Port IdmPlannerParameters to use named_vector defaults

drake/automotive/gen/idm_planner_parameters.h

@@ -37,9 +37,24 @@ class IdmPlannerParameters : public systems::BasicVector<T> {
   /// An abbreviation for our row index constants.
   typedef IdmPlannerParametersIndices K;
 
-  /// Default constructor.  Sets all rows to zero.
+  /// Default constructor.  Sets all rows to their default value:
+  /// @arg @c v_ref defaults to 10.0 in units of m/s.
+  /// @arg @c a defaults to 1.0 in units of m/s^2.
+  /// @arg @c b defaults to 3.0 in units of m/s^2.
+  /// @arg @c s_0 defaults to 1.0 in units of m.
+  /// @arg @c time_headway defaults to 0.1 in units of s.
+  /// @arg @c delta defaults to 4.0 in units of dimensionless.
+  /// @arg @c bloat_diameter defaults to 4.5 in units of m.
+  /// @arg @c distance_lower_limit defaults to 1e-2 in units of m.
   IdmPlannerParameters() : systems::BasicVector<T>(K::kNumCoordinates) {
-    this->SetFromVector(VectorX<T>::Zero(K::kNumCoordinates));
+    this->set_v_ref(10.0);
+    this->set_a(1.0);
+    this->set_b(3.0);
+    this->set_s_0(1.0);
+    this->set_time_headway(0.1);
+    this->set_delta(4.0);
+    this->set_bloat_diameter(4.5);
+    this->set_distance_lower_limit(1e-2);
   }
 
   IdmPlannerParameters<T>* DoClone() const override {
@@ -49,27 +64,34 @@ class IdmPlannerParameters : public systems::BasicVector<T> {
   /// @name Getters and Setters
   //@{
   /// desired velocity in free traffic
+  /// @note @c v_ref is expressed in units of m/s.
   const T& v_ref() const { return this->GetAtIndex(K::kVRef); }
   void set_v_ref(const T& v_ref) { this->SetAtIndex(K::kVRef, v_ref); }
   /// max acceleration
+  /// @note @c a is expressed in units of m/s^2.
   const T& a() const { return this->GetAtIndex(K::kA); }
   void set_a(const T& a) { this->SetAtIndex(K::kA, a); }
   /// comfortable braking deceleration
+  /// @note @c b is expressed in units of m/s^2.
   const T& b() const { return this->GetAtIndex(K::kB); }
   void set_b(const T& b) { this->SetAtIndex(K::kB, b); }
   /// minimum desired net distance
+  /// @note @c s_0 is expressed in units of m.
   const T& s_0() const { return this->GetAtIndex(K::kS0); }
   void set_s_0(const T& s_0) { this->SetAtIndex(K::kS0, s_0); }
   /// desired time headway to vehicle in front
+  /// @note @c time_headway is expressed in units of s.
   const T& time_headway() const { return this->GetAtIndex(K::kTimeHeadway); }
   void set_time_headway(const T& time_headway) {
     this->SetAtIndex(K::kTimeHeadway, time_headway);
   }
   /// free-road exponent
+  /// @note @c delta is expressed in units of dimensionless.
   const T& delta() const { return this->GetAtIndex(K::kDelta); }
   void set_delta(const T& delta) { this->SetAtIndex(K::kDelta, delta); }
   /// diameter of circle about the vehicle's pose that encloses its physical
   /// footprint
+  /// @note @c bloat_diameter is expressed in units of m.
   const T& bloat_diameter() const {
     return this->GetAtIndex(K::kBloatDiameter);
   }
@@ -78,6 +100,7 @@ class IdmPlannerParameters : public systems::BasicVector<T> {
   }
   /// lower saturation bound on net distance to prevent near-singular IDM
   /// solutions
+  /// @note @c distance_lower_limit is expressed in units of m.
   const T& distance_lower_limit() const {
     return this->GetAtIndex(K::kDistanceLowerLimit);
   }

drake/automotive/idm_planner.cc

@@ -43,19 +43,8 @@ const T IdmPlanner<T>::Evaluate(const IdmPlannerParameters<T>& params,
 
 template <typename T>
 void IdmPlanner<T>::SetDefaultParameters(IdmPlannerParameters<T>* idm_params) {
-  // Default values from https://en.wikipedia.org/wiki/Intelligent_driver_model.
   DRAKE_DEMAND(idm_params != nullptr);
-  idm_params->set_v_ref(10.);  // desired velocity in free traffic [m/s].
-  idm_params->set_a(T(1.));    // max acceleration [m/s^2].
-  idm_params->set_b(T(3.));    // comfortable braking deceleration [m/s^2].
-  idm_params->set_s_0(T(1.));  // minimum desired net distance [m].
-  idm_params->set_time_headway(T(0.1));  // desired headway to lead vehicle [s].
-  idm_params->set_delta(T(4.));  // recommended choice of acceleration exponent.
-  idm_params->set_bloat_diameter(T(4.5));  // diameter of circle about the
-                                           // vehicle's pose that encloses its
-                                           // physical footprint.
-  idm_params->set_distance_lower_limit(T(1e-2));  // lower saturation bound on
-                                                  // the net distance.
+  idm_params->SetFrom(IdmPlannerParameters<T>());
 }
 
 // These instantiations must match the API documentation in idm_planner.h.

drake/automotive/idm_planner_parameters.named_vector

@@ -1,33 +1,51 @@
+# The default values contained below are from:
+#   https://en.wikipedia.org/wiki/Intelligent_driver_model
 element {
      name: "v_ref"
      doc: "desired velocity in free traffic"
+     doc_units: "m/s"
+     default_value: "10.0"
 }
 element {
      name: "a"
      doc: "max acceleration"
+     doc_units: "m/s^2"
+     default_value: "1.0"
 }
 element {
      name: "b"
      doc: "comfortable braking deceleration"
+     doc_units: "m/s^2"
+     default_value: "3.0"
 }
 element {
      name: "s_0"
      doc: "minimum desired net distance"
+     doc_units: "m"
+     default_value: "1.0"
 }
 element {
      name: "time_headway"
      doc: "desired time headway to vehicle in front"
+     doc_units: "s"
+     default_value: "0.1"
 }
 element {
      name: "delta"
      doc: "free-road exponent"
+     doc_units: "dimensionless"
+     default_value: "4.0"
 }
 element {
      name: "bloat_diameter"
      doc: "diameter of circle about the vehicle's pose that encloses its physical footprint"
+     doc_units: "m"
+     default_value: "4.5"
      # TODO(jadecastro): replace with vehicle geometry.
 }
 element {
      name: "distance_lower_limit"
      doc: "lower saturation bound on net distance to prevent near-singular IDM solutions"
+     doc_units: "m"
+     default_value: "1e-2"
 }