joint_limits_interface.h

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// Copyright (C) 2013, PAL Robotics S.L.
// Copyright (c) 2008, Willow Garage, Inc.
//
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// modification, are permitted provided that the following conditions are met:
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//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright
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//     documentation and/or other materials provided with the distribution.
//   * Neither the name of PAL Robotics S.L. nor the names of its
//     contributors may be used to endorse or promote products derived from
//     this software without specific prior written permission.
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#ifndef JOINT_LIMITS_INTERFACE_JOINT_LIMITS_INTERFACE_H
#define JOINT_LIMITS_INTERFACE_JOINT_LIMITS_INTERFACE_H

#include <algorithm>
#include <cassert>
#include <cmath>
#include <limits>

#include <boost/shared_ptr.hpp>

#include <ros/duration.h>

#include <hardware_interface/internal/resource_manager.h>
#include <hardware_interface/joint_command_interface.h>

#include <joint_limits_interface/joint_limits.h>
#include <joint_limits_interface/joint_limits_interface_exception.h>

namespace joint_limits_interface
{

namespace internal
{

template<typename T>
T saturate(const T val, const T min_val, const T max_val)
{
  return std::min(std::max(val, min_val), max_val);
}

}

class PositionJointSaturationHandle
{
public:
  PositionJointSaturationHandle(const hardware_interface::JointHandle& jh, const JointLimits& limits)
  {
    jh_ = jh;
    limits_ = limits;

    if (limits_.has_position_limits)
    {
      min_pos_limit_ = limits_.min_position;
      max_pos_limit_ = limits_.max_position;
    }
    else
    {
      min_pos_limit_ = -std::numeric_limits<double>::max();
      max_pos_limit_ = std::numeric_limits<double>::max();
    }

    prev_cmd_ = std::numeric_limits<double>::quiet_NaN();
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& period)
  {
    if (std::isnan(prev_cmd_))
      prev_cmd_ = jh_.getPosition();

    double min_pos, max_pos;
    if (limits_.has_velocity_limits)
    {
      const double delta_pos = limits_.max_velocity * period.toSec();
      min_pos = std::max(prev_cmd_ - delta_pos, min_pos_limit_);
      max_pos = std::min(prev_cmd_ + delta_pos, max_pos_limit_);
    }
    else
    {
      min_pos = min_pos_limit_;
      max_pos = max_pos_limit_;
    }

    const double cmd = internal::saturate(jh_.getCommand(), min_pos, max_pos);
    jh_.setCommand(cmd);
    prev_cmd_ = cmd;
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
  double min_pos_limit_, max_pos_limit_;
  double prev_cmd_;
};

// TODO: Leverage %Reflexxes Type II library for acceleration limits handling?
class PositionJointSoftLimitsHandle
{
public:
  PositionJointSoftLimitsHandle()
    : prev_cmd_(std::numeric_limits<double>::quiet_NaN())
  {}

  PositionJointSoftLimitsHandle(const hardware_interface::JointHandle& jh,
                                const JointLimits&                     limits,
                                const SoftJointLimits&                 soft_limits)
    : jh_(jh),
      limits_(limits),
      soft_limits_(soft_limits),
      prev_cmd_(std::numeric_limits<double>::quiet_NaN())
  {
    if (!limits.has_velocity_limits)
    {
      throw JointLimitsInterfaceException("Cannot enforce limits for joint '" + getName() +
                                           "'. It has no velocity limits specification.");
    }
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& period)
  {
    assert(period.toSec() > 0.0);

    using internal::saturate;

    // Current position
    // TODO: Doc!
    if (std::isnan(prev_cmd_)) {prev_cmd_ = jh_.getPosition();} // Happens only once at initialization
    const double pos = prev_cmd_;

    // Velocity bounds
    double soft_min_vel;
    double soft_max_vel;

    if (limits_.has_position_limits)
    {
      // Velocity bounds depend on the velocity limit and the proximity to the position limit
      soft_min_vel = saturate(-soft_limits_.k_position * (pos - soft_limits_.min_position),
                              -limits_.max_velocity,
                               limits_.max_velocity);

      soft_max_vel = saturate(-soft_limits_.k_position * (pos - soft_limits_.max_position),
                              -limits_.max_velocity,
                               limits_.max_velocity);
    }
    else
    {
      // No position limits, eg. continuous joints
      soft_min_vel = -limits_.max_velocity;
      soft_max_vel =  limits_.max_velocity;
    }

