simon/tricycle-mechanical-design
1
0
Fork 0
Code Issues Pull requests Actions Packages Projects Releases Wiki Activity

First render with hull!

Browse source
This commit is contained in:
Simon Brooke 2025-09-17 10:46:53 +01:00
parent b95f639c30
commit 1befca0a60
5 changed files with 95 additions and 45 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
README.md
View file

@ -2,7 +2,7 @@
Design of a highly experimental recumbent tricycle, not software at all. Design of a highly experimental recumbent tricycle, not software at all.
![Subframe and four bar linkage](subframe-and-fourbar.png) ![Latest render](sketches/latest-render.png)
## Status ## Status
@ -14,12 +14,12 @@ The current model is built with [OpenSCAD](https://openscad.org/); to render the
The following libraries are used into this model. They should be downloaded and installed into your [OpenSCAD library directory](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Libraries), which on Linux systems is usually `$HOME/.local/share/OpenSCAD/libraries`. The following libraries are used into this model. They should be downloaded and installed into your [OpenSCAD library directory](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Libraries), which on Linux systems is usually `$HOME/.local/share/OpenSCAD/libraries`.
| Library | Referenced as | Author | Licence | | Library | Referenced as | Author | Licence | Notes |
| ------------------------------------------------------------ | ------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | | ------------------------------------------------------------ | ------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | -------------------------------------------------------- |
| [BentSim](https://github.com/PRouzeau/BentSim) | BentSim | [Pierre Rouzeau](https://rouzeau.net/) | [GPL](https://github.com/PRouzeau/BentSim/blob/master/LICENSE) | | [BentSim](https://github.com/PRouzeau/BentSim) | BentSim | [Pierre Rouzeau](https://rouzeau.net/) | [GPL](https://github.com/PRouzeau/BentSim/blob/master/LICENSE) | Currently not used; appears to have conflicts with BOSL2 |
| [Sprocket Generator V2](https://www.thingiverse.com/thing:3059422) | SprocketGenerator2 | [Hampus Andersson](https://www.thingiverse.com/haand001/designs) | [Creative Commons Attribution](https://creativecommons.org/licenses/by/4.0/) | | [Sprocket Generator V2](https://www.thingiverse.com/thing:3059422) | SprocketGenerator2 | [Hampus Andersson](https://www.thingiverse.com/haand001/designs) | [Creative Commons Attribution](https://creativecommons.org/licenses/by/4.0/) | |
| [NACA Airfoils - 4 digit fully parametric](https://www.thingiverse.com/thing:898554)] | NACAAirfoils | [Rudolf Huttary](https://www.thingiverse.com/parkinbot/designs) | [Creative Commons - Attribution - Non-Commercial](https://creativecommons.org/licenses/by-nc/4.0/) | | [NACA Airfoils - 4 digit fully parametric](https://www.thingiverse.com/thing:898554)] | NACAAirfoils | [Rudolf Huttary](https://www.thingiverse.com/parkinbot/designs) | [Creative Commons - Attribution - Non-Commercial](https://creativecommons.org/licenses/by-nc/4.0/) | |
| [The Belfry OpenScad Library, v2](https://github.com/BelfrySCAD/BOSL2) | BOSL2 | Numerous contributors | [BSD 2-Clause](https://github.com/BelfrySCAD/BOSL2/blob/master/LICENSE) | | [The Belfry OpenScad Library, v2](https://github.com/BelfrySCAD/BOSL2) | BOSL2 | Numerous contributors | [BSD 2-Clause](https://github.com/BelfrySCAD/BOSL2/blob/master/LICENSE) | |

7
model/hull.scad
View file

@ -34,11 +34,10 @@ module hull_i() {
module hull() { module hull() {
intersection() { intersection() {
translate([2500,0,500]) translate([1850,0,500])
rotate([180, 90, 0]) rotate([180, 90, 0])
scale([20, 15.5, 20]) scale([20, 15.5, 15.5])
rotate_extrude() rotate_extrude()
//rotate([ 0, 90, 0])
import("library/hull-volume-of-rotation.svg"); import("library/hull-volume-of-rotation.svg");
translate([-400,0, 350]) translate([-400,0, 350])
@ -64,4 +63,4 @@ module hull() {
} }
} }
//hull(); // hull();

