Add wrench offset for admittance controller (ros-controls#1249)

Author: firesurfer

admittance_controller/doc/userdoc.rst

@@ -32,6 +32,9 @@ Topics
 ~/joint_references (input topic) [trajectory_msgs::msg::JointTrajectoryPoint]
   Target joint commands when controller is not in chained mode.
 
+~/wrench_reference (input topic) [geometry_msgs::msg::WrenchStamped]
+  Target wrench offset (WrenchStamped has to be in the frame of the FT-sensor).
+
 ~/state (output topic) [control_msgs::msg::AdmittanceControllerState]
   Topic publishing internal states.
 

admittance_controller/include/admittance_controller/admittance_controller.hpp

@@ -133,6 +133,8 @@ class AdmittanceController : public controller_interface::ChainableControllerInt
   // ROS subscribers
   rclcpp::Subscription<trajectory_msgs::msg::JointTrajectoryPoint>::SharedPtr
     input_joint_command_subscriber_;
+  rclcpp::Subscription<geometry_msgs::msg::WrenchStamped>::SharedPtr
+    input_wrench_command_subscriber_;
   rclcpp::Publisher<control_msgs::msg::AdmittanceControllerState>::SharedPtr s_publisher_;
 
   // admittance parameters
@@ -144,6 +146,7 @@ class AdmittanceController : public controller_interface::ChainableControllerInt
   // real-time buffer
   realtime_tools::RealtimeBuffer<std::shared_ptr<trajectory_msgs::msg::JointTrajectoryPoint>>
     input_joint_command_;
+  realtime_tools::RealtimeBuffer<geometry_msgs::msg::WrenchStamped> input_wrench_command_;
   std::unique_ptr<realtime_tools::RealtimePublisher<ControllerStateMsg>> state_publisher_;
 
   trajectory_msgs::msg::JointTrajectoryPoint last_commanded_;

admittance_controller/src/admittance_controller.cpp

@@ -27,6 +27,23 @@
 
 namespace admittance_controller
 {
+
+geometry_msgs::msg::Wrench add_wrenches(
+  const geometry_msgs::msg::Wrench & a, const geometry_msgs::msg::Wrench & b)
+{
+  geometry_msgs::msg::Wrench res;
+
+  res.force.x = a.force.x + b.force.x;
+  res.force.y = a.force.y + b.force.y;
+  res.force.z = a.force.z + b.force.z;
+
+  res.torque.x = a.torque.x + b.torque.x;
+  res.torque.y = a.torque.y + b.torque.y;
+  res.torque.z = a.torque.z + b.torque.z;
+
+  return res;
+}
+
 controller_interface::CallbackReturn AdmittanceController::on_init()
 {
   // initialize controller config
@@ -116,6 +133,7 @@ AdmittanceController::on_export_reference_interfaces()
   reference_interfaces_.resize(num_chainable_interfaces, std::numeric_limits<double>::quiet_NaN());
   position_reference_ = {};
   velocity_reference_ = {};
+  input_wrench_command_.reset();
 
   // assign reference interfaces
   auto index = 0ul;
@@ -265,6 +283,24 @@ controller_interface::CallbackReturn AdmittanceController::on_configure(
   input_joint_command_subscriber_ =
     get_node()->create_subscription<trajectory_msgs::msg::JointTrajectoryPoint>(
       "~/joint_references", rclcpp::SystemDefaultsQoS(), joint_command_callback);
+
+  input_wrench_command_subscriber_ =
+    get_node()->create_subscription<geometry_msgs::msg::WrenchStamped>(
+      "~/wrench_reference", rclcpp::SystemDefaultsQoS(),
+      [&](const geometry_msgs::msg::WrenchStamped & msg)
+      {
+        if (
+          msg.header.frame_id != admittance_->parameters_.ft_sensor.frame.id &&
+          !msg.header.frame_id.empty())
+        {
+          RCLCPP_ERROR_STREAM(
+            get_node()->get_logger(), "Ignoring wrench reference as it is on the wrong frame: "
+                                        << msg.header.frame_id << ". Expected reference frame: "
+                                        << admittance_->parameters_.ft_sensor.frame.id);
+          return;
+        }
+        input_wrench_command_.writeFromNonRT(msg);
+      });
   s_publisher_ = get_node()->create_publisher<control_msgs::msg::AdmittanceControllerState>(
     "~/status", rclcpp::SystemDefaultsQoS());
   state_publisher_ =
@@ -398,8 +434,10 @@ controller_interface::return_type AdmittanceController::update_and_write_command
   // get all controller inputs
   read_state_from_hardware(joint_state_, ft_values_);
 
+  auto offsetted_ft_values = add_wrenches(ft_values_, input_wrench_command_.readFromRT()->wrench);
+
   // apply admittance control to reference to determine desired state
-  admittance_->update(joint_state_, ft_values_, reference_, period, reference_admittance_);
+  admittance_->update(joint_state_, offsetted_ft_values, reference_, period, reference_admittance_);
 
   // write calculated values to joint interfaces
   write_state_to_hardware(reference_admittance_);

doc/release_notes.rst

@@ -7,6 +7,7 @@ This list summarizes the changes between Iron (previous) and Jazzy (current) rel
 admittance_controller
 ************************
 * Remove ``robot_description`` parameter from parameter YAML, because it is not used at all (`#963 <https://github.com/ros-controls/ros2_controllers/pull/963>`_).
+* Added ``~/wrench_reference`` input topic which allows to provide a force-torque offset as WrenchStamped (`#1249 <https://github.com/ros-controls/ros2_controllers/pull/1249>`_).
 
 diff_drive_controller
 *****************************