First Real Look At My Ez-b Controlled Full Size Lis B9 Robot

Thanks Tony. That means alot coming from you.

Ya, fiddling with these settings are a real pain. I am close but I still have a little way to go. I thought I had it this afternoon but tests show I need to get better acceleration and I'm still overshooting the setpoint. Here's a vid I made thinking I had it whipped but ..... well, you'll see. This is kinda dull and technical. sleep

More tinkering today with the settings. This time I think I'm finally there. I'm thankful to a follow builder and friend that gave me a call this morning to brainstorm some ideas on this issue and give some moral support. Thanks David M! He came up with a great idea (which I haven't tried yet). My arm elbow motor draws so much current (up to 26 amps!) that suggested adding a large capacitor near the motor to give it a boost when lifting. In simple terms, the idea is to take some of the load off the power supply and smooth out the startup so it doesn't fly past the dead band. May just work!

Hi Dave, Great to see that you are still making good progress on B9. It is looking awesome! Was wondering if you could tell me what is the range value of the Softpot that you are using? Is there a minimum (range) value that the Kangaroo needs?

Rex

Hi Rex! Good to hear from you and glad you're lurking around here. LOL. Glad you like the way the B9 is turning out. As I've told you before; "He's a labor of love". I've been building on him for 5 years now pretty steady. Shortly after I started drilling and sanding in late 2011, I found EZ Robot in 2012 and realized that my dream of a fully animated Lost in Space robot could come true.

The Circular Soft Potentiometer made by Spectra Symbol is a really neat pressure sensitive membrane sensor. There is very little information from Spectra Symbol on how to use these because they are so simple to use. The best way I've found is to connect one side pin (pin 3) to ground via a 10K resistor in series, connect the other side pin (pin 1) to your Vcc power line (3V, 5V etc) via a different 10K resistor in series. Then read the analog voltage on the center pin (pin 2). It will range from 1/3 Vcc to 2/3 Vcc.

It's Dielectric Value is @ 500VAC for 1 minute so it will handle any voltage you would put through it from your robot. You're most likely going to feed either 3 or 5 vdc through it. You need the resistors in series on each of the outside legs to limit the voltage going through the pot itself. This is because if you put pressure across both rails on the tail It will burn a hole through it. The resistors limit the voltage to a point where this doesn't happen. This is very important and I've actually burnt up a couple of these running 5 vdc through them without resistors in series. I actually use 1k resistors and works well to limit the voltage.

I'll list the specs below but if you want to see the actual Data Sheet go here. Hoep this helps:

Softpot Data Sheet

Mechanical Specifications:
Life Cycle: >1 million  (Ha! That's I Million wipes!) 
Height:	=0.51mm (0.020?)
Actuation Force (with a 10mm wide active cavity):	-40°C 0.8 to 1.8 N
-25°C 0.8 to 1.8 N
+23°C 0.6 to 1.5 N
+50°C 0.6 to 1.5 N

Electrical Specifications:
Resistance - Standard: 10k Ohms(lengths >300mm = 20k Ohms)
Resistance - Custom:	1k to 100k Ohms
Resistance Tolerance:	±20%
Effective Electrical Travel:	8 to 2000mm
Linearity (Independent): Linear ±1% & 3% Rotary ±3% & 5%
Repeatability:	No hysteresis, but with any wiper looseness some hysteresis will occur.
Power Rating (depending on size, varies with length and temperature):	1 Watt max. @ 25°C, =0.5 Watt recommended.
Resolution:	Analog output theoretically infinite; affected by variation of contact wiper surface area.
Dielectric Value:	No affect @ 500VAC for 1 minute.

EDIT: The Kangaroo will supply 5vdc to your pot or encoder. It gets it from the Sabertooth's onboard voltage regulator. Just run wires from the proper header pins. As mentioned 5vdc will work well with the Softpot.

After two years + of design, building and rebuilding I've finally got a set of working and functional arms for my B9. Here's a YouTube link to a short vid showing a simple animation showing both arms moving in and out with only the claws working. The other three joints do move nicely but I got excited and took a short glamor video of what I have so far. This is only some simple scripting I wrote in a few minutes. Scripting for the rest of the arm and having both work in tandem will take more time then I have to spend this Sunday late afternoon. Enjoy this one and stay tuned for more. Thanks for watching! I've also attach a few pics for your viewing pleasure. LOL!

Dave Schulpius

Looks fantastic!

Simply Superb Dave !

Wow, what a slick bunch of engineering!