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4 wheel independent drive & independent steering (“swerve”)

by: **Ether***calculate robot-centric and field-centric wheel speeds and wheel steering angles for a vehicle with four-wheel independent drive and independent steering (“swerve” drive)*

UPDATED FILES ARE AT THE BOTTOM, SO SCROLL ALL THE WAY DOWN

Derivation of inverse kinematic equations for three-degree-of-freedom (3 DoF) control for 4-wheel independent steering and independently driven swerve.

Equations and pseudo-code for above.

Convert Ackermann commands to 3 DoF control.

Convert Cartesian coordinates to 0 to 360 degrees, CW or CCW, from +/- X or Y axis, or from an arbitrary Initial Ray. **See Errata note below**

Inverse kinematics Excel spreadsheet with graphical display to test and display swerve wheel speed and steering angle calculations.

Forward kinematics calculator implemented in Maxima.

Inverse Kinematics for swerve with 3 or more wheels. The wheels can be located anywhere on the robot; they don’t have to be at the corners of a rectangle.

Errata:

There is a typo on Page 2 of document convert_XY_degrees RevE.PDF: The equation should read theta -= 360*floor(0.5+theta/360)

Derivation of Inverse Kinematics for Swerve.pdf (48.1 KB)

Calculate Swerve Wheel Speeds and Steering angles.pdf (15.3 KB)

Ackermann7a.pdf (49.2 KB)

swerve_tester_6.xls (27.5 KB)

convert_XY_degrees revE.pdf (25.3 KB)

swerve_tester_8.xls (28 KB)

swerveForwardKinematics.zip (16.3 KB)

CWYdeg.pdf (9.32 KB)

Cartesian2angle.zip (6.6 KB)

moon.pdf (25.6 KB)

rotary.pdf (25 KB)

dosado.pdf (25.6 KB)

swerveN.pdf (60.2 KB)

convert_XY_degrees revF.pdf (36.9 KB)