hardware_interface_adapter.h

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// Copyright (C) 2014, SRI International
// Copyright (C) 2013, PAL Robotics S.L.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
//   * Neither the name of SRI International nor the names of its
//     contributors may be used to endorse or promote products derived from
//     this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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#ifndef GRIPPER_ACTION_CONTROLLER_HARDWARE_INTERFACE_ADAPTER_H
#define GRIPPER_ACTION_CONTROLLER_HARDWARE_INTERFACE_ADAPTER_H

#include <cassert>
#include <string>
#include <vector>

#include <boost/shared_ptr.hpp>

#include <ros/node_handle.h>
#include <ros/time.h>

#include <control_toolbox/pid.h>
#include <hardware_interface/joint_command_interface.h>

template <class HardwareInterface>
class HardwareInterfaceAdapter
{
public:
  bool init(hardware_interface::JointHandle& joint_handle, ros::NodeHandle& controller_nh)
  {
    return false;
  }

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

  double updateCommand(const ros::Time&     time,
                       const ros::Duration& period,
                       double desired_position,
                       double desired_velocity,
                       double error_position,
                       double error_velocity,
                       double max_allowed_effort) { return 0.0;}

};

template<>
class HardwareInterfaceAdapter<hardware_interface::PositionJointInterface>
{
public:
  HardwareInterfaceAdapter() : joint_handle_ptr_(0) {}

  bool init(hardware_interface::JointHandle& joint_handle, ros::NodeHandle& controller_nh)
  {
    // Store pointer to joint handles
    joint_handle_ptr_ = &joint_handle;

    return true;
  }

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

  double updateCommand(const ros::Time&     /*time*/,
                       const ros::Duration& period,
                       double desired_position,
                       double desired_velocity,
                       double error_position,
                       double error_velocity,
                       double max_allowed_effort)
  {
    // Forward desired position to command
    (*joint_handle_ptr_).setCommand(desired_position);
    return max_allowed_effort;
  }

private:
  hardware_interface::JointHandle* joint_handle_ptr_;
};

template<>
class HardwareInterfaceAdapter<hardware_interface::EffortJointInterface>
{
public:
  HardwareInterfaceAdapter() : joint_handle_ptr_(0) {}

  bool init(hardware_interface::JointHandle& joint_handle, ros::NodeHandle& controller_nh)
  {
    // Store pointer to joint handles
    joint_handle_ptr_ = &joint_handle;

    // Initialize PIDs
    ros::NodeHandle joint_nh(controller_nh, std::string("gains/") + joint_handle.getName());

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

  void starting(const ros::Time& time)
  {
    if (!joint_handle_ptr_) 
    {
      return;
    }
    // Reset PIDs, zero effort commands
    pid_->reset();
    (*joint_handle_ptr_).setCommand(0.0);
  }

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

  double updateCommand(const ros::Time&     /*time*/,
                       const ros::Duration& period,
                       double desired_position,
                       double desired_velocity,
                       double error_position,
                       double error_velocity,
                       double max_allowed_effort)
  {
    // Preconditions
    if (!joint_handle_ptr_) {return 0.0;}

    // Update PIDs
      double command = pid_->computeCommand(error_position, error_velocity, period);
      command = std::min<double>(fabs(max_allowed_effort), std::max<double>(-fabs(max_allowed_effort), command));
      (*joint_handle_ptr_).setCommand(command);
      return command;
  }

private:
  typedef boost::shared_ptr<control_toolbox::Pid> PidPtr;
  PidPtr pid_;
  hardware_interface::JointHandle* joint_handle_ptr_;
};

#endif // header guard