Ronan

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12 years, 133 days
East Grinstead, United Kingdom

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Happy new year everyone. Instead on making my usual new year resolutions, I though I would put up a request for some helpful  improvements here.

1) Please make search work properly. Allow searches to target specific sections. Posts, Questions, My own account, Other users. etc,

2) Add links to Maple help. Is there an online way of viewing Maple document? Or build Maple viewer into this site.

3) Add links to Maple Learn.

A question was raised recently on Stewart Gough platforms.  I decided to tidy up some old code to show platform position and leg lengths for any given displacement.
 

restart

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Hexapod Setup Data

 

RotZ := proc (delta) options operator, arrow; Matrix(1 .. 3, 1 .. 3, {(1, 1) = cos(delta), (1, 2) = -sin(delta), (1, 3) = 0, (2, 1) = sin(delta), (2, 2) = cos(delta), (2, 3) = 0, (3, 1) = 0, (3, 2) = 0, (3, 3) = 1}, datatype = anything, storage = rectangular, order = Fortran_order, subtype = Matrix) end proc

a[1] := Vector(3, [.5, 3.0, 0]); a[2] := evalf(RotZ(20*((1/180)*Pi)).a[1]); a[3] := evalf(RotZ(100*((1/180)*Pi)).a[2]); a[4] := evalf(RotZ(20*((1/180)*Pi)).a[3]); a[5] := evalf(RotZ(100*((1/180)*Pi)).a[4]); a[6] := evalf(RotZ(20*((1/180)*Pi)).a[5])

b[1] := evalf(.7*RotZ(-40*((1/180)*Pi)).a[1]); b[2] := evalf(RotZ(100*Pi*(1/180)).b[1]); b[3] := evalf(RotZ(20*Pi*(1/180)).b[2]); b[4] := evalf(RotZ(100*Pi*(1/180)).b[3]); b[5] := evalf(RotZ(20*Pi*(1/180)).b[4]); b[6] := evalf(RotZ(100*Pi*(1/180)).b[5])

Zeroposn := Vector(3, [0, 0, 3])

Tx := Vector(3, [1, 0, 0]); Ty := Vector(3, [0, 1, 0]); Tz := Vector(3, [0, 0, 1])

``

``

NULL

Procedures

 

PlatPosn := proc (x := 0, y := 0, z := 0, alpha := 0, beta := 0, delta := 0) local i, v, Rot, L1, L2, L3, L4, L5, L6; global txn, tyn, tzn, ctrp; description "Calculates the platform position in the Global Coordinates, Unit normals and Leg Lengths"; v := Vector(3, [x, y, z]); ctrp := Zeroposn+v; Rot := Matrix(1 .. 3, 1 .. 3, {(1, 1) = cos(delta)*cos(beta), (1, 2) = -sin(delta)*cos(alpha)+cos(delta)*sin(beta)*sin(alpha), (1, 3) = sin(delta)*sin(alpha)+cos(delta)*sin(beta)*cos(alpha), (2, 1) = sin(delta)*cos(beta), (2, 2) = cos(delta)*cos(alpha)+sin(delta)*sin(beta)*sin(alpha), (2, 3) = -cos(delta)*sin(alpha)+sin(delta)*sin(beta)*cos(alpha), (3, 1) = -sin(beta), (3, 2) = cos(beta)*sin(alpha), (3, 3) = cos(beta)*cos(alpha)}, datatype = anything, storage = rectangular, order = Fortran_order, subtype = Matrix); for i to 6 do bn || i := Zeroposn+v+Rot.b[i] end do; txn := Rot.Tx; tyn := Rot.Ty; tzn := Rot.Tz; print(" Platform centre Global", ctrp); print(" Platform corner Co-ords Global", bn1, bn2, bn3, bn4, bn5, bn6); print("Platform Triad Vectors  ", "X green ", txn, "Y blue", tyn, "Z red ", tzn); L1 := sqrt((bn1-a[1])^%T.(bn1-a[1])); L2 := sqrt((bn2-a[2])^%T.(bn2-a[2])); L3 := sqrt((bn3-a[3])^%T.(bn3-a[3])); L4 := sqrt((bn4-a[4])^%T.(bn4-a[4])); L5 := sqrt((bn5-a[5])^%T.(bn5-a[5])); L6 := sqrt((bn6-a[6])^%T.(bn6-a[6])); print("Leg Lengths"); print("L1= ", L1); print("L2= ", L2); print("L3= ", L3); print("L4= ", L4); print("L5= ", L5); print("L6= ", L6) end proc

``

PlatPlot := proc () local Base, Platformdisplacement, picL1, picL2, picL3, picL4, picL5, picL6; global tx0, ty0, tz0; description "Displays the Hexapod"; Base := plots:-polygonplot3d(Matrix([a[1], a[2], a[3], a[4], a[5], a[6]], datatype = float), color = black, transparency = .5); Platformdisplacement := plots:-polygonplot3d(Matrix([seq(bn || i, i = 1 .. 6)]), color = cyan, transparency = .5); picL1 := plots:-arrow(a[1], bn || 1-a[1], colour = green); picL2 := plots:-arrow(a[2], bn || 2-a[2], colour = blue); picL3 := plots:-arrow(a[3], bn || 3-a[3], colour = blue); picL4 := plots:-arrow(a[4], bn || 4-a[4], colour = blue); picL5 := plots:-arrow(a[5], bn || 5-a[5], colour = blue); picL6 := plots:-arrow(a[6], bn || 6-a[6], colour = orange); tx0 := plots:-arrow(ctrp, txn, colour = green); ty0 := plots:-arrow(ctrp, tyn, colour = blue); tz0 := plots:-arrow(ctrp, tzn, colour = red); plots:-display(Base, picL1, picL2, picL3, picL4, picL5, picL6, Platformdisplacement, tx0, ty0, tz0, axes = box, labels = [X, Y, Z], scaling = constrained) end proc

``

NULL

``

``

PlatPosn()

"L6= ", 3.586394355

(1)

PlatPlot()

 

NULL

PlatPosn(.52, -.89, .7, .2, .67, .3)

"L6= ", 3.055217994

(2)

PlatPlot()

 

NULL

NULL

 

NULL

print('tzn' = LinearAlgebra:-CrossProduct(txn, tyn), `= `, tzn)

tzn = Vector[column](%id = 18446744074564617750), `= `, Vector[column](%id = 18446744074328082542)

(3)

``

``NULL

NULL

Rotation Matrices

NULL

``

 

RotZ := Matrix(3, 3, {(1, 1) = cos(delta), (1, 2) = -sin(delta), (1, 3) = 0, (2, 1) = sin(delta), (2, 2) = cos(delta), (2, 3) = 0, (3, 1) = 0, (3, 2) = 0, (3, 3) = 1})

RotY := Matrix(3, 3, {(1, 1) = cos(beta), (1, 2) = 0, (1, 3) = sin(beta), (2, 1) = 0, (2, 2) = 1, (2, 3) = 0, (3, 1) = -sin(beta), (3, 2) = 0, (3, 3) = cos(beta)})

RotX := Matrix(3, 3, {(1, 1) = 1, (1, 2) = 0, (1, 3) = 0, (2, 1) = 0, (2, 2) = cos(alpha), (2, 3) = -sin(alpha), (3, 1) = 0, (3, 2) = sin(alpha), (3, 3) = cos(alpha)})

NULL

ROT := RotZ.RotY.RotX

Matrix(%id = 18446744074564619310)

(4)

``

``

``


 

Download Reverse_Kinematics_Stewart_Gough_Platform.mw

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