16 May

After wrapping up testing the accuracy of NTP, this week I worked on creating new Optitrack Markers for the two new robots and landmarks we plan to add. Creating our own custom markers provides a cheaper, faster, and more flexible alternative to ordering genuine Optitrack markers.3D Printed Mark...

09 May

Last week I tested the ping between computers on the same local network and found that the round trip time of a packet inconsistently ranged between 3.4 ms to 588 ms. Typically, packets sent within the same local network should be less than 10 ms, but for some unknown reason the latency in our netw...

30 Apr

In my last blog post, I described an approach for synchronizing the broadcast intervals of the RF modules in the network based on the system clock. In this blog post, I’d like to compare and contrast this open-loop approach with an alternative approach to synchronize the modules in lock-step. Bo...

18 Apr

The RFM69HCW radio modules that we plan to use for CoLo PE are only capable of half-duplex communication, meaning that it can either transmit or receive packets but not both at the same time. In a typical setup, this issue would be addressed by either setting the modules to automatically retransmit...

10 Apr

Returning to the problem of measuring the cost of different operations for robot localization, I revisited the Spirals research group's PowerAPI toolkit for software power meters. In the time since I had last used PowerAPI, it appeared that the research group had discontinued development of the too...

13 Feb

After revising our requirements, we decided that in addition to the received signal strength, we also needed to collect information on the link quality in order to better characterize the connection between two devices. Link quality is an important measure that indicates whether or not a message se...

31 Jan

During Weeks 1 and 2 I worked on improving the way we started the robots CoLo-PE by moving from using Ubuntu's Remote Desktop solution to issuing remote commands with ssh.To emulate the functionality of the robot_full_run.sh script which opens up several xterm windows each running a different ROS...

04 Dec

These past few weeks my role has been to add networking/communication to CoLo-PE (CoLo Physical Experiments). Previously when evaluating the performance of a localization algorithm, CoLo would infer the connection strength between each of the robots from the relative distance between each of them (...

29 Nov

Last week I measured the performance impact of sending and receiving messages over a Bluetooth link to see how well it would scale up if needed. The metrics I chose were the percentages of CPU and RAM used by the running process. To collect this data, two common tools came to mind: ps and top....

20 Nov

The PyBlueZ library provides an easy to use interface for communicating over Bluetooth in Python. While Python has native support for Bluetooth with its sockets interface, it is only available for Python v3.3 and up. In addition the PyBlueZ provides a lower-level interface for Bluetooth that can b...

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