Page 100 - Dynamic Vision for Perception and Control of Motion

3 Subjects and Subject Classes
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forces are applied at proper wheels. This device has
been introduced as a mass product (especially in O
Europe) after the infamous “moose tests” of a Swed- F fr
ish journalist with a brand new type of vehicle. F fl
He was able to topple over this vehicle toward
the end of a maneuver intended to avoid collision
with a moose on the road; the first sharp turn did not cg a
do any serious harm. Only the combination of three
sharp turns in opposite directions at a certain fre- F
quency in resonance with the eigenfrequencies of rl b Tr F
the car suspension produced this effect. Again, this rr
indicates how important knowledge of dynamic be-
Figure 3.15. Frictional and
havior of the car and “maneuvers” as stereotypical inertial forces yield torques
control sequences can be. around all axes; in curves,

3.4.3 Basic Modes of Control Defining Skills

In general, there are two components of control activation involved in intelligent
systems. If a payoff function is to be optimized by the maneuver, previous experi-
ence will have shown that certain control time histories perform better than others.
It is essential knowledge for good or even optimal control of dynamic systems to
know, in which situations what type of maneuver should be performed with which
set of parameters; usually, the maneuver is defined by certain time histories of (co-
ordinated) control input. The unperturbed trajectory corresponding to this nominal
feed-forward control time history is also known, either stored or computed in par-
allel by numerical integration of the dynamic model exploiting the given initial
conditions and the nominal control input. If perturbations occur, another important
knowledge component is how to link additional control inputs to the deviations
from the nominal (optimal) trajectory to counteract the perturbations effectively
(see Figure 3.7). This has led to the classes of feed-forward and feedback control in
systems dynamics and control engineering:

1. Feed-forward components U ff derived from a deeper understanding of the proc-
ess controlled and the maneuver to be performed.
2. Feedback components u fb to force the trajectory toward the desired one despite
perturbations or poor models underlying step 1.

3.4.3.1 Feed-forward Control: Maneuvers

There are classes of situations for which the same (or similar) kinds of control laws
are useful; some parameters in these control laws may be adaptable depending on
the actual states encountered.
Heading change maneuvers: For example, to perform a change in driving direc-
tion, the control time history input displayed in Figure 3.13 is one of a generic
class of realizations. It has three phases with constant steering rate, two of the same