    // Position bounds
    const double dt = period.toSec();
    double pos_low  = pos + soft_min_vel * dt;
    double pos_high = pos + soft_max_vel * dt;

    if (limits_.has_position_limits)
    {
      // This extra measure safeguards against pathological cases, like when the soft limit lies beyond the hard limit
      pos_low  = std::max(pos_low,  limits_.min_position);
      pos_high = std::min(pos_high, limits_.max_position);
    }

    // Saturate position command according to bounds
    const double pos_cmd = saturate(jh_.getCommand(),
                                    pos_low,
                                    pos_high);
    jh_.setCommand(pos_cmd);

    // Cache variables
    prev_cmd_ = jh_.getCommand();
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
  SoftJointLimits soft_limits_;

  double prev_cmd_;
};

class EffortJointSaturationHandle
{
public:
  EffortJointSaturationHandle(const hardware_interface::JointHandle& jh, const JointLimits& limits)
  {
    jh_ = jh;
    limits_ = limits;
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& /* period */)
  {
    double min_eff, max_eff;
    if (limits_.has_effort_limits)
    {
      min_eff = -limits_.max_effort;
      max_eff = limits_.max_effort;
    }
    else
    {
      min_eff = -std::numeric_limits<double>::max();
      max_eff = std::numeric_limits<double>::max();
    }

    if (limits_.has_position_limits)
    {
      const double pos = jh_.getPosition();
      if (pos < limits_.min_position)
        min_eff = 0;
      else if (pos > limits_.max_position)
        max_eff = 0;
    }

    if (limits_.has_velocity_limits)
    {
      const double vel = jh_.getVelocity();
      if (vel < -limits_.max_velocity)
        min_eff = 0;
      else if (vel > limits_.max_velocity)
        max_eff = 0;
    }

    jh_.setCommand(internal::saturate(jh_.getCommand(), min_eff, max_eff));
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
};

// TODO: This class is untested!. Update unit tests accordingly.
class EffortJointSoftLimitsHandle
{
public:
  EffortJointSoftLimitsHandle() {}

  EffortJointSoftLimitsHandle(const hardware_interface::JointHandle& jh,
                              const JointLimits&                     limits,
                              const SoftJointLimits&                 soft_limits)
  : jh_(jh),
    limits_(limits),
    soft_limits_(soft_limits)
  {
    if (!limits.has_velocity_limits)
    {
      throw JointLimitsInterfaceException("Cannot enforce limits for joint '" + getName() +
                                           "'. It has no velocity limits specification.");
    }
    if (!limits.has_effort_limits)
    {
      throw JointLimitsInterfaceException("Cannot enforce limits for joint '" + getName() +
                                           "'. It has no effort limits specification.");
    }
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& /*period*/)
  {
    using internal::saturate;

    // Current state
    const double pos = jh_.getPosition();
    const double vel = jh_.getVelocity();

    // Velocity bounds
    double soft_min_vel;
    double soft_max_vel;

    if (limits_.has_position_limits)
    {
      // Velocity bounds depend on the velocity limit and the proximity to the position limit
      soft_min_vel  = saturate(-soft_limits_.k_position * (pos - soft_limits_.min_position),
                               -limits_.max_velocity,
                                limits_.max_velocity);

      soft_max_vel = saturate(-soft_limits_.k_position * (pos - soft_limits_.max_position),
                              -limits_.max_velocity,
                               limits_.max_velocity);
    }
    else
    {
      // No position limits, eg. continuous joints
      soft_min_vel = -limits_.max_velocity;
      soft_max_vel =  limits_.max_velocity;
    }

    // Effort bounds depend on the velocity and effort bounds
    const double soft_min_eff = saturate(-soft_limits_.k_velocity * (vel - soft_min_vel),
                                         -limits_.max_effort,
                                          limits_.max_effort);

    const double soft_max_eff = saturate(-soft_limits_.k_velocity * (vel - soft_max_vel),
                                         -limits_.max_effort,
                                          limits_.max_effort);

    // Saturate effort command according to bounds
    const double eff_cmd = saturate(jh_.getCommand(),
                                    soft_min_eff,
                                    soft_max_eff);
    jh_.setCommand(eff_cmd);
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
  SoftJointLimits soft_limits_;
};


class VelocityJointSaturationHandle
{
public:
  VelocityJointSaturationHandle () {}

