Question

我正在ROS中实现故障安全切换过程，并且正在使用python脚本来这样做。我正在使用鼠标的光学传感器来控制物体的加速度，以便可以检测到何时跌落。一切似乎都正常，但是现在我想在宣布成功切换之前限制监视过程（比如说1000次）。问题是，我用于鼠标的函数读取卡住了，如果未检测到移动，则不会执行下一次迭代。如何在不遇到此问题的情况下从设备读取信息？

这是我用来从鼠标读取的代码：

def getMouseEvent():
    buf = file.read(3)
    x, y = struct.unpack( "bb", buf[1:] )  # <--- X and Y deltas.
    return [x , y]

这是我要实现的循环

release_grasp()
rospy.loginfo( "Force detected -- Release mode active")
# If the object is falling regrasp it.      
detected= False
trials = 0
while (not(detected) and trials < 1000):
    trials = trials + 1
    rospy.loginfo ("Acc monitored for the" + str(trials) + "th time"
    if fall_test():
        cilindrical_grasp()
        rospy.loginfo("Fall detected -- Object regrasped")
        detected = True     
    rate.sleep()

我得到的输出将阻止给定迭代，直到鼠标没有检测到某种运动为止。

更新：这是完整的代码

#!/usr/bin/env python2
import rospy
import numpy  
import struct
from reflex_sf_msgs.msg import SFPose
from matteo.msg import force
from matteo.msg import acc

# Defining force treshold in each direction ( to be completed and tuned )


rospy.init_node('DetectionFail')
xt = 0.5
yt = xt
zt = 0.3
# For the future try to handle the initialization.
fx = None
fy = None
fz = None
ax = None
ay = None

rate = rospy.Rate(100) # <--- Rate Hz

#-----------------------------MOUSE-----------------------------------#
# Open the mouse device. To be sure if it is "mouse2" type in the terminal: cat     /proc/bus/input/devices, look for the device whose name is "Logitech optical USB mouse"     and get the name of the handler. If you need root permissions type: sudo chmod 777  /dev/input/(handler)
file = open ("/dev/input/mouse3" , "rb")

#Defining the function to read mouse deltas.
def getMouseEvent():
    buf = file.read(3);
x,y = struct.unpack( "bb", buf[1:] ); # <--- X and Y deltas.
    return [x , y]

#Defining the function to estimate the acceleraton.
def acc_comp():
    vx_old = 0 
    vy_old = 0
    vx_new = getMouseEvent()[0]
    vy_new = getMouseEvent()[1]
    x_acc = (vx_old - vx_new)*100
    y_acc = (vy_old - vy_new)*100
    vx_old = vx_new
    vy_old = vy_new
    return [x_acc , y_acc]

#---------------------------------------------------------------------#
#Defining function fall test
def fall_test():
    if ( acc_comp()[1] >= 3000 or acc_comp()[1] <= -3000 ):
        return True
    else:
        return False

#---------------------------------------------------------------------#

# Initialize hand publisher.
hand_pub = rospy.Publisher('/reflex_sf/command', SFPose, queue_size=1)
rospy.sleep(0.5)

#---------------------------------------------------------------------#

# Defining sferical grasp.
def cilindrical_grasp():
hand_pub.publish ( 2.5 , 2.5 , 2.5, 0)

#---------------------------------------------------------------------#

# Define release position.
def release_grasp():
    hand_pub.publish ( 2,  2 , 2 , 0)

#---------------------------------------------------------------------#

# Define test for the force measure
def force_treshold ( fx, fy , fz):  
    if ( fx > xt and fy > yt or fz > zt):
        return True
    else:
        return False    

#---------------------------------------------------------------------#
# Callback function to save the datas obtained by the force sensor
def callback_force(msg):
    global fx
    global fy
    global fz
    fx = msg.fx
    fy = msg.fy
    fz = msg.fz


    # Main loop.
    def main():
        #Apply the sferical grasp.
        rospy.loginfo("Applying grasp")
        cilindrical_grasp()
            while not(rospy.is_shutdown()): 

                 rospy.Subscriber("/Forces", force, callback_force )

                    if force_treshold ( fx , fy , fz ):
                          release_grasp()
                          rospy.loginfo( "Force detected -- Release mode active")
                          # If the object is falling regrasp it.        
                          detected= False
                          trials = 0
                          while (not(detected) and trials < 1000):
                              trials = trials +1 
                              if fall_test():
                                 cilindrical_grasp()
                                 rospy.loginfo("Fall detected -- Object regrasped")
                                 detected = True        
            rate.sleep()
    if rospy.is_shutdown() :
        break

昨天我给出了以下代码：

#!/usr/bin/env python
import struct
import rospy
from matteo.msg import acc
import struct
import os
import time

i = 0

# Mouse read with a non blocking structure, the problem is that does not provide the same       output as 
# mouse_clean.py, probably there is a problem with the unpacking or the reading.

while i < 1000:
        i += 1
        try:
            file = os.open("/dev/input/mouse0", os.O_RDONLY | os.O_NONBLOCK)
            time.sleep(0.1)
            buf = os.read(file , 3)
            x,y = struct.unpack( "bb", buf[1:] ) # <--- X and Y deltas.
            print ( "X:" +str ( x ) + "---" +"Y:" +str ( y ) )
        except  OSError as err:
            if err.errno == 11:
                print ( "No motion detected")
                continue
        os.close(file)

它工作正常，如果没有动作，则消息会打印出来，但是，如果出现动作，我得到的输出与“香草”模式完全不同。

我如何以非阻塞方式读取鼠标数据

0 个答案: