Skip to content

README.md

Latest commit

 

History

History
58 lines (41 loc) · 2.84 KB

README.md

File metadata and controls

58 lines (41 loc) · 2.84 KB

DD24 ToF Sensors — Learning Experience

This Learning Experience introduces you to the Time-of-Flight (ToF) range sensors on the Duckiedrone DD24. You will learn what a ToF sensor measures, how the five VL53L1X sensors on the DD24 are wired, how the readings flow from hardware through DTPS to a standard ROS 2 sensor_msgs/Range topic, and how to write a ROS 2 node that consumes them in real time and turns them into a simple obstacle-proximity indicator.

What You Will Learn

  • The physics of time-of-flight sensing, and the VL53L1X datasheet in particular
  • How ToF data flows on the DD24: VL53L1X (I²C) → DTPS driver → ROS 2 bridge → /<robot>/range
  • How to subscribe to sensor_msgs/Range topics from a ROS 2 Jazzy node
  • The tradeoffs between SHORT_RANGE / LONG_RANGE modes and how timing budget limits the update rate
  • How to combine readings from multiple sensors into a single proximity indicator

Notebooks

Work through the notebooks in order:

# Notebook Description
1 1-tof-basics.ipynb How time-of-flight sensing works; the VL53L1X datasheet in one page
2 2-dd24-tof-architecture.ipynb DD24 data flow from hardware to /<robot>/range
3 3-subscribing-to-tof.ipynb Write a ROS 2 node that reads sensor_msgs/Range messages
4 4-tof-modes-and-efficiency.ipynb SHORT_RANGE vs LONG_RANGE; multi-sensor timing budget
5 5-obstacle-proximity.ipynb Fuse five ToFs into a single closest-obstacle indicator

What You Implement

In packages/solution/solution/tof_subscriber.py you implement a ToFSubscriber class that:

  • Subscribes to one or more sensor_msgs/Range topics (per configured sensor name)
  • Keeps the latest reading from each sensor in latest_readings
  • Flags invalid readings (out-of-range sentinel, NaN, below min_range, above max_range)
  • Logs a one-line summary at 1 Hz and raises a proximity alert when the closest valid reading drops below a configurable threshold

The pure-Python helpers (ToFReading, closest_valid, proximity_alert, ToFMode, combined_max_rate_hz) live in packages/solution/solution/tof_math.py so they can be imported from the notebooks and unit tests without needing rclpy.

Your written answers to the theory questions go in packages/solution/solution/answers_tof.md.

Running the Unit Tests

cd dd24-sensors-tof-lx-solution
pytest tests/

Running the Listener

# Build on the robot
dts code build -R DRONE_NAME

# Launch the ToF listener (robot_namespace defaults to the VEHICLE_NAME env var)
ros2 launch tof_listener tof_listener_node.launch.py \
    robot_namespace:=DRONE_NAME \
    sensor_names:="['bottom']" \
    sensor_topics:="['/range']"

On the virtual drone, note that the Duckiematrix renderer must be running to get physically-meaningful ToF values.