Adaptive Controls

These controls function by reading the input and output speeds over 140 times a second and responding to each new reading. This provides the friction element control needed to make smooth clutch-to-clutch shifts for all gear changes without the use of overrunning clutches. As with most automatic transaxles, all shifts involve releasing one element and applying a different element. In simplified terms, the upshift logic allows the releasing element to slip backwards slightly to ensure that it does not have excess capacity; the apply element is filled until it begins to make the speed change to the higher gear; its apply pressure is then controlled to maintain the desired rate of speed change until the shift is complete. The key to providing excellent shift quality is precision; for example, as mentioned, the release element for upshifts is allowed to slip backwards slightly; the amount of that slip is typically less than a total of 20 degrees. To achieve that precision, the transmission control module learns the characteristics of the particular transaxle that it is controlling. It learns:
- The release rate of the releasing element.
- The apply time of the applying element.
- The rate the apply element builds pressure.

This method achieves more precision than would be possible with exacting tolerances. It can also adapt to any changes that occur with age or environment.
For kickdown shifts, the control logic allows the releasing element to slip. Then controls the rate at which the input (and engine) accelerate. When the lower gear speed is achieved, the releasing element reapplies to maintain that speed until the apply element is filled, This provides quick response and a smooth torque exchange since the release element can control the rate of torque increase. This control can make any powertrain feel more responsive without increasing harshness.
Adaptive controls respond to input speed changes. They compensate for changes in engine or friction element torque. Thus providing consistent shift quality for the life of the transaxle.