I am Charles from Malta. My son Luca is doing a thesis on a Otto Bock wheelchair B500. The thesis consists of a remote cordless control for the wheelchair. Can you help him how you did the remote cordless control for the wheel chair please?
for the switch that changes between R/C or joystick input, did you need 8x SPST switches (one for each pin), or do you have a switch driving a digital input pin on the arduino to swtich between the 8x wire array?
Actually, I only used 4 wires. The other 4 (I suspect) are for the +5v and ground connections to the potentiometers inside the joystick. As for the ones I used, there are two redundant wires for forward/backward and two for left/right. You could probably just connect the two wires together for each channel and it would still work just fine, that's what I did when controlling them from the Arduino - both forward/backward wires are connected to just one filtered PWM pin, the same for the left/right wires. But when I wanted to drive from the joystick I decided it would be better just to have it connected the way it originally was, so I got two DPDT switches, one for the two forward/backward wires and one for the other two left/right wires. There is another switch shown in the video, and that is just a power switch for the Arduino and radio, because the 5v supply I tapped into on the wheelchair does not shut off when the wheelchair is off.
alnwlsn Hey - Sorry for all the questions, but I'm using your arduino sketch (I built the RC lowpass filters) ... am currently wondering about how to tap into ground. Basically (as per the tutorial you wrote on dropbox), I'm leaving all the ribbon cables from the joystick to the controller connected, except for 2,4,5, and 7 (L/R,L/R,F/R,F/R, respectively). 2,4,5 and 7 are connected to the filtered outputs from the programmed Arduino ... however, the filter circuits are going to the Arduino's ground, when they should probablty (well, most certainly, I think) be going to the controller circuit hardware ground. The problem is, I haven't been able to identify which pin that is, since there are a few that are nominally at 0, and a couple +5 volt ones. Your tutorial has been a great help, but I'm just not quite sure how to bring together the filters and inject them into the existing connection to the joystick, since I didn't disassemble the actual joystick pots and replace them - I just disconnected their pins. I know this is a pretty elementary question, but any advice is appreciated. Thanks!
Matthew Foglia Ah. The voltages are between the ground of the wheelchair and the wires for each channel, not between them. So the arduino and wheelchair share a common ground. If you can find a connection on the controller board that is ground, that is what I used. Most often it connects to the negative terminal of the battery. Ground connects to ground, filtered PWM connects to the (redundant) two wires for each channel.
alnwlsn Thanks for clearing it up - going to whip out the multimeter and have a look. I just realized that while the 8-pin 2.54mm IDC connector is the same as the jazzy (or whatever joystick you and the people you've referenced are using), the pinout for the joystick I'm using (the joystick that comes with the Goldenmotor e-chair conversion kit, www.goldenmotor.com/Joystick%20Controller%20IM50A%20User%20Guide.pdf) is different. Which probably explains why I've been having so much trouble - I just assumed all these joysticks with 8 pins and linear pot joysticks with 2.5v reference voltages all shared the same pinout. I'm going to just wire the joystick back up, tap into the ribbon cable, and record the voltage change on x and y movement, then use that pinout. If that doesn't work, then I'm just going to take the joystick off the table and use a motor driver I have. If I pull this off with this particular joystick, is there any place you recommend I post it, for other people who might be trying to do the same? Thanks again for all your help!
+Michael J. Champ Jr. Besides a little bit of electronics knowledge, you will need an R/C hobby radio with 2 or more channels that controls typical R/C servos (I found mine at a garage sale, something like www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGRM7 would work. There are others, but I am not that into R/C stuff.) Then, you will need an Arduino (Uno is fine) to convert the servo output to a PWM signal. After that, two low pass filters (a single resistor and capacitor each, see hackaday.com/2011/06/16/beginner-concepts-using-a-low-pass-filter-to-smooth-pwm-output/) convert the PWM into a voltage which is what the wheelchair controller expects.
Carlos Rodas Sadly, I've never made a proper tutorial for this. However, you may wish to take a look at my notes dl.dropboxusercontent.com/u/3299461/wheelchair/wheelchair.txt Also I found mowstation.blogspot.com/ extremely helpful, as this guy had already figured out the wiring for my exact model of controller. Your mileage may vary. This project works by tapping into the joystick, and as I understand it there are two types of joystick out there. Mine uses some potentiometers to output a variable voltage (between about 1 and 4 volts, not 0 and 5, oddly) If this is the case you can just disconnect the outputs from the control board and replace them with your own variable voltage source (a microcontroller). The other kind of joystick is inductive, and works by moving a metal slug into or out of a coil. I don't know how to tap into that one. Of course, you could always just move the joystick mechanically with some RC servos.
Will you sell a ready kit for this project? Or how can I contact you, Great idea and execution
Thank you
I am Charles from Malta. My son Luca is doing a thesis on a Otto Bock wheelchair B500. The thesis consists of a remote cordless control for the wheelchair. Can you help him how you did the remote cordless control for the wheel chair please?
for the switch that changes between R/C or joystick input, did you need 8x SPST switches (one for each pin), or do you have a switch driving a digital input pin on the arduino to swtich between the 8x wire array?
