I'm a beginner in python. I'm currently try to deal with use the IK to move the robot arm. When I try to run my program the arm was able to move to the my setted starting position but when it's going to next step it shows me this error:AttributeError: 'bool' object has no attribute 'items'
This is my program:
class Pick_Place (object):
#def __init__(self,limb,hover_distance = 0.15):
def __init__(self,limb):
self._limb = baxter_interface.Limb(limb)
self._gripper = baxter_interface.Gripper(limb)
self._gripper.calibrate(limb)
#self.gripper_open()
#self._verbose = verbose
ns = "ExternalTools/" + limb + "/PositionKinematicsNode/IKService"
self._iksvc = rospy.ServiceProxy(ns,SolvePositionIK)
rospy.wait_for_service(ns, 5.0)
def move_to_start (self,start_angles = None):
print ("moving.....")
if not start_angles:
print ("it is 0")
start_angles = dict(zip(self._joint_names, [0]*7))
self._guarded_move_to_joint_position(start_angles)
self.gripper_open()
rospy.sleep(1.0)
print ("moved!!!")
#########################IK_Server################################################
def ik_request (self,pose):
hdr = Header(stamp=rospy.Time.now(),frame_id='base')
ikreq = SolvePositionIKRequest()
ikreq.pose_stamp.append(PoseStamped(header=hdr, pose=pose))
try:
resp = self._iksvc (ikreq)
except (rospy.ServiceException, rospy.ROSException), e:
rospy.logerr("Service call failed: %s" % (e,))
return False
limb_joints = {}
limb_joints = dict(zip(resp.joints[0].name, resp.joints[0].position))
return limb_joints
###################################################################################
def _guarded_move_to_joint_position(self,joint_angles):
print ("joint position.....")
self._limb.move_to_joint_positions(joint_angles)
def gripper_open (self):
self._gripper.open()
rospy.sleep(1.0)
def gripper_close (self):
self._gripper.close()
rospy.sleep(1.0)
#################################Individual_Motion####################################
def _approach (self, pose):
print ("\nApproaching.....")
approach = copy.deepcopy(pose)
approach.position.z = approach.position.z #+ self._hover_distance
joint_angles = self.ik_request(approach)
self._guarded_move_to_joint_position(joint_angles)
print ("\nApproached.....")
def _retract (self):
print ("\nRetracting.....")
current_pose = self._limb.endpoint_pose()
ik_pose = Pose()
ik_pose.position.x = current_pose['position'].x
ik_pose.position.y = current_pose['position'].y
ik_pose.position.z = current_pose['position'].z #+ self._hover_distance
ik_pose.orientation.x = current_pose['orientation'].x
ik_pose.orientation.y = current_pose['orientation'].y
ik_pose.orientation.z = current_pose['orientation'].z
ik_pose.orientation.w = current_pose['orientation'].w
joint_angles = self.ik_request(ik_pose)
self._guarded_move_to_joint_position(joint_angles)
print ("\nRetracted......")
def _servo_to_pose (self, pose):
print ("\nPosing.....")
joint_angles = self.ik_request(pose)
self._guarded_move_to_joint_position(joint_angles)
print ("\nPosed.....")
##########################Motion_of_pick_and_place#####################################
def pick (self,pose):
print ("\nPicking_1.....")
# open the gripper
self.gripper_open()
# servo above pose
self._approach(pose)
# servo to pose
self._servo_to_pose(pose)
# close gripper
self.gripper_close()
# retract to clear object
self._retract()
print ("\nPicked")
def place (self,pose):
print ("\nPlacing_1.....")
# servo above pose
self._approach(pose)
# servo to pose
self._servo_to_pose(pose)
# open the gripper
self.gripper_open()
# retract to clear object
self._retract()
print ("\nPlaced")
###########################Main_Program############################################
def main():
print ("Initializing....")
rospy.init_node("ylj_ik_traTest")
print("Getting the robot state.....")
rs= baxter_interface.RobotEnable()
print ("Enabling....")
rs.enable()
limb = 'left'
#hover_distance = 0.15
starting_joint_angles = {'left_s0': -0.50,
'left_s1': -1.30,
'left_e0': -0.60,
'left_e1': 1.30,
'left_w0': 0.20,
'left_w1': 1.60,
'left_w2': -0.30}
#pnp = Pick_Place(limb,hover_distance)
pnp = Pick_Place(limb)
overhead_orientation = Quaternion(
x=-0.0249590815779,
y=0.999649402929,
z=0.00737916180073,
w=0.00486450832011)
ball_poses = list()
#1st ball point
ball_poses.append(Pose(
position = Point(x=0.7, y=0.15, z=-0.1),
orientation = overhead_orientation))
#2nd ball point
ball_poses.append(Pose(
position = Point(x=0.75, y=0.0, z=-0.1),
orientation = overhead_orientation))
pnp.move_to_start(starting_joint_angles)
idx = 0
while not rospy.is_shutdown():
print ("\nPicking.....")
pnp.pick(ball_poses[idx])
print ("\nPlacing.....")
idx = (idx+1) % len(ball_poses)#?????
pnp.place(ball_poses[idx])
return 0
if __name__ == '__main__':
sys.exit(main())
And this is the error shows me:
Initializing....
Getting the robot state.....
Enabling....
[INFO] [WallTime: 1466477391.621678] Robot Enabled
moving.....
joint position.....
moved!!!
Picking.....
Picking_1.....
Approaching.....
joint position.....
Traceback (most recent call last):
File "/home/baxter/ros_ws/src/baxter_examples/scripts/ylj_research/ylj_ik_traTest.py", line 197, in <module>
sys.exit(main())
File "/home/baxter/ros_ws/src/baxter_examples/scripts/ylj_research/ylj_ik_traTest.py", line 188, in main
pnp.pick(ball_poses[idx])
File "/home/baxter/ros_ws/src/baxter_examples/scripts/ylj_research/ylj_ik_traTest.py", line 122, in pick
self._approach(pose)
File "/home/baxter/ros_ws/src/baxter_examples/scripts/ylj_research/ylj_ik_traTest.py", line 88, in _approach
self._guarded_move_to_joint_position(joint_angles)
File "/home/baxter/ros_ws/src/baxter_examples/scripts/ylj_research/ylj_ik_traTest.py", line 72, in _guarded_move_to_joint_position
self._limb.move_to_joint_positions(joint_angles)
File "/home/baxter/ros_ws/src/baxter_interface/src/baxter_interface/limb.py", line 368, in move_to_joint_positions
diffs = [genf(j, a) for j, a in positions.items() if
AttributeError: 'bool' object has no attribute 'items'
Does anyone had met this kind of error before? Please help me, thank you.
The error tells you that booleans (either True or False) don't have an attribute "items".
When you call
self._limb.move_to_joint_positions(joint_angles) you are passing the argument "joint_angles" which becomes "positions" in the function
move_to_joint_positions().
Looking into the source code of the library you're using, it tells you what it wants positions to be:
@type positions: dict({str:float})
In short, it wants joint_angles to be a dictionary mapping strings to floats and you passed a boolean. Let's look into how you got joint_angles:
joint_angles = self.ik_request(ik_pose)
In the body of your method, you return False every time:
def ik_request (self,pose):
...
except (rospy.ServiceException, rospy.ROSException), e:
rospy.logerr("Service call failed: %s" % (e,))
return False
Returning a boolean is clearly not what you want to do, and it is the cause of this error.