Arduino controlled wheelchair

[woodygb]

Hi woodygb,

Would you have a closer image of the 419 schematic, can't see the yellow lines too well.
But it seems that you pull S2 of the DG419 to ground with a 270ohm resistor
Thanks

Clicking on the image should have had it open in another tab at an increased size.

https://www.wheelchairdriver.com/board/ ... &mode=view

[woodygb]

Here is the code that I use with the altered board.

NANO_DYNAMIC.zip

(7.54 KiB) Downloaded 84 times

[gcebiker]

Bhuja you might be overthinking it...the code works, my website is down for remodeling but follow the links to my YouTube ch and you'll see videos of it in action.
Use the right code with the right version of the board and you wont need to worry about a thing.

I mostly did this as I had little to no money and no spare chairs to use as a power base, only my daily driver to experiment on, while i was sitting in it.

There are robotics power modules available that are very good value for money if you dont have a need to use the Dynamic Controls Power Module.

[bhuja]

It turns out that I was using the wrong setting on my logic analyzer.

I changed it to the following(shown below in the image)

However, the wheelchair still doesn't recognize any commands even though the packets seem to be correct.
I even hardcoded a series of packets to match the original remote from startup to a stationary packet to a motion packet.

Are there any guides on wiring the Arduino directly to the joystick potentiometer? I would rather not spend extra money on a robotics power module.

[gcebiker]

Check that you have the Shark Bus connected the right way by swapping the two wires and see what happens.
The data lines, not the power.
You will need to have the ground from the Power module connected to ground of your Arduino.

[gcebiker]

Other small variations in updated libraries 'may' have an effect.
Variations in the Arduino you are using, eg if the clock speed is lower than needed.

- As i have written in the notes
The start up chip I used (DG419) was able to cope with repeated pulses of up to Vcc of a fully charged power-wheelchair.
If your start up pulse is not in the range of the voltages the power module is expecting to see, the power module will not turn on.
It will instead not start up and/or shut down and/or go into limp mode.


Supply voltage to your Power Module.
Supply voltage / voltage sag in either the MCU or Power Module.

[woodygb]

It turns out that I was using the wrong setting on my logic analyzer.

I changed it to the following(shown below in the image)

However, the wheelchair still doesn't recognize any commands even though the packets seem to be correct.
I even hardcoded a series of packets to match the original remote from startup to a stationary packet to a motion packet.

Are there any guides on wiring the Arduino directly to the joystick potentiometer? I would rather not spend extra money on a robotics power module.

The joystick is embedded into the board and I doubt that it is possible to hack into the circuit.

Are you confident that the ON pulse is being sent?

Could you post your code and a diagram / pic of your setup.

[bhuja]

The circuit I constructed was based on the following image:
https://www.wheelchairdriver.com/board/ ... &mode=view

The board I made is here, but it is probably a bit hard to view it

Right now I believe I am getting the pulse, however, after using a min/max function on a multimeter, I see that the pulse seems to only have a maximum voltage of 5.24V, nowhere close to the 20-24V required to move into the dominant state.

Here is the pulse captured through a logic analyzer:

startup_pulse.png (10.31 KiB) Viewed 3026 times

And here is the startup packet which comes after it:

startup.png (5.02 KiB) Viewed 3026 times

[woodygb]

Disconnect your board from the power module and manually ( 5v power to pin 6 ) turn ON / OFF the DG419 and check that the output voltage on pin 1 rises to 24v.

[woodygb]

In your pic ( to the right of the blue of wire ) is that a link between pins 2 and 3 of your DG419 ?!

Here is how I have my DG419 wired up.

[woodygb]

Added some voltage values.

There is also a 0.1uf cap between pins 3 & 4 ...not shown in pic.

[woodygb]

In your pic ( to the right of the blue of wire ) is that a link between pins 2 and 3 of your DG419 ?!

Here is how I have my DG419 wired up.

dg419.png

IGNORE that question.... I have ...I think ....deciphered your wiring.

[woodygb]

Here is my layout on veroboard / strip board for the interface using a relay and a Arduino Pro mini.

NOTE:- This was drawn for ME whilst building , has extra bits like led's and a push button for R/C signal calibration . ...and may also contain mistakes.

The interface was a success.

[bhuja]

I think my DG419 Chip may be damaged, when it is disconnected from the circuit and I test pins 1/2 there is a resistance there of 800 Ohms or so.

In addition, pins 1 and 8 are not an open circuit as expected.

[woodygb]

Seems that you have identified the problem .

Bhuja ...Can you please update your profile with your general location.

EDIT...I might have a NEW spare 419 kicking around ...if so I will measure the values on mine.

[gcebiker]

I think my DG419 Chip may be damaged, when it is disconnected from the circuit and I test pins 1/2 there is a resistance there of 800 Ohms or so.

In addition, pins 1 and 8 are not an open circuit as expected.

[bhuja]

Hi,

It has been a while since I have retried to get it to work. I believe I am correctly sending a startup packet as there is a response from the SPM. The startup pulse was measured to be 24V so it should be more than enough to do so.

These recordings are of the Shark Bus High Line.

I also compared the recordings of my SR to the PCB I built. The SR response of the first packet(packet after the startup packet) was:

SR_v1.png (6.85 KiB) Viewed 2776 times

Alternatively, my PCB response was the following:

If we compare the two images and look at the second half of bundled bytes, they seem to differ in bytes 1,2, and 8. I guess byte 8 is the checksum so it can be ignored for being different. I am also assuming that 0x61 maybe some sort of incoming message padding. So therefore the byte 1 would correspond to byte 0 and so on.
So by referencing the SPM General Information from the Shark Bus Communication pdf I could tell that:

Byte 0 (0xB2 -> 1011 0010):
Bit 5 being set would mean DCI Slowdown is set(not too sure what that means). (Edit: from reading documentation found here, https://www.dynamiccontrols.com/sites/d ... ss%207.pdf, I believe this is a drive inhibitor).

Byte 1 (0xC9 -> 1100 1001):
Bit 6 being set means DRIVE is INHIBITED.
Bit 3-0 indicate a "Shark Cable Fault".

So in summary, I think I am getting a "SHARK CABLE FAULT" which is causing no drive response.

I am still able to use the remote control to move the chair around so I don't think it is an issue with my cables. It is probably some way that I am connecting up my cables that it is causing this issue to occur (grounding, etc). Does anyone have any guesses as to what may cause this fault or if I am analysing the problem the wrong way?

Thanks in advance!

[woodygb]

So in summary, I think I am getting a "SHARK CABLE FAULT" which is causing no drive response.

I somehow doubt that ...as it is just 2 wires .

Drive Inhibit would be my guess and you MIGHT perhaps be creating an INHIBIT connection / signal with your board.

Go into programming and if possible turn off all inhibits.

[222dipa]

Hello everyone! I am a programmer and I am interested in the project!
I have an Invacare Dragon wheelchair and I bought the card from this link http://dirtypcbs.com/store/designer/details/11063/5125/nano-shark-hat-v3-23-zip and all the necessary components. Initially I would like to drive it with a remote control and then I would like to connect arduino with a raspberry or odroid xu4 board, but I can't figure out what the latest version of the working code is.
Could any of you help me?

Thank you!