What parts to use for the next LMR Start Here robot

Community General Discussions
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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 https://www.robotshop.com/letsmakerobots/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Please let me know if you think anything on the present Start Here - project is outdated / could be done smarter / cheaper.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 :)

2

The Sh robot is easy because

The Sh robot is easy because you don’t have to build a chassis for it. You just tape the parts together and you’re done. But the robot is slow, you loose interest and want to try something speedier. I know it’s good for beginners to have time to see what is happening, but I think it would be better to have speedier motors and have them run half speed at first. I think Solarbotics have some speedier motors (GM8?) that can be used.

If one wants to use a cheaper standard servo, check out this one: http://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=3743 but i would recommend a smaller servo for the scanning sensor. I have used the “blue servos” - HXT900 but found that they do not have a linear range, as the middle is 80 instead of 90 degrees and they don’t go full 180 degrees. I got this servo and was impressed how precise scans degree by degree from 1 to 180 with 90 in the middle. I definitely recommend it: http://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=8499&Product_Name=Turnigy_S3101S_Servo__17g_/2.5kg/_.14sec

3

Here are some

Here are some additional things to consider.

We appear to be on the verge of coming up with an Arduino version of the SHR. Maybe the new SHR should be designed with the potential for varients in the main processor and other items.  

Immediately after completing the SHR (or sometimes before), builders start thinking about what they could do different or better, and what features they could add. The choices they make can be creative and fun, and I’d hate to stiffle that. However, we might consider making the SHR a platform that is easy to add to. Leaving space for line following sensors, bump switches, edge detectors, etc. I have mixed feelings about this. A nice little kit like this one includes most of what you get with the SHR, but also a little base plate to build on. Such a base could be designed that would be easy to add on extra sensors or actuators. However, then all SHR robots would look exactly the same. Maybe that’s not what we want. 

Another possible substitution that might save a few pennies is to substitute a Picaxe-18x and Picaxe-18 High Power Board. This would provide adequate power ina i/o for the SHR, I think. However, it does leave the buyer with less flexibility for the future.

4

Man, you’re making me

Man, you’re making me announce my robot kit before it is finished. I came up with the

OctoBotino:

  • metal geared motors from Pololu with brackets and small wheels
  • octagonal base made from acrylic, cut on my CNC at first, then laser cut by Pololu for mass production
  • 2 AA batteries holders (2 AA on each), an extra one can be added for more voltage when using rechargeable
  • small plastic ball caster from Pololu
  • 4 standoffs, 1" long to mount the electronics board
  • 2 standoffs, 3/4" long for micro size servo mount on the base
  • one piece of 1/4" acrylic pre-drilled for Sharp and US sensors mount
  • uBotino microcontroller board

The base will have holes for mounting scanning servo, motor brackets, battery holders, electronics board, various edge sensors, including line following sensors. I will present the CAD soon in a special topic.

5

an arduino based SHR would

an arduino based SHR would be a brilliant idea.

Having as many components be open source as possible would be good, this way any retailers that want to could manufacture the boards, instead of having to purchase them from a specific source as they currently do with the picaxe version.

Any parts that can’t be open source should have several second source manufacturers if at all possible to prevent this happening again.

6

My boards are (will have all

My boards are (will have all the docs soon) Open Source, that is you can build for your own use but can’t sell it as is (I’ll look up the proper license). You can modify the design and sell it as a different product.

The robot kit it’s basic, everyone has build a somewhat similar robot, there is nothing proprietary there. It will just make things easy for some people that are not so mechanically inclined to DIY.

7

to be open source it has to

to be open source it has to be free for commercial and noncommercial use.

8

Should we make a challenge

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.

9

I am not sure I understand

I am not sure I understand you; Who should make the challenge, and how should one “find” the next…?

10

I’m currently commissioning

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

11

I think that might be better

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

12

What if we build a MicroSHR?

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!

13

Interesting ideas, but I

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.

14

I thought that was skynet.

I thought that was skynet.

15

Maybe a challenge isn’t a

Maybe a challenge isn’t a good idea at all, so forget about it.

Maybe a bunch of SHRs will be better, for different platforms: Arduino, ARM, AVR, PIC, PICAXE, etc. This could be existing or new robot projects tagged as  ‘start here robot’. They must be according to Fritls rules above and should be well documented, of cause.

16

True, a LiPo is not

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.