Robotic Sushi - FAO Davy

[anonymous]

Hi Andy,

It's all looking very

Hi Andy,

It's all looking very good.

I will do the software mods we discussed.

Just another idea how about a shear pin/ weak link etc in the linkage to protect the servo?

David

[Guest]

That may well be worth

That may well be worth investigating.

I don't think the tail itself will provide much strain on the servo to be honest.

I have a toy fish I purchased off of ebay. It flaps about all day long with just two pencells (provided much amusement at the sub run last month).

Clearly I expect better performance from this beasty, and I think we will get it.

Andy

[Guest]

Electronics are done-

http://img.photobucket.com/albums/v293/subculture84/set-up1.jpg

The black box

Electronics are done-



The black box in the foreground is housing the three switches and PIC board.

That's the electrickery side of things done with for now.

Onto the mechanics............

Andy

[anonymous]

http://www.subcommittee.com/forum/Swimmer chips.jpg

Hi Andy,

Voila the Swimmer



Hi Andy,

Voila the Swimmer chip Version 2 ! (On the right)

It is as we discussed. It has smoothing in software and an extra pin to give half speed. Otherwise identical to the first chip. (If you don't want half speed the pin will need to be earthed.)

I will send it to you in the next day.

I will also send you one of the PWM chips to have a go with(On the left.)
These chips decode the receiver output from each channel to give a high stick, mid stick and low stick output - suitable for the swimmer chip.

So I will use one channel for full ahead, half speed and stop, one channel for right , straight and left, and one for dive and surface.

A three channel fish!

The three chip soilution was neatest and quickest to do in software and it means that the swimmer chip is still compatible with your switching method.

One thing I have noticed is that all the chips need a a good clean power suppply at no lower than 5v.

How is the tail coming along?

David

[Guest]

Hello,

Great stuff. So with the

Hello,

Great stuff. So with the PWM chip, no switchers required? Or have I picked up the wrong end of the stick?

The tail is coming. I've been experimenting with different sizes of tail- in a bucket(!) and have also been playing about with the tail linkage.

I now have a working concept, and just need to cut the parts from GRP sheet (been using wood, bamboo and crunchy nut cornflake packets upto now).

I want to put the tail on a target first of all, just to see how it swims.

If that is successful, then it's time to make a fish proper.

A link you may be interested in-

http://openservo.com/

Andy



Edited By Sub culture on 1153954668

[anonymous]

Hi Andy,

Yes thats it. The

Hi Andy,

Yes thats it. The PWM chip is a 3 way switcher. I plan to use it for other projects too. So a separate chip seemed a good idea.

I would be grateful for youir opinion and if you could try it out with a differerent transmitter/ receiver etc.

The swimmer chip V2.0 will plug straight in to your existing setup but will need the 4.7k resistor between the half speed pin and +5v. (Earthing this pin will give you half speed - sorry I had it the wrong way round in earlier post.)

I really like the idea of testing the tail on a target first! A finning warship perhaps?

David

[Guest]

Received the chips today. http://www.subcommittee.com/forum/icon_smile.gif

Received the chips today.

Now just to clarify- the PWM chip pins act as earths for the pins of the other PIC chip?

Just want to be sure- don't want to blow the chip, I know these things don't tend to give second chances.

Andy

[anonymous]

Exactly that.

You may find it

Exactly that.

You may find it easier as a trial to connect LED's to each pin (With a 1k or so resistor in series with each one.)

As you move the transmitter stick you will see one LED at a time go OFF. (ie it is at 0v or earth. You only need 2 of these pins as input to the swimmer chip.

If you would like another one (due to accident or design! ) let me know the chip costs less than £1. (Mind you the software is priceless)

David

[anonymous]

Hi Andy,

Forgot to say -

Hi Andy,

Forgot to say - but free to you

David

[Guest]

Ha!

Okay all clear now.

I'll wire

Ha!

Okay all clear now.

I'll wire this new chip up and see how it goes.

With one eye on the future, I've been looking over the openservo site. Priced up the cost of a servo conversion, which is under £10 each- reasonable when you consider the sophistication on offer, and much cheaper than the Hitec robotic servos.

That board enables control via I2C protocol, which is compatible with a number of PIC processors, including the OOPIC.

What the OOPIC doesn't have is an 'object' for a PWM input (has an output though, for driving servos etc.).

Now the oopic is based on a normal PIC, so you can access the normal PIC code and create a new object. I'm wondering if this is the way to go for a fully articulated fish, or perhaps better off programming a normal PIC or perhaps one of the PICAXE range (which are very cheap in comparison).

My knowledge of programming is nix, however I have been able to get the basics of oopic programming. The assembler used for normal PIC's came across as like trying to knit fog!

Andy

[Guest]

Wired it all up. One

Wired it all up. One Ken Hewitt switcher removed.

Works fine.

PWM PIC is fine on 6 volts, but the swimmer PIC doesn't like it- got very warm before I quickly removed the power and jumpered back to 5 volts

Curious as to know why a 'mid' position was included on the PWM PIC, as there isn't a pin that i can earth that to on the Swimmer PIC.

Seems to work well enough without it.

Andy

[himszy]

Andy, how's this going? You

Andy, how's this going? You planning on taking it to the Norwich Sub Run?

Michael