TasV

They are omiwheels (two of these: http://www.rotacaste...ub--2-pack.html) on the back (holonomic). This gives him increased stability without affecting the turning ability. Yes... that's what I thought too and is why I am questioning it.

I'd like him to try and make it a little more robust with a 5x7 frame... but having tested it on a linefollow track tonight I'm still not sure if it makes much difference. It seems to work well... but I'm not sure if it's any better than if it wasn't there and the two wheels were disconnected. Because the two back wheels (it's front-wheel drive) can also be attached so they aren't connected in the middle we compared it and the inside and outside wheels still turn at different rates when the front wheels are turning the robot. It doesn't turn like a conventional car either because it's running a linefollow program and it turns by driving the left and right motors on the front wheels alternately... so it wiggles down the line.

I was checking my Son's latest robot tonight and noticed he'd put a differential on some non-driven wheels and my first thought was... cool! But then I started wondering... would a non-driven differential even work? Would you still get the same beneficial variable rotation of the inside and outside wheels when turning or would it merely serve as a connection between the left and right wheel that still allows them to turn independently (see pic.. forget that he's forgotten to install one of the bevel gears... he's doing pretty awesome for a 12yr old).

That's what I meant... I've actually got this working today. No need to convert anything to text...

Would that mean the compare block wouldn't work then?

I have LED lights connected to a motor port that is run by a parallel program all the time. This largely overcomes the lighting issues. This is a programming issue, somewhere, and I can't work out where I've made a mistake. Why would I need to convert the sensor values to text? Adding stops to the motors helped it track but it crawled at a snails pace.

Spinning around is one of the things it does... it doesn't seem to be sensing the black line. I've backed the power right down while we are getting it right so it doesn't spin out of control... it just doesn't seem to be sensing the line and if it does it does not correct itself... more like a little pause in its motion and on it goes. I've put a motion block after the switch now and set it to all motors stopped to see if that helps.

I've posted this over on Mindboards but it seems a bit slow over there atm... I hope it's in the right place here. I'm trying to do a basic linefollow program which I can do without using variables easily enough but I thought I'd try and be a little more creative and put a calibration routine in, based loosely on the nxtprograms.com smoothfollow program calibration routine. As such I have four variables; White, Black, Grey, and Light. Light is a dynamic variable that is frequently rewritten from the light intensity value (0-100) from a single light sensor. White and Black are measured by scanning to the left (and back again) whilst values are continually fed back so that the max. is set as White and the min. is set as Black. Grey is just (Black + White)/2. This, and the turn on green routine I've made, work but the line follow part based on the light sensors data and the variables don't work. What I want to do is use these variables to control the duration of a motor block. I want it to move either left or right until it is either greater or less than Grey but nothing I've tried works. So far I've been doing things like this: and These do not work and I can't see why... how can I make this work? Can someone tell me what's wrong with my thinking here? TIA, Simon

1 must be the light sensor: http://botbench.com/blog/wp-content/uploads/2011/09/CIMG0939.jpg

I notice the new EV3 colour sensors are centrally aligned. I wonder if they are compatible with NXT 2.0?

WOW! No wonder we can't get the values to match up... one light detector faces the outside of the robot whilst the other faces the middle of it. Thank you for the help. I think I will either get some HiTechnic Colour senses or just go and get a few Lego Light Sensors instead so the lamps and sensors are in line.

My Son and I are struggling with getting two colour sensors (running as light sensors) to give similar values due to differences in orientation to ambient light sources. We have installed two white LEDs in front of the sensor (you can just see it in the top of the photo as a yellow spot), in the hope that if we install our own light source we can even out any variations in the readings caused by different orientations relative to the ambient light source(s) and to reduce the chances of errors being made when the robot must pass through an overhang that blocks all light from the top. It has worked quite well but in some orientations it really throws the values out too if the ambient light source is drastically different on one side than another. The effect is that they combine and throw the two sensors out by as much as 20%. So, I'm trying to understand what each of the parts of the colour sensor does so that we can maybe orient the LEDs in a more optimal position for both sensors and/or create some kind of shield in the appropriate place to prevent the sensor from 'seeing' the majority of the ambient light. This is a photo of the bottom of the colour sensor showing the different parts. I know the part on the right is the RGB LEDs and I think the part labelled 1 senses reflected and ambient light. What does the part labelled 2 do or does it measure the ambient light and 1 measure reflected light? I have looked for this information and it is eluding me.

