Let's Make Robots!

What parts to use for the next LMR Start Here robot

As you may have seen in the LMR Live Show, we need a replacement for the Sharp sensor used in the Start HEre kit, as the sensor used till now is no longer being produced.

On http://letsmakerobots.com/node/22657 a lot of really new and interesting sensors came to my attention.

Now, since I am going to do a whole ned version anyway (we cant have instructions with images that doesnt match), I was wondering if there would be other parts that should also come in to the modern times?

Please let me know if you think anything on the present Start Here - project is outdated / could be done smarter / cheaper.

Mind you that of course one can build a cheaper robot, but there are reasons for picking as I did, and new variations should also keep this in mind:

* All items must be commonly available in shops

* Language must be the esiest kind; as little to explain as possible, this is about starting, not learning as such

* As little soldering as possible - and in general as fast building as possible

* Must cover as many basics as possible; Motion, servo, distance measuring, programming at least

So I think the present version is close. However; Let me know if you see anything that I have missed, or if you know of any new parts, trends, techniques etc that should be implemented.

Thank you for helping to make the worlds most popular "How to make a robot" even better :)

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What if we build a MicroSHR? Let's say we get 3 HXT900 servos, take out the electronics from 2 and use them as geared motors (or just use them as continuous rotation servos) and the third for scanning, use a small LiPo and a small microcontroller board of your choice. 

On the other hand, the SHR uses the Sharp sensor mainly to find out where is an obstacle and where it's an opening. Cheaper proximity sensors may be used for this, OddBot is a specialist in building such things, but I think a simple directional IR sensor mounted on the scanning servo can do this easily and will reduce the price.

I have a board in the works that uses a Tiny25/45/85 at 3.3V, controls 3 micro servos and reads 2 sensors and has an onboard MAX1555 for LiPo charging from USB or any 4.5-6V source. Oh, and it's programmable in Arduino!

Interesting ideas, but I have some concerns about some of them for a SHR.

For a true SHR, we would need a source for the modified servos. We don't want to require a beginner to have to hack their servos.

I think LiPo batteries may not be the best choice for a beginner, because they are more difficult to charge. If the onboard Lipo charging you mentioned handles this safely, perhaps it is OK, but I'd be nervous about putting LiPos in a beginner's hands.

If the microcontroller is going to be a 3.3V system, are we requiring the beginner to work with a multi-voltage system? Again, this may not be the best route for a beginner.

I don't mean to be sour on your ideas. I think there is room for a more complex robot package on LMR, and your ideas could be perfect for that.

The one idea that I really liked for the SHR was to explore an alternative proximity sensor. I agree with you 100% that for the SHR, it only needs fairly short range detection. I would recommend that this component be something available to purchase, and not a kit or DIY project. Again, this is for beginners.

True, a LiPo is not something to take easily. But the MAX1555 charger IC takes care of everything charging related. The only thing we need to be careful is to get LiPo batteries that have the built in cut off protection. SparkFun sells such LiPos and I have found them in a few other places.

The electronics will work on 3.3V only, with the microcontroller at 8MHz, internal. The simple IR sensors work with whatever voltage we want, all it needs is to change the resistors for the LEDs. Pull up is still 10k and the capacitors are fine. Simple IR photo diodes or transistors can be used or the low voltage tolerant TSOP4838. The servos are powered directly from the battery. For a small robot that doesn't need a high precision servo, a lower voltage power supply like the 3.7V works fine.

Another cheap IR proximity sensor may be made with a Sharp IS471F sensor that has a modulated output pin to drive an external IR LED.

I plan on selling cheap small servos modified for continuous rotation, small LiPo batteries and electronics for such a robot. I'll find or build simple IR sensors for it. Something like OddBot's IR Eye, but with only one pair of Led/diode shrouded to make it more directional. Also dual and triple "eyes" may be nice on one board. I think there are already similar products out there, especially the tiny sensors for the MegaBitty board.

I'm currently commissioning a project that uses one of these nice servos, maybe one can be squeezed into the new SHB =)

I think that might be better for the FHR (Finish Here Robot).

I thought that was skynet.

Considering Frits was the one to ask for the sensor mounting bracket, that it was designed here on LMR and has LMR printed on it I suggest that the bracket or possibly the Pan/Tilt assembly which includes 2 miniature servos should be part of the kit.


Good point - It will increase price though, and is a step up from "absolute basics", but I'll see what I can do, depending on what sensor and what else. (A lot of intel is waiting to come my way)


Should we make a challenge about it: "find the next start here robot"? That comes in my mind, because I'm working on a Arduino based SHR too.

I am not sure I understand you; Who should make the challenge, and how should one "find" the next..?