Fitxategi:Centipede forward propagation.gif
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Centipede_forward_propagation.gif ((320 × 240 pixel, fitxategiaren tamaina: 1,28 MB, MIME mota: image/gif), kiribildua, 50 irudi, 1,5s)
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Laburpena
DeskribapenaCentipede forward propagation.gif |
English: Most centipedes and all millipedes, and indeed 4-legged creatures, walk with the rear legs leading the legs in front. In centipedes, this results in waves propagating from back to front. This simulation was created in w:OpenSCAD using a leg motion in which each foot spends half the time on the ground, and the motion of legs in adjacent segments are offset in phase by 45°. Changing the sign of the phase offset results in forward locomotion with the waves propagating from front to back, which is a characteristic of some centipedes such as scolopendra heros. See also File:Centipede backward propagation.gif. |
Data | |
Jatorria | Norberak egina, scaled from the original in my blog article at https://www.nablu.com/2022/12/metachronal-waves-of-legs.html |
Egilea | Anachronist |
OpenSCAD source code
/* OpenSCAD code for centiped walking model To animate in OpenSCAD, go to View -> Animate. In the animation fields, set FPS to 3 and Steps to a value between 20-50. The purpose of this script is to visualize the motion of a centipede's legs in both modes of locomotion: with leg waves propagating from back to front, and front to back -- with both modes resulting in forward movement of the centipede. Each segment of the centipede has a pair of legs that constantly windmill around. Each successive segment has the phase of the windmilling offset by 45 degrees from the previous segment. The offset direction is controlled by the 'phase_direction' parameter. The phase_direction values 1 or -1 result in forward or backward propagation, respectively. The legs flex at the knees to look more natural. */ // ---------- customizable values ---------- phase_direction = 1; // Set to 1 (back-to-front waves) or -1 segspacing = 12; // spacing between segments nsegs = 21; // number of segments leglen = 22; // leg length at max extension legr = 2; // leg radius legkneeht = 3; // knee height at max leg extension legangle = 15; // overal downward leg tilt angle from body // ---------- calculated values ---------- bodywid = 1.5*segspacing; // body segment width body_elev = leglen*sin(legangle); // elevation of bottom of body above floor legseglen = sqrt(leglen*leglen*0.25 + legkneeht*legkneeht); // length of a leg segment (each leg is 2 segments) xmotion = 1.7*segspacing; // front-to-back motion of each foot in the x direction llmin = leglen*cos(asin(0.5*xmotion/leglen)); // minimum leg length when leg is perpendicular to body and foot is on the floor // --------- render ---------- // $t is set internally by the animation option; initially it is zero. // It ranges from 0 to 1 in increments determined by Steps, and repeats. centipede(360*$t); floor(360*$t); // ---------- modules ---------- // render the whole centipede module centipede(phase=0) { ns2 = nsegs/2; for(i=[0:nsegs-1]) translate([segspacing*(i-ns2),0,0]) bodyseg(phase, phase_direction*i*45); translate([segspacing*(-1-ns2),0,0]) head(); } // single body segment with legs positioned at phase angle 'phase' with phase offset 'offset' module bodyseg(phase=0, offset=0) { bodyblank(); translate([0,0,body_elev]) color("orange") { translate([0,bodywid,legr]) rotate([-legangle,0,0]) leg(phase, offset); mirror([0,1,0]) translate([0,bodywid,legr]) rotate([-legangle,0,0]) leg(phase+180, offset); } } // head includes eyes and antennae, but no legs module head() { bodyblank(); // eyes translate([-bodywid/3,bodywid/2,body_elev+bodywid/3]) color("#00FF00") sphere(r=bodywid/4, $fn=20); translate([-bodywid/3,-bodywid/2,body_elev+bodywid/3]) color("#00FF00") sphere(r=bodywid/4, $fn=20); // antennae rotate([20,0,-45]) translate([0,0,body_elev+1]) color("brown") cylinder(bodywid*1.3, r=legr/2, $fn=8); rotate([-20,0,45]) translate([0,0,body_elev+1]) color("brown") cylinder(bodywid*1.3, r=legr/2, $fn=8); } // blank body segment, used by bodyseg() and head() module bodyblank() { translate([0,0,body_elev]) color("gray") scale([0.618,1,1]) { cylinder(2*legr, r=bodywid, $fn=24); translate([0,0,2*legr]) scale([1,1,0.382]) sphere(r=bodywid, $fn=24); } } // Model of one leg. // The 'foot' of the leg follows a straight line backward on the floor, and arches // over forward in a semicircle. The knee flexes to accommodate moving backward in // a straight line, with full extension in the forward and back positions. module leg(phase=0, offset=0) { ph = (phase + offset + 3600) % 360; if (ph < 180) { x = 0.5*xmotion*cos(ph); y = 0.5*xmotion*sin(ph); zrot = -asin(x/leglen); xrot = asin(y/leglen); rotate([0,0,zrot]) rotate([xrot,0,0]) ballcylinder([0,0,0], [0,leglen/2,legkneeht], [0,leglen,0]); } else { x = xmotion * ((ph-180)/180 - 0.5); zrot = -asin(x/leglen); ll = sqrt(llmin*llmin + x*x); kneeht = sqrt(legseglen*legseglen - ll*ll*0.25); rotate([0,0,zrot]) ballcylinder([0,0,0], [0,ll/2,kneeht], [0,ll,0]); } } // the leg is two segments with a knee; parameters are coordinates of the root, knee, and foot. module ballcylinder(p1, p2, p3, r=legr) { fn = 10; hull() { translate(p1) sphere(r=r, $fn=fn); translate(p2) sphere(r=r, $fn=fn); } hull() { translate(p2) sphere(r=r, $fn=fn); translate(p3) sphere(r=r, $fn=fn); } } // moving floor tiles module floor(phase=0) { xp = phase/360 * 2*xmotion; for(i=[0:nsegs+6]) let(x=(i-nsegs/2-3)*xmotion) for(j=[0:10]) let(y=(j-5)*xmotion, col = (i+j)%2==0 ? "white":"lightblue") translate([x+xp,y,0]) color(col) cube([xmotion,xmotion,0.1], center=true); }
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29 ekaina 2022
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Data/Ordua | Iruditxoa | Neurriak | Erabiltzailea | Iruzkina | |
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oraingoa | 04:30, 4 uztaila 2022 | 320 × 240 (1,28 MB) | Anachronist | Uploaded own work with UploadWizard |
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