pr2_gripper_grasp_controller.cpp

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#include <ros/ros.h>

#include <actionlib/server/simple_action_server.h>
#include <actionlib/client/simple_action_client.h>

#include <pr2_controllers_msgs/Pr2GripperCommandAction.h>

#include <sensor_msgs/JointState.h>

#include <object_manipulation_msgs/GraspHandPostureExecutionAction.h>
#include <object_manipulation_msgs/GraspStatus.h>

static const std::string JOINT_STATES_TOPIC = "joint_states";


class PR2GripperGraspController
{
private:

  ros::NodeHandle root_nh_;

  ros::NodeHandle priv_nh_;

  actionlib::SimpleActionClient<pr2_controllers_msgs::Pr2GripperCommandAction> *gripper_action_client_;

  actionlib::SimpleActionServer<object_manipulation_msgs::GraspHandPostureExecutionAction> *action_server_;

  ros::ServiceServer query_srv_;

  std::string gripper_virtual_joint_name_;

  //-------------------------------- Constants ---------------------------------

  double gripper_open_gap_value_;
  static const double DEFAULT_GRIPPER_OPEN;

  double gripper_closed_gap_value_;
  static const double DEFAULT_GRIPPER_CLOSED;

  double gripper_object_presence_threshold_;  
  static const double DEFAULT_GRIPPER_OBJECT_PRESENCE_THRESHOLD;

  double gripper_max_effort_;
  static const double DEFAULT_GRIPPER_MAX_EFFORT;

  std::string gripper_type_;

  //------------------------------ Functionality -------------------------------

  bool getGripperValue(double &value)
  {
    //get the joint states
    sensor_msgs::JointState::ConstPtr joint_states = 
      ros::topic::waitForMessage<sensor_msgs::JointState>(JOINT_STATES_TOPIC, root_nh_);
    if (!joint_states)
    {
      ROS_ERROR("pr2 gripper grasp status: joint states not received");
      return false;
    }
    
    //find the gripper joint
    size_t i;
    for (i=0; i<joint_states->name.size(); i++)
    {
      if (joint_states->name[i] == gripper_virtual_joint_name_) break;
    }
    if (i==joint_states->name.size())
    {
      ROS_ERROR("pr2_gripper grasp status: gripper joint %s not found in joint state", 
                gripper_virtual_joint_name_.c_str());
      return false;
    }
    if (joint_states->position.size() <= i)
    {
      ROS_ERROR("pr2_gripper grasp status: malformed joint state message received");
      return false;
    }
    value = joint_states->position[i];
    return true;
  }


  double jointToGap(double jointValue)
  {
    if (gripper_type_ == "pr2") return jointValue / 0.5 * 0.0857;
    else if (gripper_type_ == "lcg") return 2.0 * ( cos(jointValue)*60.0 + 17.5 - 6.0 ) * 1.0e-3;
    else {ROS_ERROR_STREAM("pr2_gripper_grasp_controller: unknown gripper type: " << gripper_type_); return 0.0;}
  }

  void executeCB(const object_manipulation_msgs::GraspHandPostureExecutionGoalConstPtr &goal)
  {
    //prepare the gripper command based on the goal
    pr2_controllers_msgs::Pr2GripperCommandGoal gripper_command;
    switch (goal->goal)
    {
    case object_manipulation_msgs::GraspHandPostureExecutionGoal::GRASP:
      if (goal->grasp.grasp_posture.position.empty())
      {
        ROS_ERROR("pr2 gripper grasp execution: position vector empty in requested grasp");
        action_server_->setAborted();
        return;
      }
      gripper_command.command.position = gripper_closed_gap_value_;
      //gripper_command.command.position = jointToGap( goal->grasp.grasp_posture.position[0] );
      if (goal->grasp.grasp_posture.effort.empty())
      {
        if(goal->max_contact_force > 0)
        {
          ROS_INFO("limiting max contact force to %f", goal->max_contact_force);
          gripper_command.command.max_effort = goal->max_contact_force;
        }
        else gripper_command.command.max_effort = gripper_max_effort_;
        ROS_WARN("pr2 gripper grasp execution: effort vector empty in requested grasp, using max force");
        //action_server_->setAborted();
        //return;
      }
      //we use the effort in the first joint for going to the grasp
      else 
      {
        if(goal->grasp.grasp_posture.effort.at(0) < goal->max_contact_force || goal->max_contact_force == 0)
          gripper_command.command.max_effort = goal->grasp.grasp_posture.effort.at(0);
        else gripper_command.command.max_effort = goal->max_contact_force;
      }
      break;
    case object_manipulation_msgs::GraspHandPostureExecutionGoal::PRE_GRASP:
      if (goal->grasp.pre_grasp_posture.position.empty())
      {
        ROS_ERROR("pr2 gripper grasp execution: position vector empty in requested pre_grasp");
        action_server_->setAborted();
        return;
      }
      //gripper_command.command.position = GRIPPER_OPEN;
      gripper_command.command.position = jointToGap( goal->grasp.pre_grasp_posture.position.at(0) );
      ROS_DEBUG("pre grasp posture opening is %.3f", gripper_command.command.position);
      if (goal->grasp.pre_grasp_posture.effort.empty())
      {
        gripper_command.command.max_effort = gripper_max_effort_;
        ROS_WARN("pr2 gripper grasp execution: effort vector empty in requested pre_grasp, using max");
      }
      else 
      {
        gripper_command.command.max_effort = goal->grasp.pre_grasp_posture.effort.at(0);
      }
      break;      
    case object_manipulation_msgs::GraspHandPostureExecutionGoal::RELEASE:
      gripper_command.command.position = gripper_open_gap_value_;
      gripper_command.command.max_effort = gripper_max_effort_;
      break;
    default:
      ROS_ERROR("pr2 gripper grasp execution: unknown goal code (%d)", goal->goal);
      action_server_->setAborted();
      return;
    }

