RoboSavvy Forum

Is my reasoning ok?

2007-08-28T11:24:38+01:00

The PWM ports are available for In and out as ports 46, 47 and 48.

Thats excellent, thanks Richard .

I think these are much more suitable/convenient ports to use for I2C, I will change mine over.

Chris

Statistics: Posted by NovaOne — Tue Aug 28, 2007 11:24 am

Is my reasoning ok?

2007-08-28T11:12:03+01:00

I missed this question in the earlier post.

The PWM ports are available for In and out as ports 46, 47 and 48.

Statistics: Posted by i-Bot — Tue Aug 28, 2007 11:12 am

Is my reasoning ok?

2007-08-28T07:29:57+01:00

One of the things I use in all my robots is a power filtering system

Hi Humanoido,

Other than capacitors, do use use inductors in your filter networks?

I liked your water analogy...great for beginners.

Chris

Statistics: Posted by NovaOne — Tue Aug 28, 2007 7:29 am

Is my reasoning ok?

2007-08-27T22:02:20+01:00

I've found the drop in battery voltage to affect all systems. It would be worthwhile to have a new battery on hand and for testing or constantly meter the one in use. One of the things I use in all my robots is a power filtering system. Having a voltage regulator is very good but it also needs the filtering on the line. Every time a servo is engaged, there is a drain on the supplied power. It's like watering your garden with a water hose that has a flushing toilet on the same line, where the water hose may actually move a little due to the changes in the water supply. What works well is to introduce good filtering capacitors, some of small values and a larger one. This acts like a water reservoir taking care of the spikes. You should probably scope this out on an oscilloscope to see what's happening.

humanoido

Statistics: Posted by Humanoido — Mon Aug 27, 2007 10:02 pm

Is my reasoning ok?

2007-08-27T21:40:18+01:00

NovaOne wrote:
With your experience, can you think of any simple processing techniques i can do on board with a microcontroller?

Unfortunately I've never worked with microcontroller for image recognition I always worked with Personal Computers, infact with my Robonova all the processing (both image recognition and movement) is done on the laptop, the robot simply performs what the program in the laptop tells it to do. Any way if the microcontroller language supports arrays (in assembly it is a little bit more difficult) you can do whatever processing you like. Since microcontrollers have limited memory (sometimes enough to hold just one camera shot), you can down sample an image to 5x7 a technique used in OCR and then pass it through a Kohonen Neural net to get the corresponding character or shape. You can write simple programs on your PC to gather a database of down-sampled images, store them in an SD card and then use a card reader on your robot such as this one:

http://www.active-robots.com/products/accessories/ummc.shtml

to compare images using various techniques, including Neural Networks, BUT again, I prefer the processing to be done on the PC as resources such as RAM, Storage space, and processing power are less limited.

Oops, I was going to forget, there is also the gumstix which you can use, they are quite powerful and I'm sure that for you it isn't difficult to interface it with your Robonova. You can also connect the CMU cam to this small computer and you can perform all of the things I've mentioned. I haven't chosen this technique for two reasons -
1. it is expensive
2. I surely don't have enough space in my RN for a gumstix!!!

Charles

Statistics: Posted by JavaRN — Mon Aug 27, 2007 9:40 pm

Is my reasoning ok?

2007-08-27T21:14:42+01:00

I doubt it, a 4k7 will draw 1.7mA less than a 1k8

In fact i was considering increasing the value of my pull-pulls to 4k7

Chris

PS
Please keep us updated on your vision system progress.

With your experience, can you think of any simple processing techniques i can do on board with a microcontroller?

Statistics: Posted by NovaOne — Mon Aug 27, 2007 9:14 pm

Is my reasoning ok?

2007-08-27T20:54:12+01:00

Thanks again for your feedback I will start with the 1000uf capacitor first to see if it makes any effect. By the way, excuse my ignorance, can it be because I used 4K7 resistors on the SP03 board for SCL and SDA that all this is happening?

Charles

Statistics: Posted by JavaRN — Mon Aug 27, 2007 8:54 pm

Is my reasoning ok?

2007-08-27T15:40:56+01:00

Unfortunately I couldn't find a low voltage drop regulator in the electronics shop and someone suggested using the 7806 instead of the 7805. What do you think?

Charles

A 7806 would not help at all, it would need about 7.5volts to function properly.

As a stop gap measure only, if you really can't get a regulator put at least one 1n4001 diode in series, with the 6.5v line, it will add a bit of protection and should reduce the voltage onto the Sp03 board.

I suggest you order a MIC29202BT 0.4A from:

http://www.rapidonline.com/

Chris

Statistics: Posted by NovaOne — Mon Aug 27, 2007 3:40 pm

Is my reasoning ok?

2007-08-27T15:02:55+01:00

Unfortunately I couldn't find a low voltage drop regulator in the electronics shop and someone suggested using the 7806 instead of the 7805. What do you think?

Charles

Statistics: Posted by JavaRN — Mon Aug 27, 2007 3:02 pm

Is my reasoning ok?

2007-08-26T22:44:49+01:00

In fact the back cover was the first mod I did to my RN, because of the limited space. Its made of 2mm Polycarbonate (lexan if you prefer the brand name).

