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Author Topic: Cleaver (with Nice Aluminum Wheels)  (Read 8570 times)

Duane Degn

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Cleaver (with Nice Aluminum Wheels)
« on: October 08, 2015, 12:06:39 PM »
Cleaver

Cleaver141226a.jpg
*Cleaver141226a.jpg (263.7 kB . 757x613 - viewed 1616 times)

A while ago Parallax gave me some of their nice Arlo hardware in exchange for modifying the firmware for their "Eddie" robot. I think I did a good job of modifying the firmware to work with the new hardware and I think I also improved the firmware for the original hardware.

While Parallax hadn't sent one of their decks for the Arlo, I wanted to give my robot the same wheel spacing as the Arlo. I figured out the wheel spacing from the drawings of the deck and cut some expanded PVC (ePVC) (aka foamed PVC). I'll provide more detail about the construction post #5.

I'm going to experiment a bit with this robot post and use this top post as a sort of table of contents for additional posts to this thread.

In this top post I plan to give a basic overview of the robot and I'll add additional details in the following posts.

Top Post. Overview, table of contents.
Reply Numbers and Content of Reply
#1. Videos of the robot. (Nothing very interesting so far.)
#2. Bill of material.
#3. Details about parts and build process.
#4. Description of software used by the robot.
#5. Plans for the future.
#6. One spare post of something I haven't thought of yet.

I hope you guys don't mind if I reserve six more posts.
« Last Edit: October 08, 2015, 08:04:14 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #1 on: October 08, 2015, 12:07:30 PM »
Videos of Cleaver

Here's a video of an encoder test. (It's not very exciting but it's probably the best video of the robot.)



Below are links to some older videos. These are painfully boring.

Old precision test. Boring, don't watch.

Extremely boring video of figure 8.

Early test with MC33926 h-bridge. Boring, don't watch.
« Last Edit: October 08, 2015, 06:49:28 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #2 on: October 08, 2015, 12:07:47 PM »
Bill of Material

The major components of this robot were supplied by Parallax.

ParallaxParts141111a.jpg
*ParallaxParts141111a.jpg (63.01 kB . 657x652 - viewed 577 times)

In exchange for this hardware, I modified the "Eddie" firmware to work with the Propeller Activity Board and two HB-25 motor controller instead of the original Eddie Control Board.

Here's a picture of the Motor Mount and Wheel Kit.

ParallaxParts141111e.jpg
*ParallaxParts141111e.jpg (201.92 kB . 823x673 - viewed 640 times)

The motors are controlled with two HB-25 Motor Controllers.

ParallaxParts141111c.jpg
*ParallaxParts141111c.jpg (205.66 kB . 758x589 - viewed 598 times)

Here's the caster wheel Parallax sent.

ParallaxParts141111b.jpg
*ParallaxParts141111b.jpg (120.61 kB . 532x616 - viewed 584 times)

I also received an Arlo Power Distribution Board.

ParallaxParts141111d.jpg
*ParallaxParts141111d.jpg (110.02 kB . 611x443 - viewed 583 times)

It wasn't part of the original package, but I asked Parallax for a Propeller Activity Board so I could use the one I had purchased myself for a different robot.

Parallax doesn't sell an all inclusive Arlo kit. Instead they list the parts one might want to use and let the customer pick the parts they wish to purchase. Ken correctly assumed I could build a robot with the parts sent. I wasn't sent the Base Deck. I'm not sure I would have wanted to build my robot exactly like an Arlo even if all the hardware were supplied. I wanted to follow David Anderson's advice on the placement of drive wheels and caster wheel.

I've added some sensors to the robot but I haven't incorporated sensor feedback into the control algorithm.

I'm using two Ping sensors and two IR sensors on the robot. These are mounted on pan and tilt gizmos. The first photo shows a Laser Rangefinder also mounted to a pan and tilt device. The Laser Rangefinder was partial payment for another coding job I had done for Parallax.


