机器人

ROS机器人Diego 1#制作（十五）机械臂的控制---通过键盘控制机械臂舵机

robot
2020年4月30日
582

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。