struct Vector3 {
x: f64 = 0.0
y: f64 = 0.0
z: f64 = 0.0
}
struct Quaternion{
xyz: Vector3
w: f64 = 0.0
}
struct Twist{
linear: Vector3
angular: Vector3
}
struct Twist{
// This expresses velocity in free space with uncertainty.
twist: Twist
// Row-major representation of the 6x6 covariance matrix
// The orientation parameters use a fixed-axis representation.
// In order, the parameters are:
// (x, y, z, rotation about X axis, rotation about Y axis, rotation about Z axis)
covariance: float64[36]
}