hardware_interface_adapter.h

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// this is for emacs file handling -*- mode: c++; indent-tabs-mode: nil -*-

// -- BEGIN LICENSE BLOCK ----------------------------------------------
// Copyright 2019 FZI Forschungszentrum Informatik
//
// 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.
// -- END LICENSE BLOCK ------------------------------------------------

//----------------------------------------------------------------------
//----------------------------------------------------------------------

#ifndef UR_CONTROLLERS_HARDWARE_INTERFACE_ADAPTER_H_INCLUDED
#define UR_CONTROLLERS_HARDWARE_INTERFACE_ADAPTER_H_INCLUDED

#include <joint_trajectory_controller/hardware_interface_adapter.h>
#include "ur_controllers/scaled_joint_command_interface.h"

template <class State>
class HardwareInterfaceAdapter<ur_controllers::ScaledPositionJointInterface, State>
{
public:
  HardwareInterfaceAdapter() : joint_handles_ptr_(0)
  {
  }

  bool init(std::vector<ur_controllers::ScaledJointHandle>& joint_handles, ros::NodeHandle& /*controller_nh*/)
  {
    // Store pointer to joint handles
    joint_handles_ptr_ = &joint_handles;

    return true;
  }

  void starting(const ros::Time& /*time*/)
  {
    if (!joint_handles_ptr_)
    {
      return;
    }

    // Semantic zero for commands
    for (auto& jh : *joint_handles_ptr_)
    {
      jh.setCommand(jh.getPosition());
    }
  }

  void stopping(const ros::Time& /*time*/)
  {
  }

  void updateCommand(const ros::Time& /*time*/, const ros::Duration& /*period*/, const State& desired_state,
                     const State& /*state_error*/)
  {
    // Forward desired position to command
    const unsigned int n_joints = joint_handles_ptr_->size();
    for (unsigned int i = 0; i < n_joints; ++i)
    {
      (*joint_handles_ptr_)[i].setCommand(desired_state.position[i]);
    }
  }

private:
  std::vector<ur_controllers::ScaledJointHandle>* joint_handles_ptr_;
};

namespace ur_controllers
{
template <class State>
class ClosedLoopHardwareInterfaceAdapter
{
public:
  ClosedLoopHardwareInterfaceAdapter() : joint_handles_ptr_(0)
  {
  }

  bool init(std::vector<ur_controllers::ScaledJointHandle>& joint_handles, ros::NodeHandle& controller_nh)
  {
    // Store pointer to joint handles
    joint_handles_ptr_ = &joint_handles;

    // Initialize PIDs
    pids_.resize(joint_handles.size());
    for (unsigned int i = 0; i < pids_.size(); ++i)
    {
      // Node handle to PID gains
      ros::NodeHandle joint_nh(controller_nh, std::string("gains/") + joint_handles[i].getName());

      // Init PID gains from ROS parameter server
      pids_[i].reset(new control_toolbox::Pid());
      if (!pids_[i]->init(joint_nh))
      {
        ROS_WARN_STREAM("Failed to initialize PID gains from ROS parameter server.");
        return false;
      }
    }

    // Load velocity feedforward gains from parameter server
    velocity_ff_.resize(joint_handles.size());
    for (unsigned int i = 0; i < velocity_ff_.size(); ++i)
    {
      controller_nh.param(std::string("velocity_ff/") + joint_handles[i].getName(), velocity_ff_[i], 0.0);
    }

    return true;
  }

  void starting(const ros::Time& /*time*/)
  {
    if (!joint_handles_ptr_)
    {
      return;
    }

    // Reset PIDs, zero commands
    for (unsigned int i = 0; i < pids_.size(); ++i)
    {
      pids_[i]->reset();
      (*joint_handles_ptr_)[i].setCommand(0.0);
    }
  }

  void stopping(const ros::Time& /*time*/)
  {
  }

  void updateCommand(const ros::Time& /*time*/, const ros::Duration& period, const State& desired_state,
                     const State& state_error)
  {
    const unsigned int n_joints = joint_handles_ptr_->size();

    // Preconditions
    if (!joint_handles_ptr_)
      return;
    assert(n_joints == state_error.position.size());
    assert(n_joints == state_error.velocity.size());

    // Update PIDs
    for (unsigned int i = 0; i < n_joints; ++i)
    {
      const double command = (desired_state.velocity[i] * velocity_ff_[i]) +
                             pids_[i]->computeCommand(state_error.position[i], state_error.velocity[i], period);
      (*joint_handles_ptr_)[i].setCommand(command);
    }
  }

private:
  typedef std::shared_ptr<control_toolbox::Pid> PidPtr;
  std::vector<PidPtr> pids_;

  std::vector<double> velocity_ff_;

  std::vector<ur_controllers::ScaledJointHandle>* joint_handles_ptr_;
};
}  // namespace ur_controllers

template <class State>
class HardwareInterfaceAdapter<ur_controllers::ScaledVelocityJointInterface, State>
  : public ur_controllers::ClosedLoopHardwareInterfaceAdapter<State>
{
};

#endif  // ifndef UR_CONTROLLERS_HARDWARE_INTERFACE_ADAPTER_H_INCLUDED