[MFGJR]

Originally Posted by Matt Romanowski

You could do it where to default to which ever input is great as that is doing the most i.e. if the driver is giving it 40% throttle and only 10% brake, then the car is still accellerating.

I guess you have to step back and say what are we really trying to see? If we want to see the major thing the driver is doing, then we just need whichever input is greater. That is an easier problem to solve. If we want to see all inputs, then we have to figure something different out. I'm not sure the best way to do that.

Originally Posted by MFGJR

I like picking the dominant input when both throttle and brakes are applied outside of the downshift scenario, but better yet let's use longitudinal accel as the arbiter. I'm not sure that comparing the gross values of throttle and brakes will actually identify the dominant input--25% brakes probably trumps 30% throttle, for example--but long accel will. If the car is decelerating beyond a nominal threshold (long acel < say, 0.1), then the brake input is dominant. Otherwise, throttle is dominant. We need the threshold before picking brakes to allow for lifting the throttle, in which case I think that what’s going on with the throttle is the information we’re most interested in. I’ll look at some of Randy’s data to find an appropriate threshold.

Originally Posted by Matt Romanowski

The standard I've seen for choosing whether someone is on the brakes or not using Long G is .25 G. I would guess something around that would be good here too.

Here are the rules that I came up with to accommodate heel-toe downshifting and left foot braking. Not quite as simple as what I started with.

If the clutch is in, use brake pressure. If it’s a heel-toe downshift, we want the brake input and this ignores the throttle blip. If it’s a non-heel-toe downshift or an upshift, there’s 0 brake and 0 throttle input—effectively coasting—so the 0 brake input reflects both brake and throttle input.

If the clutch is out, and if the throttle is down, and if the brakes are also down, and if long accel exceeds the braking threshold, use brake pressure. This is the left foot braker giving both throttle and brake inputs, and braking is the dominant input.

If the clutch is out, and if the throttle is down, and if the brakes are also down, and if longitudinal acceleration does not exceed the braking threshold, use throttle position. This is the left foot braker giving both throttle and brake inputs, but the inputs are equal or throttle is dominant. We us the threshold to allow for some manipulation of the throttle as acceleration begins. Note that the threshold is a negative value, so “exceeding” means more negative, i.e., less than the threshold. Looking at Randy’s data, coasting generally resulted in up to -0.16 longitudinal accel, so I’ll use that as the threshold.

If the clutch is out, and if the throttle is down, and if the brakes are not down, use throttle position. Straightforward acceleration.

If the clutch is out, and if the throttle is not down, and if the brakes are down, use brake pressure. Straightforward braking.

If the clutch is out, and if the throttle is not down, and if the brakes are not down, use throttle position. This is coasting, with 0 brake and 0 throttle inputs. The 0 throttle position value will represent both.

When If-THEN-ELSEd, some items above become “THENs” and others ‘ELSEs”. With the statements nested together, it looks like this:

( IF clutch is in , THEN use negative brake pressure , ELSE ( IF throttle is down , THEN ( IF brakes are down , THEN ( IF longitudinal acceleration exceeds the threshold , THEN use brake pressure , ELSE use throttle position ) , ELSE use throttle position ) , ELSE ( IF brakes are down , THEN use brake pressure , ELSE use throttle position ) ) )

Note that wherever we use brake pressure, we’re using the negative of the logged value as we want braking to appear “below the line” on the Measures Graph. In RS2 syntax, and using the channel names from the Z4M ECU protocol, it looks like this:

IF(EQ(Z4M_CLUTCH_SW,1),-Z4M_BRAKE_PR,IF(GT(Z4M_PPS,0),IF(GT(Z4M_BRAKE_PR,0 ),IF(LE(GPS_LonAcc,-0.16),-Z4M_BRAKE_PR,Z4M_PPS),Z4M_PPS),IF(GT(Z4M_BRAKE_PR, 0),-Z4M_BRAKE_PR,Z4M_PPS)))

This exactly replicates my simple “throttle – brakes” approach using Randy’s data, which doesn’t include heel-toeing or left foot braking/simultaneous throttle input. I’ll work out a test protocol involving those techniques, and will see how the formula works with those. Might be after the holidays before I can do that and report back.

My head hurts now. Time for a beer.