TEMPER Robot Update:

MikeDYur

Just wanted to give any interested forum members an update on what I have done lately with my robot,

Gimbal joystick control with high resolution in steering and throttle.

4.8vdc to 12vdc step up convertion for B&W WA HD Camera and 400mw FPV transmitter. gives a good 90 minutes run time.

XBee-PRO 900HP long range radio's.

High speed, high torque servo motors. these servo's from Pololu Robotics are shown being tested.

And also I am working on the recieving end by incorporating OSD over FPV, i.e. video overlay of sensor data.

After adjusting my steering linkage to full Ackermann steering geometry, I decided not to re-code and test because because of the limited turning radius.

Some things I need to accomplish are: dedicated control boards, water resistant housing and try to make the servo motors water resistant. After all my original idea was to monitor the enviroment in my general area.

I will keep this thread updated of my progress,
Just in case anybody thought my P.O.C. was'nt sufficiently substantiated.

Mike

erco

Sounds neat. Got any video? Would love to see your overlay HUD.

MikeDYur

HUD still in the works, not sure if I am going with a MAX7456 or the Propeller Backpack circuit.

erco

That's some serious toe out in your Ackerman linkage!

MikeDYur

@erco, I adjusted the linkage as per diagram, anything different from what I started with ruduced turning radius, so I went back to my original design, like you have written many times, "Just add more power".

erco

Yup, that diagram is exactly right. At the extreme turning angle in your photo, the correct toe out looks wild.

Related, I just got front wheel alignments on both of our cars. It's mainly just for peace of mind, kinda like an oil change. In your mind, you know it's the right thing to do, but there's no visible or tangible difference after the service. Hard to know if there's any savings in tire life or gas mileage.

But at any rate it was fun to watch the laser light show from the fancy schmancy alignment machine. I know that was a pricey piece of hardware.

Phil Pilgrim (PhiPi)

erco wrote:

Related, I just got front wheel alignments on both of our cars. It's mainly just for peace of mind, kinda like an oil change. In your mind, you know it's the right thing to do, but there's no visible or tangible difference after the service. Hard to know if there's any savings in tire life or gas mileage.

You did well, erco. I neglected mine, the camber was way off, and it cost me a pair of tires due to premature edge wear. Lesson learned.

-Phil

erco

You can spend $100 on a wheel alignment or a pair of cheap tires. The difference is, one good hit to a curb or a parking lot stop undoes a wheel alignment. Like throwing money away. My wife won't tell me when she hits something. So it's a Smile shoot, depending on how far you drive. Will the tires rot off before the tread runs out?

MikeDYur

Phil Pilgrim (PhiPi) wrote: »

You did well, erco. I neglected mine, the camber was way off, and it cost me a pair of tires due to premature edge wear. Lesson learned.

-Phil

I had new tires and an alignment two years ago when the front end seemed solid, bought new tires again after replacing both front hubs and tie rod ends, another alignment is next.

MikeDYur

Correction, another alignment after replacing the front shocks.

MikeDYur

Just thought I would show that my robot can do more than move. I will post a video later this afternoon, showing sensor data as recieved by the XBee and shown on the PST.

Mike


TEMPER Avalable Sensors;

Parallax, RXM-SG GPS
Parallax, HMC5883L 3-Axis Compass
Parallax, Sensirion SHT-11, Tempurature and Humditty
Parallax, MX2125 Accelerometer
Parallax, PING))) Sensor, Forward
Parallax, PING))) Sensor, Aftward
Parallax, PIR Sensor, Port
Parallax, PIR Sensor, Starboard
Parallax, 29124 Altimeter-Barometer
Taos, TLS230 Light to Frequency
Generic Rain Sensor
Generic Sound Impact Sensor


TEMPER Misc. Outputs;

IR Headlights-on/off
WS2812 RGB LED
SD Memory Datalogger
GIS, Emic 2 Text-to-Speech Module
Piezo Speaker
Aux. Audio output


Proposed Sensors;

Geophone
Anemometor
Wind Direction

erco

TEMPER boasts an impressive array of sensors, Mike. Sounds like it could be an autonomous storm chaser. Get a government grant and make a dozen for evaluation!

