Hyundai Sonata: lateral torque custom ff

[twilsonco]

Same as custom torque for Chevy Volt, but for Sonata.

Unlike the Volt, this is still a linear feedforward w.r.t. lateral acceleration, but it includes a speed dependence to resolve low-speed issues. The effect is to increase low-speed feedforward, based on the data that indicate the amount of steering torque necessary to hold a given lateral acceleration at a given speed. The speed-dependence is significant. More so for Palisade.

This cuts feedforward error in half compared to linear feedforward, using the params.yaml max lat acceleration value to determine kf (0.35) for the comparison:

STD old 0.3828, new 0.2319

Fit from around 5.2 hours of driving data: 1.1 million samples filtered down to 1657 points with constant curvature rate, no saturation, and no driver torque.

describe(steer_offsets) = DescribeResult(nobs=1114146, minmax=(-4.021855354309082, 5.805548191070557), mean=-0.04294795383310292, variance=0.4337575485851953, skewness=0.5776027928213927, kurtosis=5.4416345277293825)
Samples: 659493

Regularized samples: 1657

speed: DescribeResult(nobs=1657, minmax=(3.8551877475920175, 34.86912155151367), mean=18.47563591727422, variance=37.38501038503589, skewness=-0.15137777709401073, kurtosis=-0.24800719124959114)
angle: DescribeResult(nobs=1657, minmax=(-3.3460993669537373, 4.258131831871131), mean=0.016330547001693167, variance=0.8556872533901201, skewness=0.14323546604620502, kurtosis=0.9803802511551987)
steer: DescribeResult(nobs=1657, minmax=(-3.596901416509924, 3.983225806759249), mean=0.2110790710868405, variance=0.6545499240843514, skewness=-0.09025266441000007, kurtosis=1.7571489967239113)

lat_accel 0.00-0.20:438, lat_accel 0.21-0.41:271, lat_accel 0.43-0.63:215, lat_accel 0.64-0.84:159, lat_accel 0.86-1.06:121
lat_accel 1.07-1.27:107, lat_accel 1.29-1.49:97, lat_accel 1.50-1.70:57, lat_accel 1.71-1.91:37, lat_accel 1.93-2.13:25
lat_accel 2.14-2.34:16, lat_accel 2.36-2.56:16, lat_accel 2.57-2.77:7, lat_accel 2.79-2.99:7, lat_accel 3.00-3.20:4

mph 08-13:38, mph 13-18:66, mph 18-23:89, mph 23-28:94, mph 28-33:127
mph 33-38:191, mph 38-43:267, mph 43-48:212, mph 48-53:304, mph 53-58:71
mph 58-63:128, mph 63-68:39, mph 68-73:16, mph 73-78:8, mph 78-83:7
mph 83-88:0, mph 88-93:0, 

~~Waiting on testers before taking out of draft.~~ Working with tester. Others please do not test until I update.