srh_joint_velocity_controller.cpp

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/*
* Copyright 2011 Shadow Robot Company Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include "sr_mechanism_controllers/srh_joint_velocity_controller.hpp"
#include "angles/angles.h"
#include "pluginlib/class_list_macros.h"
#include <algorithm>
#include <string>
#include <sstream>
#include <math.h>
#include "sr_utilities/sr_math_utils.hpp"

#include <std_msgs/Float64.h>

PLUGINLIB_EXPORT_CLASS(controller::SrhJointVelocityController, controller_interface::ControllerBase)

using std::min;
using std::max;

namespace controller
{

  SrhJointVelocityController::SrhJointVelocityController()
          : velocity_deadband(0.015)
  {
  }

  bool SrhJointVelocityController::init(ros_ethercat_model::RobotStateInterface *robot, ros::NodeHandle &n)
  {
    ROS_ASSERT(robot);

    std::string robot_state_name;
    node_.param<std::string>("robot_state_name", robot_state_name, "unique_robot_hw");

    try
    {
      robot_ = robot->getHandle(robot_state_name).getState();
    }
    catch(const hardware_interface::HardwareInterfaceException& e)
    {
      ROS_ERROR_STREAM("Could not find robot state: " << robot_state_name << " Not loading the controller. " <<
        e.what());
      return false;
    }

    node_ = n;

    if (!node_.getParam("joint", joint_name_))
    {
      ROS_ERROR("No joint given (namespace: %s)", node_.getNamespace().c_str());
      return false;
    }

    pid_controller_velocity_.reset(new control_toolbox::Pid());
    if (!pid_controller_velocity_->init(ros::NodeHandle(node_, "pid")))
    {
      return false;
    }

    controller_state_publisher_.reset(new realtime_tools::RealtimePublisher<control_msgs::JointControllerState>
                                              (node_, "state", 1));

    ROS_DEBUG(" --------- ");
    ROS_DEBUG_STREAM("Init: " << joint_name_);

    // joint 0s e.g. FFJ0
    has_j2 = is_joint_0();
    if (has_j2)
    {
      get_joints_states_1_2();
      if (!joint_state_)
      {
        ROS_ERROR("SrhVelocityController could not find the first joint relevant to \"%s\"\n", joint_name_.c_str());
        return false;
      }
      if (!joint_state_2)
      {
        ROS_ERROR("SrhVelocityController could not find the second joint relevant to \"%s\"\n", joint_name_.c_str());
        return false;
      }
    }
    else
    {
      joint_state_ = robot_->getJointState(joint_name_);
      if (!joint_state_)
      {
        ROS_ERROR("SrhVelocityController could not find joint named \"%s\"\n", joint_name_.c_str());
        return false;
      }
    }

    friction_compensator.reset(new sr_friction_compensation::SrFrictionCompensator(joint_name_));

    // get the min and max value for the current joint:
    get_min_max(robot_->robot_model_, joint_name_);

    serve_set_gains_ = node_.advertiseService("set_gains", &SrhJointVelocityController::setGains, this);
    serve_reset_gains_ = node_.advertiseService("reset_gains", &SrhJointVelocityController::resetGains, this);

    after_init();
    return true;
  }

  void SrhJointVelocityController::starting(const ros::Time &time)
  {
    resetJointState();
    pid_controller_velocity_->reset();
    read_parameters();

    if (has_j2)
      ROS_WARN_STREAM(
              "Reseting PID for joints " << joint_state_->joint_->name << " and " << joint_state_2->joint_->name);
    else
      ROS_WARN_STREAM("Reseting PID for joint  " << joint_state_->joint_->name);
  }

  bool SrhJointVelocityController::setGains(sr_robot_msgs::SetPidGains::Request &req,
                                            sr_robot_msgs::SetPidGains::Response &resp)
  {
    pid_controller_velocity_->setGains(req.p, req.i, req.d, req.i_clamp, -req.i_clamp);
    max_force_demand = req.max_force;
    friction_deadband = req.friction_deadband;
    velocity_deadband = req.deadband;

    // Setting the new parameters in the parameter server
    node_.setParam("pid/p", req.p);
    node_.setParam("pid/i", req.i);
    node_.setParam("pid/d", req.d);
    node_.setParam("pid/i_clamp", req.i_clamp);

    node_.setParam("pid/max_force", max_force_demand);
    node_.setParam("pid/velocity_deadband", velocity_deadband);
    node_.setParam("pid/friction_deadband", friction_deadband);

    return true;
  }

  bool SrhJointVelocityController::resetGains(std_srvs::Empty::Request &req, std_srvs::Empty::Response &resp)
  {
    resetJointState();

    if (!pid_controller_velocity_->init(ros::NodeHandle(node_, "velocity_pid")))
    {
      return false;
    }

    read_parameters();

