gripper_action_controller_impl.h

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// Copyright (C) 2014, SRI International
//
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//     this list of conditions and the following disclaimer.
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//     contributors may be used to endorse or promote products derived from
//     this software without specific prior written permission.
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#ifndef GRIPPER_ACTION_CONTROLLER_GRIPPER_ACTION_CONTROLLER_IMPL_H
#define GRIPPER_ACTION_CONTROLLER_GRIPPER_ACTION_CONTROLLER_IMPL_H

namespace gripper_action_controller
{
namespace internal
{
std::string getLeafNamespace(const ros::NodeHandle& nh)
{
  const std::string complete_ns = nh.getNamespace();
  std::size_t id   = complete_ns.find_last_of("/");
  return complete_ns.substr(id + 1);
}  

urdf::ModelSharedPtr getUrdf(const ros::NodeHandle& nh, const std::string& param_name)
{
  urdf::ModelSharedPtr urdf(new urdf::Model);

  std::string urdf_str;
  // Check for robot_description in proper namespace
  if (nh.getParam(param_name, urdf_str))
  {
    if (!urdf->initString(urdf_str))
    {
      ROS_ERROR_STREAM("Failed to parse URDF contained in '" << param_name << "' parameter (namespace: " <<
        nh.getNamespace() << ").");
      return urdf::ModelSharedPtr();
    }
  }
  // Check for robot_description in root
  else if (!urdf->initParam("robot_description"))
  {
    ROS_ERROR_STREAM("Failed to parse URDF contained in '" << param_name << "' parameter");
    return urdf::ModelSharedPtr();
  }
  return urdf;
}

std::vector<urdf::JointConstSharedPtr> getUrdfJoints(const urdf::Model& urdf, const std::vector<std::string>& joint_names)
{
  std::vector<urdf::JointConstSharedPtr> out;
  for (unsigned int i = 0; i < joint_names.size(); ++i)
  {
    urdf::JointConstSharedPtr urdf_joint = urdf.getJoint(joint_names[i]);
    if (urdf_joint)
    {
      out.push_back(urdf_joint);
    }
    else
    {
      ROS_ERROR_STREAM("Could not find joint '" << joint_names[i] << "' in URDF model.");
      return std::vector<urdf::JointConstSharedPtr>();
    }
  }
  return out;
}

} // namespace

template <class HardwareInterface>
inline void GripperActionController<HardwareInterface>::
starting(const ros::Time& time)
{  
  command_struct_rt_.position_ = joint_.getPosition();
  command_struct_rt_.max_effort_ = default_max_effort_;
  command_.initRT(command_struct_rt_);

  // Hardware interface adapter
  hw_iface_adapter_.starting(ros::Time(0.0));
  last_movement_time_ = time;
}
 
template <class HardwareInterface>
inline void GripperActionController<HardwareInterface>::
stopping(const ros::Time& time)
{
  preemptActiveGoal();
}

template <class HardwareInterface>
inline void GripperActionController<HardwareInterface>::
preemptActiveGoal()
{
  RealtimeGoalHandlePtr current_active_goal(rt_active_goal_);
   
  // Cancels the currently active goal
  if (current_active_goal)
  {
    // Marks the current goal as canceled
    rt_active_goal_.reset();
    if(current_active_goal->gh_.getGoalStatus().status == actionlib_msgs::GoalStatus::ACTIVE)
      current_active_goal->gh_.setCanceled();
  }
}

template <class HardwareInterface>
GripperActionController<HardwareInterface>::
GripperActionController()
: verbose_(false) // Set to true during debugging
{}

template <class HardwareInterface>
bool GripperActionController<HardwareInterface>::init(HardwareInterface* hw,
                                                      ros::NodeHandle&   root_nh,
                                                      ros::NodeHandle&   controller_nh)
{
  using namespace internal;
  
  // Cache controller node handle
  controller_nh_ = controller_nh;
  
  // Controller name
  name_ = getLeafNamespace(controller_nh_);
  
  // Action status checking update rate
  double action_monitor_rate = 20.0;
  controller_nh_.getParam("action_monitor_rate", action_monitor_rate);
  action_monitor_period_ = ros::Duration(1.0 / action_monitor_rate);
  ROS_DEBUG_STREAM_NAMED(name_, "Action status changes will be monitored at " << action_monitor_rate << "Hz.");
  
  // Controlled joint
  controller_nh_.getParam("joint", joint_name_);
  if (joint_name_.empty()) 
  {
    ROS_ERROR_STREAM_NAMED(name_, "Could not find joint name on param server");
    return false;
  }
  
  // URDF joints
  urdf::ModelSharedPtr urdf = getUrdf(root_nh, "robot_description");
  if (!urdf) 
  {
    return false;
  }
  
  std::vector<std::string> joint_names;
  joint_names.push_back(joint_name_);
  std::vector<urdf::JointConstSharedPtr> urdf_joints = getUrdfJoints(*urdf, joint_names);
  if (urdf_joints.empty()) 
  {
    return false;
  }
  
  // Initialize members
  // Joint handle
  try 
  {
    joint_ = hw->getHandle(joint_name_);
  }
  catch (...)
  {
    ROS_ERROR_STREAM_NAMED(name_, "Could not find joint '" << joint_name_ << "' in '" <<
                           this->getHardwareInterfaceType() << "'.");
    return false;
  }

  ROS_DEBUG_STREAM_NAMED(name_, "Initialized controller '" << name_ << "' with:" <<
                         "\n- Hardware interface type: '" << this->getHardwareInterfaceType() << "'" <<
                         "\n");
  
