Cerberus - Robot Protector of The Realm!

Joined
Feb 5, 2008
Messages
471
Location
Elma, WA
Website
miscdotgeek.com
I remember when I was a kid, I didn't realize that the only difference between 75mhz and 72mhz was the band allocation. I thought that 75mhz was unsuitable for RC planes, and 72mhz would fail on the ground. There were also a lot of superstitions about the antenna length- I was terrified to mess up the antennae on my receivers! LOL. I really do look forward to seeing what you do. You also might consider 900mhz or even 433mhz band stuff. The options are definitely open! Not sure if you have your ham radio license, but you know, some of the data protocols on HF would be pretty nifty to use for C+C backup :D
 

Radical Brad

Garage Hacker!
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Joined
Mar 13, 1999
Messages
5,954
Location
Kakabeka Falls, Ontario, Canada
My other remotely operated bots used 75MHz for the control link and 900MHz for the video link. I made a 5 watt amp for the 900MHz link, and it gave me about a mile. The weak link was the 75MHz RC transmitter, and I started a "boot" for that as well but never did finish it.

Here is one of my oldies with 75MHz control, 900MHz video, and 433MHz audio...

5037

I have some long range 5G sector radios I may use this time. I have tested them up to 5 miles line of sight, and they are solid. The bonus there is that I can carry control, audio, and video data on one single system using short antennas. The disadvantage is the radios are somewhat directional, so I may try a base antenna turret.

Long range link prototyping won't happen until next year, so i have all winter to think about my options.

Yeah... I know my old RF systems were "pirate", but I do live a long way from anyone out here!

Brad

I remember when I was a kid, I didn't realize that the only difference between 75mhz and 72mhz was the band allocation. I thought that 75mhz was unsuitable for RC planes, and 72mhz would fail on the ground. There were also a lot of superstitions about the antenna length- I was terrified to mess up the antennae on my receivers! LOL. I really do look forward to seeing what you do. You also might consider 900mhz or even 433mhz band stuff. The options are definitely open! Not sure if you have your ham radio license, but you know, some of the data protocols on HF would be pretty nifty to use for C+C backup :D
 

Radical Brad

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Messages
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Kakabeka Falls, Ontario, Canada
Interesting! I do have booster amps for that band as well. I am planning to cover my entire 160 acre yard, so I will probably mount a base antenna on the house (30 foot mast) and then require at least a watt of transmit power if using anything in the gigahertz range.

This "FPV" you mentioned.... is this some new type of transmitter that includes control and a video link all in one?

Control is from base to robot and video is from robot to base.
During autonomous operation, communications will probably happen both ways as I may offload some of the machine vision processing to a base station.

Brad

Modern RC tx/rx is 2.4 GHz, and a brandnew 6 channel set can be yours for about €60.
I don 't know a lot of FPV stuff, but that could solve the video part of this project.
 
Joined
Jan 16, 2011
Messages
263
Location
Vilvoorde / Flanders / Belgium
FPV, First Person View. It's a parallel setup to the RC TX/RX, using 2.4 or 5GHz to transmit stereo video to 3D viewing systems. A lot of Drone and long distance flyers use this technology.
Some mount the stereo camera on a gimbal, and use 2 channels and some clever interfacing to have the camera follow head movement.

As I wrote, no personal experience, but have seen enough of that irl.
 

Radical Brad

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Ok thanks, there are plenty of links with equipment. Basically, it is what I have shown on the robot above. I do have a 2.4GHz video TX as well, but the 900MHz version with the 2.5 watt amplifier worked better. I am going to have to find something in the 10 watt range for what I need if I end up going back to old school video.

Brad

FPV, First Person View. It's a parallel setup to the RC TX/RX, using 2.4 or 5GHz to transmit stereo video to 3D viewing systems. A lot of Drone and long distance flyers use this technology.
Some mount the stereo camera on a gimbal, and use 2 channels and some clever interfacing to have the camera follow head movement.

As I wrote, no personal experience, but have seen enough of that irl.
 
Joined
Apr 15, 2013
Messages
1,877
Location
Washington state
has anybody tried using a cellphone to transmit RC signals. Use DTMF signals for controlling your robot.
Not sure if it is even legal??
 

Radical Brad

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Messages
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Kakabeka Falls, Ontario, Canada
On an early bot, I did DTMF control through hacked FRS radio.
It works for very basic control, but in this case I need a LOT more data bandwidth.

Just the arm alone will have 8 individual channels to control all of its motors and actuators.

This is why I am still steering towards full WiFi linking and writing my own control signal.
If there is enough bandwidth for the control + video + audio, then I do have some nice long range radios to try.

Brad

has anybody tried using a cellphone to transmit RC signals. Use DTMF signals for controlling your robot.
Not sure if it is even legal??
 

Radical Brad

Garage Hacker!
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Joined
Mar 13, 1999
Messages
5,954
Location
Kakabeka Falls, Ontario, Canada
Ok, I keep saying the next photos are going on the new blog, so these will be the last until then!
Finally welded the base frame to the diff and moved the bot up the hill so I can keep it safe from the elements.
I will soon be into the motor and electronics, so I needed shelter. I will work on this in a cloth car shelter.

5039

5040

It's not much to look at yet, but the 3 wheel steering works great. Turns a circle in less than 10 feet!
The entire bot will have a body, so none of the ugly framing will be seen, which means I can just paint it all black.

The most work will go into the complex multi-joint robotic arm, which will probably need10 large gear-motors motors to control it. Good thing I stock piled parts from a dozen electric power wheelchairs over the last 10 years.

The main drive motor will be the 2hp DC motor I used on the Sparky Minibike Plan. Since the bot only needs to move at a fast walking pace, this is plenty of torque.

Next photos will be on the blog, this thread is officially at an end!

Later!
Brad
 
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