B.O.M.
1 x Motor Mount and Wheel Kit - Aluminum
2 x HB-25 Motor Controller
1 x Caster Wheel Kit Rev. B
1 x Arlo Power Distribution Board
1 x Propeller Activity Board
2 x PING))) Ultrasonic Distance Sensor
1 x SF02 Laser Rangefinder
2 x Sharp GP2Y0A2YK IR Infrared Range Sensor
3 x Pan/Tilt Device (these are available on eBay and may other places, don't pay more than $4 for one)

I also used ePVC, aluminum "L" beams, nuts, bolts, washers and some Command Strips (Velcro like stuff).
« Last Edit: October 08, 2015, 06:48:59 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #3 on: October 08, 2015, 12:08:15 PM »
Build Details

The firmware I was supposed to modify had been written for the Eddiebot.

eddie.jpg
*eddie.jpg (24.16 kB . 250x337 - viewed 525 times)

Parallax wanted the firmware to work with the Arlo hardware.

ArloRobotPlatformSmall.jpg
*ArloRobotPlatformSmall.jpg (27.33 kB . 309x309 - viewed 541 times)

Since I wanted the distance between the wheels of my robot to match the distance between the wheels of the Arlo platform so sized my pattern appropriately.

Here's the pattern attached to some 6mm ePVC.

Cleaver141116b.jpg
*Cleaver141116b.jpg (105.17 kB . 611x387 - viewed 539 times)

I decided on an 8 sided robot mainly to make it easy to design. I realized after I had drawn out the pattern, the pattern closely resembled the shape of an earlier Parallax robot the Stingray. Below is a picture of Chris Savage's Stingray.

StingraySmall.jpg
*StingraySmall.jpg (41.16 kB . 400x300 - viewed 515 times)

I don't think I was thinking of the Stingray as I was designing Cleaver but the Stingray's design could have easily subconsciously influenced the design of Cleaver.

The motors I was using required holes be cut through the ePVC. I cut these holes and drilled holes for the mounting bolts into the ePVC.

Here are the coordinates I used for these cutouts. The OpenOffice Draw file is attached to this post at the Parallax forum.



Initially my robot looked pretty plain but it was enough to test the new software I was writing.

Cleaver141116c.jpg
*Cleaver141116c.jpg (222.62 kB . 681x537 - viewed 900 times)

I later added pan and tilt mechanisms for the Ping sensors and added IR sensors to these mechanisms. I added a second level to add the Laser Range Finder.

After adding a second level, I found the main deck of Cleaver bowed a bit. The bowing wasn't very bad when I took the photo below but as I added weight to the robot, the bowing got worse.

Cleaver141121c.jpg
*Cleaver141121c.jpg (176.54 kB . 896x410 - viewed 836 times)

The distance between the bottom of the wheels was a bit more than the distance of the top of the wheels. In order to firm up the deck and hold the wheels in alignment, I added aluminum "L" beams to the robot.

Cleaver150522a.jpg
*Cleaver150522a.jpg (236.44 kB . 843x593 - viewed 533 times)

Adding an aluminum brace across the bottom of the deck help to keep it from bowing but the wheels still pulled outward a bit. I wanted to preserve as much ground clearance as possible so I didn't want to add a support which ran across the bottom of the two motor mounts. Instead I built a more complicated brace which pulled the inner section of the motor mount toward the deck. I won't claim it's a work of art but I think it gets the job done.

I didn't have any appropriately sized metal bolts so I ended up using nylon bolts in several places. I'll probably replace these nylon bolts with metal bolts.

As partial payment for another software project I did for Parallax, I received a SF02 Laser Rangefinder. I mounted the laser rangefinder on a pan/tilt gimbal.



I'm not sure how well this will work on the robot. Here's a link to some experiments I did with this rangefinder.

I thought the second level and the rangefinder improved the looks of the robot.



