Optimize Your Betaflight Filter Settings with Blackbox Explorer

Table of Contents

1. Introduction
2. What are Filters and Why Do We Need to Tune Them?
3. The Importance of Filters in Protecting Motors
4. The Problem with Default Filter Settings in Betaflight
5. Understanding Phase Delay and Its Effects on Quad Performance
6. Prop Wash and the Difficulty of Reacting Quickly
7. The Benefits of Reducing Filters
8. Adjusting Filter Settings in Betaflight 4.2
9. Activating the RPM Filters for Better Performance
10. Optimizing Filter Values in the Configuration Tab
11. Using Blackbox Explorer for Tuning Filters
12. Setting Up the Blackbox for Recording Gyro Data
13. Conducting a Test Flight to Gather Data
14. Analyzing Noise and Fine-Tuning the Filters
15. Interpreting Blackbox Data in the Graph Analyzer
16. Finding the Right Balance for Filter Settings
17. Considerations for Safety and Motor Protection
18. Conclusion

Introduction

In this article, we will be discussing filter tuning in Betaflight. Filters play a crucial role in ensuring the smooth operation of your quadcopter by reducing noise and protecting your motors. However, default filter settings in Betaflight often Apply more filtering than necessary, resulting in a phase delay that can cause difficulties in reacting quickly to oscillations. By reducing the amount of filtering, you can improve overall performance while maintaining motor safety. We will explore the process of adjusting filter settings in Betaflight 4.2, including activating the RPM filters and optimizing filter values. We will also Delve into the use of Blackbox Explorer for fine-tuning filters and analyzing gyro data. So, let's dive in and uncover the secrets of filter tuning in Betaflight!

What are Filters and Why Do We Need to Tune Them?

Filters are essential components in the flight controller of a quadcopter that help reduce noise in the gyroscope signal. The gyroscope sends a noisy signal to the flight controller, which can interfere with proper motor operation. Without filters, the motors would try to react to these fast oscillations, leading to overheating and potential damage. The primary purpose of filters is to protect the motors by cleaning the gyroscope signal. However, the default filter settings in Betaflight often apply more filtering than necessary, resulting in a phase delay.

The Importance of Filters in Protecting Motors

Filters play a significant role in protecting the motors of your quadcopter. By reducing noise in the gyroscope signal, filters ensure that the motors do not try to react to fast oscillations that can lead to overheating and burnout. These filters act as a safeguard to prevent damage to your quadcopter's motors, making them an essential aspect of tuning.

The Problem with Default Filter Settings in Betaflight

While filters are crucial for protecting motors, the default filter settings in Betaflight often apply more filtering than necessary. This excessive filtering leads to a phase delay, causing difficulties in reacting quickly to oscillations. As a result, the quadcopter may struggle to adapt fast enough, leading to issues like prop wash. Prop wash occurs when the quadcopter tries to compensate but is always a bit late, leading to continuous oscillations.

Understanding Phase Delay and Its Effects on Quad Performance

Phase delay refers to the delay in receiving the filtered signal due to the time taken for filters to Collect and process data. Although the phase delay is only a few milliseconds, it can become problematic when the quadcopter needs to react rapidly. The small delay can hamper the quadcopter's ability to adapt quickly to oscillations or changes in flight conditions. By reducing the amount of filtering, the phase delay can be minimized, resulting in better overall performance.

Prop Wash and the Difficulty of Reacting Quickly

Prop wash is a phenomenon that occurs when the quadcopter experiences turbulence or disturbances in the flying environment. It leads to unstable flight characteristics, particularly during quick maneuvers. The default filter settings in Betaflight, with excessive filtering, can exacerbate prop wash by introducing phase delay. The small delay in reacting to prop wash oscillations can result in continuous oscillations and instability.

The Benefits of Reducing Filters

Reducing the amount of filtering in Betaflight yields several benefits. By minimizing the filters, You can reduce the phase delay, allowing the quadcopter to react more quickly to oscillations or changes in flight conditions. This can result in improved overall performance and stability. However, it is vital to strike the right balance between reducing filters for performance and ensuring enough filtering to prevent motor overheating.

Adjusting Filter Settings in Betaflight 4.2

To adjust filter settings in Betaflight 4.2, you need to access the filter settings tab. This section allows you to control the gyro filters and the D-term filtering. The gyro filters can be controlled using a slider, while the D-term filtering has a separate slider for control. It is important to strike a balance between reducing filters and maintaining enough filtering to protect the motors from overheating or damage.

