Analysis of RTK Positioning Issues and Classifications

Chapter 1: Analysis of Location Mode Issues

After unboxing and completing the setup of the Data Center (DC), one of the key differences between the 2024 and 2023 models is the addition of the "Select DC Address" step. In this process, the normal performance is as follows:

1. Interface Feedback: In the app, you will see four options: Poor, Fair, Good, and Excellent. At this point, the DC indicator light should be solid yellow.
2. Success in Moving to the Next Step: When the yellow button lights up and you are allowed to click "Next" to proceed to the Data Center Initialize screen, it indicates that the following conditions are met:
   • The DC's RTK antenna and hardware are functioning properly.
   • The chosen DC placement location is suitable for RTK positioning requirements.

It is important to note that this step is mainly influenced by the environment and the DC itself, and is not directly related to the status of the rover.

Common Issues and Solutions

Issue 1: Unable to Connect to DC

Description: You can see nearby DCs in the app, but you are unable to connect successfully.

Possible Causes:

1. Bluetooth distance issue:
   • The distance between the phone and the DC is too far, exceeding the Bluetooth search range.
2. Bluetooth Connection Conflict:
   • The DC's Bluetooth can only connect to one device at a time.
   • If the DC is already connected to another device (such as a family member's phone or iPad), other devices will not be able to connect to the DC.

Solution:

• Ensure your phone is close to the DC and try connecting again.
• Check if any other devices are already connected to the DC. If so, disconnect their Bluetooth before trying again.
• Especially during the DC firmware upgrade process, similar connection issues may occur, and the handling method is the same.

Issue 2: Difficulty in Selecting Location and Unable to Proceed to Next Step

Description: Although the DC connects successfully, the system's high environmental requirements make it difficult to find an optimal location. Furthermore, the "Next" button behaves inconsistently, hindering a smooth setup process.

1. Environmental Obstruction
   • Possible Cause: The DC's location lacks sufficient visibility, preventing it from receiving adequate RTK satellite signals. Even if the sky appears open, surrounding obstacles such as tall buildings or trees may interfere with the signal.
   • Solution:
     • Optimize the Location: Place the DC in an open area with an unobstructed view to ensure it can receive more satellite signals.
     • Multi-point testing: Try setting up the DC in multiple locations, compare the signal stability at each spot, and select the location with the best RTK positioning performance.
     • Explanation of the Fair status: If the DC maintains a stable Fair status (moderate signal), it may slightly impact Yarbo's positioning but remains an acceptable operational state. There’s no need to worry excessively, but ensure that both Yarbo and the DC have a clear view of the sky. This shared satellite visibility can improve positioning accuracy.
2. Loose or poor contact with the RTK antenna
   • Possible causes:The RTK antenna is not securely tightened. In extreme low-temperature environments, there's possibility that the antenna connection may suffer from poor contact.
   • Solutions:
     • Ensure the antenna is tightly secured.
     • If the issue persists, consider using a backup antenna connector (reach out to Yarbo support for the connector) for antenna bridging to eliminate potential contact issues at the interface.

Chapter 2: Importance of DC Initialize and Common Issues

The Role of DC Initialize: This step establishes Yarbo’s coordinate system with the DC as the origin and writes this origin information into the positioning chip of the DC.

• If this step is skipped before creating a map (although some older firmware versions might allow such a process), the coordinate origin won’t be correctly written. As a result, after the DC is powered off and restarted, map drift issues may occur, leading to inaccurate device positioning.

Common Issues and Solutions

Issue 1: After clicking Initialize, the process keeps loading and cannot complete.

Possible Causes and Solutions:

1. Outdated firmware on 2023 models or weak RTK signals in the operating environment
   • Cause: Early firmware versions may require the rover to receive strong RTK signals for this step. These signals are typically unavailable when the rover is placed indoors.
   • Solutions:
     • Upgrade the firmware to the latest version.
     • Ensure the rover is in an open area and verify RTK GPS is available in the app.
     • Repeat the Initialize process several times until successful.
2. Unupdated firmware on 2024 models
   • Cause: Some 2024 models have outdated DC firmware with insufficient system robustness.
   • Solutions:
     • Complete the location selection step and secure the DC in a stable position to avoid movement.
     • Update the DC firmware. It is recommended to use the latest firmware released after 22nd Nov 2024 to significantly improve system stability.
     • Data transmission may occasionally fail, requiring multiple attempts.

Notes:

• The 2024 DC Initialize step mainly depends on environmental conditions and the DC itself, with no direct relation to the status of the rover.
• Moving the DC after selecting its location may cause Yarbo’s map to drift. Therefore, it is recommended to secure the DC in place once the location is selected and avoid unnecessary movement.
• In the current version, reinitializing the DC via the app will reset any completed maps, requiring them to be redrawn. In future versions, we plan to introduce a "Replace Data Center" feature to address DC damage scenarios. This feature will allow users to replace the DC without needing to replan the map, saving time and simplifying the user experience.

