Name ports and add @System documentation for InverseDynamicsController (

#13879)

systems/controllers/inverse_dynamics_controller.cc

@@ -61,11 +61,11 @@ void InverseDynamicsController<T>::SetUp(const VectorX<double>& kp,
 
   // Exposes estimated state input port.
   input_port_index_estimated_state_ =
-      builder->ExportInput(pass_through->get_input_port());
+      builder->ExportInput(pass_through->get_input_port(), "estimated_state");
 
   // Exposes reference state input port.
-  input_port_index_desired_state_ =
-      builder->ExportInput(pid_->get_input_port_desired_state());
+  input_port_index_desired_state_ = builder->ExportInput(
+      pid_->get_input_port_desired_state(), "desired_state");
 
   if (!has_reference_acceleration_) {
     // Uses a zero constant source for reference acceleration.
@@ -77,12 +77,12 @@ void InverseDynamicsController<T>::SetUp(const VectorX<double>& kp,
   } else {
     // Exposes reference acceleration input port.
     input_port_index_desired_acceleration_ =
-        builder->ExportInput(adder->get_input_port(1));
+        builder->ExportInput(adder->get_input_port(1), "desired_acceleration");
   }
 
   // Exposes inverse dynamics' output force port.
   output_port_index_control_ =
-      builder->ExportOutput(inverse_dynamics.get_output_port_force());
+      builder->ExportOutput(inverse_dynamics.get_output_port_force(), "force");
 
   builder->BuildInto(this);
 }

systems/controllers/inverse_dynamics_controller.h

@@ -26,6 +26,16 @@ namespace controllers {
  * `q` and `v` stand for the generalized position and velocity, and `vd` is
  * the generalized acceleration. `*` indicates reference values.
  *
+ * @system
+ * name: InverseDynamicsController
+ * input_ports:
+ * - estimated_state
+ * - desired_state
+ * - desired_acceleration*
+ * output_ports:
+ * - force
+ * @endsystem
+ *
  * This controller always has a BasicVector input port for estimated robot state
  * `(q, v)`, a BasicVector input port for reference robot state `(q*, v*)` and
  * a BasicVector output port for computed torque `torque`. A constructor flag
@@ -36,7 +46,7 @@ namespace controllers {
  * Note that this class assumes the robot is fully actuated, its position
  * and velocity have the same dimension, and it does not have a floating base.
  * If violated, the program will abort. This controller was not designed for
- * closed loop systems: the controller accounts for neither constraint forces
+ * closed-loop systems: the controller accounts for neither constraint forces
  * nor actuator forces applied at loop constraints. Use on such systems is not
  * recommended.
  *