joint_trajectory_action_controller.py

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# -*- coding: utf-8 -*-
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# Copyright (c) 2010-2011, Antons Rebguns.
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from __future__ import division


__author__ = 'Antons Rebguns'
__copyright__ = 'Copyright (c) 2010-2011 Antons Rebguns'

__license__ = 'BSD'
__maintainer__ = 'Antons Rebguns'
__email__ = 'anton@email.arizona.edu'


from threading import Thread

import roslib
roslib.load_manifest('dynamixel_controllers')

import rospy
import actionlib

from std_msgs.msg import Float64
from trajectory_msgs.msg import JointTrajectory
from control_msgs.msg import FollowJointTrajectoryAction
from control_msgs.msg import FollowJointTrajectoryFeedback
from control_msgs.msg import FollowJointTrajectoryResult


class Segment():
    def __init__(self, num_joints):
        self.start_time = 0.0                   # trajectory segment start time
        self.duration = 0.0                     # trajectory segment duration
        self.positions = [0.0] * num_joints
        self.velocities = [0.0] * num_joints

class JointTrajectoryActionController():
    def __init__(self, controller_namespace, controllers):
        self.update_rate = 1000
        self.state_update_rate = 50
        self.trajectory = []
        
        self.controller_namespace = controller_namespace
        self.joint_names = [c.joint_name for c in controllers]
        
        self.joint_to_controller = {}
        for c in controllers:
            self.joint_to_controller[c.joint_name] = c
            
        self.port_to_joints = {}
        for c in controllers:
            if c.port_namespace not in self.port_to_joints: self.port_to_joints[c.port_namespace] = []
            self.port_to_joints[c.port_namespace].append(c.joint_name)
            
        self.port_to_io = {}
        for c in controllers:
            if c.port_namespace in self.port_to_io: continue
            self.port_to_io[c.port_namespace] = c.dxl_io
            
        self.joint_states = dict(zip(self.joint_names, [c.joint_state for c in controllers]))
        self.num_joints = len(self.joint_names)
        self.joint_to_idx = dict(zip(self.joint_names, range(self.num_joints)))

    def initialize(self):
        ns = self.controller_namespace + '/joint_trajectory_action_node/constraints'
        self.goal_time_constraint = rospy.get_param(ns + '/goal_time', 0.0)
        self.stopped_velocity_tolerance = rospy.get_param(ns + '/stopped_velocity_tolerance', 0.01)
        self.goal_constraints = []
        self.trajectory_constraints = []
        self.min_velocity = rospy.get_param(self.controller_namespace + '/joint_trajectory_action_node/min_velocity', 0.1)
        
        for joint in self.joint_names:
            self.goal_constraints.append(rospy.get_param(ns + '/' + joint + '/goal', -1.0))
            self.trajectory_constraints.append(rospy.get_param(ns + '/' + joint + '/trajectory', -1.0))
            
        # Message containing current state for all controlled joints
        self.msg = FollowJointTrajectoryFeedback()
        self.msg.joint_names = self.joint_names
        self.msg.desired.positions = [0.0] * self.num_joints
        self.msg.desired.velocities = [0.0] * self.num_joints
        self.msg.desired.accelerations = [0.0] * self.num_joints
        self.msg.actual.positions = [0.0] * self.num_joints
        self.msg.actual.velocities = [0.0] * self.num_joints
        self.msg.error.positions = [0.0] * self.num_joints
        self.msg.error.velocities = [0.0] * self.num_joints
        
        return True


    def start(self):
        self.running = True
        
        self.command_sub = rospy.Subscriber(self.controller_namespace + '/command', JointTrajectory, self.process_command)
        self.state_pub = rospy.Publisher(self.controller_namespace + '/state', FollowJointTrajectoryFeedback)
        self.action_server = actionlib.SimpleActionServer(self.controller_namespace + '/follow_joint_trajectory',
                                                          FollowJointTrajectoryAction,
                                                          execute_cb=self.process_follow_trajectory,
                                                          auto_start=False)
        self.action_server.start()
        Thread(target=self.update_state).start()

    def stop(self):
        self.running = False

    def process_command(self, msg):
        if self.action_server.is_active(): self.action_server.set_preempted()
        
        while self.action_server.is_active():
            sleep(0.01)
            
        self.process_trajectory(msg)

    def process_follow_trajectory(self, goal):
        self.process_trajectory(goal.trajectory)

    def process_trajectory(self, traj):
        num_points = len(traj.points)
        