Chapter 3: Why Does Setting the Docking Station Location Require RTK Always Strong?

The inclusion of RTK positioning during docking station setup aims to enhance overall positioning accuracy and charging reliability. However, it is not an absolute requirement. Below are the design principles and detailed explanations:

Design Principles and Rationale

During the rover’s docking phase, when it is approximately 1 meter from the docking station, the system uses sensors (such as charging plate signals and the rover's built-in positioning sensors) for secondary precise positioning to ensure successful docking. However, the following factors highlight the importance of a strong RTK signal:

• Environmental Complexity and Slippage Risks:

  Within the 1-meter range of the docking station, the rover may encounter positioning errors due to slippery, soft, or sloped ground. In the event of slippage, relying solely on wheel trajectories or sensor data may not ensure accurate positioning. A stable RTK signal provides highly precise location data, which is critical for recovery and path correction.

• Collaboration Between Sensors and RTK:

  The system integrates RTK positioning with sensor data for multi-layer verification, maximizing the success rate of docking. Test results show that under stable RTK signal conditions, the rover completes positioning and path planning more efficiently.

Thus, it is recommended to set up the docking station when the RTK status is Strong to ensure accurate docking in complex environments.

Operational Recommendations for Special Cases

If you can ensure good ground conditions along the rover’s charging path with no significant slippage risks, it is possible to set up the docking station even with lower RTK stability (status 4 or 5 fluctuations). However, note that weaker signals result in lower tolerance for sensor corrections. It is advised to monitor the rover's docking performance under such conditions.

• For optimal performance:Setting up the docking station with a Strong RTK status provides additional security in complex environments and prevents positioning deviations.
• For ideal environments:Lowering the RTK requirements can be a feasible option if the conditions are favorable.

Important Notes:

Due to the positioning limitations of the docking station, you may see an Adjustangle of -2 in the Diagnosis interface. To rule out issues caused by the right-side antenna, place the rover in an open area and check if the RTK status remains stable.

• If the RTK status is consistently stable: It is strongly recommended to relocate the charging dock.

Chapter 4: Common RTK Issues During Map Creation

After completing the onboarding process, users proceed to map creation. During this phase, the following RTK-related issues frequently occur:

1. Mapping is Not Allowed Until RTK Status is Strong
   • The system restricts mapping until RTK reaches a Strong status to ensure positioning accuracy.
2. Intermittent Network and GPS Signals During Mapping
   • Users observe unstable network and GPS signals displayed in the app, disrupting the mapping process.
3. Position Drift Near Completion
   • As the map is nearly finished, the rover's position deviates from the initial path. Despite this, users may confirm the next step to connect the map and establish a work plan.

To better understand the solutions, we need to understand the RTK communication modes first.

Understanding RTK Communication Modes

RTK communication operates via two data link modes, each with specific characteristics and use cases:

• Local Area Network (LAN) Mode
  • Description:

    The DC (Data Center) connects directly to the rover using Halow technology to transmit RTK data.

  • Analogy:

    This can be visualized as a 100-500 meter long “invisible cable” providing a stable, low-latency data link.

  • Advantages:
    • Minimal latency and strong signals.
    • Ideal for short-range, high-accuracy positioning.
• Internet Mode (Default Mode)
  • Description:

    The DC uploads RTK data to a server, and the rover subscribes to the data via the internet, transmitting it to the device.

  • Characteristics:
    • In theory, as long as both the DC and the rover are connected to the internet, RTK data transmission distance is unlimited.
    • However, optimal positioning accuracy is achieved within a 30-kilometer range.
  • Advantages:
    • Suitable for long-distance scenarios.
    • Requires a stable network connection.

Mode Switching Mechanism

• Trigger:

  When the DC or the rover experiences network instability, the RTK data link automatically switches from Internet mode to LAN mode.

• Reversion:

  Once the DC’s network stabilizes and the machine is within the DC’s connection range, the system automatically reverts to Internet mode.

Switching Times

• Internet to LAN Mode:

  Typically takes about 60 seconds to complete.

• LAN to Internet Mode:

  Depends on the user’s home network stability, generally completing within 2 minutes.

By understanding these RTK communication modes and their switching behavior, users can better address and mitigate issues during the mapping process.

The Relationship Between RTK Signal and Rover Network

The stability of RTK data transmission is highly dependent on the network connection status of the rover. To ensure a stable network, the system automatically switches the connection method based on the following logic:

1. Default Connection: Halow
   • Description:

     Halow is the primary communication method between the DC (Data Center) and the rover, with a coverage range of approximately 100-500 meters. However, beyond 100 meters, environmental factors significantly impact its performance and must be tested in real scenarios.

