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Remote Control Golf Caddy — Parallax Forums

Remote Control Golf Caddy

172heavy172heavy Posts: 55
edited 2011-08-15 13:23 in Propeller 1
So a friend of mine has asked me to hack a Jazzy Jet Mobility scooter. He is an avid golfer and a little overweight, his Dr. suggested he walk the course instead of ride. He has asked me to make this scooter remote control from a 5 button keyfob to carry is golf bag. The scooter is interesing because all of the motor controls charging control circuits dc drivers etc are in the handle. I told him that we could abandon the handle and buy some dc motor controllers and contol the scooter with a prop chip etc but that is too expensive, my budget is $200.00USD. So my plan is to keep the controller intact and just send signals that mimic the joystick signals. I put the joystick on the Scope and get a range of 1.3 to about 4.1 vdc. 2.5 is neutral. My plan is to generate a PWM signal from the prop to mimic these signals. My question to the group is this what is the most efficient way of doing this? I have a couple of ideas I just want to see if there could be a better way. any input would help. I am not charging my friend anything for this, i just like to tinker. My plan is to have a 2 outputs, one for the x axis and one for the y axis. the keyfob has 5 buttons one in the center that would be used for ALL_STOP and the other 4 at cardinal points. I will have 10 steps in each direction to simulate the degree of handle command from the joystick. For example he would have to press the top button 10 times for full speed forward and if he wants to turn right he could press the right button say 3 times this would reduce the value of the foward variable by three and increase the value of the right variable by 3. Hopefully this will work! this is the fun part.

thanks

Comments

  • W9GFOW9GFO Posts: 4,010
    edited 2011-07-16 12:52
    This was my approach to controlling an electric wheelchair;

    http://forums.parallax.com/showthread.php?122594-What-could-you-use-this-for-It-s-a-two-channel-RC-controlled-digital-pot.&highlight=digital+pot

    Oh, on another wheelchair I removed the original electronics and used two HB-25s. It is not as fast because of the 12V limitation and the controllers will shutdown under heavy loads, but it is strong enough to ride around on on level ground.

    Rich H
  • 172heavy172heavy Posts: 55
    edited 2011-07-16 13:16
    W9GFO wrote: »
    This was my approach to controlling an electric wheelchair;

    http://forums.parallax.com/showthread.php?122594-What-could-you-use-this-for-It-s-a-two-channel-RC-controlled-digital-pot.&highlight=digital+pot

    Oh, on another wheelchair I removed the original electronics and used two HB-25s. It is not as fast because of the 12V limitation and the controllers will shutdown under heavy loads, but it is strong enough to ride around on on level ground.

    Rich H

    thank you for the reply. I thought about using a remote control from an RC car but I don't think he would want to carry the remote around and i Don't want to deal with recharging batteries etc...
  • 172heavy172heavy Posts: 55
    edited 2011-07-16 13:24
    I was wondering what the most efficient method to generate a PWM signal from the PROP? 1 to 4 volts. I was thinking of using a transistor and sending a PWM signal to the base with the collector to +5 and emmiter to ground.
  • W9GFOW9GFO Posts: 4,010
    edited 2011-07-16 18:41
    172heavy wrote: »
    thank you for the reply. I thought about using a remote control from an RC car but I don't think he would want to carry the remote around and i Don't want to deal with recharging batteries etc...

    The digital pot is the important part. It simulates the joystick. Whatever sends the digital pot the signals is completely up to you, it does not have to be an RC remote.

    Rich H
  • 172heavy172heavy Posts: 55
    edited 2011-07-24 16:59
    W9GFO wrote: »
    The digital pot is the important part. It simulates the joystick. Whatever sends the digital pot the signals is completely up to you, it does not have to be an RC remote.

    Rich H

    I overlooked the "digital pot" I have tried this and it works great. All I have to do is make sure the output from the pots it 2.5 volts when the chair's CPU starts up and all is fine. Thank you for your help!
  • 172heavy172heavy Posts: 55
    edited 2011-08-15 08:09
    W9GFO wrote: »
    This was my approach to controlling an electric wheelchair;

    http://forums.parallax.com/showthread.php?122594-What-could-you-use-this-for-It-s-a-two-channel-RC-controlled-digital-pot.&highlight=digital+pot

    Oh, on another wheelchair I removed the original electronics and used two HB-25s. It is not as fast because of the 12V limitation and the controllers will shutdown under heavy loads, but it is strong enough to ride around on on level ground.

    Rich H

    Rich,

    I appreciate your advice with the digital pots. Just a quick question, how many amps do the motors usually draw? I am asking because after I got the digital pots working I made a bonehead mistake and fried the original controller and motor drive circuit for the wheel chair. The original circuit used 8 MOSFETs Ntype with 4 halfbridge IC's These FETs are rated to a MAX 80amps so I am guessing this thing was designed for <25 amps continous. The contoller is rated for 50amps but I am not sure if that is per channel--motor--or 50 amps total. Anyway I figured you seem to have more experience with these chairs that I do. Any help or advise would be appreciated.

    Josh
  • W9GFOW9GFO Posts: 4,010
    edited 2011-08-15 13:23
    Hi Josh. I have not done any testing on the actual current that the motors will draw. I had assumed that the 50 amp spec for wheelchair controllers was a combined rating. I can tell you that when running them at 12 Volts using HB-25s, that the HB-25s will go into shut down when driven aggressively.

    I have purchased a pair of Jaguar 24V controllers to replace the HB-25s but have not installed them yet.
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