【20160404】Follower Motion Schemes
. h0 X) O1 s5 ~" a, U! F从动件运动模式# i- N- ?( `6 t# d
6 g4 l3 W- E% C* z1 gIn designing a cam, the objective is to identify a suitable shape for the cam. The primary interest is to ensure that the follower will achieve the desired displacements. The shape of the cam is merely a means to obtain this motion.( A; s0 r- Y* o; Q; E5 u
设计凸轮时，我们的目标是找出合适的凸轮外形。但最初的目的是确保从动件将按照预期进行运动。凸轮外形仅仅是获得此种运动的方式。( \/ U j3 H) R- F7 Z, ~& s$ w
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Constant Velocity：Uniform velocity, and zero acceleration
* D" ~/ H( ^; |8 y" f' L常速运动：匀速，加速度为零3 o! _) _. ]3 L2 H/ [2 l
Problems：The instantaneous jump from one constant value of velocity to another constant value of velocity results in an infinite acceleration.9 V# m# R# @4 Z1 B* ~- u5 l( Z) R
问题：从一种匀速状态到另一状态，所需加速度无限大。
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constant velocity
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Constant Acceleration：Constant positive and negative accelerations
+ f8 X$ m9 w; e" ^6 @4 N匀加速运动：加速度连续同向
' Z$ t- X9 F& pProblems：The abrupt changes of acceleration at the end of the motion result in abrupt changes in inertial forces.
+ K% i' s6 d; ^! D9 o问题：加速度突然转变，所需内力无限大。
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constant acceleration
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Harmonic Motion：Harmonic motion is derived from trigonometric functions, thus exhibiting very smooth motion curves.6 d! D& [# g+ |" q- C" x( l
简谐运动：三角函数推导而来，因此具有平滑的运动曲线。/ X* h, U- D* Y' a \+ R8 b' v& w5 g
Problems：It has a sudden change of acceleration at the ends of the motion, which can be objectionable at higher speeds.
/ Y3 [0 k0 ^+ F9 U8 @% [7 J/ {% ^问题：在运动末尾加速度会突变，这在高速下十分不便。
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harmonic motion
/ |* c: v" s8 ~1 E: FCycloidal Motion：Cycloidal motion is another motion scheme derived from trigonometric functions.! N) [) e% z4 t
摆线运动：另一种由三角函数导出的运动类型。
n5 D4 T. m+ ?! KThis scheme does not have the sudden change in acceleration at the ends of the motion, which makes it popular for high-speed applications.2 [1 U$ V; e$ e$ x% }% m9 ^4 ^
加速度不突变，在高速运动中广为应用。( U8 A0 b" I8 j9 a
cycloidal motion
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$ p" z. Z! R! u/ A7 G! XThe time derivative of the acceleration is referred to as jerk.% n( z) y, t! T
加速度对时间的导数称为急动度。
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( Q2 n* }9 y' H& L. O, w5 vA summary of the peak velocity, peak acceleration, and peak jerk for the different motion schemes, as a function of the rise H and period of the interval T, is shown in Table 9.5.' `0 W5 Y h3 C& ^3 P. S
如表所示是各种运动模式的速度峰值、加速度峰值及急动度峰值的对比。
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Table 9.5
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楼主: 黑森林的鹿
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发表于 2016-4-2 19:44:06
楼主
、表示上个学期也是力学拖了大后腿，6级也就是勉强过了，想想自己刷分目标仅是过500，再看看楼主，实在是惭愧。这个学期在搞机械创新，感觉知识实在是不够用，不过也因此更加有兴趣去学专业课，嗯，向楼主学习，据说，不带手机上课就成功了一半呢
