#!/usr/bin/env python

from time import sleep

import numpy as np

import rospy

pos = currentPosition + mi*r

print “pos: “, pos

pub.publish(pos)

sleep(0.05)

currentPosition = targetPosition

print “pos-e: “, currentPosition

pub.publish(currentPosition)

def listener():

if __name__ == ‘__main__’:

listener()

想要测试伺服机顺畅的动作，就要启动Python脚本，将讯息发布到「/head/tilt/smooth」，这样一来即可检视顺畅的动作。

$ ./servoencoder.py

$ rostopic pub -1 /head/tilt/smoothstd_msgs/Float32 1

$ rostopic pub -1 /head/tilt/smoothstd_msgs/Float32 0

ROS当中的名称也可以重新测绘。只要将「/head/tilt/smooth」重新测绘为「/head/tilt」，程序就能向伺服机发出命令，而不会意识到正弦曲线的数值在变化。

迎向未来

虽然这里只说明了简单的伺服机控制，ROS却有更多功能。假如想要知道妨碍机器人的东西是什么，不妨使用已经支持ROS的Kinect。就算导航堆栈使用这项数据测绘，也可以馈送简短的Python脚本，让伺服机动起来，命令机器人追踪附近的物体。没错，眼睛真的会追逐物体。

Terry是室内用机器人，搭载2个Kinect。一个专门用来导航，另一个则用于深度测绘。Terry使用6个Arduinos，能够从用了ROS的网络接口或PS3遥控器直接操作。

Houndbot是设计成要在户外使用。里头有遥控器、GPS、罗盘和ROS耳形控制器。后续计划要搭载导航用的PS4双镜头摄影机，因为Kinect不能在阳光下使用。这台机器人重量为20公斤。还可以追加了悬吊系统，为此需要自行制造铝合金客制化零件。

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