add gimbal moudle for stabilizing sensors such as camera

[tongtybj]

@k-okada @iKrishneel @cretaceous-creature As discussed before, the gimbal may not be very necessary. How after I added gimbal for the downward camera, I found that the teleoperation is quite easier than before. Please check #65 Add execute following command.
$roslaunch jsk_mbzirc_tasks jsk_mbzirc_task_1.launch use_ground_truth:=false gimbal:=true

When drone changes its speed rapidly, it will tilt a lot. But right now the camera keeps downwards, and the leg of drone will be captured in the image sometimes.

[cretaceous-creature]

Why dont u follow PR #60 since we change the location of the downward camera and the legs are out of the camera view now...... And I dont know how to deal with the conflict between several PRs...

[cretaceous-creature]

It seems only some files in jsk_mbzirc_tasks got some conflict......
perhaps we can manually fix that....

[cretaceous-creature]

Better to get this done fast so that I can test your program and come up with new solutions.

[tongtybj]

@k-okada Right now we develop our codes based on different branch. My consideration is that different parts should be checked individually. But right now lots of conflicts occur. So what is the best strategy to deal with this kind of issue?

[k-okada]

Separate your branch into multiple PR, it seems to stop or slowdown your
development, but good to refactor and understand your progress.

◉ Kei Okada

On Mon, Apr 18, 2016 at 12:02 PM, 趙 漠居 notifications@github.com wrote:

@k-okada https://github.com/k-okada Right now we develop our codes
based on different branch. My consideration is that different parts should
be checked individually. But right now lots of conflicts occur. So what is
the best strategy to deal with this kind of issue?

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#66 (comment)

[tongtybj]

@k-okada I totally understand and agree with sensei's opinion. My only question is that when the pr should be merged? What is the critical condition?

[k-okada]

we'll merge when the PR looks, good,
as for https://github.com/start-jsk/jsk_mbzirc/pull/65/files

• separate trunk plugin and gimbal plugin
• do not mix style change (add white line at
  https://github.com/start-jsk/jsk_mbzirc/pull/65/files#diff-433a4239774d4a1d4415a562516e0e03R12
  and new feature)
• putting doron into truck plugin does not seems good
• why you do not control them via normal controller plugin for gimbal, I
  strongly suggest to add wide-lens camera for the initial trial , then move
  forward to use gimbal. otherwize you can get evidence that your strategy is
  better then usual idea

◉ Kei Okada

On Mon, Apr 18, 2016 at 2:05 PM, 趙 漠居 notifications@github.com wrote:

@k-okada https://github.com/k-okada I totally understand and agree with
sensei's opinion. My only question is that when the pr should be merged?
What is the critical condition?

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#66 (comment)

[tongtybj]

Camera(FOV=160) with gimbal while moving rapidly

[tongtybj]

Camera(FOV=160) without gimbal while moving rapidly

[cretaceous-creature]

So we can design to gimbal region focus controller and lock the tracking
objects in the image plane..
BTW, how many DOF is this gimbal...

2016-04-20 10:38 GMT+09:00 趙 漠居 notifications@github.com:

Camera without gimbal while moving rapidly
[image: test]
https://cloud.githubusercontent.com/assets/3666095/14660867/ec266024-06e3-11e6-9008-00a575015114.gif

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#66 (comment)

[tongtybj]

this is 2DOF gimbal (pitch and roll). If necessary 3DOF is also possible

[cretaceous-creature]

I think 2D is enough since we can change the yaw of the drone.... roll and
pitch is what drone cant maintain....
ddd666

2016-04-20 11:02 GMT+09:00 趙 漠居 notifications@github.com:

this is 2DOF gimbal (pitch and roll). If necessary 3DOF is also possible

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#66 (comment)

[tongtybj]

@k-okada

• separate trunk plugin and gimbal plugin
  Sorry, I can not understand this request... It seems that those plugins are already separated from the beginning.
• do not mix style change (add white line at https://github.com/start-jsk/jsk_mbzirc/pull/65/files#diff-433a4239774d4a1d4415a562516e0e03R12 and new feature)
  Fixed most of bad style.
• putting doron into truck plugin does not seems good
  Separate the drone part to an independent plugin called "bzirc_gazebo_drone_additional_plugin", which publishes the height and also checks whether hitting to the ground.
• why you do not control them via normal controller plugin for gimbal
  Normal controller was also an option. In that case, I should also write another plugin to generate the desired servo angles. On the other hand, the original gimbal plugin puts the controller part and desired attitude calculation part together.
• I strongly suggest to add wide-lens camera for the initial trial , then move forward to use gimbal. otherwize you can get evidence that your strategy is better then usual idea
  Two gif above may show the difference. Both camera have wide angle(FOV=160). Actually, if there is no gimbal, the occlusion about the ground must occur in the image while the drone tilts a lot.

[k-okada]

• Sorry, I can not understand this request... It seems that those plugins are already separated from the beginning.

separate PR into trunk plugin and gimbal plugin, one plugin should have 1
improvement or 1 bug fix

•  Fixed most of bad style.
  

  separate PR into style fix and any improvement / bugfixes
  I also suggest if you care about style, you 'd better to check with lint
  program within travis, other wise you have never-ending battle on style
  change, each people have their own "good" style

• Separate the drone part to an independent plugin called "bzirc_gazebo_drone_additional_plugin", which publishes the height and also checks whether hitting to the ground.

height of the drone can be published from p3d, is it correct?

• Two gif above may show the difference. Both camera have wide angle(FOV=160). Actually, if there is no gimbal, the occlusion about the ground must occur in the image while the drone tilts a lot.

This is nice comparison, please describe the velocity and tilting angle of
this experiment, and also check behavior of your drone with same velocity.