ch":	12,
"tracking_trigger_ch_thresh_temp":	1200,
"tracking_trigger_ch_thresh_new":	1800,

The user can choose which RC channel is used to start tracking (default: 12) as well as the channel value threshold.

voxl-portal

AOI Yaw tracking can also be started, stopped, and reset via voxl-portal

voxl-vtx

Yaw Tracking AOI, crosshairs, target, etc. can also be transmitted via voxl-vtx and rendered directly onto user’s screen via voxl-vrx.

In order to enable this, users can modify /etc/modalai/voxl-vtx.conf, enable ai_detection_enable, and set ai_detection_source to that of voxl-nano-tracker (object_tracker_meta)

{
    "name": "Default",
    "mcs": 0,
    "mtu": 1000,
    "power": 1000,
    "source": "hires_default_misp_encoded",
    "invert_toggle": -1,
    "joystick_toggle": -1,
    "ai_detection_enable": true,
    "ai_detection_source": "object_tracker_meta",
    "ai_detection_qty": 3,
    "ai_detection_threshold": 0.5
}