srh_muscle_joint_position_controller.cpp

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#include "sr_mechanism_controllers/srh_muscle_joint_position_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::SrhMuscleJointPositionController, controller_interface::ControllerBase)

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

namespace controller
{

  SrhMuscleJointPositionController::SrhMuscleJointPositionController()
          : position_deadband(0.015), command_acc_(0)
  {
  }

  bool SrhMuscleJointPositionController::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_, "pid")))
    {
      return false;
    }

    controller_state_publisher_.reset(
            new realtime_tools::RealtimePublisher<sr_robot_msgs::JointMusclePositionControllerState>
                    (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("SrhMuscleJointPositionController could not find the first joint relevant to \"%s\"\n",
                  joint_name_.c_str());
        return false;
      }
      if (!joint_state_2)
      {
        ROS_ERROR("SrhMuscleJointPositionController 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("SrhMuscleJointPositionController could not find joint named \"%s\"\n", joint_name_.c_str());
        return false;
      }
    }

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

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

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

    after_init();
    return true;
  }

  void SrhMuscleJointPositionController::starting(const ros::Time &time)
  {
    resetJointState();
    pid_controller_position_->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 SrhMuscleJointPositionController::setGains(sr_robot_msgs::SetPidGains::Request &req,
                                                  sr_robot_msgs::SetPidGains::Response &resp)
  {
    ROS_INFO_STREAM("Setting new PID parameters. P:" << req.p << " / I:" << req.i <<
                    " / D:" << req.d << " / IClamp:" << req.i_clamp << ", max force: " << req.max_force <<
                    ", friction deadband: " << req.friction_deadband << " pos deadband: " << req.deadband);
    pid_controller_position_->setGains(req.p, req.i, req.d, req.i_clamp, -req.i_clamp);
    max_force_demand = req.max_force;
    friction_deadband = req.friction_deadband;
    position_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/position_deadband", position_deadband);
    node_.setParam("pid/friction_deadband", friction_deadband);

    return true;
  }

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

    if (!pid_controller_position_->init(ros::NodeHandle(node_, "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 SrhMuscleJointPositionController::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 SrhMuscleJointPositionController::update(const ros::Time &time, const ros::Duration &period)
  {
    // The valve commands can have values between -4 and 4
    int8_t valve[2];

    ROS_ASSERT(robot_ != NULL);
    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_);

    // IGNORE the following  lines if we don't want to use the pressure sensors data
    // We don't want to define a modified version of JointState, as that would imply using
    // a modified version of robot_state.hpp, controller manager,
    // ethercat_hardware and ros_etherCAT main loop
    // So we have encoded the two uint16 that contain the data from the muscle pressure
    // sensors into the double effort_. (We don't
    // have any measured effort in the muscle hand anyway).
    // Here we extract the pressure values from joint_state_->effort_ and decode that back into uint16.
    double pressure_0_tmp = fmod(joint_state_->effort_, 0x10000);
    double pressure_1_tmp = (fmod(joint_state_->effort_, 0x100000000) - pressure_0_tmp) / 0x10000;
    uint16_t pressure_0 = static_cast<uint16_t> (pressure_0_tmp + 0.5);
    uint16_t pressure_1 = static_cast<uint16_t> (pressure_1_tmp + 0.5);

    // ****************************************

    command_ = clamp_command(command_);

    // Compute position demand from position error:
    double error_position = 0.0;

    if (has_j2)
    {
      error_position = (joint_state_->position_ + joint_state_2->position_) - command_;
    }
    else
    {
      error_position = joint_state_->position_ - command_;
    }

    bool in_deadband = hysteresis_deadband.is_in_deadband(command_, error_position, position_deadband);

    // don't compute the error if we're in the deadband.
    if (in_deadband)
    {
      error_position = 0.0;
    }

    // Run the PID loop to get a new command, we don't do this at the full rate
    // as that will drive the valves too hard with switch changes. Instead we
    // store a longer time in the command accumulator to keep using at the full
    // loop rate.
    if (loop_count_ % 50 == 0)
    {
      double commanded_effort = pid_controller_position_->computeCommand(-error_position, period);

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

      if (!in_deadband)
      {
        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);
        }
      }

      command_acc_ = commanded_effort;
    }

    // Drive the joint from the accumulator. This runs at full update speed so
    // we can keep valves open continuously (with high enough P). A value of 4 fills
    // the valve for the whole of the next 1ms. 2 for half that time etc. Negative
    // values empty the valve.
    // The 2 involved muscles will act complementary for the moment, when one inflates,
    // the other deflates at the same rate
    double amt = abs(command_acc_) < 4 ? fabs(command_acc_) : 4;
    if (abs(command_acc_) == 0)
    {
      valve[0] = 0;
      valve[1] = 0;
    }
    else if (command_acc_ > 0)
    {
      command_acc_ -= amt;
      valve[0] = amt;
      valve[1] = -amt;
    }
    else
    {
      command_acc_ += amt;
      valve[0] = -amt;
      valve[1] = amt;
    }


    // ************************************************
    // After doing any computation we consider, we encode the obtained valve
    // commands into joint_state_->commanded_effort_
    // We don't want to define a modified version of JointState, as that would
    // imply using a modified version of robot_state.hpp, controller manager,
    // ethercat_hardware and ros_etherCAT main loop
    // So the controller encodes the two int8 (that are in fact int4) that contain
    // the valve commands into the double commanded_effort_. (We don't
    // have any real commanded_effort_ in the muscle hand anyway).

    uint16_t valve_tmp[2];
    for (int i = 0; i < 2; ++i)
    {
      // Check that the limits of the valve command are not exceded
      if (valve[i] > 4)
      {
        valve[i] = 4;
      }
      if (valve[i] < -4)
      {
        valve[i] = -4;
      }
      // encode
      if (valve[i] < 0)
      {
        valve_tmp[i] = -valve[i] + 8;
      }
      else
      {
        valve_tmp[i] = valve[i];
      }
    }

    // We encode the valve 0 command in the lowest "half byte" i.e. the lowest 16 integer
    // values in the double var (see decoding in simple_transmission_for_muscle.cpp)
    // the valve 1 command is encoded in the next 4 bits
    joint_state_->commanded_effort_ = static_cast<double> (valve_tmp[0]) + static_cast<double> (valve_tmp[1] << 4);

    // *******************************************************************************

    // Send status msg
    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_.error = error_position;
        controller_state_publisher_->msg_.time_step = period.toSec();
        controller_state_publisher_->msg_.pseudo_command = command_acc_;
        controller_state_publisher_->msg_.valve_muscle_0 = valve[0];
        controller_state_publisher_->msg_.valve_muscle_1 = valve[1];
        controller_state_publisher_->msg_.packed_valve = joint_state_->commanded_effort_;
        controller_state_publisher_->msg_.muscle_pressure_0 = pressure_0;
        controller_state_publisher_->msg_.muscle_pressure_1 = pressure_1;


        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_++;
  }

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

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

  void SrhMuscleJointPositionController::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:
 */