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Revision 834 - (hide annotations) (download) (as text)
Thu Aug 31 05:39:14 2006 UTC (17 years, 10 months ago) by johnpye
File MIME type: text/x-ascend
File size: 1288 byte(s)
Added little 'fourbar' model for a four bar linkage.
Added 'plotfourbar.a4c' as well, for graphical output
using the present plot system (as a bit of a test).
Fixed support for plotting (bug #282)
1 johnpye 834 REQUIRE "atoms.a4l";
2    
3     (*
4     Model of a four-bar linkage
5    
6     The pivots are at A, B, C, D. Sides are named after the
7     end points. The 'default' configuration being modelled is
8     of a quadrilater with A and D fixed and B and C free.
9     The angle at A, alpha (to the positive x axis) will also be fixed
10    
11     *)
12    
13     MODEL fourbar;
14     x_A,y_A IS_A delta_distance;
15     x_B,y_B IS_A delta_distance;
16     x_C,y_C IS_A delta_distance;
17     x_D,y_D IS_A delta_distance;
18    
19     AB,BC,CD,DA IS_A distance;
20     alpha, beta, gamma, delta IS_A angle;
21    
22     x_B = x_A + AB*cos(alpha);
23     y_B = y_A + AB*sin(alpha);
24    
25     (x_C-x_B)^2 + (y_C-y_B)^2 = BC^2;
26     beta = arctan((y_C-y_B)/(x_C-x_B));
27    
28     x_D = x_C + CD*cos(gamma);
29     y_D = y_C + CD*sin(gamma);
30    
31     x_A = x_D + DA*cos(delta);
32     y_A = y_D + DA*sin(delta);
33    
34     METHODS
35     METHOD default_self;
36     y_B := 0.5 {m}; x_B := 0.8 {m};
37     y_C := -0.5{m}; x_C := 1.2 {m};
38     x_D := 2 {m}; y_D := 0 {m};
39     END default_self;
40    
41     METHOD specify;
42     FIX x_A, y_A;
43     FIX AB, BC, CD, DA;
44     FIX alpha, delta;
45     END specify;
46     METHOD values;
47     x_A := 0 {m};
48     y_A := 0 {m};
49     delta := 180 {deg};
50     AB := 1 {m};
51     BC := 1 {m};
52     CD := 1 {m};
53     DA := 2 {m};
54    
55     alpha:= 30 {deg};
56     END values;
57    
58     METHOD on_load;
59     RUN reset;
60     RUN values;
61     RUN default_self;
62     END on_load;
63     END fourbar;
64    

john.pye@anu.edu.au
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