Some question about the code to calculate the velocity #7
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intergrated urdf model from francesco to the controller of dane. renamed some phantom omni stuff to geomagic (not all) added a few parameters in the launch file
added a hint for zero joint values
rviz won't display the robot model if the parameter pointing to geomagic_description/urdf/omni.urdf is missing. RobotModel will throw the error: "Parameter [Geomagic_robot_description] does not exist, and was not found by searchParam()".
Add parameter "Geomagic_robot_description" from headless to rviz launch
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This was many years ago so I can't really say for sure. But based on the code comments it looks like maybe I was applying a low-pass filter to clean up the velocity signal (attenuate signal >20hz), and using a 2nd order backwards differential estimation, since directly estimating velocity from a series of high-frequency position signals is pretty noisy. By the way, this repo is unmaintained so if you have suggested improvements you should probably fork it. Thanks :) |
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vel_buff = (omni_state->position * 3 - 4 * omni_state->pos_hist1
+ omni_state->pos_hist2) / 0.002; //mm/s, 2nd order backward dif
omni_state->velocity = (.2196 * (vel_buff + omni_state->inp_vel3)
+ .6588 * (omni_state->inp_vel1 + omni_state->inp_vel2)) / 1000.0
- (-2.7488 * omni_state->out_vel1 + 2.5282 * omni_state->out_vel2
- 0.7776 * omni_state->out_vel3); //cutoff freq of 20 Hz
The code above to calculate the velocity, I'm confused about what that means? can you tell me something about that?