History of MembersPage/ShellEcoMarathonHungary/SteerByWire
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2011-05-06 12:50:08 . . . . 3e44a184.adsl.enternet.hu [joystick voltages and servo input]
2011-05-04 17:10:31 . . . . 3e44a184.adsl.enternet.hu [input voltages needed]
2011-05-04 15:58:56 . . . . 3e44a184.adsl.enternet.hu [steer by wire on round ]
2011-04-30 20:27:16 . . . . 3e44a184.adsl.enternet.hu [servo data]


Changes by last author:

Added:
Steer by wire

analog => PWM (speed dependent conversion) by round boostcontrol function.

Measured analog voltage output of the joystick.

* extreme left turn: 1.25 V

* just in the middle: 2.5 V (trimmed to mid-position)

* extreme right turn: 3.88 V

With extreme trimming 0-5V can be reached (though not at the same trimming-position). Joystick powered from dedicated 5V regulator, as the servo-supply was "nervous" during servo movements.

Needs extensive testing. Use only at non-lethal vehicle speeds (max 40km/h in a protected chassis).

* steering can be configured with 17 point curve.

** At higher wheelspeed the steering the end-positions are narrowed

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Special Round feature

* Needs special 0.5.2 firmware

* Use the second Analog input ( Dsub15/pin 5 )for wheel input

** the analog value will limited in firmware:

*** 0..10km/h: no limit ( 0-5V )

*** 10-26km/h: limit gradually 0..50%. For example at 18km/h (used min: 0.6V ... max: 4.4V so first 2 and last 2 configured values cannot be reached).

*** 26km/h...: limit 50% ( used min: 1.25V; max: 3.75V so first 4 and last 4 configured values cannot be reached).

** the limited analog value goes through the 17 point analog input 2 curve

** the result of the curve goes out on the pwm_0 output ( Dsub15/pin 2 )

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Servo data

Tested with v3 boost alternate function 1.1.8x firmware

* 375 Hz

* inverted p259 output pulled up to +5V

* 25 .. 99% output was reasonable

Achieved best results with 57 Hz PWM frequency, pulse high for appr. 1-2 msec. The time of low level seems to not make a difference in position-command. But at higher freq the servo was a bit nervous with more small back-n-forth adjustments.