# How to do transformation to get correct linear velocity from linear acceleration IMU data?

Hi I have IMU sensor that gives me the raw data such as orientation, Angular and Linear acceleration. Im using ROS and doing some Gazebo UUV simulation. Furthermore, I want to get linear velocity from the raw IMU data. If I do integration over time there will be accumulated error and will not be accurate with the time when for example the robot makes turns. So If I use

```
acceleration_x = (msg->linear_acceleration.x + 9.81 * sin(pitch)) * cos(pitch);
acceleration_y = (msg->linear_acceleration.y - 9.81 * sin(roll)) * cos(roll);
```

So integrating linear acceleration is very bad,

```
Velocity_x= Velocity_old_x+acceleration_x*dt;
```

because integrates the acceleration without taking into account any possible rotation of the sensor, which means that the results will probably be terrible if the sensor rotates at all. So I need some ROS package that takes into account all this transformation and gives me the most accurate estimation of the linear velocity. Any Help? Thanks