ROS Hexapod project Golem: MX-64 4dof

[KevinO]

Ha! Yes of course. See! I didn't even notice that.
I think there was something else there at one time and this was where I left it. I will push the change up today or tomorrow.

[KevinO]

So I have everything working in ROS now. I have a hexapod_locomotion node I've created based off my standalone code. It subscribes to three topics. A joystick topic, an IMU topic and a third topic to manipulate the travel coordinates directly. The pointgrey gigE camera is also functioning wonderfully! Lastly the node currently publishes the leg angles as well as the body coordinates. I'm working on a model for visualization. A bit of a learning curve but once you are in it it's pretty straight forward. ROS is pretty slick I must say.

[Zenta]

Sounds good Kevin, glad you got it to work!

[KevinO]

Thanks Zenta, Took a bit of time to get my head wrapped around the concept but it kinda clicked after a while.

[KevinO]

So figured I'd give a update on the ROS progress. I currently have my ROS stack working. Xacro/URDF built, IMU active and publishing odom messages, the point grey camera streaming and just put on the Prime Sense depth sensor a few days ago (not in video). I am using depthimage_to_laserscan so I can use gmapping.

In regards to odometry I have had to slow the gait down a considerable bit. Below is a test of the "slow gait," it is using simple cosine and sine waves with a pretty high sample rate, so high I've lowered it a bit since this video as you will see it added a bit of shaking on the coxa joints due to rounding. I currently have one package that handles the leg motion but as far as ROS knows it is just the "base" of the robot. It simplifies the command structure to a simple Twist message for velocity. The max speed is rather slow at 8cm per second, anything higher the IMU gets to much of the impact of the legs in its readings...even with a low pass filter applied.

Next is implementing the ROS navigation stack since I have the base tf, the odometry, and the laser scan data ready. That will give me the autonomous path navigation which will be probably the end goal in the development process of this project.

The more and more I learn ROS I constantly say "Why aren't we funding this!" :P It really is a great system.

Cheers,
Kevin Ochs

[CogswellCogs]

Wow ! Really great work !

[KurtEck]

Again great work! I like how smooth the sine/cosine version of the gait is working. Will be fun to experiment with some of that soon!

Kurt

[Zenta]

Awesome, love smooth gait.

[KevinO]

A couple of pics from testing tonight.

[adammck]

Love that smooth slow gait. The tarsi seem to remain perfectly perpendicular to the ground throughout each step, but I can't see any jitter at all -- are you somehow setting the movement speed dynamically for each joint, or is the framerate just sufficiently high that the jitter isn't noticeable?