09 May, 2013

BWF and DSP

Winter has passed and mowing season is here! The PurpleMow team has spent the winter time playing with Raspberry Pi doing DSP. The purpose is to find a way of detecting if the mower escapes out of bounds. With the current analog technique we have no way of knowing if the mower is inside or outside the BWF wire. Using DSP this can easily be achieved by detecting the phase shift of the...

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02 April, 2013

10 Apps in 10 Days

Mobile application number one Sterisol Skin Business case: Being at the right place at the right time is critical, even with the simplest products. Reaching out to your customers at the place and time they need it can make a huge difference for your business. Creating a mobile presence in this case means that customers can read and learn how to protect themselves when they need...

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04 March, 2013

10 Apps in 10 Days

1 Mobile App a day, 5 Apps a week 10 Apps in 10 days We challenge you! Be part of a mobile app challenge that aims to deliver 10 apps in 10 days between the 1 and 12 of April  2013. Qualify for the campaign and send in your mobile app application now. You pay 15000 SEK and get an app ready for delivery and built to deliver your information. Do you have an iPhone app but...

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16 January, 2013

Front is now rear

To get better momentum when turning away or closer to the BWF wire, the BWF sensor (receiver) had to be moved away from the center of the machine. The only place to put it was at the "tail". But as we needed the BWF sensor to sit in the front of the machine, the tail is now the front. Get it? Look at the pictures and film to get a grasp of the latest development. Note how much...

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05 January, 2013

Follow the wire, ramping it up!

Over the Holidays the PurpleMow team has been busy! We have done major improvements on the Android application. While experimenting with the follow-the-wire algorithm we saw a need to easily change a number of parameters without having to go back to the development environment and recompile. So a GUI has been created to take care of this and along with that improving the event driven...

On the BWF side we discovered that with the sensor in an upright position the signal was better 15 cm away from the wire than on the actual wire. Our intention is for the robot to find it's way back on the inside of the wire. With the setup of one vertical coil the machine sometimes wandered off to the outer side of the wire and eventually escaping out of bounds. Inspired by what fellow...

Questions? purplemow@purplescout.se

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11 December, 2012

Follow the wire!

Last session we worked on getting the mower to follow the BWF. This would be a useful feature in order to find the way home to the charging station when the battery gets low. As we have not yet implemented the functionality to detect battery low state, we emulated this state with a check box in the display. After some fine tuning we got it working! I managed to get a video on a part of the...

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19 November, 2012

BWF schema using KiCad

I got a tip from a fellow robot engnineer to use an OpenSource tool for cadding called KiCad. I gave it a try attempting to create a layout for the BWF sender/receiver. Below you can see the result. The principle used in the BWF is built on a phenomena called "Electrical resonance". The sender outputs a square wave on the burried wire with a base frequency of about 22 kHz. The...

Questions? purplemow@purplescout.se

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12 November, 2012

Improving BWF

The functionality to find the charging station will in the first attempt do this by following the BWF wire. During the latest sessions, session 8 and 9, we have worked on improving the BWF electronics. The previous one worked OK but sometimes the machine escaped out of bounds and the reading was a bit inaccurate. With the help from a fellow robot lawn mower constructor (Johan Persson a.k.a....

Questions? purplemow@purplescout.se

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17 October, 2012

PurpleMow Icon

Mia has helped us creating a set of stunning icons for use in the Android app.

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11 October, 2012

Titanium Mobile events

Purple Scout - Free Titanium Mobile event Ti.UI.createMicroCodeStrong({top: notch}); Gothenburg adress is: Kyrkogatan 20-22, Göteborg Stockholm adress is: Hälsingegatan 43, 113 31, Stockholm Welcome to a full day event on Titanium Mobile as we will give you deep technical talks on JavaScript CommonJS and resource management. The first half of the day will be...

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