prediction: bug fix in ValidationChecker; minor code refactor

modules/prediction/common/validation_checker.cc

@@ -33,8 +33,8 @@ double ValidationChecker::ProbabilityByCentripetalAcceleration(
   double centripetal_acc_cost_sum = 0.0;
   double centripetal_acc_cost_sqr_sum = 0.0;
   for (int i = 0; i < lane_sequence.path_point_size(); ++i) {
-    const PathPoint& path_point = lane_sequence.path_point(i);
-    double centripetal_acc = speed * speed * path_point.kappa();
+    const auto& path_point = lane_sequence.path_point(i);
+    double centripetal_acc = speed * speed * std::fabs(path_point.kappa());
     double centripetal_acc_cost =
         centripetal_acc / FLAGS_centripedal_acc_threshold;
     centripetal_acc_cost_sum += centripetal_acc_cost;
@@ -47,12 +47,8 @@ double ValidationChecker::ProbabilityByCentripetalAcceleration(
 
 bool ValidationChecker::ValidCentripetalAcceleration(
     const std::vector<TrajectoryPoint>& trajectory_points) {
-  std::size_t num_point = trajectory_points.size();
-  if (num_point < 2) {
-    return true;
-  }
-  double max_centripedal_acc = 0.0;
-  for (std::size_t i = 0; i + 1 < num_point; ++i) {
+  double max_centripetal_acc = 0.0;
+  for (auto i = 0; i + 1 < trajectory_points.size(); ++i) {
     const auto& first_point = trajectory_points[i];
     const auto& second_point = trajectory_points[i + 1];
     double theta_diff = std::abs(common::math::NormalizeAngle(
@@ -63,11 +59,11 @@ bool ValidationChecker::ValidCentripetalAcceleration(
     if (time_diff < FLAGS_double_precision) {
       continue;
     }
-    double v = (first_point.v() + second_point.v()) / 2.0;
+    double v = (first_point.v() + second_point.v()) * 0.5;
     double centripedal_acc = v * theta_diff / time_diff;
-    max_centripedal_acc = std::max(max_centripedal_acc, centripedal_acc);
+    max_centripetal_acc = std::max(max_centripetal_acc, centripedal_acc);
   }
-  return max_centripedal_acc < FLAGS_centripedal_acc_threshold;
+  return max_centripetal_acc < FLAGS_centripedal_acc_threshold;
 }
 
 bool ValidationChecker::ValidTrajectoryPoint(