Set init position & yaw angle in the same frame as /hydrus/uav/cog/odom topic in simulator

[HarukiKozukapenguin]

I'm now using HYDRUS simulator following this instruction
I now want to set initial position and initial yaw as I want by setting spawn_x, spawn_y, spawn_yaw in bringup.launch
in the following coordinate:, which is the same coordinate as /hydrus/uav/cog/odom topic

• position is CoG of hydrus
• yaw is the direction of link2

But, I found that this initial position and yaw angle is "initial edge of link1 before changing the servo angle set in Servo.yaml (before this change, all link is 0 deg)"

So, I tuned the initial position in the following way

1. set joint angle in Servo.yaml file
2. launch w/o any spawn argument, and check initial yaw angle by rostopic echo /hydrus/uav/cog/odom
3. launch again by setting argument spawn_yaw = -(2's yaw angle) , and check initial position by rostopic echo /hydrus/uav/cog/odom
4. launch again by setting argument spawn_x:=-(3's x) spawn_y:=-(3's y) spawn_yaw:= -(2's yaw angle) and the hydrus show up in the origin and yaw direction is link2 direction

In the above algorithm, it is difficult to set initial spwawn position as I want in the desired coodinate, so, in my personal code, I make new argument in bringup.launch (init_(x,y,yaw)_error) to tune and spawn easily now.

Question
Is there any other ways to set initial position in /hydrus/uav/cog/odom coodinate?