Matek Optical Flow Module

The Matek 3901-L0X is an optical flow sensor with integrated short-range lidar, designed to improve drone position control, especially in GPS-denied environments.

Overview

The Matek 3901-L0X combines an optical flow camera with a VL53L0X laser time-of-flight lidar. It communicates with flight controllers via UART using the MSP V2 protocol, supported by both INAV and ArduPilot. The module is lightweight and intended for mounting on the underside of multirotor drones, with the camera lens pointing downward and the small arrow on the sensor pointing forward for correct orientation.

Key Features

Optical Flow Sensor: Functions like an optical mouse to detect motion relative to the ground, enabling precise horizontal position hold without GPS. Integrated Lidar: Short-range lidar with a maximum range of 2 meters, primarily for altitude hold between 0–2 meters when enabled.

MC

U Update: Uses STM32L051 instead of STM32F051 due to MCU shortages. Communication: UART MSP V2 protocol; ensure correct serial port mapping according to your flight controller manual. Mounting Requirements: Lens must be at least 2 cm above the ground during initialization for proper optical flow operation.

Installation and Setup

Mount the sensor under the drone, aligned with the forward direction. Adjust FLOW_POS_X and FLOW_POS_Z parameters to match the sensor's offset from the drone's center of rotation (e.g., 2 cm forward, 5 cm below) for optimal performance. While the onboard lidar can be used, it is not recommended for outdoor use due to its short range; a longer-range lidar is suggested for better altitude control.

Practical ApplicationsGPS-denied flight: Maintains stable horizontal positioning indoors or in areas with poor GPS signal. Altitude hold: Works in combination with the lidar for low-altitude hovering.

FP

V and racing drones: Lightweight design and compatibility with INAV make it suitable for high-speed multirotor applications.

Accessories and Mounting

Custom housings are available to protect the sensor and ensure proper alignment. Materials like PETG-CF or TPU provide rigidity, vibration damping, and crash resistance for drone applications. The Matek 3901-L0X is widely available through Matek resellers and online marketplaces, and it is compatible with standard multirotor builds running INAV, Betaflight, or ArduPilot with optical flow support.