为了便于调试，特意写了一个通过键盘控制机械臂舵机的代码，来调试舵机，代码是基于teleop_twist_keyboard修改的。在arduino_node.py中已经声明了舵机读和写的ROS Service：
# A service to position a PWM servo
rospy.Service('~servo_write', ServoWrite, self.ServoWriteHandler)
# A service to read the position of a PWM servo
rospy.Service('~servo_read', ServoRead, self.ServoReadHandler)配合上一篇微博中arduino端的舵机驱动，我们只需要实现这两个ROS Service的client就可以控制舵机了，具体原理请看代码中的注释代码如下：
#!/usr/bin/env python
import roslib; roslib.load_manifest('teleop_twist_keyboard')
import rospy
from geometry_msgs.msg import Twist
from ros_arduino_msgs.srv import *
from math import pi as PI
import sys, select, termios, tty
msg = """
Reading from the keyboard and Publishing to Twist, Servo or sensor!
---------------------------
Moving around:
u i o
j k l
, : up (+z)
. : down (-z)
m : stop
----------------------------
Left arm servo control:控制机器人左臂，每次调整0.09弧度
+ 1 2 3 4 5 6
- q w e r t y
----------------------------
Right arm servo control:控制机器人右臂，每次调整0.09弧度
+ a s d f g h
- z x c v b n
p : init the servo 初始化舵机
CTRL-C to quit
"""
moveBindings = {
'i':(1,0,0,0),
'o':(1,0,0,1),
'j':(-1,0,0,-1),
'l':(-1,0,0,1),
'u':(1,0,0,-1),
'k':(-1,0,0,0),
',':(0,0,1,0),
'.':(0,0,-1,0),
}
#右臂舵机的控制数组，1表示增加0.09弧度，0表示减少0.09弧度
rightArmServo={
'1':(0,1),
'2':(1,1),
'3':(2,1),
'4':(3,1),
'5':(4,1),
'6':(5,1),
'q':(0,0),
'w':(1,0),
'e':(2,0),
'r':(3,0),
't':(4,0),
'y':(5,0),
}
#左臂舵机的控制数组，1表示增加0.09弧度，0表示减少0.09弧度
leftArmServo={
'a':(6,1),
's':(7,1),
'd':(8,1),
'f':(9,1),
'g':(10,1),
'h':(11,1),
'z':(6,0),
'x':(7,0),
'c':(8,0),
'v':(9,0),
'b':(10,0),
'n':(11,0),
}
#手臂臂舵机的控制命令数组
armCmd={
'[':(0,1),#左臂初始化
']':(1,1),#右臂初始化
}
def getradians(angle):
return PI*angle/180
def getKey():
tty.setraw(sys.stdin.fileno())
select.select([sys.stdin], [], [], 0)
key = sys.stdin.read(1)
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, settings)
return key
#舵机当前位置读取，调用servo_read service
def servoRead(servoNum):
rospy.wait_for_service('/arduino/servo_read')
try:
readServo=rospy.ServiceProxy('/arduino/servo_read',ServoRead)
return readServo(servoNum)
except rospy.ServiceException, e:
print "Service call failed: %s"%e
#舵机位置写，根据舵机标号设置舵机的位置0~π,注意这里的value对应的是弧度
def servoWrite(servoNum, value):
rospy.wait_for_service('/arduino/servo_write')
try:
servo_write=rospy.ServiceProxy('/arduino/servo_write',ServoWrite)
servo_write(servoNum,value)
print servoNum
print value
except rospy.ServiceException, e:
print "Service call failed: %s"%e
#初始化右臂舵机角度，要根据实际情况调整舵机角度
def initRightArm():
servoWrite(0,getradians(60))
servoWrite(1,getradians(80))
servoWrite(2,getradians(90))
servoWrite(3,getradians(90))
servoWrite(4,getradians(90))
servoWrite(5,getradians(90))
#初始化左臂舵机角度，要根据实际情况调整舵机角度
def initLeftArm():
servoWrite(6,getradians(90))
servoWrite(7,getradians(90))
servoWrite(8,getradians(90))
servoWrite(9,getradians(90))
servoWrite(10,getradians(90))
servoWrite(11,getradians(90))
def vels(speed,turn):
return "currently:\tspeed %s\tturn %s " % (speed,turn)
if __name__=="__main__":
settings = termios.tcgetattr(sys.stdin)
pub = rospy.Publisher('cmd_vel', Twist, queue_size = 1)
rospy.init_node('teleop_twist_keyboard')
speed = rospy.get_param("~speed", 0.5)
turn = rospy.get_param("~turn", 1.0)
x = 0
y = 0
z = 0
th = 0
status = 0
try:
print msg
print vels(speed,turn)
while(1):
key = getKey()
print key
if key in moveBindings.keys():
x = moveBindings[key][0]
y = moveBindings[key][1]
z = moveBindings[key][2]
th = moveBindings[key][3]
elif key in leftArmServo.keys():#左臂舵机控制
value=servoRead(leftArmServo[key][1]).value
if(leftArmServo[key][1]==0):
value=value-getradians(5)
if value<=0:
value=0
else:
value=value+getradians(5)
if value>=PI:
value=PI
servoWrite(leftArmServo[key][0], value)
elif key in rightArmServo.keys():#右臂舵机控制
value=servoRead(rightArmServo[key][1]).value
if(rightArmServo[key][1]==0):
value=value-getradians(5)
if value<=0:
value=0
else:
value=value+getradians(5)
if value>=PI:
value=PI
servoWrite(rightArmServo[key][0], value)
elif key in armCmd.keys():#舵机初始化
if(armCmd[key][0]==0):
initRightArm()
elif(armCmd[key][0]==1):
initLeftArm()
else:
x = 0
y = 0
z = 0
th = 0
if (key == '\x03'):
break
twist = Twist()
twist.linear.x = x*speed; twist.linear.y = y*speed; twist.linear.z = z*speed;
twist.angular.x = 0; twist.angular.y = 0; twist.angular.z = th*turn
pub.publish(twist)
except BaseException,e:
print e
finally:
twist = Twist()
twist.linear.x = 0; twist.linear.y = 0; twist.linear.z = 0
twist.angular.x = 0; twist.angular.y = 0; twist.angular.z = 0
pub.publish(twist)
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, settings)
这里需要强调一下硬件的使用过程中，一定要保证供电的功率足够，否则的话会出现串口通信异常，机械臂乱动等现象，这都是电源供电不足的问题导致的。