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Robot_mower update

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  • Robot_mower update

  • #2
    Cool! Gettn' someplace!


    • #3
      Cool, you do any of the interfacing yet with the R/C system?


      • #4
        Cool Gypsie! When do you take off the training wheels (handle bars). I see'em as a good handle for the hound to latch onto!

        Looks like you got a good start going for you.
        - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

        It is true, there is nothing free about freedom, don't be so quick to give it away.


        • #5
          BillH: Using the Devantech 50amp/50 volt motor drives there is no interfacing, you select switches to configure.($122 each x 2) Using a stamp, you can use either bulldozer steer or two stick without involvement from the stamp. (hook radio right to drives)

          I opt'ed for the single stick drive. I did a percentage steer, subtract one side from the other. Not tried it out yet. The RC reciever interfaces with the stamp, a pulsin commandm output to the drives can be either a II2, or Pulsout command (what I did) the sonar module SRF08 works with a timing differntial between ping, and Return ping sound. Camera works great up to 150' from the house reciever. I am mounting it on a servo ran by the "other stick" on the controller.
          The chassis will have to be played with to tune it all.

          The stinking wheels are too small, motors are too low to the ground. I am going to play with it like it is thou.

          The Moto board, programs in C++ and a queer language Tea, almost C, also Java, Also...
 is thier site. Interesting devices. I've sent them about a grand so far. Some items for the next shop bot tho. Probably half that in this project.

          Interesting? the 4ch opto-22 board direct ttl connects to the stamp for the brakes.
          I ended up with a futaba FM 4 ch ground radio to play with.

          I just woke up from a great nap. No milk and cookies tho. I think I was depressed.

          David Cofer, Of:
          Tunnel Hill, North Georgia


          • #6
            Wow, a grand would rent the kid next door for 10 years, longer than the mower will run, without putting more money in it.

            David, just giving you crap.


            • #7
              Yeah, and I used to spend that on a weekend of drinking.. SO? Of course the dancers would hand me more than that for Friday night's tips. And, they were so much fun I didn't have to go out looking for/paying for ........

              I have my own servo drive nearly together from this board, a 2 axis drive I have the code on, feedback with chinese scales, 232 communication back to computer.

              So far, the robot mower is up to $900 total. No encoders, no positioner, no fancy works but basically the same as the $2200 one on the net. I got a new laptop for diff/ building my own and still got the mower.


              • #8
                Ibew, I think I may make a Dual H bridge motor driver with mixing from an Atmel ATMega48 chip, reads the receiver directly.Use it for my R/C tank I bought for 25$ In future, have it display OSD of how many amps the tank is drawing, and even perhaps what you did with the laser, have the turret track a red dot. Well, Thats all over myu head at the moment, the DUal H bridge and mixwer will be first project.
                Yeh Dave, at a later date I will inquire about how to hook up those OPTO 22 boards you sent me.


                • #9
                  You running all that off a battery? How you gonna get that 4.5 to run an alternator?

                  Needs More Power! The battery would be dead just mowin' the strips along my driveway.


                  • #10
                    Actually I am working on a 1/2hp perm magnet motor turned into a generator.

                    This one is toast I may put it into the paper, and it is not done yet.

                    I need hydraulics and more power. I need the speed of a zero turn commercial mower. This brings a whole bunch of controls into play.



                    • #11
                      David -
                      You mentioned possibly making a buck or two with this mower - you mean like making it a product, selling it as a "one-off", or simply hiring it out and having fun with it? Just curious.

                      Also, that tube frame you came up with - is that a fresh design, or did you incorporate existing materials or frame? The rest of the parts I see I think I recognize - are those electric wheelchair drives?

                      Again, nice work. Thanks for posting.



                      • #12

                        I made the plates the casters bolt to, laid the tubing out on top of a mower deck off my rider mower.. made it fit that, then when I decided to go with a mower I made it fit that. Then.. yeah, inside is 30" wide and I forget how long it is now.. I think 40" of so. With dozer steer you need to be wider than long. Wheelbase is about square. Notice mower is hanging by the wheel axles, you can raise and lower the deck by factory handles.

                        2# Devantech 20amp (thought they were 50's) servo drives, configurable, serial, pulse, analog inputs @$122

                        1 Futaba 4ch radio.. $142 Tower hobbies.

                        2 used wheelchair motors/gearboxes Ebay @45 each, $118 total.

                        1 Murray lawnmower @ $122?

                        2 rear wheels @ $9 each Harbor freight

                        2 caster wheels @ 10.99 ea Harbor freight

                        Basic stamp, activity board Bought in the 80s.. Not sure what they cost.

                        I think I am up to $890 on it including the sonar module, Radio nanny camera.

                        I had two batteries from a friends wheelchair. I replaced them and hauled the old ones off. They were a year old and not hurt.

                        I don't have a 24vdc charger or altenator to recharge the batteries yet.. SO I am not in a hurry to discharge them. I have the controls working here on the bench.

                        Radio freq reciever direct wires into stamp, Freq out direct wires from stamp to drives, no complications, nothing hard to wire. Software is done with steering if anyone wants to see what I have done with the steering by one stick.. other stick will aim camera.

