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00001 #!/usr/bin/env python 00002 00003 """ 00004 follow_controller.py - controller for a kinematic chain 00005 Copyright (c) 2011 Vanadium Labs LLC. All right reserved. 00006 00007 Redistribution and use in source and binary forms, with or without 00008 modification, are permitted provided that the following conditions are met: 00009 * Redistributions of source code must retain the above copyright 00010 notice, this list of conditions and the following disclaimer. 00011 * Redistributions in binary form must reproduce the above copyright 00012 notice, this list of conditions and the following disclaimer in the 00013 documentation and/or other materials provided with the distribution. 00014 * Neither the name of Vanadium Labs LLC nor the names of its 00015 contributors may be used to endorse or promote products derived 00016 from this software without specific prior written permission. 00017 00018 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 00019 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 00020 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 00021 DISCLAIMED. IN NO EVENT SHALL VANADIUM LABS BE LIABLE FOR ANY DIRECT, INDIRECT, 00022 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 00023 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 00024 OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 00025 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 00026 OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 00027 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00028 """ 00029 00030 import rospy, actionlib 00031 00032 from control_msgs.msg import FollowJointTrajectoryAction 00033 from trajectory_msgs.msg import JointTrajectory 00034 from diagnostic_msgs.msg import * 00035 00036 from ax12 import * 00037 from controllers import * 00038 00039 class FollowController(Controller): 00040 """ A controller for joint chains, exposing a FollowJointTrajectory action. """ 00041 00042 def __init__(self, device, name): 00043 Controller.__init__(self, device, name) 00044 self.interpolating = 0 00045 00046 # parameters: rates and joints 00047 self.rate = rospy.get_param('~controllers/'+name+'/rate',50.0) 00048 self.joints = rospy.get_param('~controllers/'+name+'/joints') 00049 self.index = rospy.get_param('~controllers/'+name+'/index', len(device.controllers)) 00050 for joint in self.joints: 00051 self.device.joints[joint].controller = self 00052 00053 # action server 00054 name = rospy.get_param('~controllers/'+name+'/action_name','follow_joint_trajectory') 00055 self.server = actionlib.SimpleActionServer(name, FollowJointTrajectoryAction, execute_cb=self.actionCb, auto_start=False) 00056 00057 # good old trajectory 00058 rospy.Subscriber(self.name+'/command', JointTrajectory, self.commandCb) 00059 self.executing = False 00060 00061 rospy.loginfo("Started FollowController ("+self.name+"). Joints: " + str(self.joints) + " on C" + str(self.index)) 00062 00063 def startup(self): 00064 self.server.start() 00065 00066 def actionCb(self, goal): 00067 rospy.loginfo(self.name + ": Action goal recieved.") 00068 traj = goal.trajectory 00069 00070 if set(self.joints) != set(traj.joint_names): 00071 msg = "Trajectory joint names does not match action controlled joints." + str(traj.joint_names) 00072 rospy.logerr(msg) 00073 self.server.set_aborted(text=msg) 00074 return 00075 00076 if not traj.points: 00077 msg = "Trajectory empy." 00078 rospy.logerr(msg) 00079 self.server.set_aborted(text=msg) 00080 return 00081 00082 try: 00083 indexes = [traj.joint_names.index(joint) for joint in self.joints] 00084 except ValueError as val: 00085 msg = "Trajectory invalid." 00086 rospy.logerr(msg) 00087 self.server.set_aborted(text=msg) 00088 return 00089 00090 if self.executeTrajectory(traj): 00091 self.server.set_succeeded() 00092 else: 00093 self.server.set_aborted(text="Execution failed.") 00094 00095 rospy.loginfo(self.name + ": Done.") 00096 00097 def commandCb(self, msg): 00098 # don't execute if executing an action 00099 if self.server.is_active(): 00100 rospy.loginfo(self.name+": Received trajectory, but action is active") 00101 return 00102 self.executing = True 00103 self.executeTrajectory(msg) 00104 self.executing = False 00105 00106 def executeTrajectory(self, traj): 00107 rospy.loginfo("Executing trajectory") 00108 rospy.loginfo(traj) 00109 # carry out trajectory 00110 try: 00111 indexes = [traj.joint_names.index(joint) for joint in self.joints] 00112 except ValueError as val: 00113 return False 00114 time = rospy.Time.now() 00115 start = traj.header.stamp 00116 r = rospy.Rate(self.rate) 00117 last = [ self.device.joints[joint].position for joint in self.joints ] 00118 for point in traj.points: 00119 while rospy.Time.now() + rospy.Duration(0.01) < start: 00120 rospy.sleep(0.01) 00121 desired = [ point.positions[k] for k in indexes ] 00122 endtime = start + point.time_from_start 00123 while rospy.Time.now() + rospy.Duration(0.01) < endtime: 00124 err = [ (d-c) for d,c in zip(desired,last) ] 00125 velocity = [ abs(x / (self.rate * (endtime - rospy.Time.now()).to_sec())) for x in err ] 00126 rospy.logdebug(err) 00127 for i in range(len(self.joints)): 00128 if err[i] > 0.001 or err[i] < -0.001: 00129 cmd = err[i] 00130 top = velocity[i] 00131 if cmd > top: 00132 cmd = top 00133 elif cmd < -top: 00134 cmd = -top 00135 last[i] += cmd 00136 self.device.joints[self.joints[i]].setControlOutput(last[i]) 00137 else: 00138 velocity[i] = 0 00139 r.sleep() 00140 return True 00141 00142 def active(self): 00143 """ Is controller overriding servo internal control? """ 00144 return self.server.is_active() or self.executing 00145 00146 def getDiagnostics(self): 00147 """ Get a diagnostics status. """ 00148 msg = DiagnosticStatus() 00149 msg.name = self.name 00150 msg.level = DiagnosticStatus.OK 00151 msg.message = "OK" 00152 if self.active(): 00153 msg.values.append(KeyValue("State", "Active")) 00154 else: 00155 msg.values.append(KeyValue("State", "Not Active")) 00156 return msg 00157