Older blog entries for JamesBruton (starting at number 30)

So, android 9 is almost walking. I have the top section of one of the legs pretty much doing the right thing at the right time, just need to do the same with the other and it will locomote. If I get around to doing the bottom sections of the legs it should walk quite well.

I've been a bit busy recently doing stuff over at www.914pcbots.com as I've established admin rights (for now...). Hopefuly Whitebox Robotics will deliver the first shipment of robots soon and then we'll have a full blown fan site. There are already 100's of registered users although most are 'lurking' for now. From the stats is looks like there are around 300 visitors a day so it will be good once the product is available.

On top of that I've been thinking about creating a new android called 'Android X' as it will be the tenth and also matches the Website name of XRobots. Android 9 will probably be ok but I usualy get bored at this point in development and have better ideas.

I'd quite like to use actuators/motors on all the joints instead of having passive ankles because that's the hardest thing to work with. I'd also like propper knees again rather than my on-going parallel mechanism that I've used since android 3. I quite like the balsa wood construction but next time I'll use RE/RS540 motors and make my own gearboxes out of plastic gears, using skateboard wheel bearings for the output shafts. It will look a bit like the RoboOne robots that use R/C style servos but scaled up to about 4 feet / 1.5m tall.

I've made a video in both WMV and DivX format of the android leaning side to side and using the gyro to make sure it doesn't tip over. The videos are in the bottom of the article here.

Next stage will be to sort out the leg motor controllers to make small movements so it can locomote.

Just posted some pics of the android around the house so you can get an idea for it's physical size - it's exactly 1m/39inches tall, they are here, here, and here.

I'm doing ok with dynamic stability testing, more in the article here.

26 May 2006 (updated 26 May 2006 at 10:27 UTC) »

Since my last post here I've mainly finished the mechanical construction of Android 9. I've got a few bits left to tidy up but I've now moved onto the electronics to control it. I'm using mainly Picaxe microcontrollers because they are cheap and have lots of built in functions like RS232 / PWM etc - a bit like a very low cost Basic Stamp on one chip (~$5/10). They are also pin-for-pin compatable with a standard pic (since that's what they are made from).

The basic summary for control is that the side-to-side leaning joints at the ankles are compleatly passive, i.e. no motors. The android will be dynamically stable, getting feedback from a GWS PG-03 gyro so that the hip motors can push it's weight off centre onto each leg in turn, but not tipping so far it falls over, even with momentum builds up. To start, effectively the gyro will act as a kind of safety switch to kill the momentum if the android leans too far outside a predefined safety zone.

I've already started building the picaxe/Gyro 'warning alarm'/measuring circuit so there should be something working soon...

I'm back in the land of the robots now I've mostly finished redecorating my house. Android 9 is underway again and there should be regular updates on my website including some more this week. The legs have their motors attached so it's on with the body which will hold all the electronics.

I'll be coming back to attached the sideways-leaning motors once I know how far it will have to lean to stand on one leg, it's kind of hard to tell at the moment but once I get a feel for how tall it is and how the arms will look it will be easier to find the right place for the extra hip motors. It's going to end up over 1m / 3ft tall by the looks of it...

A few people have asked me if there will more updates on my website soon as I haven't posted as much as I have done previously. So I've started a blog which I'll update every few days with robot things (mainly my thought process etc) as I have a few other things going on in the background at the moment: XRobots Blog

I've started the actual construction of the android now, the front and back sections of the legs are complete, pics are here... More coming this week.

I have ordered the parts for the new android. All of it so far has come from an educational website that supplies schools, but also the general public. They are located in the UK and have some very reasonable prices. Check out: www.mutr.co.uk.

I'll be using mainly balsa wood for this biped but I'm still aiming to make the legs about 50cm long so the whole thing comes to about 90/100cm (approx 3ft) tall. It will use some of the high torque linear actuators although I haven't seen them in real life yet so I've no idea if they're up to it. The plan is to move the leg joints as little as possible for walking in order to 'gear down' the actuators and increase power through levering.

I may still use aluminium tube for some of it but the main concept will be a balsa box construction with heavy card glued on with PVA to make the structure rigid. Anything that needs extra strength will be reinforced with 0.5mm aluminium sheet. All the joints will be made from 3mm steel rod rotating inside polythene bushes so I'm hoping that the whole construction will be light but relatively strong.

I'll start a new article on my site and start posting pics as soon as I get the items delivered...

Well, xmas and new year are out of the way...

I'm currently is the process of refitting my kitchen and bathroom... and then redecorating the whole house from concrete floors up. So not much time for updating my projects, however, my plans for the new year are:

Finishing the last part of Mr stick legs's actual legs which involves another two wiper motors (now makes 5 it total for everything) and some bycycle brake cords to help him stand on one foot. Part of it is done but the page is not yet updated. I'll also post another video when it's done and walking. For now the linux mini-itx system is not on-board and I've not worked on the arms any more.

I'm thinking about building another biped exactly the same but only about 3ft tall instead of 5/6 as the others have been. This will be made from tubular aluminium, some plastic parts from DIY stores as well as polymorph prototyping plastic and use cheaper plastic gearboxes. I've pretty much reaslised that as well as wiper motors being super strong for robots they are also heavy, this means that the android structure has to be stronger (and heavier) and so it's just a vicious circle of power-weight-actuators-power-weight...

There's a rumor about the RoboSapien v3 will be around 3ft tall and be available in 2007 so it seems like a reaslisitc target to work towards for a hobby robot. I'd also like to get further with building arms/head next time before starting at legs again so I think smaller is better.

17 Nov 2005 (updated 17 Nov 2005 at 13:51 UTC) »

Hello, I've finally added some content to my new website 'www.music-chat.com - the home of robotic music and sounds'.

Mostly links to related content although I've explored some future content / projects that I'll create and add.

Any suggestions, let me know what you'd like to see.

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