    //check the requested effort
    if (gripper_command.command.max_effort > gripper_max_effort_)
    {
      ROS_WARN("pr2 gripper grasp execution: effort exceeds max value for gripper, reducing to max");
      gripper_command.command.max_effort = gripper_max_effort_;
    }

    //send the command to the gripper
    gripper_action_client_->sendGoal(gripper_command);
    gripper_action_client_->waitForResult();

    //process the result
    if(gripper_action_client_->getState() == actionlib::SimpleClientGoalState::SUCCEEDED) 
    {
      ROS_INFO("Gripper goal achieved");
      action_server_->setSucceeded();
    } 
    else 
    {
      if (goal->goal == object_manipulation_msgs::GraspHandPostureExecutionGoal::GRASP)
      {
        //this is probably correct behavior, since there is an object in the gripper
        //we can not expect to reach our goal
        action_server_->setSucceeded();
      }
      else
      {
        ROS_WARN("Gripper goal not achieved for pre-grasp or release");
        //this might become a failure later, for now we're still investigating
        action_server_->setSucceeded();
      }
    }
  }

  bool serviceCallback(object_manipulation_msgs::GraspStatus::Request &request,
                       object_manipulation_msgs::GraspStatus::Response &response)
  {
    double gripper_value;
    if (!getGripperValue(gripper_value)) return false;    

    double min_gripper_opening = gripper_object_presence_threshold_;
    if (gripper_value < min_gripper_opening) 
    {
      ROS_INFO("Gripper grasp query false: gripper value %f below threshold %f", 
               gripper_value, min_gripper_opening);
      response.is_hand_occupied = false;
    }
    else 
    {
      ROS_DEBUG("Gripper grasp query true: gripper value %f above threshold %f", 
               gripper_value, min_gripper_opening);
      response.is_hand_occupied = true;
    }
    return true;
  }
                       

public:
  PR2GripperGraspController() :
    root_nh_(""),
    priv_nh_("~")
  {
    std::string gripper_action_name = root_nh_.resolveName("gripper_action_name");
    gripper_action_client_ = new actionlib::SimpleActionClient<pr2_controllers_msgs::Pr2GripperCommandAction>
      (gripper_action_name, true);
    while(!gripper_action_client_->waitForServer(ros::Duration(2.0)) && root_nh_.ok())
    {
      ROS_INFO_STREAM("Waiting for gripper action client on topic " << gripper_action_name);
    }
    if (!root_nh_.ok()) exit(0);
    ROS_INFO_STREAM("Using gripper action client on topic " << gripper_action_name);

    priv_nh_.param<std::string>("gripper_virtual_joint_name", gripper_virtual_joint_name_, "undefined");
    if ( gripper_virtual_joint_name_ == "undefined" )
    {
      ROS_ERROR("Gripper virtual joint name not defined; set the parameter "
                "gripper_virtual_joint_name in the launch file");
      exit(0);
    }

    priv_nh_.param<double>("gripper_object_presence_threshold", gripper_object_presence_threshold_,
                           DEFAULT_GRIPPER_OBJECT_PRESENCE_THRESHOLD);
    priv_nh_.param<double>("gripper_open_gap_value", gripper_open_gap_value_, DEFAULT_GRIPPER_OPEN);
    priv_nh_.param<double>("gripper_closed_gap_value", gripper_closed_gap_value_, DEFAULT_GRIPPER_CLOSED);
    priv_nh_.param<double>("gripper_max_effort", gripper_max_effort_, DEFAULT_GRIPPER_MAX_EFFORT);
    priv_nh_.param<std::string>("gripper_type", gripper_type_, "pr2");

    std::string query_service_name = root_nh_.resolveName("grasp_query_name");   
    query_srv_ = root_nh_.advertiseService(query_service_name, &PR2GripperGraspController::serviceCallback, this);    
    ROS_INFO_STREAM("pr2_gripper grasp query service started on topic " << query_service_name);

    std::string posture_action_name = root_nh_.resolveName("posture_action_name");
    action_server_ = new actionlib::SimpleActionServer<object_manipulation_msgs::GraspHandPostureExecutionAction>
      (root_nh_, posture_action_name, boost::bind(&PR2GripperGraspController::executeCB, this, _1), false);
    action_server_->start();
    ROS_INFO_STREAM("pr2_gripper grasp hand posture action server started on topic " << posture_action_name);
  }

  ~PR2GripperGraspController()
  {
    delete action_server_;
    delete gripper_action_client_;
  }

};

//Note that all these values are set for the PR2 gripper
const double PR2GripperGraspController::DEFAULT_GRIPPER_OPEN = 0.086;
const double PR2GripperGraspController::DEFAULT_GRIPPER_CLOSED = 0.0;
const double PR2GripperGraspController::DEFAULT_GRIPPER_OBJECT_PRESENCE_THRESHOLD = 0.0021;
const double PR2GripperGraspController::DEFAULT_GRIPPER_MAX_EFFORT = 100;

int main(int argc, char **argv)
{
  ros::init(argc, argv, "pr2_gripper_grasp_controller");
  PR2GripperGraspController node;
  ros::spin();
  return 0;  
}