  // Default tolerances
  controller_nh_.param<double>("goal_tolerance", goal_tolerance_, 0.01);
  goal_tolerance_ = fabs(goal_tolerance_);
  // Max allowable effort 
  controller_nh_.param<double>("max_effort", default_max_effort_, 0.0);
  default_max_effort_ = fabs(default_max_effort_);
  // Stall - stall velocity threshold, stall timeout
  controller_nh_.param<double>("stall_velocity_threshold", stall_velocity_threshold_, 0.001);
  controller_nh_.param<double>("stall_timeout", stall_timeout_, 1.0);
  
  // Hardware interface adapter
  hw_iface_adapter_.init(joint_, controller_nh_);

  // Command - non RT version
  command_struct_.position_ = joint_.getPosition();
  command_struct_.max_effort_ = default_max_effort_;

  // Result
  pre_alloc_result_.reset(new control_msgs::GripperCommandResult());
  pre_alloc_result_->position = command_struct_.position_;
  pre_alloc_result_->reached_goal = false;
  pre_alloc_result_->stalled = false;

  // ROS API: Action interface
  action_server_.reset(new ActionServer(controller_nh_, "gripper_cmd",
                                        boost::bind(&GripperActionController::goalCB,   this, _1),
                                        boost::bind(&GripperActionController::cancelCB, this, _1),
                                        false));
  action_server_->start();    
  return true;
}

template <class HardwareInterface>
void GripperActionController<HardwareInterface>::
update(const ros::Time& time, const ros::Duration& period)
{
  command_struct_rt_ = *(command_.readFromRT());

  double current_position = joint_.getPosition();
  double current_velocity = joint_.getVelocity();

  double error_position = command_struct_rt_.position_ - current_position;
  double error_velocity = - current_velocity;
    
  checkForSuccess(time, error_position, current_position, current_velocity);

  // Hardware interface adapter: Generate and send commands
  computed_command_ = hw_iface_adapter_.updateCommand(time, period,
                                                      command_struct_rt_.position_, 0.0, 
                                                      error_position, error_velocity, command_struct_rt_.max_effort_);
}

template <class HardwareInterface>
void GripperActionController<HardwareInterface>::
goalCB(GoalHandle gh)
{
  ROS_DEBUG_STREAM_NAMED(name_,"Recieved new action goal");
  
  // Precondition: Running controller
  if (!this->isRunning())
  {
    ROS_ERROR_NAMED(name_, "Can't accept new action goals. Controller is not running.");
    control_msgs::GripperCommandResult result;
    gh.setRejected(result);
    return;
  }

  // Try to update goal
  RealtimeGoalHandlePtr rt_goal(new RealtimeGoalHandle(gh));

  // Accept new goal
  preemptActiveGoal();
  gh.setAccepted();

  // This is the non-realtime command_struct
  // We use command_ for sharing
  command_struct_.position_ = gh.getGoal()->command.position;
  command_struct_.max_effort_ = gh.getGoal()->command.max_effort;
  command_.writeFromNonRT(command_struct_);

  pre_alloc_result_->reached_goal = false;
  pre_alloc_result_->stalled = false;

  last_movement_time_ = ros::Time::now();
    
  // Setup goal status checking timer
  goal_handle_timer_ = controller_nh_.createTimer(action_monitor_period_,
                                                  &RealtimeGoalHandle::runNonRealtime,
                                                  rt_goal);
  goal_handle_timer_.start();
  rt_active_goal_ = rt_goal;
}

template <class HardwareInterface>
void GripperActionController<HardwareInterface>::
cancelCB(GoalHandle gh)
{
  RealtimeGoalHandlePtr current_active_goal(rt_active_goal_);
  
  // Check that cancel request refers to currently active goal (if any)
  if (current_active_goal && current_active_goal->gh_ == gh)
  {
    // Reset current goal
    rt_active_goal_.reset();
    
    // Enter hold current position mode
    setHoldPosition(ros::Time(0.0));
    ROS_DEBUG_NAMED(name_, "Canceling active action goal because cancel callback recieved from actionlib.");
    
    // Mark the current goal as canceled
    current_active_goal->gh_.setCanceled();
  }
}

template <class HardwareInterface>
void GripperActionController<HardwareInterface>::
setHoldPosition(const ros::Time& time)
{
  command_struct_.position_ = joint_.getPosition();
  command_struct_.max_effort_ = default_max_effort_;
  command_.writeFromNonRT(command_struct_);
}

template <class HardwareInterface>
void GripperActionController<HardwareInterface>::
checkForSuccess(const ros::Time& time, double error_position, double current_position, double current_velocity)
{
  RealtimeGoalHandlePtr current_active_goal(rt_active_goal_);

  if(!current_active_goal)
    return;

  if(current_active_goal->gh_.getGoalStatus().status != actionlib_msgs::GoalStatus::ACTIVE)
    return;

  if(fabs(error_position) < goal_tolerance_)
  {
    pre_alloc_result_->effort = computed_command_;
    pre_alloc_result_->position = current_position;
    pre_alloc_result_->reached_goal = true;
    pre_alloc_result_->stalled = false;
    current_active_goal->setSucceeded(pre_alloc_result_);
  }
  else
  {
    if(fabs(current_velocity) > stall_velocity_threshold_)
    {
      last_movement_time_ = time;
    }
    else if( (time - last_movement_time_).toSec() > stall_timeout_)
    {
      pre_alloc_result_->effort = computed_command_;
      pre_alloc_result_->position = current_position;
      pre_alloc_result_->reached_goal = false;
      pre_alloc_result_->stalled = true;
      current_active_goal->setAborted(pre_alloc_result_);
    }
  }
}

} // namespace

#endif // header guard