7
model/tricycle.scad
View file

@ -9,13 +9,14 @@ include <fourbar.scad>
include <hull.scad> include <hull.scad>
rotate([0, 0, 270]) rotate([0, 0, 270])
translate([0, 1200, 180]) translate([0, 1300, 180])
subframe(structure="carbon"); subframe(structure="carbon");
translate([0, 0, 320]) translate([0, 0, 320])
fourbar(700, 100, 30, 35, 650); fourbar(700, 100, 30, 35, 650);
translate([500, 0, 100]) translate([800, 0, 120])
rotate([0, 3, 0]) rotate([0, 4, 0])
color("forestgreen")
hull(); hull();
/* /*

BIN
sketches/latest-render.png Normal file
View file

Binary file not shown.
Side by side

After

Width:  |  Height:  |  Size: 94 KiB

112
sketches/subframe-bed-schematic.svg
View file

@ -9,6 +9,9 @@
id="svg1" id="svg1"
inkscape:version="1.4 (e7c3feb100, 2024-10-09)" inkscape:version="1.4 (e7c3feb100, 2024-10-09)"
sodipodi:docname="subframe-bed-schematic.svg" sodipodi:docname="subframe-bed-schematic.svg"
inkscape:export-filename="../../blogiv/content/img/subframe-bed-schematic.png"
inkscape:export-xdpi="96"
inkscape:export-ydpi="96"
xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
xmlns="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg"
@ -24,13 +27,13 @@
inkscape:deskcolor="#d1d1d1" inkscape:deskcolor="#d1d1d1"
inkscape:document-units="mm" inkscape:document-units="mm"
showgrid="true" showgrid="true"
inkscape:zoom="0.50394254" inkscape:zoom="1.4279216"
inkscape:cx="1185.651" inkscape:cx="600.17302"
inkscape:cy="646.89914" inkscape:cy="338.60403"
inkscape:window-width="1920" inkscape:window-width="2256"
inkscape:window-height="1011" inkscape:window-height="1423"
inkscape:window-x="0" inkscape:window-x="0"
inkscape:window-y="32" inkscape:window-y="0"
inkscape:window-maximized="1" inkscape:window-maximized="1"
inkscape:current-layer="layer1"> inkscape:current-layer="layer1">
<inkscape:grid <inkscape:grid
@ -132,9 +135,9 @@
id="tspan5">Not to scale.</tspan></text> id="tspan5">Not to scale.</tspan></text>
<path <path
style="fill:#333333;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#333333;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 222.0075,144.29526 h -61.91966 c 0,0 -1.04383,-0.10397 -1.47594,0.32814 -0.43211,0.43211 -0.4594,1.40307 -0.4594,1.40307 v 25.68556 c 0,0 13.32318,-1.47673 21.16125,-3.65677 7.83807,-2.18004 18.13538,-6.68042 25.245,-10.76625 7.10962,-4.08583 17.44875,-12.99375 17.44875,-12.99375 z" d="m 170.84683,165.47093 -0.65956,-18.73945 c -0.009,-1.00751 -0.87344,-2.40589 -2.44613,-2.43622 l -7.6533,0 c -1.18532,-0.0991 -1.96991,1.07942 -2.03306,2.53738 l 0.0977,24.87939 c 0,0 15.15086,-1.80846 21.16125,-3.65677 -5.60227,0.66912 -7.56138,0.23907 -8.46692,-2.58433 z"
id="path7" id="path7"
sodipodi:nodetypes="cczcczzc" /> sodipodi:nodetypes="cccccccc" />
<path <path
style="fill:none;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:none;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 166.64485,172.09259 c 0,0 -4.27128,0.71919 -7.19297,3.01642 -1.93119,1.28301 -2.96095,3.05138 -3.80531,5.15109" d="m 166.64485,172.09259 c 0,0 -4.27128,0.71919 -7.19297,3.01642 -1.93119,1.28301 -2.96095,3.05138 -3.80531,5.15109"
@ -283,76 +286,91 @@
style="fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.1" style="fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.1"
x="103.39312" x="103.39312"
y="188.66234" y="188.66234"
id="tspan47">moulding)</tspan></text> id="tspan47">moulding, for easier</tspan><tspan
<path sodipodi:role="line"
style="fill:#333333;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.1"
d="m 75.712175,144.29526 h 61.919655 c 0,0 1.04383,-0.10397 1.47594,0.32814 0.43211,0.43211 0.4594,1.40307 0.4594,1.40307 v 25.68556 c 0,0 -13.32318,-1.47673 -21.16125,-3.65677 -7.83807,-2.18004 -18.13538,-6.68042 -25.244995,-10.76625 -7.10962,-4.08583 -17.44875,-12.99375 -17.44875,-12.99375 z" x="103.39312"
id="path25" y="193.95399"
