DHFactor

Simplify symbolic link transform expressions

f = dhfactor(s) is an object that encodes the kinematic model of a robot provided by a string s that represents a chain of elementary transforms from the robot's base to its tool tip. The chain of elementary rotations and translations is symbolically factored into a sequence of link transforms described by DH parameters.

For example:

s = 'Rz(q1).Rx(q2).Ty(L1).Rx(q3).Tz(L2)';

indicates a rotation of q1 about the z-axis, then rotation of q2 about the x-axis, translation of L1 about the y-axis, rotation of q3 about the x-axis and translation of L2 along the z-axis.

Methods

base	the base transform as a Java string
tool	the tool transform as a Java string
command	a command string that will create a SerialLink() object representing the specified kinematics
char	convert to string representation
display	display in human readable form

Example

>> s = 'Rz(q1).Rx(q2).Ty(L1).Rx(q3).Tz(L2)';
>> dh = DHFactor(s);
>> dh
DH(q1+90, 0, 0, +90).DH(q2, L1, 0, 0).DH(q3-90, L2, 0, 0).Rz(+90).Rx(-90).Rz(-90)
>> r = eval( dh.command('myrobot') );

Notes

Variables starting with q are assumed to be joint coordinates.
Variables starting with L are length constants.
Length constants must be defined in the workspace before executing the last line above.
Implemented in Java.
Not all sequences can be converted to DH format, if conversion cannot be achieved an error is generated.

Reference

A simple and systematic approach to assigning Denavit-Hartenberg parameters, P.Corke, IEEE Transaction on Robotics, vol. 23, pp. 590-594, June 2007.
Robotics, Vision & Control, Sec 7.5.2, 7.7.1, Peter Corke, Springer 2011.

DHFactor

Methods

Example

Notes

Reference

See also