planning: if front obstacle is too close, skip side pass scenario for safety.

modules/planning/common/planning_gflags.cc

@@ -449,3 +449,7 @@ DEFINE_double(
 
 DEFINE_double(max_trajectory_len, 1000.0,
               "(unit: meter) max possible trajectory length.");
+
+DEFINE_double(side_pass_min_front_obstacle_distance, 2.0,
+              "(unit: meter) if the distance between front obstacle is less "
+              "than this threshold, side_pass scenario is skipped for safety.");

modules/planning/common/planning_gflags.h

@@ -233,3 +233,4 @@ DECLARE_bool(enable_record_debug);
 DECLARE_double(default_front_clear_distance);
 
 DECLARE_double(max_trajectory_len);
+DECLARE_double(side_pass_min_front_obstacle_distance);

modules/planning/scenarios/side_pass/side_pass_scenario.cc

@@ -188,6 +188,12 @@ bool SidePassScenario::HasBlockingObstacle(const Frame& frame) {
       continue;
     }
 
+    if (adc_sl_boundary.end_s() + FLAGS_side_pass_min_front_obstacle_distance >
+        obstacle->PerceptionSLBoundary().start_s()) {
+      // front obstacle is too close to side pass
+      continue;
+    }
+
     // check driving_width
     constexpr double kLBufferThreshold = 0.3;  // unit: m
     const auto& reference_line = reference_line_info.reference_line();