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Comments by Kevin
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Kevin's mini-sumo robot: Roku
- 17 October 2018Hi, Dev.
I made a ZIP file available here, containing the laser cutting patterns as DXFs and the Sketchup model. Please note that I made some changes to the laser files but didn't update the model to match; for example, there is a spacer piece behind the sensors (to allow clearance for the modules' through-hole pins) that is not shown in the model.
Kevin
Now available: VL53L1X library for Arduino
- 19 September 2018Hi, Kevin J.
Sure, please start a discussion on our forum and I (or the other engineers here) can respond to your questions.
Kevin
Kevin's mini-sumo robot: Roku
- 26 July 2018Hi, Jeff.
Most of the important parts I used are listed in the "Related products" section above. Other than those, there are the chassis itself (laser cut from acrylic and steel), battery (from an RC hobby store), power button, fishing weights, and various screws, standoffs, and wires.
Kevin
New product: A-Star 328PB Micro
- 17 April 2018Hi, Brad.
I'm sorry you've been having trouble working with your A-Star 328PBs. You are right about the cause of the error, and we've published a new version of our A-Star boards package to fix it. Please try updating to the latest version (4.0.2) through the Arduino IDE's Boards Manager and see if it works for you.
If you continue to have trouble, our forum is a better place for troubleshooting, so please post there.
Kevin
Understanding battery capacity: Ah is not A
- 3 January 2017Hi, Sean J.
To expand on Jan's reply: regardless of the absolute numbers involved, the math does stay the same for the relationship between your discharge rate and how long the battery will last, given a specific battery capacity. However, it is important to note that real-world batteries often don't exhibit ideal behavior: increasing the current drawn from a battery usually decreases its effective capacity (the amount of energy it can provide).
Lead-acid batteries usually have their capacity specified based on a 20-hour discharge period (0.05C discharge rate), as J. Lumsden mentioned in the first comment here. In your case, the discharge rate is more like 1C. Looking at this graph, you should probably only expect to get about 2/3 of the battery's 18 Ah rated capacity at that discharge rate, or about 11-12 Ah.
That seems like it would be marginally okay for your application (11 Ah / 18 A = ~0.6 hours), but you might consider using a larger battery to be on the safe side, especially if you want to keep the battery from discharging to too low of a level (which could shorten its lifespan). On that note, you should also ensure that you use a deep-cycle battery that is designed to be discharged down a substantial portion of its capacity.
Kevin
R2-DR, Kevin's dead reckoning robot
- 8 March 2016Hi, Jordi.
To clarify, I have not made the plans or design files for my robot available. I used some drawings from the R2-D2 Builders Club when designing my robot to make it match the shapes and proportions of the real R2-D2. It's been a while and I don't remember all of the exact drawings I used, but I think I found the ones in "Files > 002-OFFICIAL_BLUEPRINTS > OUTLINE DRAWINGS" to be the most useful.
- Kevin
New product: LPS25H pressure/altitude sensor carrier
- 26 November 2014Hi, Jeff.
The data for this comparison was taken with a sampling rate of 12.5 Hz for both sensors and all other settings left at their power-on defaults (except for additionally enabling the hardware moving average for some tests); see the
enableDefault()function here:https://github.com/pololu/lps-arduino/blob/master/LPS/LPS.cpp.
- Kevin
Understanding battery capacity: Ah is not A
- 12 March 2014The capacity of any particular battery also depends on several things other than its size, including its chemistry and manufacturer, but this Wikipedia article lists some typical capacities for common sizes:
http://en.wikipedia.org/wiki/List_of_battery_sizes
- Kevin
Continuous-rotation servos and multi-turn servos
- 9 August 2012Hi, David.
We don't know of any specific considerations with digital servos, but I think it's going to depend on the particular model of servo, and we haven't tried modifying that one. You should get a pretty good idea of whether it will be practical as soon as you open it up.
- Kevin (engineer at Pololu)