# Revision history [back]

### Does fixed joint have a bug in sdf ?

I use gazebo7 with ubuntu16.04 to simulate a four wheel robot. 1. If my sdf model has a fixed joint (not for the wheel but for a cemera) like below, the wheel rotation velocity will oscillate, see the picture below the code.

<!-- the zed joint -->
<joint type="fixed" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>
</joint>


1. If I change the fixed joint to a revolute joint whit all other things the same as below, the result will be much better.

<joint type="revolute" name="zed_hinge"><pose>0 0 0 0 0 0</pose>


<child>stereocamera</child> <parent>base_link</parent> <axis> <xyz>0 0 1</xyz> </axis> </joint>

### Does fixed joint have a bug in sdf ?

I use gazebo7 with ubuntu16.04 to simulate a four wheel robot. 1. If my sdf model has a fixed joint (not for the wheel but for a cemera) like below, the wheel rotation velocity will oscillate, see the picture below the code.

<!-- the zed joint -->
<joint type="fixed" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>
</joint>


1. If I change the fixed joint to a revolute joint whit all other things the same as below, same, the result will be much better.better shown below.

 <joint type="revolute" name="zed_hinge"><pose>0 name="zed_hinge">
<pose>0 0 0 0 0 0</pose>


<child>stereocamera</child> <parent>base_link</parent> <axis> <xyz>0 0 1</xyz> </axis> </joint>

### Does fixed joint have a bug in sdf ?

I use gazebo7 with ubuntu16.04 to simulate a four wheel robot. 1. robot. If my sdf model has a fixed joint (not for the wheel but for a cemera) like below, the wheel rotation velocity will oscillate, see the picture below the code.

<!-- the zed joint -->
<joint type="fixed" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>
</joint>


1. If I change the fixed joint to a revolute joint whit all other things the same, the result will be much better shown below.

<!-- the zed joint -->
<joint type="revolute" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>
<axis>
<xyz>0 0 1</xyz>
</axis>
</joint></joint>


I want to know, does fixed joint works properly?

### Does fixed joint have a bug in sdf ?

I use gazebo7 with ubuntu16.04 to simulate a four wheel robot. If my sdf model has a fixed joint (not for the wheel but for a cemera) like below, the wheel rotation velocity will oscillate, see the picture below the code.

<!-- the zed joint -->
<joint type="fixed" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>
</joint>


If I change the fixed joint to a revolute joint whit with all other things the same, the result will be much better shown below.

<!-- the zed joint -->
<joint type="revolute" name="zed_hinge">
<pose>0 0 0 0 0 0</pose>
<child>stereocamera</child>