robots.net blog for cschur

10 Sep 2007

Mon, 10 Sep 2007 17:01:16 GMT

HI all,

With the Picbot V project behind us, we have now started the next project, which will incorporate a PCB with everything we optimised in the entire picbot series. Called SweepBot I, its primary task is to live in the bathroom, and daily sweep the tile floor of cat litter that has escaped the cat box. This sounds easy, but is no trivial task, since cat litter goes from large pebble sized pieces to fine dust.

Write me.

Chris comets133@yahoo.com

12 Aug 2007

Sun, 12 Aug 2007 04:02:15 GMT

Hi all,

The gigantic "Docking Logic" Article is done, and posted! This has been one of our biggest robot research projects yet, and after 7 months of hard work I can now present to you the final report:

http://www.schursastrophotography.com/robotics/dockinglogic. html

If someone in this group could please review this work, and if they feel it can contribute to the robotics community, Id very much appreciate that you post it as an article on this robots.net home page. Thanks!

Chris

2 Aug 2007

Thu, 2 Aug 2007 21:57:12 GMT

HI all,

Well, we have finished the first five chapters and are on the last one on our Docking Logic article. Weve covered all the theory and graphics, and now the final chapter - actual lab experiments testing the different technologies.

I hope to get the majority of the last chapter done by this time next week.

Write me.

Chris comets133@yahoo.com

12 Jul 2007

Thu, 12 Jul 2007 22:19:31 GMT

Well, its been a whole month since I last posted, so here is our progress on the Docking Logic Project. The illustration graphics have been really killing me! So many of them, in such detail. Anyway I only have about ten more to go and ALL of the photos, movies, CAD graphics and yes schematics for the giant article will be DONE.

Maybe after this weekend. Then I have to start writing the mega article for you guys. we will cover beacons arrays, beacon sources, charging teqniques, docking tricks and methods, charging contacts and yes, even some of the pitfalls of the commonly used teqniques.

Im looking at getting this whole thing done in about a month I hope. But you know how that goes! ;)

Chris Schur Sr. Robotics Engineer Image Cam, Inc. Scottsdale, Az.

6 Jun 2007

Wed, 6 Jun 2007 16:18:45 GMT

Hi all, Here is an update for the "Docking Logic" research.

We are on the last configuration to evaluate. So far, we have fully tested the pros and cons of these types:

1. Dual hoops contacts 2. cylinder contacts 3. Flat plate on wall

The final configuration is a bit uncertain at this point, but we are going to evaluate the method of simply driving the robot onto a flat charge plate to replenish. Its not as easy at it sounds! Using some sort conductive wheels is not a good choice, you dont want to know what metal wheels do to our wood floors in the house. Contacts that drag or drop to the ground may be one solution. I dont like dragging a set of contact brushes around the wood floor either. Once we have fully evaluated this technique, all the primary research is complete, and we will start the huge write up on the "Docking Logic" subject.

If you have some novel way your robot docks to charge, write us, we'd love to hear from you!

Chris

(comets133@yahoo.com)

8 May 2007

Tue, 8 May 2007 16:40:44 GMT

HI all,

The programming, and hardware on the robot is finished for our "Docking Logic" program, with the PICbot 5. We have a huge amount of writing up to do on what has been learned so far, a very in depth knowledge base for building a self charging robot.

We are now left with evaluation of three different contact configurations on the charging base:

Dual brass hoops

Antenna Post

Antenna flat plate

Here is the latest images, two new ones and a mpg movie of the PIC bot V with the charging base we are now evaluating:

http://www.schursastrophotography.com/robotics/picbot5main.h tml

Let me know what you think!

Chris comets133@yahoo.com

9 Apr 2007

Mon, 9 Apr 2007 17:37:03 GMT

HI all,

We are about halfway through the "Docking Logic" research project after this weekend. It appears to be quite clear at this point, it requires four sensors to successfully dock your robot to a beacon localized charger, with a high percentage of success. These sensors are:

1. An omni directional "system" which detects proximity to the charger.

2. A precise becon homing sensor for final homing.

3. A frontal contact switch (could be bumper) to determine physical contact with the charger. Could also be a photocell.

4. A distance sensing device, such as IR ranging or sonar that allows the robot to slow to a fractional speed when very close to the charger to prevent it from "ramming" it at full speed. (you wont beleive how important this is!)

We have finished the omni cone prox sensor docking, and we are now replacing it with a multiple sensor ring around the robot to give it a rough idea which direction the beacon is when in the prox mode. The cone was fun, but this may be a better solution. (?)

The design of the shape and technique of electrical contacts is next, the two best contenders at this point are frontal contact plates which contact a pair of hoops at any angle, or whiskers that V into a post with contacts.

It must be remembered here that while any one can make a robot dock with its charger, doing it successfully and in a totally repeatalbe manner is lacking in the home robot world at this point. (and Im not talking about the horrendous helter skelter way robot vacs dock)

Write me about your docking experiences!

Chris

comets133@yahoo.com

24 Mar 2007

Sat, 24 Mar 2007 22:04:17 GMT

Hi all,

Our Docking Logic program is proceedng smoothly, and Ive posted a few intermediate images of the project in progress for you to see. The Picbot 5 robot has many faces during this program, sometimes a huge omni sensor on its back, other times a brass bladed beacon homing seonsor. Take a look:

http://www.schursastrophotography.com/robotics/picbot5main.h tml

Chris

12 Mar 2007

Mon, 12 Mar 2007 17:53:55 GMT

Hi all,

we made great progress this weekend on our Docking Logic program. After determining the range and current requirements for detection with a PNA4602 last week, we next constructed an "Omni Cone" sensor. This is a reflective cone which directs the light from all directions to a single sensor below, and indicates the proximity to the charging base, but not its direction.

It took five pages of hand written mathematics to define how to make such a cone, and how to make one from a flat piece of reflective material starting with a circle with a pie shaped cutout.

Once the cone was made, we place the sensor under it at the calculated distance, and confirmed its optical properties by shining a laser horizontally at the inverted cone, and the beam hit square on to the center of the sensor, from all angles around the cone! Ill of coarse be posting this set of calculations so you can make an omni sensor for your robot as well in the final write up.

Next, we are working with directional sensors, and how to home in with perfect accuracy on the charging beacon.

Write me,

Chris

comets133@yahoo.com

1 Mar 2007

Thu, 1 Mar 2007 16:21:13 GMT

Hi all,

We are proceeding well with the first tests of the huge Docking Logic program. The sensitivity of the PNA4602 is startling to say the least! First we constructed an wave form generator by programming a PIC 12F629 chip to go high 12uS, and low 12us. We used a 20mhz xtal for accuracy. WE got 38.46mhz on the counter. That drives a 2n3904 which drives the IR Led. The range was tested with various in line current limiting resistors.

I first started with a standard 270 ohm, and had a range of over 20 feet to make the PNA device active! So powerful was the beam that the whole room lit up in IR and specular sources were everywhere. Next we put a 50k pot in line, and adjusted to set the distance the device would activate. Much to our suprise, even at 50k, the PNA device would slam on at about a foot. Phenomenal. For our testing, we will now vary the power level to simulate the effect of the beacon and how the robot will react to it at its limits as well as when it is strong.

Happy robots.

PS: did you get your wowee robots from macdonalds yet???

Chris