ExternalForce.cpp

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#include "ExternalForce.h"
 
#include <mujoco/mujoco.h>
 
#include <iostream>
 
namespace MujocoRosUtils
{
 
void ExternalForce::RegisterPlugin()
{
  mjpPlugin plugin;
  mjp_defaultPlugin(&plugin);
 
  plugin.name = "MujocoRosUtils::ExternalForce";
  plugin.capabilityflags |= mjPLUGIN_PASSIVE;
 
  const char * attributes[] = {"topic_name", "vis_scale"};
 
  plugin.nattribute = sizeof(attributes) / sizeof(attributes[0]);
  plugin.attributes = attributes;
 
  plugin.nstate = +[](const mjModel *, // m
                      int // plugin_id
                   ) { return 0; };
 
  plugin.nsensordata = +[](const mjModel *, // m
                           int, // plugin_id
                           int // sensor_id
                        ) { return 0; };
 
  plugin.needstage = mjSTAGE_ACC;
 
  plugin.init = +[](const mjModel * m, mjData * d, int plugin_id)
  {
    auto * plugin_instance = ExternalForce::Create(m, d, plugin_id);
    if(!plugin_instance)
    {
      return -1;
    }
    d->plugin_data[plugin_id] = reinterpret_cast<uintptr_t>(plugin_instance);
    return 0;
  };
 
  plugin.destroy = +[](mjData * d, int plugin_id)
  {
    delete reinterpret_cast<ExternalForce *>(d->plugin_data[plugin_id]);
    d->plugin_data[plugin_id] = 0;
  };
 
  plugin.reset = +[](const mjModel * m, double *, // plugin_state
                     void * plugin_data, int plugin_id)
  {
    auto * plugin_instance = reinterpret_cast<class ExternalForce *>(plugin_data);
    plugin_instance->reset(m, plugin_id);
  };
 
  plugin.compute = +[](const mjModel * m, mjData * d, int plugin_id, int // capability_bit
                    )
  {
    auto * plugin_instance = reinterpret_cast<class ExternalForce *>(d->plugin_data[plugin_id]);
    plugin_instance->compute(m, d, plugin_id);
  };
 
  plugin.visualize = +[](const mjModel * m, mjData * d, const mjvOption * opt, mjvScene * scn, int plugin_id)
  {
    auto * plugin_instance = reinterpret_cast<class ExternalForce *>(d->plugin_data[plugin_id]);
    plugin_instance->visualize(m, d, opt, scn, plugin_id);
  };
 
  mjp_registerPlugin(&plugin);
}
 
ExternalForce * ExternalForce::Create(const mjModel * m, mjData * d, int plugin_id)
{
  // topic_name
  const char * topic_name_char = mj_getPluginConfig(m, plugin_id, "topic_name");
  std::string topic_name = "";
  if(strlen(topic_name_char) > 0)
  {
    topic_name = std::string(topic_name_char);
  }
 
  // vis_scale
  const char * vis_scale_char = mj_getPluginConfig(m, plugin_id, "vis_scale");
  mjtNum vis_scale = 0.1;
  if(strlen(vis_scale_char) > 0)
  {
    vis_scale = strtod(vis_scale_char, nullptr);
  }
 
  // Set body_id
  int body_id = 0;
  for(; body_id < m->nbody; body_id++)
  {
    if(m->body_plugin[body_id] == plugin_id)
    {
      break;
    }
  }
  if(body_id == m->nbody)
  {
    mju_error("[ExternalForce] Plugin not found in bodies.");
    return nullptr;
  }
 
  std::cout << "[ExternalForce] Create." << std::endl;
 
  return new ExternalForce(m, d, body_id, topic_name, vis_scale);
}
 
ExternalForce::ExternalForce(const mjModel *, // m
                             mjData *, // d
                             int body_id,
                             const std::string & topic_name,
                             mjtNum vis_scale)
: body_id_(body_id), topic_name_(topic_name), vis_scale_(vis_scale)
{
  if(topic_name_.empty())
  {
    topic_name_ = "/external_force";
  }
 
  int argc = 0;
  char ** argv = nullptr;
  if(!ros::isInitialized())
  {
    ros::init(argc, argv, "mujoco_ros", ros::init_options::NoSigintHandler);
  }
 
