【20160404】Follower Motion Schemes
9 d1 A3 w D2 a' z( j从动件运动模式6 `* p& [- \' `" `) ?; L* z; a
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In 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.' ?$ Z- z( I: Y2 }) _, g+ X
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。
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Constant Velocity：Uniform velocity, and zero acceleration0 b& A" \* W% q+ R" ~) Y
常速运动：匀速，加速度为零' y& n( i8 r! V
Problems：The instantaneous jump from one constant value of velocity to another constant value of velocity results in an infinite acceleration.
4 r) H. C4 V; g2 _* [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 Acceleration：Constant positive and negative accelerations
/ K2 s9 {, u$ k! q3 L8 {匀加速运动：加速度连续同向
0 B6 _% s* n% y1 L; s2 D, pProblems：The abrupt changes of acceleration at the end of the motion result in abrupt changes in inertial forces.- R0 O& b% L/ M- f2 Y8 Q n
问题：加速度突然转变，所需内力无限大。
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6 B7 S- P; Q$ Z9 e1 dHarmonic Motion：Harmonic motion is derived from trigonometric functions, thus exhibiting very smooth motion curves.
3 m, [ m' M; G$ z) Y; b9 P简谐运动：三角函数推导而来，因此具有平滑的运动曲线。: B$ ?3 w1 G% o$ k! Q, x3 i3 ^/ v
Problems：It has a sudden change of acceleration at the ends of the motion, which can be objectionable at higher speeds.* L+ d8 T0 n- G
问题：在运动末尾加速度会突变，这在高速下十分不便。8 Q" O5 _' z. _. W; s0 b& R8 r8 T
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Cycloidal Motion：Cycloidal motion is another motion scheme derived from trigonometric functions.
& C" a5 c0 P+ {- }摆线运动：另一种由三角函数导出的运动类型。
/ n! ^" H9 v7 hThis scheme does not have the sudden change in acceleration at the ends of the motion, which makes it popular for high-speed applications.: q1 _0 ?9 x/ {3 `/ }
加速度不突变，在高速运动中广为应用。9 H5 e$ l+ v( K C" n; {+ P& A
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The time derivative of the acceleration is referred to as jerk.' @8 w2 ^% w$ B. b; {
加速度对时间的导数称为急动度。
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A 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.$ V% H0 v" U* m# P
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。- O- M$ Z& x. D% j. C& H' T. i
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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
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、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