Just the interface for a combined gripper+manipulator.

examples/manipulation_station/BUILD.bazel

@@ -75,6 +75,17 @@ drake_cc_library(
     ],
 )
 
+drake_cc_library(
+    name = "combined_arm_and_gripper_model",
+    hdrs = [
+        "combined_arm_and_gripper_model.h",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//multibody/tree",
+    ],
+)
+
 drake_cc_binary(
     name = "mock_station_simulation",
     srcs = [

examples/manipulation_station/combined_arm_and_gripper_model.h

@@ -0,0 +1,87 @@
+#pragma once
+
+#include "drake/common/eigen_types.h"
+#include "drake/multibody/tree/multibody_tree_indexes.h"
+#include "drake/systems/framework/context.h"
+#include "drake/systems/framework/diagram.h"
+
+namespace drake {
+
+namespace systems {
+template <typename T>
+class DiagramBuilder;
+}
+
+namespace multibody {
+template <typename T>
+class MultibodyPlant;
+}
+
+namespace examples {
+namespace manipulation_station {
+
+/**
+ * A virtual class for adding a combined arm/gripper model and its
+ * controller to a Diagram and querying aspects of that model.
+ */
+template <typename T>
+class CombinedArmAndGripperModel {
+ public:
+  explicit CombinedArmAndGripperModel(
+      multibody::MultibodyPlant<T>* plant) : plant_(plant) {}
+  virtual ~CombinedArmAndGripperModel() {}
+
+  /// Gets the number of joints in the gripper.
+  virtual int num_gripper_joints() const = 0;
+
+  /// Gets the gripper generalized positions.
+  virtual VectorX<T> GetGripperPositions(
+      const systems::Context<T>& plant_context) const = 0;
+
+  /// Sets the gripper generalized positions to the default "open" position.
+  virtual void SetGripperPositionsToDefaultOpen(
+    const systems::Context<T>& plant_context,
+    systems::State<T>* plant_state) const = 0;
+
+  /// Sets the gripper generalized positions.
+  virtual void SetGripperPositions(
+    const systems::Context<T>& plant_context,
+    const Eigen::Ref<const VectorX<T>>& q,
+    systems::State<T>* plant_state) const = 0;
+
+  /// Gets the gripper generalized velocities.
+  virtual VectorX<T> GetGripperVelocities(
+      const systems::Context<T>& plant_context) const = 0;
+
+  /// Sets the gripper generalized velocities.
+  virtual void SetGripperVelocities(
+    const systems::Context<T>& plant_context,
+    const Eigen::Ref<const VectorX<T>>& v,
+    systems::State<T>* plant_state) const = 0;
+
+  /// This method adds the arm and gripper models to the internal plant.
+  virtual AddRobotModelToMultibodyPlant() = 0;
+
+  /// This method builds the control diagram for the arm and gripper
+  /// and adds it to the given builder for a Diagram.
+  virtual void BuildControlDiagram(systems::DiagramBuilder<T>* builder) = 0;
+
+  /// Gets a reference to the plant used for control.
+  virtual const multibody::MultibodyPlant<T>& get_controller_plant() const = 0;
+
+  /// Gets the model instance for the arm in the internal plant.
+  virtual multibody::ModelInstanceIndex arm_model_instance() const = 0;
+
+  /// Gets the model instance for the gripper in the internal plant.
+  virtual multibody::ModelInstanceIndex gripper_model_instance() const = 0;
+
+ protected:
+  // The MultibodyPlant holding the robot model (and possibly other models as
+  // well).
+  multibody::MultibodyPlant<T>* plant_{nullptr};
+};
+
+}  // namespace manipulation_station
+}  // namespace examples
+}  // namespace drake
+