linear_trajectory.cpp

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#include <spline_smoother/linear_trajectory.h>

namespace spline_smoother
{

  LinearTrajectory::LinearTrajectory()
  {
    apply_limits_ = true;
  }

  double LinearTrajectory::calculateMinimumTime(const trajectory_msgs::JointTrajectoryPoint &start, 
                                                const trajectory_msgs::JointTrajectoryPoint &end, 
                                                const std::vector<arm_navigation_msgs::JointLimits> &limits)
  {
    double minJointTime(MAX_ALLOWABLE_TIME);
    double segmentTime(0);
    int num_joints = (int) start.positions.size();

    for(int i = 0; i < num_joints; i++)
    {
      double diff = jointDiff(start.positions[i],end.positions[i],limits[i]);
      minJointTime = fabs(diff) / limits[i].max_velocity;
      if(segmentTime < minJointTime)
        segmentTime = minJointTime;
    }
    return segmentTime;
  }

  bool LinearTrajectory::parameterize(const trajectory_msgs::JointTrajectory& trajectory_in, 
                                      const std::vector<arm_navigation_msgs::JointLimits> &limits,
                                      spline_smoother::SplineTrajectory& spline)
  {
    int num_traj = trajectory_in.points.size();
    int num_joints = trajectory_in.joint_names.size();
    spline.names = trajectory_in.joint_names;
    spline.segments.resize(num_traj-1);

    for(int i=0; i<num_joints; i++)
    {
      if(!limits[i].has_velocity_limits)
      {
        ROS_ERROR("Trying to apply velocity limits without supplying them. Set velocity_limits in the message and set has_velocity_limits flag to true.");
        return false;
      }
    }
    for (int i=1; i< num_traj; ++i)
    {
      spline.segments[i-1].joints.resize(num_joints);
      for(int j=0; j < num_joints; j++)
      {
        spline.segments[i-1].joints[j].coefficients.resize(2);
      }

      double dT = (trajectory_in.points[i].time_from_start - trajectory_in.points[i-1].time_from_start).toSec();
      if(apply_limits_)
      {
        double dTMin = calculateMinimumTime(trajectory_in.points[i-1],trajectory_in.points[i],limits);
        if(dTMin > dT) // if minimum time required to satisfy limits is greater than time available, stretch this segment
          dT = dTMin;      
      }
      spline.segments[i-1].duration = ros::Duration(dT);
      for(int j=0; j<num_joints; j++)
      {
        spline.segments[i-1].joints[j].coefficients[0] = trajectory_in.points[i-1].positions[j];
        spline.segments[i-1].joints[j].coefficients[1] = jointDiff(trajectory_in.points[i-1].positions[j],trajectory_in.points[i].positions[j],limits[j])/spline.segments[i-1].duration.toSec();
      }
    }
    return true;
  }
}