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5. 2

Base PCG Parameterization

By applying the balance control of Chapter 4 to various base PCGs, it is possible to achieve

controlled variations on basic walking motions such as balanced turns, bent over walks, and

different stride rates. A more powerful feature of these gait variations is that they can sometimes

be predictably interpolated.

That is, given two different styles of walking, based on PCGs B1

and B2, it is possible to interpolate the control in order to obtain a motion that qualitatively

interpolates the respective motions.

More precisely, the interpolation procedure can be described as follows:

Define bas the balance control process which operates on a base PCG to balance it as described in Chapter 3. Given B1and B2, the parameter sets defining two base PCGs, and given that b( B1 )and

b( B2 )are both successful (i.e. that they don't fall), we often find that

interpolation

the

control

b( aB1 + (1 - a)B2 )

varies smoothly with aand is qualitatively similar to what we might imagine a physically

correct motion interpolation to be, namely

ab( B1 ) + (1 - a)b( B2 ).

There is no guarantee that any such successful interpolation exists.

In

practice,

however,

smoothly interpolating parameterizations can be found often enough to make them useful.