Computational Intelligence - November 2013 - 32

Code fragment 4.1 The compiled high level MATLAB script
that represents the name tag "following trajectory".
function following_trajectory (MyTraj)

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StateDes = updating_target_state (MyTraj);

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[Acc , Om] = obtaining_inertial_states;

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[St ,Dcm] = forming_current_state (Acc, Om);

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Sigm = generating_guidance_potential (St, StateDes);

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U = generating_control_signal (St, Sigm);

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T = determining_thrust_vector (U, Dcm);

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implementing_thrust_vector (T);

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current state St and desired state Statedes.
figure 3 Editing agent code in an sEnglish plug-in under Eclipse.

MATLAB development language. The result is a series of interconnected m-files that are built from the user prescribed text,
linked to the core ontology that defines the conceptual data
structures used by the system.
First we illustrate the development of a medium level agent
skill that corresponds to the meaning tag following_trajectory, resulting in procedural code to perform the function of following a specific trajectory. Considering the abstractions that may complete this control action, intuitively one
must obtain a target (kinematic) state, determine the current
system state, implement a control law to produce a control signal that will act to drive the error between the desired and
actual states to zero and then implement this control signal in
hardware. Figure 3 illustrates the Eclipse based editor window
for the definition of a sentence Follow trajectory
Mytraj. with activity name following trajectory.
The following is a listing of a definition file (SEP-file = sEnglish Procedure file) to define the physical activity of "following
a trajectory" that may have been created by a mental activity of
the agent:
procedure name :: following trajectory
senglish sentences :: Follow trajectory
Mytraj.
process, repeat mode :: physproc, runOnce
input classes and local names::
trajectory[Mytraj]
output classes and local names::
senglish code :: Update the orbital target
state Statedes for trajectory Mytraj using
temporal progression. Obtain linear acceleration Acc and angular velocity Om from the
gyroscope. Form the current state St and the
direction cosine matrix Dcm using vision
information and angular velocity Om. Generate
guidance potential function Sigma based upon

32

IEEE ComputatIonal IntEllIgEnCE magazInE | novEmbEr 2013

Generate control signal U based upon current
state St and guidance potential function
Sigma. Determine the required thrust vector T
using the control signal U and direction
cosine matrix Dcm. Implement the required
thrust vector T on hardware.
matlab routines url:: www.sysbrain.org/asterocraft
conceptual graph:: [I]-(action)-[following](subj)-[trajectory:Mytraj]
testing formula:: Mytraj=rand_
object('trajectory');
following_trajectory(Mytraj);
section number :: 4
input defaults :: create_object('trajectory');

In "Code Fragment 4.1" each elemental abstraction to an
senglish code, the high level abstraction of followi n g _ t r a j e c t o r y may be completely defined in a
structured and meaningful way; its meaning is completely
and transparently described by the subsequent abstractions.
The meaning of sentences is exactly the senglish code
implemented for dealing with trajectory following and upon
compilation. The generated following trajectory.m
file will be of the format:
In the above development all meaning tags are names of
actions formed from verbs. At any time the current agent
activity may be queried to result in a meaningful response,
which is useful for a human operator querying the current
actions of an agent. A naive human operator may query the
system to ask what it is doing and why, with the response
being given in a natural language format, supplemented with
reasoned logic behind the execution of these actions. Each
sEnglish sentence is matched with a routine call in MATLAB as well as with a similar looking predicate for logic
operations that abstracts away the (code based) meaning
behind the predicates. Basic predicate abstractions from sentences are applied to both the world environment and the
spacecraft model; these are passed by the Physical Engine to
http://www.sysbrain.org/astero
Table of Contents for the Digital Edition of Computational Intelligence - November 2013