    if (has_j2)
      ROS_WARN_STREAM(
              "Reseting controller gains: " << joint_state_->joint_->name << " and " << joint_state_2->joint_->name);
    else
      ROS_WARN_STREAM("Reseting controller gains: " << joint_state_->joint_->name);

    return true;
  }

  void SrhJointVelocityController::getGains(double &p, double &i, double &d, double &i_max, double &i_min)
  {
    pid_controller_velocity_->getGains(p, i, d, i_max, i_min);
  }

  void SrhJointVelocityController::update(const ros::Time &time, const ros::Duration &period)
  {
    ROS_ASSERT(robot_);
    ROS_ASSERT(joint_state_->joint_);

    if (!initialized_)
    {
      resetJointState();
      initialized_ = true;
    }
    if (has_j2)
    {
      command_ = joint_state_->commanded_velocity_ + joint_state_2->commanded_velocity_;
    }
    else
    {
      command_ = joint_state_->commanded_velocity_;
    }
    command_ = clamp_command(command_);

    double error_velocity = 0.0;
    double commanded_effort = 0.0;

    if (has_j2)
    {
      error_velocity = (joint_state_->velocity_ + joint_state_2->velocity_) - command_;
    }
    else
    {
      error_velocity = joint_state_->velocity_ - command_;
    }

    bool in_deadband = hysteresis_deadband.is_in_deadband(command_, error_velocity, velocity_deadband);
    // are we in the deadband?
    if (in_deadband)
    {
      error_velocity = 0.0;  // force the error to zero to not further change the pid control terms
      // if the requested velocity is smaller than the velocity_deadband, consider no movement is wanted.
      if (std::fabs(command_) < velocity_deadband)
      {
        pid_controller_velocity_->reset();
      }
    }

    // compute the effort demand using the velocity pid loop
    commanded_effort = pid_controller_velocity_->computeCommand(-error_velocity, period);

    // clamp the result to max force
    commanded_effort = min(commanded_effort, (max_force_demand * max_force_factor_));
    commanded_effort = max(commanded_effort, -(max_force_demand * max_force_factor_));

    if (has_j2)
    {
      commanded_effort += friction_compensator->friction_compensation(
              (joint_state_->position_ + joint_state_2->position_),
              (joint_state_->velocity_ + joint_state_2->velocity_),
              static_cast<int>(commanded_effort),
              friction_deadband);
    }
    else
    {
      commanded_effort += friction_compensator->friction_compensation(joint_state_->position_,
                                                                      joint_state_->velocity_,
                                                                      static_cast<int>(commanded_effort),
                                                                      friction_deadband);
    }

    joint_state_->commanded_effort_ = commanded_effort;

    if (loop_count_ % 10 == 0)
    {
      if (controller_state_publisher_ && controller_state_publisher_->trylock())
      {
        controller_state_publisher_->msg_.header.stamp = time;
        controller_state_publisher_->msg_.set_point = command_;
        if (has_j2)
        {
          controller_state_publisher_->msg_.process_value = joint_state_->velocity_ + joint_state_2->velocity_;
        }
        else
        {
          controller_state_publisher_->msg_.process_value = joint_state_->velocity_;
        }
        controller_state_publisher_->msg_.error = error_velocity;
        controller_state_publisher_->msg_.time_step = period.toSec();
        controller_state_publisher_->msg_.command = commanded_effort;

        double dummy;
        getGains(controller_state_publisher_->msg_.p,
                 controller_state_publisher_->msg_.i,
                 controller_state_publisher_->msg_.d,
                 controller_state_publisher_->msg_.i_clamp,
                 dummy);
        controller_state_publisher_->unlockAndPublish();
      }
    }
    loop_count_++;
  }

  double SrhJointVelocityController::clamp_command(double cmd)
  {
    return SrController::clamp_command(cmd, vel_min_, vel_max_);
  }

  void SrhJointVelocityController::read_parameters()
  {
    node_.param<double>("pid/max_force", max_force_demand, 1023.0);
    node_.param<double>("pid/velocity_deadband", velocity_deadband, 0.015);
    node_.param<int>("pid/friction_deadband", friction_deadband, 5);
  }

  void SrhJointVelocityController::setCommandCB(const std_msgs::Float64ConstPtr &msg)
  {
    joint_state_->commanded_velocity_ = msg->data;
    if (has_j2)
    {
      joint_state_2->commanded_velocity_ = 0.0;
    }
  }

  void SrhJointVelocityController::resetJointState()
  {
    if (has_j2)
    {
      joint_state_->commanded_velocity_ = joint_state_->velocity_;
      joint_state_2->commanded_velocity_ = joint_state_2->velocity_;
      command_ = joint_state_->velocity_ + joint_state_2->velocity_;
    }
    else
    {
      joint_state_->commanded_velocity_ = joint_state_->velocity_;
      command_ = joint_state_->velocity_;
    }
  }
}  // namespace controller

/* For the emacs weenies in the crowd.
Local Variables:
   c-basic-offset: 2
End:
 */