Ford: higher curvature rate limits at low speed (commaai#2065)

* use closer to EPS limits

* raise to upper bound of spread from injection plot

* we've seen ~0.009 at 7 m/s, so allow that

* fix test

* rounding errors cause the 2 to round to the same value

* adjust for latest opendbc change

* we should actually match what safety is doing! fix lack of test coverage near first brake point

fix

* and fix test

board/safety/safety_ford.h

@@ -114,11 +114,11 @@ static const SteeringLimits FORD_STEERING_LIMITS = {
   .max_angle_error = 100,           // 0.002 * FORD_STEERING_LIMITS.angle_deg_to_can
   .angle_rate_up_lookup = {
     {5., 25., 25.},
-    {0.0002, 0.0001, 0.0001}
+    {0.00045, 0.0001, 0.0001}
   },
   .angle_rate_down_lookup = {
     {5., 25., 25.},
-    {0.000225, 0.00015, 0.00015}
+    {0.00045, 0.00015, 0.00015}
   },
 
   // no blending at low speed due to lack of torque wind-up and inaccurate current curvature

tests/safety/test_ford.py

@@ -86,8 +86,8 @@ class TestFordSafetyBase(common.PandaCarSafetyTest):
   CURVATURE_ERROR_MIN_SPEED = 10.0  # m/s
 
   ANGLE_RATE_BP = [5., 25., 25.]
-  ANGLE_RATE_UP = [0.0002, 0.0001, 0.0001]  # windup limit
-  ANGLE_RATE_DOWN = [0.000225, 0.00015, 0.00015]  # unwind limit
+  ANGLE_RATE_UP = [0.00045, 0.0001, 0.0001]  # windup limit
+  ANGLE_RATE_DOWN = [0.00045, 0.00015, 0.00015]  # unwind limit
 
   cnt_speed = 0
   cnt_speed_2 = 0
@@ -290,7 +290,7 @@ def test_curvature_rate_limit_up(self):
 
     for speed in np.arange(0, 40, 0.5):
       limit_command = speed > self.CURVATURE_ERROR_MIN_SPEED
-      max_delta_up = np.interp(speed, self.ANGLE_RATE_BP, self.ANGLE_RATE_UP)
+      max_delta_up = np.interp(speed - 1, self.ANGLE_RATE_BP, self.ANGLE_RATE_UP)
       max_delta_up_lower = np.interp(speed + 1, self.ANGLE_RATE_BP, self.ANGLE_RATE_UP)
 
       cases = [
@@ -313,7 +313,7 @@ def test_curvature_rate_limit_down(self):
 
     for speed in np.arange(0, 40, 0.5):
       limit_command = speed > self.CURVATURE_ERROR_MIN_SPEED
-      max_delta_down = np.interp(speed, self.ANGLE_RATE_BP, self.ANGLE_RATE_DOWN)
+      max_delta_down = np.interp(speed - 1, self.ANGLE_RATE_BP, self.ANGLE_RATE_DOWN)
       max_delta_down_lower = np.interp(speed + 1, self.ANGLE_RATE_BP, self.ANGLE_RATE_DOWN)
 
       cases = [