        # make sure the joints in the goal match the joints of the controller
        if set(self.joint_names) != set(traj.joint_names):
            res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.INVALID_JOINTS)
            msg = 'Incoming trajectory joints do not match the joints of the controller'
            rospy.logerr(msg)
            self.action_server.set_aborted(result=res, text=msg)
            return
            
        # make sure trajectory is not empty
        if num_points == 0:
            msg = 'Incoming trajectory is empty'
            rospy.logerr(msg)
            self.action_server.set_aborted(text=msg)
            return
            
        # correlate the joints we're commanding to the joints in the message
        # map from an index of joint in the controller to an index in the trajectory
        lookup = [traj.joint_names.index(joint) for joint in self.joint_names]
        durations  = [0.0] * num_points
        
        # find out the duration of each segment in the trajectory
        durations[0] = traj.points[0].time_from_start.to_sec()
        
        for i in range(1, num_points):
            durations[i] = (traj.points[i].time_from_start - traj.points[i-1].time_from_start).to_sec()
            
        if not traj.points[0].positions:
            res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.INVALID_GOAL)
            msg = 'First point of trajectory has no positions'
            rospy.logerr(msg)
            self.action_server.set_aborted(result=res, text=msg)
            return
            
        trajectory = []
        time = rospy.Time.now() + rospy.Duration(0.01)
        
        for i in range(num_points):
            seg = Segment(self.num_joints)
            
            if traj.header.stamp == rospy.Time(0.0):
                seg.start_time = (time + traj.points[i].time_from_start).to_sec() - durations[i]
            else:
                seg.start_time = (traj.header.stamp + traj.points[i].time_from_start).to_sec() - durations[i]
                
            seg.duration = durations[i]
            
            # Checks that the incoming segment has the right number of elements.
            if traj.points[i].velocities and len(traj.points[i].velocities) != self.num_joints:
                res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.INVALID_GOAL)
                msg = 'Command point %d has %d elements for the velocities' % (i, len(traj.points[i].velocities))
                rospy.logerr(msg)
                self.action_server.set_aborted(result=res, text=msg)
                return
                
            if len(traj.points[i].positions) != self.num_joints:
                res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.INVALID_GOAL)
                msg = 'Command point %d has %d elements for the positions' % (i, len(traj.points[i].positions))
                rospy.logerr(msg)
                self.action_server.set_aborted(result=res, text=msg)
                return
                
            for j in range(self.num_joints):
                if traj.points[i].velocities:
                    seg.velocities[j] = traj.points[i].velocities[lookup[j]]
                if traj.points[i].positions:
                    seg.positions[j] = traj.points[i].positions[lookup[j]]
                    
            trajectory.append(seg)
            
        rospy.loginfo('Trajectory start requested at %.3lf, waiting...', traj.header.stamp.to_sec())
        rate = rospy.Rate(self.update_rate)
        
        while traj.header.stamp > time:
            time = rospy.Time.now()
            rate.sleep()
            
        end_time = traj.header.stamp + rospy.Duration(sum(durations))
        seg_end_times = [rospy.Time.from_sec(trajectory[seg].start_time + durations[seg]) for seg in range(len(trajectory))]
        
        rospy.loginfo('Trajectory start time is %.3lf, end time is %.3lf, total duration is %.3lf', time.to_sec(), end_time.to_sec(), sum(durations))
        
        self.trajectory = trajectory
        traj_start_time = rospy.Time.now()
        
        for seg in range(len(trajectory)):
            rospy.logdebug('current segment is %d time left %f cur time %f' % (seg, durations[seg] - (time.to_sec() - trajectory[seg].start_time), time.to_sec()))
            rospy.logdebug('goal positions are: %s' % str(trajectory[seg].positions))
            
