Shenton's critics, it should be pointed out, can fall back on spherical trigonometry and astronomical observations that date right back to Aristotle in 330BC.

有必要说明一下，早在公元前300年的亚里士多德时期，那时的球面三角学和天文观测结果就批驳了珊顿的地平论观点。

The physical model of a 2-DOF spherical 5R parallel mechanism had been studied. The constraint equations of the parallel manipulator were established by using the spherical trigonometry.

研究球面二自由度5R并联机器人机构模型，借助球面解析几何理论，建立了机构的约束方程；