  VelocityJointSaturationHandle(const hardware_interface::JointHandle& jh, const JointLimits& limits)
    : jh_(jh),
      limits_(limits)
  {
    if (!limits.has_velocity_limits)
    {
      throw JointLimitsInterfaceException("Cannot enforce limits for joint '" + getName() +
                                           "'. It has no velocity limits specification.");
    }
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& period)
  {
    using internal::saturate;

    // Velocity bounds
    double vel_low;
    double vel_high;

    if (limits_.has_acceleration_limits)
    {
      assert(period.toSec() > 0.0);
      const double vel = jh_.getVelocity();
      const double dt  = period.toSec();

      vel_low  = std::max(vel - limits_.max_acceleration * dt, -limits_.max_velocity);
      vel_high = std::min(vel + limits_.max_acceleration * dt,  limits_.max_velocity);
    }
    else
    {
      vel_low  = -limits_.max_velocity;
      vel_high =  limits_.max_velocity;
    }

    // Saturate velocity command according to limits
    const double vel_cmd = saturate(jh_.getCommand(),
                                    vel_low,
                                    vel_high);
    jh_.setCommand(vel_cmd);
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
};

class VelocityJointSoftLimitsHandle
{
public:
  VelocityJointSoftLimitsHandle(const hardware_interface::JointHandle& jh, const JointLimits& limits,
                                const SoftJointLimits& soft_limits)
  {
    jh_ = jh;
    limits_ = limits;
    soft_limits_ = soft_limits;
    if (limits.has_velocity_limits)
      max_vel_limit_ = limits.max_velocity;
    else
      max_vel_limit_ = std::numeric_limits<double>::max();
  }

  std::string getName() const {return jh_.getName();}

  void enforceLimits(const ros::Duration& period)
  {
    using internal::saturate;

    double min_vel, max_vel;
    if (limits_.has_position_limits)
    {
      // Velocity bounds depend on the velocity limit and the proximity to the position limit.
      const double pos = jh_.getPosition();
      min_vel = saturate(-soft_limits_.k_position * (pos - soft_limits_.min_position),
                         -max_vel_limit_, max_vel_limit_);
      max_vel = saturate(-soft_limits_.k_position * (pos - soft_limits_.max_position),
                         -max_vel_limit_, max_vel_limit_);
    }
    else
    {
      min_vel = -max_vel_limit_;
      max_vel = max_vel_limit_;
    }

    if (limits_.has_acceleration_limits)
    {
      const double vel = jh_.getVelocity();
      const double delta_t = period.toSec();
      min_vel = std::max(vel - limits_.max_acceleration * delta_t, min_vel);
      max_vel = std::min(vel + limits_.max_acceleration * delta_t, max_vel);
    }

    jh_.setCommand(saturate(jh_.getCommand(), min_vel, max_vel));
  }

private:
  hardware_interface::JointHandle jh_;
  JointLimits limits_;
  SoftJointLimits soft_limits_;
  double max_vel_limit_;
};

template <class HandleType>
class JointLimitsInterface : public hardware_interface::ResourceManager<HandleType>
{
public:
  HandleType getHandle(const std::string& name)
  {
    // Rethrow exception with a meanungful type
    try
    {
      return this->hardware_interface::ResourceManager<HandleType>::getHandle(name);
    }
    catch(const std::logic_error& e)
    {
      throw JointLimitsInterfaceException(e.what());
    }
  }

  void enforceLimits(const ros::Duration& period)
  {
    typedef typename hardware_interface::ResourceManager<HandleType>::ResourceMap::iterator ItratorType;
    for (ItratorType it = this->resource_map_.begin(); it != this->resource_map_.end(); ++it)
    {
      it->second.enforceLimits(period);
    }
  }
  /*\}*/
};

class PositionJointSaturationInterface : public JointLimitsInterface<PositionJointSaturationHandle> {};

class PositionJointSoftLimitsInterface : public JointLimitsInterface<PositionJointSoftLimitsHandle> {};

class EffortJointSaturationInterface : public JointLimitsInterface<EffortJointSaturationHandle> {};

class EffortJointSoftLimitsInterface : public JointLimitsInterface<EffortJointSoftLimitsHandle> {};

class VelocityJointSaturationInterface : public JointLimitsInterface<VelocityJointSaturationHandle> {};

class VelocityJointSoftLimitsInterface : public JointLimitsInterface<VelocityJointSoftLimitsHandle> {};

}

#endif