FollowTarget (UORB message)
c
uint64 timestamp # time since system start (microseconds)
float64 lat # target position (deg * 1e7)
float64 lon # target position (deg * 1e7)
float32 alt # target position
float32 vy # target vel in y
float32 vx # target vel in x
float32 vz # target vel in z
uint8 est_cap # target reporting capabilities