【20160404】Follower Motion Schemes. ]% o. t" q/ ?
从动件运动模式
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. \& Q3 F5 i) |# J: D1 j4 zIn 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.( U- M N$ u, K3 d
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。. }# a% ~) K1 b P/ Y+ a
8 a4 V) I1 _4 E. D3 R) ?Constant Velocity：Uniform velocity, and zero acceleration0 F5 N# m; \7 l; Z' b
常速运动：匀速，加速度为零
# A. | N% h0 @ S( l/ n% D1 |, L: ]/ uProblems：The instantaneous jump from one constant value of velocity to another constant value of velocity results in an infinite acceleration.+ N& C8 I+ |' L
问题：从一种匀速状态到另一状态，所需加速度无限大。0 y% { I; }2 s" u. l
constant velocity
5 O- B) I( h( ^9 R& Z4 I" \5 HConstant Acceleration：Constant positive and negative accelerations
' B4 C! p9 C3 o- B% G! S) M f匀加速运动：加速度连续同向
, X( x; e8 c1 s2 T5 u: |Problems：The abrupt changes of acceleration at the end of the motion result in abrupt changes in inertial forces.
. J% w% p4 ?+ Q+ R; b& t! C. q问题：加速度突然转变，所需内力无限大。: ]8 M* J( b) z
constant acceleration
0 X- f9 F2 O, @ z+ J# Q" g# y+ }Harmonic Motion：Harmonic motion is derived from trigonometric functions, thus exhibiting very smooth motion curves.
% P% ]* ^. |, f$ X X& n) ]( k3 W简谐运动：三角函数推导而来，因此具有平滑的运动曲线。
$ }0 r# i1 o! H6 @( B0 \Problems：It has a sudden change of acceleration at the ends of the motion, which can be objectionable at higher speeds.9 y9 N' W3 d& x+ Z5 b" C
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
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Cycloidal Motion：Cycloidal motion is another motion scheme derived from trigonometric functions.) p3 `- P: ?# T/ i% q6 }
摆线运动：另一种由三角函数导出的运动类型。: Y1 o$ K2 d) c5 l1 x3 \
This scheme does not have the sudden change in acceleration at the ends of the motion, which makes it popular for high-speed applications.
3 L" w* ]7 [1 J% w c3 |+ ~% o, Q加速度不突变，在高速运动中广为应用。
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cycloidal motion
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: H' K2 l3 I' y) J! @The time derivative of the acceleration is referred to as jerk.
: {4 R. F+ o& l/ T( u加速度对时间的导数称为急动度。
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( } H- }$ ^0 ]3 m" t) B; [ Z9 `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.
; G$ C* q+ H: V _ e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
发表于 2016-4-2 19:44:06
、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