   • Switching Logic:
     • When the Halow signal weakens (typically below -82 dB), the system switches to another network (Wi-Fi or 4G).
     • When the Halow signal strengthens (typically above -78 dB), the system switches back to Halow.
2. Priority Switch to Wi-Fi
   • Description:

     If the Halow signal becomes insufficient, the rover prioritizes Wi-Fi for network connectivity.

   • Requirement:

     Ensure a strong Wi-Fi signal within the coverage range for optimal performance.

3. Fallback to 4G
   • Description:

     If both Halow and Wi-Fi are unavailable, the device uses its built-in 4G module for data transmission.

Signal Fluctuations During Network Switching

• Network switching may cause brief communication interruptions:
  • Halow → Wi-Fi or 4G: Typically recovers within 5 seconds.
  • Internet Mode → LAN Mode: Takes approximately 60 seconds, during which GPS may degrade to a Weak state.

Scenarios and User Actions

Scenario 1: Rover Exceeds Halow Coverage in Internet Mode

• Observed Behavior:

  The DC remains in Internet mode (constant green light), but the rover moves out of Halow range. The app loses connection to the machine for about 5 seconds while the network switches. Afterward, the connection resumes automatically.

• User Action:

  No action is needed. Wait for the connection to restore and continue mapping.

Scenario 2: DC Switches from Internet Mode to LAN Mode

1. Observed Behavior:
   • The DC transitions from a steady green light to a blinking green light, indicating a switch to LAN mode.
   • If the rover is within Halow range, it continues to function normally. If the DC’s network is restored, it will automatically switch back to Internet mode.
   • If the rover moves out of Halow range during this transition, the situation changes to Scenario 3.
2. User Action:

   No action is required as long as the machine remains within Halow range.

Scenario 3: DC in LAN Mode, Rover Out of Halow Range

Observed Behavior:

1. The DC remains in LAN mode (currently indicated by a blinking green light, which will be updated to steady green in the future).
2. The rover moves out of Halow coverage, resulting in:
   • Network connection to the rover is maintained (rover is online).
   • RTK status becomes unavailable because LAN mode does not support RTK transmission.
3. User Action:
   • Check the network cable connection or restart the DC to restore its network.
   • Once the DC network is restored, it will switch back to Internet mode, allowing RTK transmission to resume.

Is the rover online in the app	Does the rover have RTK
The app is within Bluetooth range and can connect to the rover via Bluetooth.	Is the rover's data link functioning properly, and has data latency increased?
After turning off Bluetooth, is the rover connected to Halow?	Is the rover hardware functioning properly, and is RTK stable in an open area with a functioning data link?
When the rover is outside the Halow connection range, is the 4G switch turned on?	Is the rover's environment normal, and is its location unobstructed?

RTK Signal Interruption During Use: Known Issues and Solutions

RTK signal interruptions during use can result from data link issues, causing a series of impacts. Below are the key issues to focus on and recommended solutions:

Known Data Link Issues

Currently, we have identified an issue related to the Halow data link:

• Phenomenon:

  When the rover moves out of the effective Halow connection range, RTK signals may (not always) be interrupted and fail to recover for an extended period, even after the rover returns to the Halow range.

• Cause:

  Existing algorithmic switching strategies may fail to recover quickly from disconnection in certain cases.

• Improvement Plan:

  We are optimizing the related algorithms, and this issue is expected to be resolved in upcoming DC and rover firmware updates.

• Tip:

  The most direct way to determine if there is a data link issue is to check the data latency in the diagnosis interface:

Meaning of Data Latency Values

• 0-15: Stable values (usually around 1 or 2) indicate normal data communication.
• Continuously Increasing: Indicates data communication issues.
• -1: No data received for 300 seconds, signaling a complete communication breakdown. In this case, restart the DC or bring the machine back within the DC’s coverage range.

Environment-Related Issues and Map Drift

After ruling out data link issues, most RTK signal anomalies can be attributed to environmental factors. A particularly noteworthy problem is position drift during map creation:

1. Phenomenon:
   • During map creation, the rover's position drifts significantly, deviating from the initial route.
   • Users may ignore the signal strength warnings in the app and continue mapping, causing the system's algorithm to automatically fill in certain areas.
   • These filled-in areas may include regions outside the actual planned boundaries, leading to map inaccuracies.
2. Result:
   • Drift directly impacts the map’s accuracy and subsequent work plans, potentially causing path planning errors.
3. Solutions:
   • Stop Mapping Upon Detecting Drift:

     If the rover's position deviates from the initial route during mapping, immediately terminate the operation and replan the map.