sodipodi:nodetypes="cczcczzc" /> id="tspan26">damage repair)</tspan></text>
<path <path
style="fill:none;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:none;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 131.07482,172.09259 c 0,0 4.27128,0.71919 7.19297,3.01642 1.93119,1.28301 2.96095,3.05138 3.80531,5.15109" d="m 131.07482,172.09259 c 0,0 4.27128,0.71919 7.19297,3.01642 1.93119,1.28301 2.96095,3.05138 3.80531,5.15109"
id="path26" id="path26"
sodipodi:nodetypes="czc" /> sodipodi:nodetypes="czc" />
<path
style="fill:#333333;stroke:#000000;stroke-width:0.499999;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 126.91564,165.50725 0.65956,-18.73945 c 0.009,-1.00751 0.87344,-2.40589 2.44613,-2.43622 h 7.6533 c 1.18532,-0.0991 1.96991,1.07942 2.03306,2.53738 l -0.0977,24.87939 c 0,0 -15.15086,-1.80846 -21.16125,-3.65677 5.60227,0.66912 7.56138,0.23907 8.46692,-2.58433 z"
id="path24"
sodipodi:nodetypes="cccccccc" />
<path <path
style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.57871;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.57871;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="M 138.30841,143.79171 H 131.319" d="M 138.30841,143.79171 H 131.319"
id="path27" /> id="path27" />
<path <path
style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 136.80857,143.06159 0.007,0.49221 h -0.47581 l -0.0656,6.34135 h -2.59232 v -6.30033 l -0.55783,-0.008 0.008,-0.57424 1.31256,0.0164 0.0492,5.61943 h -0.43794 v 1.24694 h 1.82269 v -1.27976 h -0.39212 l -0.008,-5.5784 z" d="m 136.80857,143.06159 0.007,0.49221 h -0.47581 l -0.0656,6.34135 h -2.59232 v -6.30033 l -0.55783,-0.008 0.008,-0.57424 1.31256,0.0164 c 0.13055,14.9104 1.0499,11.21576 1.03383,0.008 z"
id="path28" id="path28"
sodipodi:nodetypes="ccccccccccc" />
<path
style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 136.80857,172.78765 0.007,-0.49221 h -0.47581 l -0.0656,-6.34135 h -2.59232 v 6.30033 l -0.55783,0.008 0.008,0.57424 1.31256,-0.0164 0.0492,-5.61943 h -0.43794 v -1.24694 h 1.82269 v 1.27976 h -0.39212 l -0.008,5.5784 z"
id="path9"
sodipodi:nodetypes="ccccccccccccccccc" /> sodipodi:nodetypes="ccccccccccccccccc" />
<path
style="fill:#e9ddaf;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 136.80857,172.78092 0.007,-0.49221 h -0.47581 l -0.0656,-6.34135 h -2.59232 v 6.30033 l -0.55783,0.008 0.008,0.57424 1.31256,-0.0164 c 0.13055,-14.9104 1.0499,-11.21576 1.03383,-0.008 z"
id="path36"
sodipodi:nodetypes="ccccccccccc" />
<rect <rect
style="fill:#4d4d4d;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#4d4d4d;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
id="rect28" id="rect28"
width="1.7309476" width="1.7309476"
height="1.0418501" height="1.0418501"
x="-135.84735" x="-135.84735"
y="148.68102" y="171.74915"
transform="scale(-1,1)" /> transform="scale(-1,1)" />
<rect <rect
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.196094;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
id="rect35" id="rect35"
width="1.1484985" width="1.052405"
height="7.5308576" height="31.602308"
x="134.40686" x="134.45491"
y="141.10095" /> y="141.149" />
<rect <rect
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
id="rect29" id="rect29"
width="0.91059875" width="0.91059875"
height="1.0336534" height="1.0336534"
x="-135.40434" x="-135.40434"
y="148.68922" y="171.75735"
transform="scale(-1,1)" /> transform="scale(-1,1)" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,143.05339 1.05006,-0.26251" d="m 134.48556,142.68156 1.05006,-0.26251"
id="path29" /> id="path29" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,142.8565 1.05006,-0.26251" d="m 134.48556,142.48467 1.05006,-0.26251"
id="path30" /> id="path30" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,142.64321 1.05006,-0.26251" d="m 134.48556,142.27138 1.05006,-0.26251"
id="path31" /> id="path31" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,142.42992 1.05006,-0.26251" d="m 134.48556,142.05809 1.05006,-0.26251"
