Automatic Transmission Controller

1
Automatic Transmission Controller

• Presenters
• Navjit Grewal
• Isaac Wheeler

2
Methodology

• The automatic transmission must allow the engine
  to operate in its range of speed while providing
  a comfortable, yet responsive ride.
• Design a simple electronic control system to
  actuate the changing of gears in an automatic
  transmission
• The system will monitor rotational speed of
  engine (RPM) and relative position of accelerator
  pedal (0 -100) in real time.
• Design logic to determine appropriate gear(1st,
  2nd, 3rd,) based on these inputs

3
Inputs

• Accelerator Pedal Position (0 - 100)
• Use A/D converter to sample analog voltage from
  pedal position sensor 8 bit digital value
  ranging 00 - FF
• Sample 10 times per second
• Tachometer Reading (RPM)
• Use Timer Input Capture on 6811 to measure period
  of revolution of engine, ranging 500-9000 RPM
• 1 pulse per revolution of engine triggers input
  capture interrupt in 6811, which calculates and
  stores the period of revolution.
• These Inputs are normalized to a scale

4
Software Normalizing to Scale
Pedal Position
Pedal sensor voltage
RPM range
Period of Rev.
9000
FF
FF
7ms
5V
Full Throttle
4750
13ms
50
2.5V
120ms
00
00
500
0V
0
5
Software Gear States
4
Transmission Downshift
Transmission Up shift
3
2
1
6
Transmission Shifting Logic
RPM range

• Up-shift at redline (maximum engine RPM) under
  constant acceleration
• Otherwise, up-shift at optimal RPM (derived from
  pedal position vs. RPM)

9000

• Down-shift when accelerator pedal is depressed
  and car is not accelerating (derived from pedal
  position and ?RPM 0)
• Otherwise, down-shift at minimum engine RPM

500
7
Conclusion
Questions ?