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

#include <std_msgs/Float64.h>

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

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

namespace controller
{

  SrhMixedPositionVelocityJointController::SrhMixedPositionVelocityJointController()
          : max_velocity_(1.0), min_velocity_(-1.0), prev_in_deadband_(false),
            maintained_command_(0.0), override_to_current_effort_(false),
            position_deadband(0.05), motor_min_force_threshold(0)
  {
  }

  bool SrhMixedPositionVelocityJointController::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_position_.reset(new control_toolbox::Pid());
    if (!pid_controller_position_->init(ros::NodeHandle(node_, "position_pid")))
    {
      return false;
    }

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

    controller_state_publisher_.reset(new realtime_tools::RealtimePublisher<sr_robot_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("SrhMixedPositionVelocityController could not find the first joint relevant to \"%s\"\n",
                  joint_name_.c_str());
        return false;
      }
      if (!joint_state_2)
      {
        ROS_ERROR("SrhMixedPositionVelocityController could not find the second joint relevant to \"%s\"\n",
                  joint_name_.c_str());
        return false;
      }
    }
    else  // "normal" joints
    {
      joint_state_ = robot_->getJointState(joint_name_);
      if (!joint_state_)
      {
        ROS_ERROR("SrhMixedPositionVelocityController 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", &SrhMixedPositionVelocityJointController::setGains, this);
    serve_reset_gains_ = node_.advertiseService("reset_gains", &SrhMixedPositionVelocityJointController::resetGains,
                                                this);

    ROS_DEBUG_STREAM(" joint_state name: " << joint_state_->joint_->name);
    ROS_DEBUG_STREAM(" In Init: " << getJointName() << " This: " << this
                     << " joint_state: " << joint_state_);

#ifdef DEBUG_PUBLISHER
    if (string("FFJ3").compare(getJointName()) == 0)
    {
      ROS_INFO("Publishing debug info for FFJ3 mixed position/velocity controller");
      stringstream ss2;
      ss2 << getJointName() << "debug_velocity";
      debug_pub = n_tilde_.advertise<std_msgs::Float64>(ss2.str(), 2);
    }
#endif

    after_init();
    return true;
  }

  void SrhMixedPositionVelocityJointController::starting(const ros::Time &time)
  {
    resetJointState();
    pid_controller_position_->reset();
    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 SrhMixedPositionVelocityJointController::setGains(sr_robot_msgs::SetMixedPositionVelocityPidGains::Request &req,
                                                         sr_robot_msgs::SetMixedPositionVelocityPidGains::Response
                                                         &resp)
  {
    ROS_INFO_STREAM(
            "New parameters: " << "PID pos: [" << req.position_p << ", " << req.position_i << ", " << req.position_d <<
            ", " << req.position_i_clamp << "] PID vel: [" << req.velocity_p << ", " << req.velocity_i << ", " <<
            req.velocity_d << ", " << req.velocity_i_clamp << "], max force: " << req.max_force <<
            ", friction deadband: " << req.friction_deadband << " pos deadband: " << req.position_deadband <<
            " min and max vel: [" << req.min_velocity << ", " << req.max_velocity << "]");

    // retrieve previous antiwindup settings for velocity
    double p, i, d, i_max, i_min;
    bool antiwindup;
    pid_controller_velocity_->getGains(p, i, d, i_max, i_min, antiwindup);

    pid_controller_position_->setGains(req.position_p, req.position_i, req.position_d, req.position_i_clamp,
                                       -req.position_i_clamp);

    pid_controller_velocity_->setGains(req.velocity_p, req.velocity_i, req.velocity_d, req.velocity_i_clamp,
                                       -req.velocity_i_clamp, antiwindup);
    max_force_demand = req.max_force;
    friction_deadband = req.friction_deadband;
    position_deadband = req.position_deadband;

    // setting the position controller parameters
    min_velocity_ = req.min_velocity;
    max_velocity_ = req.max_velocity;

    // Setting the new parameters in the parameter server
    node_.setParam("position_pid/p", req.position_p);
    node_.setParam("position_pid/i", req.position_i);
    node_.setParam("position_pid/d", req.position_d);
    node_.setParam("position_pid/i_clamp", req.position_i_clamp);

    node_.setParam("velocity_pid/p", req.velocity_p);
    node_.setParam("velocity_pid/i", req.velocity_i);
    node_.setParam("velocity_pid/d", req.velocity_d);
    node_.setParam("velocity_pid/i_clamp", req.velocity_i_clamp);

    node_.setParam("position_pid/min_velocity", min_velocity_);
    node_.setParam("position_pid/max_velocity", max_velocity_);
    node_.setParam("position_pid/position_deadband", position_deadband);

    node_.setParam("velocity_pid/friction_deadband", friction_deadband);
    node_.setParam("velocity_pid/max_force", max_force_demand);
    node_.setParam("velocity_pid/antiwindup", antiwindup);
    node_.setParam("motor_min_force_threshold", motor_min_force_threshold);

    return true;
  }

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

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

    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 SrhMixedPositionVelocityJointController::getGains(double &p, double &i, double &d, double &i_max, double &i_min)
  {
    pid_controller_position_->getGains(p, i, d, i_max, i_min);
  }

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

  void SrhMixedPositionVelocityJointController::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_position_ + joint_state_2->commanded_position_;
    }
    else
    {
      command_ = joint_state_->commanded_position_;
    }
    command_ = clamp_command(command_);