I like the sounds of the idler gear! Naz, do both kinds go by the part number 3711? If so, I wasn't aware that they came in two different types. I know of the old-style chains that I had as a kid ( 30 years ago), but am after the finer, smaller links.

OK.. thanks. I'll get 50 or so and play with them with 16 tooth gears.

I would like this part in a 3, 5, and 7 hole option. normal lift arms in even holed lengths would be nice too.

How loose is too loose with these things before slip becomes a problem?

I'm trying to work out how many 3711 chain link sections I need to buy to make a loop around 2 x 3647, 8 tooth gears on 15 hole lift arms (on the end holes)? Can anyone help with their size?

If it was me, I would scan the stickers and then use this to remake a new file in something like photoshop, CorelDraw, or Illustrator and then put a cutting path around each sticker so that my Dad's machine can go around and cut around the path.

You don't need to state anywhere that things you produce are covered by copyright laws. There are internationally recognised laws that prevent ANYONE from using ANYTHING that isn't their own intellectual property. The only reason people do print it is to remind people that it is wrong to take something someone else makes and distribute it as your own or for profit. The store is now closed to the general public but that does not stop anyone affected by this from pursuing any legal avenues to recover any lost revenue as a result of these actions. Bricklink would have records of any sales that occurred and the store owner's identity.

My father owns one of these machines (a vinyl cutter and a large format cutter/printer) for his business. I was thinking about the problem of colour matching the blue. In the end I thought one could leave out the blue altogether, because the model had so much blue on it, and where it was blue leave it transparent by printing onto some of the water slide paper you can buy on FleaBay. I wonder if my dad's machines can also cut on this material... will have to make an enquiry. I have vector software (CorelDraw) and Photoshop here and would be happy to do repros for anyone wanting something specific... if it works. I know he can also print on metallic material so that might be a solution to the issue of reproducing the silver in the F1 Williams set above??? PS... not sure the netiquette of not posting in old topics is very relevant. It helps keep information together so you don't have to search in 20 different places for it.

I was impressed with this: Image is clickable to source. And also noticed this:

I wrote a really long reply to this and hit post before realising I hadn't logged in yet and lost the lot... so this is the abridged version of it ;) There is another alternative that in many ways is more lucrative than selling the plans itself which also supports the free exchange of information at the same time. You could start a website or a blog and release free-to-download instructions so that the volume of traffic through the website becomes the more valuable product that people are willing to pay to be part of by way of advertising. People searching for Lego related material online generates enormous amounts of traffic and you might find yourself able to contact businesses to either purchase advertising space on your website or on the plans that you produce. As people come to realise that you have quality material for free your traffic will increase dramatically and the value of your advertising will also increase. This way the financial burden is directed away from your grass-roots fans and towards the groups that have more substantial financial means. The advertising would be Lego themed, of course, and you might find that people would actually appreciate the advertising if it promoted products and news of value to them. This is just food for thought. Feel free to take it with a grain of salt (a sip of Tequila and a bit of lemon ;) ). This is a path I have been down many times in other non-Lego areas over the last 20 years and I can assure you it has far greater income potential and is far less limiting than just selling a product.

I've started a Lego robotics class at the school I teach at and have bought 4 new sets, bringing me up to 7 full kits, plus test mats, sensors, software, teaching resources, and Omni wheels etc... so not for me personally... for the school and I have to run the course and organise the competitions. I wonder if the new M-type motor will work with NXT 2.0 bricks... that would be excellent!

What are the motors in the EV3 like? I would really like TLC to think about making different motors with inbuilt rotation encoders like the NXT 2.0 motor has but in different configurations like PF motors. My school has just spent $4000 on new NXT 2.0 kits for me... now I need to save for some EV3! Can you use NXT-G one them? I assume other languages like RobotC and LeJOS (etc) still work on them too right?

This kind of combo lock?