id="path32" /> id="path32" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,142.24944 1.05006,-0.26251" d="m 134.48556,141.87761 1.05006,-0.26251"
id="path33" /> id="path33" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,142.06896 1.05006,-0.26251" d="m 134.48556,141.69713 1.05006,-0.26251"
id="path34" /> id="path34" />
<path <path
style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" style="fill:#999999;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
d="m 134.48556,141.87207 1.05006,-0.26251" d="m 134.48556,141.50024 1.05006,-0.26251"
id="path35" /> id="path35" />
<path <path
style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)" style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)"
@ -360,8 +378,9 @@
id="path40" /> id="path40" />
<path <path
style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)" style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)"
d="m 211.6589,165.78135 -13.22578,-8.02828" d="m 211.6589,165.78135 -38.64892,-8.17232"
id="path42" /> id="path42"
sodipodi:nodetypes="cc" />
<path <path
style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)" style="fill:none;fill-opacity:1;stroke:#000000;stroke-width:0.1;stroke-dasharray:0.4, 0.1;stroke-dashoffset:0;stroke-opacity:1;marker-end:url(#DartArrow)"
d="m 172.81688,134.54994 -6.03281,7.23938" d="m 172.81688,134.54994 -6.03281,7.23938"
@ -424,5 +443,36 @@
style="fill:#000000;stroke:#000000;stroke-width:0.5;stroke-dasharray:2, 1, 0.5, 1;stroke-dashoffset:0;stroke-opacity:1" style="fill:#000000;stroke:#000000;stroke-width:0.5;stroke-dasharray:2, 1, 0.5, 1;stroke-dashoffset:0;stroke-opacity:1"
d="M 148.5,11.025561 V 197.41007" d="M 148.5,11.025561 V 197.41007"
id="path6" /> id="path6" />
<text
xml:space="preserve"
style="font-size:4.23333px;font-family:'Kells Uncial';-inkscape-font-specification:'Kells Uncial';text-align:center;writing-mode:lr-tb;direction:ltr;text-anchor:middle;opacity:0.992424;fill:#ffffff;stroke:#000000;stroke-width:2"
x="200.20596"
y="123.56631"
id="text6"><tspan
sodipodi:role="line"
id="tspan6"
style="font-style:normal;font-variant:normal;font-weight:bold;font-stretch:normal;font-size:4.23333px;font-family:'Liberation Sans';-inkscape-font-specification:'Liberation Sans Bold';fill:#000000;stroke:none;stroke-width:2"
x="200.20596"
y="123.56631">'Short stud'<tspan
style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-family:'Liberation Sans';-inkscape-font-specification:'Liberation Sans'"
id="tspan18"> inset into XPS</tspan></tspan></text>
<text
xml:space="preserve"
style="font-size:4.23333px;font-family:'Kells Uncial';-inkscape-font-specification:'Kells Uncial';text-align:start;writing-mode:lr-tb;direction:ltr;text-anchor:start;opacity:0.992424;fill:#ffffff;stroke:#000000;stroke-width:2"
x="100.58082"
y="106.2038"
id="text13"><tspan
sodipodi:role="line"
id="tspan13"
style="font-style:normal;font-variant:normal;font-weight:bold;font-stretch:normal;font-size:4.23333px;font-family:'Liberation Sans';-inkscape-font-specification:'Liberation Sans Bold';text-align:start;text-anchor:start;fill:#000000;stroke:none;stroke-width:2"
x="100.58082"
y="106.2038">'Long stud' <tspan
style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-family:'Liberation Sans';-inkscape-font-specification:'Liberation Sans'"
id="tspan17">through </tspan></tspan><tspan
sodipodi:role="line"
style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:4.23333px;font-family:'Liberation Sans';-inkscape-font-specification:'Liberation Sans';text-align:start;text-anchor:start;fill:#000000;stroke:none;stroke-width:2"
x="100.58082"
y="111.98219"
id="tspan16">bolted from under hull</tspan></text>
</g> </g>
</svg> </svg>

Side by side Swipe Overlay

Before

Width:  |  Height:  |  Size: 22 KiB

After

Width:  |  Height:  |  Size: 25 KiB