Activating the RPM Filters for Better Performance

The Betaflight 4.0 introduced the gyro RPM filters, which are highly efficient in reducing noise. To access the RPM filters, ensure that "Bidirectional DShot" is enabled in the configuration tab. While the default settings of the RPM filter do not require modification, the dynamic filter may need adjustment for optimal performance. The recommended settings for the dynamic filter include a notch Q of 250, a frequency range of 90 Hz to 350 Hz, and a 0 percent setting.

Optimizing Filter Values in the Configuration Tab

The configuration tab in Betaflight offers additional settings that can be adjusted to optimize filter values. However, it is essential to use caution and avoid reducing filters too much, as it can be dangerous for the quadcopter. If you wish to go beyond 1.5 on the filter sliders, you need to enable "expert mode." It is recommended to increase the sliders gradually, a few notches at a time, while monitoring the quadcopter's ability to handle the new settings.

Using Blackbox Explorer for Tuning Filters

Blackbox Explorer is a valuable tool for tuning filters in Betaflight. It allows you to analyze the gyro data before and after filtering, enabling you to fine-tune the filters for optimal performance. To utilize Blackbox Explorer, ensure that the Blackbox recording is enabled in the Blackbox tab. Set the logging rate at 2KHz and the debug mode to Gyro_Scaled. This will record the gyro data before filtering, allowing for a comparison with the filtered signal.

Setting Up the Blackbox for Recording Gyro Data

To obtain a good log file for analysis, it is crucial to gather a diverse range of data during your test flight. Fly the quadcopter in FPV or line of sight, preferably in acro mode. Utilize the full range of throttle by performing throttle punches. Gather data across all three axes, including flips and rolls. Additionally, introduce prop wash by flying in a manner that generates turbulence. Aim for a test flight duration of at least 2 minutes.

Conducting a Test Flight to Gather Data

After the test flight, assess the temperature of your motors by pinching them. Slight warmth is generally acceptable, but if the motors are excessively hot and cause discomfort, it indicates the need for more filtering rather than reducing it. The Blackbox Explorer can provide insights into the reasons behind motor overheating and help diagnose any issues.

Analyzing Noise and Fine-Tuning the Filters

Once you have gathered the necessary data, the Blackbox Explorer allows you to analyze noise and fine-tune the filters. Start by removing all unnecessary graphs in the graph setup and focus on the gyro, debug, and custom graphs. The gyro graph displays the noise from your quadcopter before filtering, depicting the oscillations that need to be addressed. Comparing this with the filtered signal shows the effectiveness of the filtering process.

Interpreting Blackbox Data in the Graph Analyzer

In the graph analyzer of the Blackbox Explorer, you can observe the noise from your quadcopter before filtering. The graph displays frequencies on the horizontal axis and amplitude on the vertical axis. Stick movements occupy the left part of the graph, while oscillations above represent the noise and disturbances that need to be addressed. Spike frequencies around 70 or 100 Hz typically indicate prop wash, while the wide noise represents motor noise.

Finding the Right Balance for Filter Settings

After analyzing the noise, it is crucial to fine-tune the filter settings in Betaflight to strike the right balance. By moving the filter sliders to the right, you can increase filtering and reduce noise. However, it is essential to make adjustments gradually, ensuring the quadcopter can handle the new settings. Keep an eye on motor temperatures and overall performance to determine if further adjustments are necessary.

Considerations for Safety and Motor Protection

While optimizing filter settings, it is essential to prioritize safety and motor protection. If your motors become excessively hot or if you encounter issues like damaged propellers, it is crucial to assess the impact of your filter settings. Aggressive filtering can amplify noise from damaged propellers, potentially causing harm to the motors. It is vital to find a balance between performance and motor safety to ensure the longevity and reliability of your quadcopter.

Conclusion

Fine-tuning filters in Betaflight is a critical step in optimizing the performance of your quadcopter while ensuring motor protection. By reducing excessive filtering, you can minimize phase delay and improve overall responsiveness. However, it is essential to strike the right balance and consider safety and motor protection. Utilizing tools like Blackbox Explorer can provide valuable insights into noise and help fine-tune filter settings. With patience and careful adjustments, you can achieve an optimal filter tune that maximizes performance while keeping your quadcopter safe.