I'm not sure if I'll keep this particular rangefinder on the robot.

I'll go into some detail about the software in the next post.
« Last Edit: October 08, 2015, 08:50:10 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #4 on: October 08, 2015, 12:08:29 PM »
Notes About Software

The software for this robot is located in my GitHub repository. As mentioned previously, this software is a modification of the original Eddie firmware.

The firmware for use with a Propeller Activity Board (PAB) and HB-25 Motor Controllers is named "EddieActivityBoard - Archive [Date 2015.01.01 Time 20.21].zip." This is an archive of all the files needed.

There's also a version for the original Eddie hardware. "Eddie - Archive [Date 2015.01.01 Time 20.21].zip" is intended to be used with an Eddie Control Board. I haven't tested this version of the firmware on an Eddie Control Board but I have tested the firmware on, what I believe is, equivalent hardware.

The Propeller running the Eddie firmware is intended to be use as a slave to a PC. Instructions are sent over a serial connection to the Propeller and data is requested from the Propeller over this same serial line.

While the firmware was originally intended to be used as a slave to a PC, it could be a slave to anything capable of sending commands over a serial line. I've used a variation of the firmware with a smartphone with commands being sent over Bluetooth.

In order to test the firmware, I added some code to execute commands sequentially.
« Last Edit: October 08, 2015, 07:52:58 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #5 on: October 08, 2015, 12:08:47 PM »
Plans for the Future

So far this robot isn't very smart yet. I'm wondering about two different approaching for controlling this robot.

One approach would be to use two Propellers on the robot. One Propeller would be the master controller and the second Propeller (on the Propeller Activity Board) would be the slave controller. The slave controller would be running the Eddie firmware and the master Propeller would make decisions and issue commands to the slave Prop.

The other approach would be to just use sections of the Eddie firmware and have a single Propeller both making decisions and controlling the motors directly. This second approach is more appealing to me. I've written some code with the aim of using a single Propeller to control the robot. This code is also in my GitHub repository but it's located in the "Cleaver" repository.

So far I've only written code which adds the ability to control the robot with a Wii Nunchuck. I haven't added code to avoid opticals yet.

I'd like to make Cleaver much smarter. I'd like to use the ultrasound and IR sensors to detect obstacles and dropoffs. I've experimented with a laser rangefinder but I'm not sure how practical this will be as the robot is moving.

I'd really like to get this robot smart enough to drive around our block. I'm thinking a combination of GPS and other sensors may make it possible to keep the robot on the sidewalk as it drives.
« Last Edit: October 08, 2015, 08:36:12 PM by Duane Degn »

Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #6 on: October 08, 2015, 12:09:04 PM »
Reserved 6 of 6.

erco

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #7 on: October 08, 2015, 01:59:23 PM »
That's so boss, Boss!

Cleaver, ha. Nice LI2B reference.

Eddie Haskell: "Good afternoon, Mr & Mrs Cleaver. Are Wallace & Theodore at home?"

Cleavers are all about nice wheels:


Duane Degn

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #8 on: October 08, 2015, 02:53:53 PM »
Cleaver, ha. Nice LI2B reference.

I figured "Wally" was too close to Wall-E." I suppose I could have gone with "Wallace" but I thought "Cleaver" sounded more menacing. 

Caliban

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #9 on: October 08, 2015, 05:11:07 PM »
Hi Duane,

Thanks for posting this. I'll be following with great interest. The only problem I have with the Parallax hardware is the very high cost here in the UK. Still, it does provide an incentive to see if it can be made cheaper.  ;)

Caliban

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Re: Cleaver (with Nice Aluminum Wheels)
« Reply #10 on: November 02, 2015, 04:40:42 AM »
Great details here.  I need to a bigger, sturdier bot than the BOE bot's I'm learning with now.  This post is a great reference.  Now I need to go read a little about the Eddie bot.  The xbox 360 IR sensor head really has me curious as to how it is being used.

 

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