Make sure all the edges of where your bends will be are smooth (or it will crack), then bend it COLD. (Unlike acrylic, heating makes Lexan brittle)

The LCD volt meter was instead of a LED bargraph, since it is much more efficient, its an DPM ANDERS OEM-33 from RS Components Part No. 260-303, main supply current is only 300uA.

Why don't you post some pictures of your RN it looks different!

I'd rather not take any more pictures yet due to so many half started upgrades (eg cameras etc) "bits" hanging off....

The only other mods I haven't posted any details of are the 2.5mm LCD-PC socket for debugging, under the display to the right, the "hearing" mics and LDR, which are nothing new.

When I've successfully made a ceramic amp for the Sp03 I will be mounting the Sp03 PCB in the chest, along with a extra 16 port i2c i/o board (half finished) based on the MCP23016....if it works. I need the additional i/o because except for the PWM outputs (can they be used as inputs????) I have no spare ports: ie

4 analogue ports used for Gyros, 2 for IR proxi's, 2 for accelerometers
19 digital ports used for servos, 2 for i2c, 2 for sound sensors, 1 for light sensor.

Why do I need 16 more digital i/o lines.... well I want to put lots of sensors on the feet, to stop RN stepping off a table for example. Also I've been wondering if it would help if the feet had pressure sensors and were articulated (ie had a toe "flap" section ) to enable RN to walk more naturally, not Flat Footed.....

Well that last bit was all pie in the sky.....just dreaming

Well Charles thats about it for my RN.

Having said that I have a problem closing back my RN there are so many wires that I just can't close the lid back! To make things worse I had to remove the backpack because it got heavier (with the SP03) and the robot was falling backwards almost all the time! Any suggestions to replace the back part of the robot (where the wires are).

My only suggestion for you is to balance the load on RN, rather than putting it all in the backpack. My main thought with any mod is will it affect the running of the template program routines....because they take so long to sort out if it does.

Chris signing out.

Statistics: Posted by NovaOne — Sun Aug 26, 2007 10:44 pm

Is my reasoning ok?

2007-08-26T21:25:40+01:00

Wow that's interesting! Why don't you post some pictures of your RN it looks different! - I mean - the back is transparent and there might be other things worth seeing. Having said that I have a problem closing back my RN there are so many wires that I just can't close the lid back! To make things worse I had to remove the backpack because it got heavier (with the SP03) and the robot was falling backwards almost all the time! Any suggestions to replace the back part of the robot (where the wires are).

Charles

Statistics: Posted by JavaRN — Sun Aug 26, 2007 9:25 pm

Is my reasoning ok?

2007-08-26T18:51:34+01:00

What kind of fault? I don't mind buying another battery but if there is a fault I don't know how to deal with it!!!

The best way to determine if you have a "fault" that's draining the battery, is "simply" to compare the current being drawn by an identically set up but guaranteed working RN....Easy

But seriously if everything is working, I think the most common fault on my RN (and a good few others from what I read) is insulation worn off (or trapped) servo wires.
Unless you have an infra-red camera handy?

My RN power rail voltages look just like yours, this is 2mins after power up:

Chris

Statistics: Posted by NovaOne — Sun Aug 26, 2007 6:51 pm

Is my reasoning ok?

2007-08-26T14:47:34+01:00

Sorry the SP03 didn't turn out to be "Plug-Code and Play" for you.

When I started this hobby, six months ago I knew that it was going to be a little difficult from the electronics side, but I am learning . . .

Unless you really have a bad battery or some other fault, it sounds like you need extra batteries or a higher capacity main battery.

What kind of fault? I don't mind buying another battery but if there is a fault I don't know how to deal with it!!!

Wasn't it you who was looking at a 2AH battery a while back?

Yes I was looking for a battery a while ago in fact I ordered one and I am waiting for it to come.

Thanks again all for your help I keep you informed with my progress.

Statistics: Posted by JavaRN — Sun Aug 26, 2007 2:47 pm

Is my reasoning ok?

2007-08-25T18:18:25+01:00

Sorry, my fault...a 7805 ideally needs 6.8v Input voltage......try a low voltage drop regulator as i-Bot suggested. Eg a LM1086 CS 5.0.(1.2v drop)....or better still one of the MIC29 range (max 0.4v drop), that should buy you a little more time.

Sorry the SP03 didn't turn out to be "Plug-Code and Play" for you.

Unless you really have a bad battery or some other fault, it sounds like you need extra batteries or a higher capacity main battery.

Wasn't it you who was looking at a 2AH battery a while back?

Chris

Statistics: Posted by NovaOne — Sat Aug 25, 2007 6:18 pm

Is my reasoning ok?

2007-08-25T17:39:35+01:00

I tried the 7805 3-pin voltage regulator this morning. After a full charge the SP03 works for some time then back to reset, sometimes it works sometimes it doesn't. I've noticed that with a full charge the battery marks 6.9V but then drops after sometime to 6.4V (by this time the SP03 starts rebooting) then to 6.2V. Do you think the battery needs to be replaced?

Thanks

Charles

Statistics: Posted by JavaRN — Sat Aug 25, 2007 5:39 pm