MikeDYur

Sorry but not to clear on anything but a large monitor.

Just a short clip to show sensor values being updated on the Parallax Serial Terminal, the XBee reciever is draped over the top of the monitor with status LEDs in view, values are being updated approximatly once every few seconds. PIR and ping sensors are not included in this demo, as they are coded in a closed loop, i.e. Ping roaming and stationary PIR detection, ping turret is not mounted at this time anyway. Of course final coding will have the robot just updating sensor variables to a dedicated Propeller driven transciever with joystick, switches and HUD.



@erco, Government grant would be great, but this is too expensive of a hobby to just get blown away in the wind.

MikeDYur

Finally started working on my robot again, I had to get into the mind frame to expect problems, and that's what I got, small one's anyway. The new wheel servos are slightly larger in width than the Parallax version, so in order to do it right, I had to remove the servo pods, and file .010"-.015" off of the their mounting hole, just a little time and frustration are involved dealing with the miniature SS hardware where the wheel hub attaches to the servo horn, but that had to be done anyway. Two down amd two to go, if I don't get to it this evening, it will have to be put off for a couple day's, the wife and I are celebrating are 30th wedding anniversary tommorow, so I had better leave it alone, if I know whats good for me.

MikeDYur

The wife had to run some errand's for her mother, so I got a chance to finish this swap, things went a little quicker on the rear end, as I could work on it in one piece, still needed the .010"-.015" filed off the width. Can't do any trial's right now, no decent alkaline's laying around, and the rechargeable's need six hour's, I hope to post something a little unique tomorrow. HINT: It should push the torque capabilities to the limits.

erco

Nice progress! Happy Anniversary and looking forward to your "pushing the envelope" video.

Gordon had warned of oversized servos previously. Which type are you using?

BTW Dollar Tree has 'Sunbeam' brand batteries. Four decent AA alkalines for a buck.

Or eight crappy carbon zinc AAs for a buck. "Ideal for low drain devices" like IR remote controls.

MikeDYur

Thanks erco, I am having a problem with the servos in circuit, with the power off, on the PSCU, one or two of them rotate, I guess they are powering through the signal line, trimming dosn't help. What is the warning Duane posted?

MikeDYur

Oh! I get it, the warning was about the physical size of the servos.

MikeDYur

After a preliminary check of some voltages, I come to the conclusion that the PSCU is receiving a degraded TTL signal or the board has been compromised. It is a good time to use that $23 oscilloscope, and check if I have the proper signal levels,

@erco I don't have a lot of test equipment, but I sure am feeling cramped these day's, you getting me started on eBay hasn't helped matters, did you ever figure out how many bales of hay fit inside a Corvair?

MikeDYur

Glad to know it isn't the servo controller, I twisted the steering linkage in to a figure 8, easy fix. I'm going to worry about it tomorrow, I'll try swapping the LLC.

erco

CRAMPED? That ain't cramped. You can still see desktop, and you only have one layer of stuff!

Temper is looking good. Not Temperamental at all.

MikeDYur

My problem is, my separate 5 volt regulator, measured 4.75 volts on it's output, when connected to the new servos. The signal input on the servos must be exceeding the current limits of the regulator, going to try to sub a power bank or a TO3 case @ 1A.
Sorry but, I'm going to put off a video another day, production overruns yuno.

PS: Thank you erco.

MikeDYur

Got back at it this morning and I have it figured out, after swapping the regulator, i'm just going have to power the electronics separately using a power bank, the battery voltage isnt high enough to run a five volt regulator, but I'll probably go with one of these,

https://www.pololu.com/product/2123

I cut corners while in the breadboard stage, and its time to build a power supply, so I have ample 3.3v and 5v power. I have to recharge batterys again, and I will get a video together this afternoon.