    // POSITION

    // Compute velocity demand from position error:
    double error_position = 0.0;
    if (has_j2)
    {
      error_position = command_ - (joint_state_->position_ + joint_state_2->position_);
      ROS_DEBUG_STREAM("j0: " << joint_state_->position_ + joint_state_2->position_);
    }
    else
    {
      error_position = command_ - joint_state_->position_;
    }

    // are we in the deadband?
    bool in_deadband = hysteresis_deadband.is_in_deadband(command_, error_position, position_deadband);

    if (in_deadband)  // consider the error as 0 if we're in the deadband
    {
      error_position = 0.0;
      pid_controller_position_->reset();
    }

    double commanded_velocity = 0.0;
    double error_velocity = 0.0;
    double commanded_effort = 0.0;

    // compute the velocity demand using the position pid loop
    commanded_velocity = pid_controller_position_->computeCommand(-error_position, period);
    // saturate the velocity demand
    commanded_velocity = max(commanded_velocity, min_velocity_);
    commanded_velocity = min(commanded_velocity, max_velocity_);

    // VELOCITY

    // velocity loop:
    if (!in_deadband)  // don't compute the error if we're in the deadband
    {
      prev_in_deadband_ = false;
      // we're not in the deadband, compute the error
      if (has_j2)
      {
        error_velocity = commanded_velocity - (joint_state_->velocity_ + joint_state_2->velocity_);
      }
      else
      {
        error_velocity = commanded_velocity - joint_state_->velocity_;
      }
    }
    // compute the effort demand using the velocity pid loop
    commanded_effort = pid_controller_velocity_->computeCommand(-error_velocity, period);

    // when entering the deadband, override command
    if (in_deadband && !prev_in_deadband_)
    {
      prev_in_deadband_ = true;
      if (override_to_current_effort_)
      {
        // override with current joint_effort to avoid further movements
        commanded_effort = joint_state_->effort_;
      }
      // else use the current command for further loops in deadband
      maintained_command_ = commanded_effort;
    }
    else
    {
      // when already in deadband, override command with previous command
      if (in_deadband && prev_in_deadband_)
      {
        commanded_effort = maintained_command_;
      }
    }

    // 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_));

    // Friction compensation, only if we're not in the deadband.
    int friction_offset = 0;
    if (!in_deadband)
    {
      if (has_j2)
      {
        friction_offset = 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
      {
        friction_offset = friction_compensator->friction_compensation(joint_state_->position_, joint_state_->velocity_,
                                                                      static_cast<int>(commanded_effort),
                                                                      friction_deadband);
      }

      commanded_effort += friction_offset;
    }

    // if the demand is too small to be executed by the motor, then we ask for a force
    // of 0
    if (fabs(commanded_effort) <= motor_min_force_threshold)
    {
      commanded_effort = 0.0;
    }

    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_->position_ + joint_state_2->position_;
          controller_state_publisher_->msg_.process_value_dot = joint_state_->velocity_ + joint_state_2->velocity_;
        }
        else
        {
          controller_state_publisher_->msg_.process_value = joint_state_->position_;
          controller_state_publisher_->msg_.process_value_dot = joint_state_->velocity_;
        }
        controller_state_publisher_->msg_.commanded_velocity = commanded_velocity;

        controller_state_publisher_->msg_.error = error_position;
        controller_state_publisher_->msg_.time_step = period.toSec();

        controller_state_publisher_->msg_.command = commanded_effort;
        controller_state_publisher_->msg_.measured_effort = joint_state_->effort_;

        controller_state_publisher_->msg_.friction_compensation = friction_offset;

        double dummy;
        getGains(controller_state_publisher_->msg_.position_p,
                 controller_state_publisher_->msg_.position_i,
                 controller_state_publisher_->msg_.position_d,
                 controller_state_publisher_->msg_.position_i_clamp,
                 dummy);

        getGains_velocity(controller_state_publisher_->msg_.velocity_p,
                          controller_state_publisher_->msg_.velocity_i,
                          controller_state_publisher_->msg_.velocity_d,
                          controller_state_publisher_->msg_.velocity_i_clamp,
                          dummy);

        controller_state_publisher_->unlockAndPublish();
      }
    }
    loop_count_++;
  }

  void SrhMixedPositionVelocityJointController::read_parameters()
  {
    node_.param<double>("position_pid/min_velocity", min_velocity_, -1.0);
    node_.param<double>("position_pid/max_velocity", max_velocity_, 1.0);
    node_.param<double>("position_pid/position_deadband", position_deadband, 0.015);

    node_.param<int>("velocity_pid/friction_deadband", friction_deadband, 5);
    node_.param<double>("velocity_pid/max_force", max_force_demand, 1023.0);
    node_.param<int>("motor_min_force_threshold", motor_min_force_threshold, 0);
    node_.param<bool>("override_to_current_effort", override_to_current_effort_, false);
    if (override_to_current_effort_)
      ROS_WARN_STREAM("using override commanded effort to current effort for " << joint_state_->joint_->name);
  }

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

  void SrhMixedPositionVelocityJointController::resetJointState()
  {
    if (has_j2)
    {
      joint_state_->commanded_position_ = joint_state_->position_;
      joint_state_2->commanded_position_ = joint_state_2->position_;
      command_ = joint_state_->position_ + joint_state_2->position_;
    }
    else
    {
      joint_state_->commanded_position_ = joint_state_->position_;
      command_ = joint_state_->position_;
    }
  }
}  // namespace controller

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