            # first point in trajectories calculated by OMPL is current position with duration of 0 seconds, skip it
            if durations[seg] == 0:
                rospy.logdebug('skipping segment %d with duration of 0 seconds' % seg)
                continue
                
            multi_packet = {}
            
            for port,joints in self.port_to_joints.items():
                vals = []
                
                for joint in joints:
                    j = self.joint_names.index(joint)
                    
                    start_position = self.joint_states[joint].current_pos
                    if seg != 0: start_position = trajectory[seg-1].positions[j]
                        
                    desired_position = trajectory[seg].positions[j]
                    desired_velocity = max(self.min_velocity, abs(desired_position - start_position) / durations[seg])
                    
                    self.msg.desired.positions[j] = desired_position
                    self.msg.desired.velocities[j] = desired_velocity
                    
                    motor_id = self.joint_to_controller[joint].motor_id
                    pos = self.joint_to_controller[joint].pos_rad_to_raw(desired_position)
                    spd = self.joint_to_controller[joint].spd_rad_to_raw(desired_velocity)
                    
                    vals.append((motor_id,pos,spd))
                    
                multi_packet[port] = vals
                
            for port,vals in multi_packet.items():
                self.port_to_io[port].set_multi_position_and_speed(vals)
                
            while time < seg_end_times[seg]:
                # check if new trajectory was received, if so abort current trajectory execution
                # by setting the goal to the current position
                if self.action_server.is_preempt_requested():
                    msg = 'New trajectory received. Aborting old trajectory.'
                    multi_packet = {}
                    
                    for port,joints in self.port_to_joints.items():
                        vals = []
                        
                        for joint in joints:
                            cur_pos = self.joint_states[joint].current_pos
                            
                            motor_id = self.joint_to_controller[joint].motor_id
                            pos = self.joint_to_controller[joint].pos_rad_to_raw(cur_pos)
                            
                            vals.append((motor_id,pos))
                            
                        multi_packet[port] = vals
                        
                    for port,vals in multi_packet.items():
                        self.port_to_io[port].set_multi_position(vals)
                        
                    self.action_server.set_preempted(text=msg)
                    rospy.logwarn(msg)
                    return
                    
                rate.sleep()
                time = rospy.Time.now()
                
            # Verifies trajectory constraints
            for j, joint in enumerate(self.joint_names):
                if self.trajectory_constraints[j] > 0 and self.msg.error.positions[j] > self.trajectory_constraints[j]:
                    res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.PATH_TOLERANCE_VIOLATED)
                    msg = 'Unsatisfied position constraint for %s, trajectory point %d, %f is larger than %f' % \
                           (joint, seg, self.msg.error.positions[j], self.trajectory_constraints[j])
                    rospy.logwarn(msg)
                    self.action_server.set_aborted(result=res, text=msg)
                    return
                    
        # let motors roll for specified amount of time
        rospy.sleep(self.goal_time_constraint)
        
        for i, j in enumerate(self.joint_names):
            rospy.logdebug('desired pos was %f, actual pos is %f, error is %f' % (trajectory[-1].positions[i], self.joint_states[j].current_pos, self.joint_states[j].current_pos - trajectory[-1].positions[i]))
            
        # Checks that we have ended inside the goal constraints
        for (joint, pos_error, pos_constraint) in zip(self.joint_names, self.msg.error.positions, self.goal_constraints):
            if pos_constraint > 0 and abs(pos_error) > pos_constraint:
                res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.GOAL_TOLERANCE_VIOLATED)
                msg = 'Aborting because %s joint wound up outside the goal constraints, %f is larger than %f' % \
                      (joint, pos_error, pos_constraint)
                rospy.logwarn(msg)
                self.action_server.set_aborted(result=res, text=msg)
                break
        else:
            res = FollowJointTrajectoryResult(FollowJointTrajectoryResult.SUCCESSFUL)
            msg = 'Trajectory execution successfully completed'
            rospy.loginfo(msg)
            self.action_server.set_succeeded(result=res, text=msg)

    def update_state(self):
        rate = rospy.Rate(self.state_update_rate)
        while self.running and not rospy.is_shutdown():
            self.msg.header.stamp = rospy.Time.now()
            
            # Publish current joint state
            for i, joint in enumerate(self.joint_names):
                state = self.joint_states[joint]
                self.msg.actual.positions[i] = state.current_pos
                self.msg.actual.velocities[i] = abs(state.velocity)
                self.msg.error.positions[i] = self.msg.actual.positions[i] - self.msg.desired.positions[i]
                self.msg.error.velocities[i] = self.msg.actual.velocities[i] - self.msg.desired.velocities[i]
                
            self.state_pub.publish(self.msg)
            rate.sleep()