Dasher Develops!

Before I get into the meat of the latest club robot updates, I thought we would share more images of the shenanigans at Monday’s Haberdashers battlefest!

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As you can see much fun was had by all. I was ably assisted by  Robert & Aarti from Cap Gemini, and Ernie our very own STEM Ambassador, plus Peter Chapman (IT teacher) from Adams Grammar.

Congratulations to Team Hackthon, plus members from Luke Pi Walker and Poke’Bot – who will be going to Cambridge on April 1st.

Now to Dasher’s ongoing build/redesign.

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Using 4 X 12v motors required a new chassis rebuild from 4 mm acrylic. The homemade H bridge now easily controls the motors with no signs of overheating. These don’t spin the tyres off (at max rev’) – like the previous motors!

They are drawing a current of much less than the previous motors < 1 amp.  We may even resort to using the quad motozero controller from  Pi-hut as the back up, which can cope with 0.6 amp current pull (not sure about stalling current tho!). Review of the motozero by Mike Horne on his blog.

Some Dasher updates  (it now weighs 1.5 Kg.)

We have tested straight line speed test at an impressive 5 seconds (not entirely  sure if that was using the 3 X HCSR04 sensors?

The 4WD has now reduced its turning circle – making it less maneuverable than the previous design, but that’s the pay off for more torque/power. We (Ernie) was also experiencing some serious issues with the RC car motors and speed controllers with the first design.  We need the wheels placed quite far apart for the plates that will bolt into the underneath of the chassis to hold our skittle device – which works well. A clever device power by elastic bands and triggered by a servo does the trick. We will use a similar mechanism for the golf challenge – to push the ball around.

Ernie has re-read the rules for the chassis / footprint size- which allows us some room for bolt on bits for specific challenges.

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At the last discussion we were going to use the same 11.4 V LiPo battery to power both the motors and the Pi (with a convertor/splitter). An inline fuse & fire proof bag are on the list to make the LiPo battery safe[r].

Not shown in these pictures are the addition of tiny LED screens which display the distance calculations from the 3 X sensors for maze & straight line challenges.

All coding is done in C – including the PWM speed throttling and PS3 controller to drive all this.

We are even compiling a list of spare parts ready for a day of fun in Cambridge:

Screw drivers

Motor

Hot Glue gun

Elastic bands

Pliers

Tyres

Spare hot glue stick

Suitable Nuts & Bolts

Spanners

Raspberry Pi

Electric meter

 

Tweezers

Batteries

?Oscilloscope ?

 

Wire

Shrink tubing

 

 

Wire cutters

Raspberry Pi PSU

H-Bridge

PS3 controller

Soldering Iron

Bluetooth Dongle

 

Plastic Glue

Solder

Wifi Dongle

SR04 sensors

Laptop

De-soldering pump

 

IR sensors

Ethernet X-cable

 

 

 

 

Video camera

 

 

 


 

 

 

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