The OpenShoe runtime framework and the Navigation algorithm repos has recently been updated to use time dependent time differentials. A clock register is read out on every interrupt and the resulting time differentials are used to adjust the “dt” in the mechanization equations and the filter. This we have found necessary if the IMU is free running since the IMU oscillator has clock pace variations (primarily between different units) of plus-minus 1%. Under some conditions this gives significant performance degradation. The resent patch fixes this.
Archive for March, 2012
During the last two weeks a group from KTH (including me) has been visiting our collegues at IISc and conducting a project workshop related to the joint KTH-IISc Indo-Swedish project on indoor localization. During the workshop, a current-status presentation of the OpenShoe project was given. The presentation slides can be found at here.
A first version of the conference article, which is to be published on the PLANS2012 conference later next month, has been sent in for review. The article will not be final (no major changes expected) and available here until in May. However, if you are interested in a pre-print of the article please contact us at firstname.lastname@example.org.
After getting some more IMUs from Analogue Devices last week, tonight I assembled two more complete units. I was happy to see that everything worked fine out-of-the-box. However, I managed to crack a casing when I pressed down an IMU. The tolerances of the IMUs are a couple of tenth of mm and I guess this unit was slightly bigger than the others. Be aware that this can happen!
Some small comments about new IMUs. First of all, per default they come with a 4-tap low-pass filter turned on. This can be turned off with the set_lowpass_filter_imu.m file among the Matlab control scripts. Also, out of the box, the gyros have rather large biases up to 1°/s. Therefore, the gyroscope calibration routine should be run once to make the system perform better.
A demo of the OpenShoe project” was held on the occasion of IISc Open Day on 3 Mar 2012 (also IISc Founder’s Day). It was held in the main foyer of the ECE Main building. Subhadra, Kishore and Anand demonstrated the working of the Openshoe and wireless video streaming in the context of the First-Responder system being developed under the Indo-Swedish activity. A helmet, with a webcam mounted on it, and the openshoe was worn by Subhadra Singh and he walked around the foyer of the building.
The video was streamed via the Beagle board using an ad-hoc Wi-Fi network to the command console at the entrance of the foyer which also displayed the streamed position data in real-time.
Several hundred visitors (general public) enjoyed a thrilling experience of watching the real-time streaming of trajectory and and video feed as the person walked around the foyer. A few pics attached.