admittance_rule.hpp

// Copyright (c) 2021, PickNik, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
 
#ifndef ADMITTANCE_CONTROLLER__ADMITTANCE_RULE_HPP_
#define ADMITTANCE_CONTROLLER__ADMITTANCE_RULE_HPP_
 
#include <Eigen/Core>
 
#include <memory>
#include <string>
#include <vector>
 
#include "admittance_controller/admittance_controller_parameters.hpp"
#include "control_msgs/msg/admittance_controller_state.hpp"
#include "controller_interface/controller_interface_base.hpp"
#include "kinematics_interface/kinematics_interface.hpp"
#include "pluginlib/class_loader.hpp"
#include "trajectory_msgs/msg/joint_trajectory_point.hpp"
 
namespace admittance_controller
{
struct AdmittanceTransforms
{
  // transformation from force torque sensor frame to base link frame at reference joint angles
  Eigen::Isometry3d ref_base_ft_;
  // transformation from force torque sensor frame to base link frame at reference + admittance
  // offset joint angles
  Eigen::Isometry3d base_ft_;
  // transformation from control frame to base link frame at reference + admittance offset joint
  // angles
  Eigen::Isometry3d base_control_;
  // transformation from end effector frame to base link frame at reference + admittance offset
  // joint angles
  Eigen::Isometry3d base_tip_;
  // transformation from center of gravity frame to base link frame at reference + admittance offset
  // joint angles
  Eigen::Isometry3d base_cog_;
  // transformation from world frame to base link frame
  Eigen::Isometry3d world_base_;
};
 
struct AdmittanceState
{
  explicit AdmittanceState(size_t num_joints)
  {
    admittance_velocity.setZero();
    admittance_acceleration.setZero();
    damping.setZero();
    mass.setOnes();
    mass_inv.setZero();
    stiffness.setZero();
    selected_axes.setZero();
    auto idx = static_cast<Eigen::Index>(num_joints);
    current_joint_pos = Eigen::VectorXd::Zero(idx);
    joint_pos = Eigen::VectorXd::Zero(idx);
    joint_vel = Eigen::VectorXd::Zero(idx);
    joint_acc = Eigen::VectorXd::Zero(idx);
  }
 
  Eigen::VectorXd current_joint_pos;
  Eigen::VectorXd joint_pos;
  Eigen::VectorXd joint_vel;
  Eigen::VectorXd joint_acc;
  Eigen::Matrix<double, 6, 1> damping;
  Eigen::Matrix<double, 6, 1> mass;
  Eigen::Matrix<double, 6, 1> mass_inv;
  Eigen::Matrix<double, 6, 1> selected_axes;
  Eigen::Matrix<double, 6, 1> stiffness;
  Eigen::Matrix<double, 6, 1> wrench_base;
  Eigen::Matrix<double, 6, 1> admittance_acceleration;
  Eigen::Matrix<double, 6, 1> admittance_velocity;
  Eigen::Isometry3d admittance_position;
  Eigen::Matrix<double, 3, 3> rot_base_control;
  Eigen::Isometry3d ref_trans_base_ft;
  std::string ft_sensor_frame;
};
 
class AdmittanceRule
{
public:
  explicit AdmittanceRule(
    const std::shared_ptr<admittance_controller::ParamListener> & parameter_handler)
  {
    parameter_handler_ = parameter_handler;
    parameters_ = parameter_handler_->get_params();
    num_joints_ = parameters_.joints.size();
    admittance_state_ = AdmittanceState(num_joints_);
    reset(num_joints_);
  }
 
  controller_interface::return_type configure(
    const std::shared_ptr<rclcpp_lifecycle::LifecycleNode> & node, const size_t num_joint,
    const std::string & robot_description);
 
  controller_interface::return_type reset(const size_t num_joints);
 
  bool get_all_transforms(
    const trajectory_msgs::msg::JointTrajectoryPoint & current_joint_state,
    const trajectory_msgs::msg::JointTrajectoryPoint & reference_joint_state);
 
  void apply_parameters_update();
 
  controller_interface::return_type update(
    const trajectory_msgs::msg::JointTrajectoryPoint & current_joint_state,
    const geometry_msgs::msg::Wrench & measured_wrench,
    const trajectory_msgs::msg::JointTrajectoryPoint & reference_joint_state,
    const rclcpp::Duration & period,
    trajectory_msgs::msg::JointTrajectoryPoint & desired_joint_states);
 
  const control_msgs::msg::AdmittanceControllerState & get_controller_state();
 
public:
  // admittance config parameters
  std::shared_ptr<admittance_controller::ParamListener> parameter_handler_;
  admittance_controller::Params parameters_;
 
protected:
  bool calculate_admittance_rule(AdmittanceState & admittance_state, double dt);
 
  void process_wrench_measurements(
    const geometry_msgs::msg::Wrench & measured_wrench,
    const Eigen::Matrix<double, 3, 3> & sensor_world_rot,
    const Eigen::Matrix<double, 3, 3> & cog_world_rot);
 
  template <typename T1, typename T2>
  void vec_to_eigen(const std::vector<T1> & data, T2 & matrix);
 
  // number of robot joint
  size_t num_joints_;
 
  // Kinematics interface plugin loader
  std::shared_ptr<pluginlib::ClassLoader<kinematics_interface::KinematicsInterface>>
    kinematics_loader_;
  std::unique_ptr<kinematics_interface::KinematicsInterface> kinematics_;
 
  // filtered wrench in world frame
  Eigen::Matrix<double, 6, 1> wrench_world_;
 
  // admittance controllers internal state
  AdmittanceState admittance_state_{0};
 
  // transforms needed for admittance update
  AdmittanceTransforms admittance_transforms_;
 
  // position of center of gravity in cog_frame
  Eigen::Vector3d cog_pos_;
 
  // force applied to sensor due to weight of end effector
  Eigen::Vector3d end_effector_weight_;
 
  // ROS
  control_msgs::msg::AdmittanceControllerState state_message_;
};
 
}  // namespace admittance_controller
 
#endif  // ADMITTANCE_CONTROLLER__ADMITTANCE_RULE_HPP_