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# FollowTargetEstimator (UORB message)

**TOPICS:** follow_target_estimator

## Fields

| Name                        | Type         | Unit [Frame] | Range/Enum | Description                                                                                                                               |
| --------------------------- | ------------ | ------------ | ---------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| timestamp                   | `uint64`     |              |            | time since system start (microseconds)                                                                                                    |
| last_filter_reset_timestamp | `uint64`     |              |            | time of last filter reset (microseconds)                                                                                                  |
| valid                       | `bool`       |              |            | True if estimator states are okay to be used                                                                                              |
| stale                       | `bool`       |              |            | True if estimator stopped receiving follow_target messages for some time. The estimate can still be valid, though it might be inaccurate. |
| lat_est                     | `float64`    |              |            | Estimated target latitude                                                                                                                 |
| lon_est                     | `float64`    |              |            | Estimated target longitude                                                                                                                |
| alt_est                     | `float32`    |              |            | Estimated target altitude                                                                                                                 |
| pos_est                     | `float32[3]` |              |            | Estimated target NED position (m)                                                                                                         |
| vel_est                     | `float32[3]` |              |            | Estimated target NED velocity (m/s)                                                                                                       |
| acc_est                     | `float32[3]` |              |            | Estimated target NED acceleration (m^2/s)                                                                                                 |
| prediction_count            | `uint64`     |              |            |
| fusion_count                | `uint64`     |              |            |

## Source Message

[Source file (GitHub)](https://github.com/PX4/PX4-Autopilot/blob/main/msg/FollowTargetEstimator.msg)

::: details Click here to see original file

```c
uint64 timestamp                     # time since system start (microseconds)
uint64 last_filter_reset_timestamp   # time of last filter reset (microseconds)

bool valid              # True if estimator states are okay to be used
bool stale              # True if estimator stopped receiving follow_target messages for some time. The estimate can still be valid, though it might be inaccurate.

float64 lat_est         # Estimated target latitude
float64 lon_est         # Estimated target longitude
float32 alt_est         # Estimated target altitude

float32[3] pos_est      # Estimated target NED position (m)
float32[3] vel_est      # Estimated target NED velocity (m/s)
float32[3] acc_est      # Estimated target NED acceleration (m^2/s)

uint64 prediction_count
uint64 fusion_count
```

:::