Actually, I only used 4 wires. The other 4 (I suspect) are for the +5v and ground connections to the potentiometers inside the joystick. As for the ones I used, there are two redundant wires for forward/backward and two for left/right. You could probably just connect the two wires together for each channel and it would still work just fine, that's what I did when controlling them from the Arduino - both forward/backward wires are connected to just one filtered PWM pin, the same for the left/right wires. But when I wanted to drive from the joystick I decided it would be better just to have it connected the way it originally was, so I got two DPDT switches, one for the two forward/backward wires and one for the other two left/right wires. There is another switch shown in the video, and that is just a power switch for the Arduino and radio, because the 5v supply I tapped into on the wheelchair does not shut off when the wheelchair is off.
alnwlsn Hey -
Sorry for all the questions, but I'm using your arduino sketch (I built the RC lowpass filters) ... am currently wondering about how to tap into ground. Basically (as per the tutorial you wrote on dropbox), I'm leaving all the ribbon cables from the joystick to the controller connected, except for 2,4,5, and 7 (L/R,L/R,F/R,F/R, respectively). 2,4,5 and 7 are connected to the filtered outputs from the programmed Arduino ... however, the filter circuits are going to the Arduino's ground, when they should probablty (well, most certainly, I think) be going to the controller circuit hardware ground. The problem is, I haven't been able to identify which pin that is, since there are a few that are nominally at 0, and a couple +5 volt ones.
Your tutorial has been a great help, but I'm just not quite sure how to bring together the filters and inject them into the existing connection to the joystick, since I didn't disassemble the actual joystick pots and replace them - I just disconnected their pins.
I know this is a pretty elementary question, but any advice is appreciated. Thanks!
Matthew Foglia Ah. The voltages are between the ground of the wheelchair and the wires for each channel, not between them. So the arduino and wheelchair share a common ground. If you can find a connection on the controller board that is ground, that is what I used. Most often it connects to the negative terminal of the battery. Ground connects to ground, filtered PWM connects to the (redundant) two wires for each channel.
alnwlsn Thanks for clearing it up - going to whip out the multimeter and have a look.
I just realized that while the 8-pin 2.54mm IDC connector is the same as the jazzy (or whatever joystick you and the people you've referenced are using), the pinout for the joystick I'm using (the joystick that comes with the Goldenmotor e-chair conversion kit, www.goldenmotor.com/Joystick%20Controller%20IM50A%20User%20Guide.pdf) is different. Which probably explains why I've been having so much trouble - I just assumed all these joysticks with 8 pins and linear pot joysticks with 2.5v reference voltages all shared the same pinout.
I'm going to just wire the joystick back up, tap into the ribbon cable, and record the voltage change on x and y movement, then use that pinout.
If that doesn't work, then I'm just going to take the joystick off the table and use a motor driver I have.
If I pull this off with this particular joystick, is there any place you recommend I post it, for other people who might be trying to do the same?
Thanks again for all your help!
Now you just need a a Steven Hawking Mannequin and a voice changer and your ready to change the world!
i wont this wheelchair. price? and were its available pls give me replay.....
very cool. i am paralyzed & have an old Chair to use to make one of these. can you post links to the parts you used to control the chair.
+Michael J. Champ Jr. Besides a little bit of electronics knowledge, you will need an R/C hobby radio with 2 or more channels that controls typical R/C servos (I found mine at a garage sale, something like www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGRM7 would work. There are others, but I am not that into R/C stuff.) Then, you will need an Arduino (Uno is fine) to convert the servo output to a PWM signal. After that, two low pass filters (a single resistor and capacitor each, see hackaday.com/2011/06/16/beginner-concepts-using-a-low-pass-filter-to-smooth-pwm-output/) convert the PWM into a voltage which is what the wheelchair controller expects.
Why do you need an arduino??
I thought the rc servos can be connected directly to control the joystick movements on the chair?
Hi, do you hacve a tutorial on,ine on how you did this? thanks!
Carlos Rodas Sadly, I've never made a proper tutorial for this. However, you may wish to take a look at my notes dl.dropboxusercontent.com/u/3299461/wheelchair/wheelchair.txt Also I found mowstation.blogspot.com/ extremely helpful, as this guy had already figured out the wiring for my exact model of controller. Your mileage may vary.
This project works by tapping into the joystick, and as I understand it there are two types of joystick out there. Mine uses some potentiometers to output a variable voltage (between about 1 and 4 volts, not 0 and 5, oddly) If this is the case you can just disconnect the outputs from the control board and replace them with your own variable voltage source (a microcontroller). The other kind of joystick is inductive, and works by moving a metal slug into or out of a coil. I don't know how to tap into that one. Of course, you could always just move the joystick mechanically with some RC servos.
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