CMDeviceMotion
http://nshipster.com/cmdevicemotion/ (中文翻译版 http://www.ithao123.cn/content-1352936.html)
http://www.voidcn.com/blog/wanglang3081/article/p-1769257.html
http://blog.csdn.net/xiaoxiaobukuang/article/details/51726088
http://www.cnblogs.com/wfwenchao/p/3908653.html (文中说用户加速度数据已滤波,实际感觉数据的噪声还是不小)
socket
http://www.cnblogs.com/congli0220/p/5057015.html
Quaternions四元数
http://www.amobbs.com/thread-5483278-1-1.html
Gimbal Lock
https://www.youtube.com/watch?v=zc8b2Jo7mno&t=302s (需要先解决翻墙问题)
http://www.ceeger.com/Unity/Doc/2011/Gimbal_Lock.html
accelerometer&gravity原理介绍
http://blog.csdn.net/jj2060/article/details/49533251
http://blog.csdn.net/u010076999/article/details/50922734