Mike

MikeDYur

Well here goes, this didn't turn out to be too impressive, my original idea was to pull the piece of RR track seen in the video, that was asking to much, Well I tried.

erco

Nice job. I think I'm more impressed than the four folks on the couch.

MikeDYur

Thanks erco, yeah there a tough crowd.

I did experience a servo failure after that video, don't think the company I bought them from would appreciate the abuse I gave them right out of the box. The darn thing started running wild, and adjustment made no difference, the pot actually fell back into the body, can't see it now. I will take it apart tomorrow and get a chance to see what their made of, I hope I don't have shop for new motors again. Got any recommendations on a HS HT CR servo?

MikeDYur

Here's the guts of the servo above. Looks neat enough to me, it's to bad the potentiometer wasn't more self supported.

erco

So what actually failed? The pot, electronics, soldering? How did the pot get bent back, is it fixable? At first I thought maybe it was the nylon gears or motor. Pololu says "dual ball bearing, our strongest servo." I'm surprised they don't offer a metal gear CR servo.

How much weight is on each wheel? If you can't find a metal gear, dual bearing servo you may have to consider changing to gearmotor$ & H bridge$.

All I see in a quick search is these dreadful MG995 servos which (before being modded for CR) are called the world's worst servo. http://www.robotshop.com/en/metal-gear-continuous-rotation-tower-pro-servo.html?gclid=CjwKEAjw2PK7BRD

Duane Degn

MikeDYur wrote: »

Got any recommendations on a HS HT CR servo?

I like these from HobbyKing.

I've used them both in my HalloweenHex and in rolling robots. These are some of the easiest servos to convert to CR.

Not only are they relatively easy to convert to CR, they're actually easy to convert from CR back to normal. When I was building my HalloweenHex, I found I had converted too many of my servos to CR and I didn't have enough for the hexapod. Fortunately I had save the small parts I removed from the servo and I was able to restore several CR servos back to their original configuration.

Parallax sells a really nice CR servo. This servo can operate directly from a 2S LiPo.



These cost more than the ebay specials but they are nice and fast.

MikeDYur wrote: »

to bad the potentiometer wasn't more self supported.

I'm not sure I'd call that a real potentiometer. It looks more like a trimpot which aren't made very durable. You could try bending the leads back straight, replacing the trimpot with a different trimpot (erco and I both like to use multiple turn trimpots in CR servos). You could also use the two resistor trick and trim the servo in software.

MikeDYur

Well the servo is on and running great, as far as the pot, it was user failure, I pushed it back using a phillips screwdriver to center it, the little blue one works best but hard to keep track of, can't find my Parallax version either. wiper isn't phillips friendly.

@erco, I just pushed a little to hard on it, and couldn't center it, it was an easy fix, these are ball bearing but not MG, so far I like them, and they are an upgrade in torque, but i'm not seeing the speed when installed on the robot. Leads me to believe I Need more current from the batterys, it is set up for a total of ten rechargeable AA's, or eight alkaline, two six volt banks.

Duane Degn wrote: »

These are some of the easiest servos to convert to CR.

I'm not sure I'd call that a real potentiometer. It looks more like a trimpot which aren't made very durable. You could try bending the leads back straight, replacing the trimpot with a different trimpot (erco and I both like to use multiple turn trimpots in CR servos). You could also use the two resistor trick and trim the servo in software.

Yes trimpot, sorry.



Looks like a nice one and at a good price, I like that it can be coverted and back again. And going to look into the two resistor trick, that would be great to do on the fly.

Thanks Duane.

erco

MikeDYur wrote: »

Got any recommendations on a HS HT CR servo?

Do you mean High Speed and High Torque? They usually vary inversely. For instance, Parallax has two standard-sized CR servos. The ones used in Activity Bot are higher speed (RPM) but lower torque than the original BoeBot servos, which are modded Futaba S148s.