  nh_ = std::make_shared<ros::NodeHandle>();
  // Use a dedicated queue so as not to call callbacks of other modules
  nh_->setCallbackQueue(&callbackQueue_);
  sub_ = nh_->subscribe<mujoco_ros_utils::ExternalForce>(topic_name_, 1, &ExternalForce::callback, this);
}
 
void ExternalForce::reset(const mjModel *, // m
                          int // plugin_id
)
{
  msg_ = nullptr;
}
 
void ExternalForce::compute(const mjModel *, // m
                            mjData * d,
                            int // plugin_id
)
{
  // Call ROS callback
  callbackQueue_.callAvailable(ros::WallDuration());
 
  if(end_time_ >= 0 && end_time_ <= d->time)
  {
    end_time_ = -1;
    msg_ = nullptr;
  }
 
  if(!msg_)
  {
    return;
  }
 
  mjtNum pos_local[3];
  pos_local[0] = msg_->pos.x;
  pos_local[1] = msg_->pos.y;
  pos_local[2] = msg_->pos.z;
  mjtNum force[3];
  force[0] = msg_->force.x;
  force[1] = msg_->force.y;
  force[2] = msg_->force.z;
  mjtNum pos_world[3];
  mju_rotVecMat(pos_world, pos_local, d->xmat + 9 * body_id_);
  mju_addTo3(pos_world, d->xpos + 3 * body_id_);
  mjtNum moment_arm[3];
  mju_sub3(moment_arm, pos_world, d->xipos + 3 * body_id_);
  mjtNum moment[3];
  mju_cross(moment, moment_arm, force);
 
  mjtNum * data_force = d->xfrc_applied + 6 * body_id_;
  mjtNum * data_moment = d->xfrc_applied + 6 * body_id_ + 3;
  mju_copy3(data_force, force);
  mju_copy3(data_moment, moment);
 
  if(end_time_ < 0)
  {
    end_time_ = d->time + msg_->duration.toSec();
  }
}
 
void ExternalForce::visualize(const mjModel *, // m
                              mjData * d,
                              const mjvOption *, // opt
                              mjvScene * scn,
                              int // plugin_id
)
{
  if(!msg_)
  {
    return;
  }
 
  if(vis_scale_ <= 0)
  {
    return;
  }
 
  mjMARKSTACK;
 
  mjtNum pos_local[3];
  pos_local[0] = msg_->pos.x;
  pos_local[1] = msg_->pos.y;
  pos_local[2] = msg_->pos.z;
  mjtNum force[3];
  force[0] = msg_->force.x;
  force[1] = msg_->force.y;
  force[2] = msg_->force.z;
  mjtNum pos_world[3];
  mju_rotVecMat(pos_world, pos_local, d->xmat + 9 * body_id_);
  mju_addTo3(pos_world, d->xpos + 3 * body_id_);
  mjtNum arrow_end[3];
  mju_addScl3(arrow_end, pos_world, force, vis_scale_);
  float rgba[4] = {1.0, 0.0, 0.0, 1.0};
  constexpr mjtNum width = 0.01;
  mjvGeom * force_geom = scn->geoms + scn->ngeom;
  mjv_initGeom(force_geom, mjGEOM_NONE, NULL, NULL, NULL, rgba);
  mjv_makeConnector(force_geom, mjGEOM_ARROW, width, pos_world[0], pos_world[1], pos_world[2], arrow_end[0],
                    arrow_end[1], arrow_end[2]);
  force_geom->objtype = mjOBJ_UNKNOWN;
  force_geom->objid = -1;
  force_geom->category = mjCAT_DECOR;
  force_geom->segid = scn->ngeom;
  scn->ngeom++;
 
  mjFREESTACK;
}
 
void ExternalForce::callback(const mujoco_ros_utils::ExternalForce::ConstPtr & msg)
{
  if(end_time_ > 0)
  {
    mju_warning("[ExternalForce] New message received while processing a previous message. Ignore the new message.");
    return;
  }
  msg_ = std::make_shared<mujoco_ros_utils::ExternalForce>(*msg);
}
 
} // namespace MujocoRosUtils