               'devantech drives, sonar modules, moto-board, communication modules,

               ' Stamps and other goodies.

               radio controller.


                        • #13
                          Well, if you want to see a mower built from a slightly different point of view, check out my setup.

                          Warning to dial-up users, this link takes you to a page with a couple of megs of stuff on it. There are several pictures of the mower, and to low resolution one minute videos of it in operation. I just threw the site up in less than 10 minutes with Dreamweaver, so please don't give me too much of a rednecking on its appearance.

                          I chose to use a single motor for drive, and steer the front wheels. The steering servo is a Tonegawa Seiko model which I got "refurbished" from a fellow in California who uses a lot of them in anamatronics. It actually had never been used, it was purchased and set up with a custom designed piece of firmware which had a small bug, and never went to the original buyer. I picked it up for $275, which was much better than the $550 that typically go for new, and the bug does not affect its operation on the mower. The servo runs directly on 12V, and has a separate, optically isolated input which will operate directly off a conventional hobby style RC set. That servo is so powerful that if you put a front wheel directly next to a tree and turn the wheels, it will knock the mower sideways. You need both hands and a good grip to quit it from steering :-) These photos are before I added the camera to it.

                          The electrics were powered by a $20 lawn and garden battery, which you can see mounted on the back of it. On a full charge, you could mow for about an hour. I mowed the yard with this a few times before the camera was fitted, although sometimes seeing what you are doing at the far end could be little tough. After the camera was mounted, it became a little bit easier to use. It works like this. I would go out to the shed, hook the wires up to the control system, and back the mower out into the yard. I would then start the engine and go inside. Fire up the 27 inch TV in the living room, switch from the cable to the antenna in my attic, and tune into cable channel 58(which just happens to be a frequency in the 440 MHz amateur bands, I am allowed to operate there). Then I just sit there in the air-conditioned house and mow the lawn. Of course, there were problems. The first problem was that having a 1 W transmitter located 6 inches from your receiver with its antenna less than 2 feet from the receiver's antenna tended to cause a few problems with the remote control system! A filter on the receiver's antenna and a few bypass capacitors made it quite livable within a few hundred feet, putting the receiver in a metal box with a low pass filter on the antenna and feed through capacitors for the control signal and power wires would've been a better solution, and I had plans to finish that. A bigger problem was vibration. The picture was perfect with the engine off, when she started running there was a little bit of blurring. It was still quite usable, unfortunately on the third mowing I found myself blind part way through. As I had a perfect black picture with no loss of sync, I immediately realized that something inside the camera chip had broken. Due to further declines in health, I never got around to solving the vibration problem and mounting a new camera. I must say though, it was neat while it lasted. The biggest problem I had while running it was that I was never able to finish mowing without interruption. Somebody would always stop and knock on the door to ask questions about this thing driving around my front yard!

                          I would like to give some important advice to anybody contemplating doing this on their own. While a remote-control lawnmower is a mighty neat toy, you must give consideration to what kind of trouble it can potentially cause. If you have young kids in your neighborhood, you have to make sure you can see around you at all times, even when you're backing up. Another question is what happens if the radio signal to the mower is interrupted. If you live out in the sticks or you have a fenced in yard, this is probably not a problem. It's certainly not a problem if your yard is fully fenced in. I live right on a main road, and the mower is free to drive out into traffic anytime it wants. Obviously this cannot be allowed.

                          Control loss can happen due to interference from your television transmitter, ignition noise from the engine, or the receiver can fail either from vibration or just plain bad luck. As the receiver needs 5V instead of 12, its batteries can go dead or its regulator the runs it off 12 V can fail. Ideally, and on my list to do, is to have a secondary backup system which can take control of the primary fails. I was lucky here, I had an old PCM radio from my RC car that is laying around. It was capable of storing preset positions for throttle and steering, and automatically going to these positions if it lost its signal. I simply programmed it to take the throttle to stand still and the steering to full right on loss of signal.

                          Ibew's idea of using a DC motor to charge the battery is a good one, but I think an easier way is to use a very small car alternator, like the ones you can find on some of your old Hondas. The average current draw while you're mowing with this thing was well under 10 amps, if you had the alternator geared to the engine so it was spinning just fast enough to produce a maximum of 15 amps, I don't think the engine would be loaded too heavily. Remember, the less current you're drawing, the less horsepower you use. Also note that some of the transmitters are sensitive to voltage. On mine, there was a considerable change in contrast when you are in a high current draw situation, especially as the battery was getting low. There are DC-DC converters on the market which will give you a constant 12 V out with varying amounts of input voltage, these are well worth investing in for your video system.



                          • #14
                            Neat Doctor..

                            WE are going to have several of the "slightly better ones" next year.

                            My plans are to go full auto, a laptop or home computer will operate the machines.

                            My bronchitus was so tore up for the grass/pollen two mowings back I decided to do something different. My wife, she is not going to mow. I am too cheap to have someone I don't know come into my circle and possibly steal from me again.

                            Yours looks fine, a true adaptation and good sense thinking it out. I started doing a steer job, then my buddy Doc *(nother doc) started in on the zero turn thinking. Pretty neat job.

                            A can of spray paint would make it as shiny as mine for a lot less money.