IEEE Robotics & Automation Magazine - March 2013 - 79

Motivate to Eat
Put Food or Drink
in Mouth

Obtain Food or Drink
Obtain Food
from Main Dish
Encourage Orient

Pick Up
Beverage
Encourage Orient

Obtain Food
from Side Dish
Encourage Orient

Drink
Beverage

Eat Food

Encourage Orient Encourage Orient

(a)
Motivate to Play
Memory Game
Flip Over
Card(s)
Instruction

Remove
Cards
Celebration

Flip Back
Cards
Encouragement

Help
(b)
Figure 6. Activity task graphs for (a) the meal eating activity and (b) the memory card game.

head [21]. Different combinations of face and trunk orientations may indicate that a user is attempting to be involved in
multiple courses of action, which could lead to short-term or
long-term distraction (where the latter is simply defined in
Table 2 as distracted) [21].
Robot Behavior Deliberation
Currently, a finite-state machine is used to determine the
assistive behaviors of Brian 2.1 on the basis of the activity
and user-state inputs. To promote the social dimensions of
an activity, Brian 2.1 greets a person, tells jokes, and provides general positive statements about the interaction or
the activity. Since the robot will interact with elderly people
with different interaction preferences and/or varying
degrees of cognitive impairment, it has the ability to personalize its actions on the basis of the person's user state and
task compliance.

perform a meal task. Orienting actions are designed to provide general awareness of the activity and the environment.
The robot provides encouraging behaviors using a happy
emotional state, while orientating behaviors are provided in a
neutral emotional state. When a user becomes (long-term)
distracted, the robot provides orientating behaviors in a sad
emotional state. Example robot behaviors are presented in
Table 3 and Figure 7(a) and (b).
Robot Behaviors for the Memory Card Game
The robot's behaviors for the memory card-game activity are
based on the overall objective of identifying and checking that
all pairs of cards have been matched correctly. The behaviors
are categorized into providing: 1) instructions-guiding a user
to flip cards, 2) celebration-congratulating a user on finding
a matching pair of cards, 3) encouragement-reinforcement
to try again when a match is not found, and 4) help-identifying the location of a matching card when n rounds have been
played without a match. For the study presented herein, we

Robot Behaviors for the Meal-Eating Activity
The robot's behaviors for the meal-eating
activity are based on the objective of motivatTable 3. Example robot behaviors for meal-eating activity.
ing a user to eat or drink while promoting the
social dimensions of eating (i.e., telling jokes).
Behavior Type
Example Behavior
The behaviors are categorized into prompts to
Encourage to obtain
"The main dish smells amazing. Why don't you
obtain food from a dish or lift a beverage and
food from main dish
pick up some food with your spoon."
to eat food or drink a beverage. The task
Orient to obtain food
"Your side dish is located at the bottom right corner
from side dish
of your tray." (The robot points to the side dish.)
graph for the meal-eating activity is shown in
Encourage
to
eat
food
"What you have on your spoon looks delicious.
Figure 6(a). Two techniques are used to motiWhy don't you take a bite and see how it tastes."
vate the person to complete a given meal task:
Joke and positive
"Why did the cookie go to the doctor? She was
encourage and orient. Encouraging behaviors
statements
feeling crummy." (The robot chuckles and puts
are positive reasoning tactics that are provided
one hand in front of its mouth.)
along with prompts to convince the user to
March 2013

IEEE ROBOTICS & AUTOMATION MAGAZINE

Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - March 2013