# Problem with Fixed Joints

Hey,

I want to simulate a Hokuyo lidar with a servo. So, I created a fixed joint between the servo's wheel and hokuyo link. But when I am controlling the servo with a predefined velocity, the joint is rotating with some random different velocity. But, everything is working fine when I am rotaing without the lidar attached.

Have I made a mistake in defining the joint?

<joint name="hokuyo_joint" type="fixed">
<parent>servo_ax12a::Wheel</parent>