   • Pay Attention to App Warnings:

     The app provides strong warnings during RTK signal instability (e.g., Weak state). Users should monitor these closely and avoid mapping under such conditions.

   • Perform a Boundary Dry Test:

     Before running the entire map, use the boundary dry test feature in the settings interface to check if the rover moves outside the planned boundary.

   • Avoid Environmental Interference:

     Map in open areas with minimal obstructions, such as tall buildings or large coverage areas, to ensure maximum RTK signal stability.

Program Defensive Strategies

To mitigate these issues, we have implemented defensive strategies in the program:

• Automatic Alerts:

  When significant signal anomalies are detected, the system prompts the user to stop operations.

• Map Correction:

  The system attempts to exclude regions with noticeable drift from the map.

Limitations of Defensive Strategies

Despite these measures, these strategies cannot fully replace real-time user judgment. Therefore, users must monitor signal status closely during operations.

Chapter 5: Regarding the Flashing Green Light on the Data Center (DC)

Many users have reported concerns about the reliability of the product due to the green light flashing on the DC. However, from a design perspective, the green light flashing does not indicate a malfunction of the DC. In most cases, the flashing green light does not affect the rover's normal operation. It simply represents the two different RTK communication modes of the DC (Local Area Network and Internet), as previously explained in the switching mechanism.

Planned Updates

Future updates will introduce two new features to address this concern:

• Adjustable DC Light Brightness via App:

  Users will be able to adjust the brightness of the DC lights or turn them off completely through the app.

• Green Light Always On:

  Consideration is being given to keeping the DC green light steady, with specific operating modes displayed to the user in the app.

Chapter 6: Map Drift Issues

Common Issues Users May Encounter While Using Yarbo

• Rover Exceeds Boundary During Auto-Planning:

  The rover moves beyond the boundary in reality, but the map shows it as still within the boundary.

• Rover Unable to Return to Docking Station:

  The rover is physically within the area, but the map shows it outside the area, preventing it from docking.

• Rover Stops Unexpectedly:

  The app’s map view shows the rover at the docking station, but in reality, it is not on the docking station.

How to verify Map Drift

To check for map drift, park the rover at the docking station and observe its position in the app:

• No Drift: If the app shows the rover aligned perfectly with the dock, the issue is likely due to other positioning problems.
• Drift Detection: If the app shows the rover misaligned with the dock, the issue is likely caused by map drift.

Possible Causes of Map Drift

• DC (Base Station) Moved:

  Changes to the DC’s physical position can disrupt the alignment.

• Skipped “DC Initialize” Step:

  Creating a map without completing the DC Initialize step can lead to drift.

• DC Bug:

  In rare cases, the DC may mistakenly reinitialize itself (this issue will be fixed in an upcoming update).

• Dead Reckoning Algorithm Error:

  When RTK signals are lost, the rover relies on the Dead Reckoning algorithm, which may miscalculate the position due to factors like slippage. The rover might incorrectly assume it has reached the docking station. However, it typically recalibrates to the dock’s position once RTK signals are restored.

Current Solution

If map drift is confirmed, the only available solution is:

• Reinitialize the DC: Reset the map and redraw the area.

Future Solution

In future updates, users will be able to manually correct map drift without having to delete and recreate the map.

Chapter 7: How Can You Help the Yarbo team?

To streamline issue identification and resolution for the Yarbo team, we encourage you to follow these steps when encountering problems. By working together, we can refine the core functionality of Yarbo’s RTK GPS system and ensure a better user experience. Here's how you can assist:

1. Enable Issue Record for Every Test

Activate the Issue Record feature during each test run. This will allow Yarbo to collect detailed logs and sensor data for analysis.

2. Capture and Provide Key Evidence

When an issue arises, take immediate steps to document it thoroughly.

Required Materials:

1. Screenshots of the main interface in the Yarbo app.
2. Screenshots of the Diagnosis screen from the app.
3. The approximate Eastern Time (ET) in the U.S. when the issue occurred (preferably down to the second).
4. Photos of:
   • Your Data Center (DC).
   • The rover in its current state.

3. Describe the Problem in Detail

Provide a clear narrative of the issue:

• Specify when the problem occurred during the workflow (e.g., DC initialization, map creation, or task execution).
• Detail the steps leading to the problem, including whether everything seemed normal before the issue arose.
• Mention any repetitive actions or patterns that seem to trigger the problem.

4. Submit a Comprehensive Ticket

Bundle all the materials and your detailed description into a ticket. The more specific your report, the faster the team can pinpoint and address the issue.Together, let’s shape Yarbo into a product that exceeds expectations and delivers reliable, high-precision performance. We appreciate your dedication and collaboration!