inverse dynamics
the inverse dynamics
problem consists of determining the joint
generalized forces
τ(t) (acting at the joints
of the manipulator) needed to generate the
motion specified by the joint generalized po-
sition
q(t), velocities ˙q(t), and accelerations
¨q(t). The inverse dynamics solution is used
in model based control algorithms for manip-
ulators.
inverse dynamics linearizing control
in-
verse dynamics linearizing control is an oper-
ational space control scheme that uses a feed-
back control signal that leads to the system
of double integrators. In this case, nonlinear
dynamics of the manipulator is compensated
and the inverse dynamics linearizing control
allows full trajectory tracking in the opera-
tional space.
inverse filter
for a linear time invariant
(LTI) filter, the filter which, when cascaded
with it produces white noise output for a
white noise input. The inverse filter of an
LTI filter with impulse response
h(n) has im-
pulse response
a(n), where h(n) ∗ a(n) =
δ(n). Alternatively, in the frequency domain,
the inverse filter
A(z) satisfies the relation
A(z)H (z) = 1. The inverse filter A(z) is
said to whiten the filter
h(n) to produce δ(n)
inverse Fourier transform
See
Fourier
transform
.
inverse homogeneous transformation ma-
trix
in general, the inverse of the homo-
geneous transformation matrix describes the
reference coordinate frame with respect to
the transformed frame and has the form
T
−1
=
n
x
n
y
n
z
−p · n
o
x
o
y
o
z
−p · o
a
x
a
y
a
z
−p · a
0 0 1
1
where “
·” denotes a scalar product between
two vectors.
inverse kinematics problem
for a desired
position and orientation of the end-effector
of the manipulator and the geometric link
parameters with respect to the reference co-
ordinate system, calculates a set of desired
joint variables vector. The inverse kinemat-
ics problem has usually multiple solutions.
In general, the inverse kinematics can be
solved using algebraic, interactive, or geo-
metric methods.
inverse Laplace transform
See
Laplace
transform
.
inverse Nyquist array (INA)
an array of
Nyquist plots of the elements of the inverse
frequency response matrix ˆ
Q(jω) of a multi-
input–multi-output transfer function model
Q(s) of an open loop multivariable sys-
tem. Each diagonal graph can be viewed as
a single-input–single-output inverse Nyquist
diagram from which the stability of the mul-
tivariable system can be deduced, under cer-
tain conditions relating to diagonal domi-
nance. A typical INA diagram, for a MIMO
system with two inputs and two outputs,
clearly shows the individual polar plots and
the Gershgorin circles forming a band with
canters along the diagonal elements. Rosen-
brock, H. H., Computer-Aided Control Sys-
tem Design, Academic Press, London, 1974.
See also
Gershgorin circle
.
inverse Nyquist plot
a graphical repre-
sentation of the complex function
ˆq(jw)
which is the inverse of the frequency response
model of the open loop transfer function sys-
tem
q(s) that is connected in a unity feedback
control loop. The stability of the resulting
closed loop system is deduced by the princi-
ple of the argument applied to this complex
function.
inverse problem
essentially, the prob-
lem of inverting a “forward” system. More
specifically, suppose we have some system
S(x) parameterized in terms of x, and sup-
pose we can define observations
y = O(S(x)).
c
2000 by CRC Press LLC