Assistive Technology: The Official Journal of RESNA
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Assistive Technology: The Official Journal of RESNA
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The Design of an Interactive Assistive Kitchen System
a b c
Maurizio Ficocelli Ph.D & Goldie Nejat Ph.D
a
Department of Mechanical Engineering, State University of New York, Stony Brook, New
York, USA
b
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto,
Ontario, Canada
c
Toronto Rehabilitation Institute, Toronto, Ontario, Canada
Accepted author version posted online: 13 Feb 2012.Version of record first published: 27 Sep
2012.
To cite this article: Maurizio Ficocelli Ph.D & Goldie Nejat Ph.D (2012): The Design of an Interactive Assistive Kitchen System,
Assistive Technology: The Official Journal of RESNA, 24:4, 246-258
To link to this article: http://dx.doi.org/10.1080/10400435.2012.659834
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Assistive Technology® , 24:246–258, 2012
Copyright © 2012 RESNA
ISSN: 1040-0435 print/1949-3614 online
DOI: 10.1080/10400435.2012.659834
The Design of an Interactive Assistive
Kitchen System
Maurizio Ficocelli, Ph.D1 and
Goldie Nejat, Ph.D2,3 ABSTRACT As the world’s elderly population drastically increases,
1
Department of Mechanical aging-related cognitive impairments have become one of the biggest
Engineering, State University of healthcare concerns. In this paper, we present the design of an assistive kitchen
New York at Stony Brook, Stony
system consisting of a user interface with two-way speech communication and
Brook, New York
2
Department of Mechanical
an automated cabinet system to help promote aging-in-place. The assistive
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and Industrial Engineering, kitchen system incorporates a cognitive assistance feature that helps the user
University of Toronto, Toronto, in overcoming initiation, planning, attention, and memory deficits, while
Ontario, Canada performing kitchen-based activities of daily living (ADLs) such as storing and
3
Toronto Rehabilitation retrieving items, and obtaining recipes for meal preparation. This feature works
Institute, Toronto, Ontario, synchronously with the automated kitchen cabinet to directly provide the
Canada
location of an item to a user, bring the item in closer reach and also prompt
the user to retrieve the item. An initial prototype of the assistive kitchen
system has been developed and performance testing has been conducted.
The testing has shown high success rates for users’ retrieving and storing
specified kitchen items. A small scale study was also conducted measuring the
acceptance and use of the proposed system by older adults. The results show
promise for the further development and use of the system for the outlined
kitchen ADLs.
KEYWORDS assistive kitchen system, automated cabinet, item retrieval/storage
INTRODUCTION
In the next few decades, 20%–32% of the population of a number of coun-
tries such as Canada, France, Germany, Italy, Japan, and the U.S. will be over
the age of 65 (Kinsella & Velkolt, 2001; Dobriansky, Suzman, & Hodes, 2007).
For this aging population, there is a high prevalence of cognitive impairment.
Cognitive impairment can progressively diminish a person’s memory, orienta-
tion, verbal skills, visuospatial ability, abstract reasoning, and attentional skills
(Tatemichi et al., 1994), hence, increasing the need for assistance with everyday
Address correspondence to Goldie activities. In general, this population overwhelmingly prefers to stay in their
Nejat, Mechanical and Industrial homes and age-in-place as independently as possible (Mahoney, Mahoney, &
Engineering, 5 King’s College Road,
Liss, 2009). However, a decline in cognitive abilities may make it difficult to
Toronto, Ontario, M5S 3G8 Canada.
E-mail: nejat@mie.utoronto.ca maintain such independence in the comfort of their own homes.
246
To date, research has been conducted to provide In the last few decades, kitchen designs and
solutions to promote aging-in-place. In order to match appliances have become more automated using
the high demand for health care services; various microprocessors and an assortment of sensor and
“Smart Home” initiatives are being developed. These actuator technologies, however, these kitchens have
initiatives can broadly be divided into three different still been designed without considering the needs of
categories: (1) projects focused on providing a means elderly users. When considering designing an assistive
of telecommunication or “virtual visits” between the kitchen for the elderly there are four main requirements
elderly and their relatives using remote monitoring that should be considered: (1) information providing,
(Mahoney, Mutchler, Tarlow, & Liss, 2008), (2) systems (2) storing and retrieving of items, (3) meal prepara-
that help users with cognitive and physical impair- tion and cooking, and (4) meal monitoring. In this
ments perform activities of daily living (ADLs) inde- paper, we present the design and initial prototype of
pendently (Lesser et al., 1999; Rantz et al., 2006; an interactive assistive kitchen system for the elderly
Yamazaki, 2006; Mihailidis, Boger, Craig, & Hoey, focusing on the following main activities: (1) informa-
2008), and (3) wearable accessories or devices that can tion providing in terms of recalling items’ availability
monitor the health of a person (Park & Jayaraman, and locations, (2) storing and retrieving items from cab-
2003; Korhonen, Parkka, & Van Gils, 2003; Asada, inet shelves, and (3) recipe providing. A performance
Shaltis, Reisner, Rhee, & Hutchinson, 2003; Tierney, study is also presented to verify the feasibility of the
Tamada, Potts, Jovanovic, & Garg, 2001). proposed system and its acceptance and future use.
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Our research focuses on the second category of This paper addresses the need for an assistive kitchen
smart home systems, namely on the development of system that incorporates a cognitive assistance feature
assistive technologies for the elderly in order to assist to help a user overcome initiation, planning, attention,
them with ADLs to promote aging-in-place (Nejat & and memory deficits, while performing the regular
Ficocelli, 2008; Chan, Nejat, & Chen, 2011; McColl, kitchen activities of storing and retrieving items, and
Chan, & Nejat, 2012). ADLs can be defined as (Lawton recipe finding. This feature works synchronously with
& Brody, 1969; Rogers, Meyer, Walker, & Fisk, 1998): an automated kitchen cabinet that enhances a user’s
(1) self-maintenance activities which include the abil- accessibility in physically finding, retrieving and stor-
ity to eat, dress, groom, and bathe; (2) instrumental ing kitchen items. Our intended user population for
activities which include the ability to prepare food, the assistive kitchen system will range from individuals
do housekeeping, organize finances, buy necessities having mild to moderate cognitive decline as defined
and manage medications; and (3) enhanced activities by the Global Deterioration Scale (Reisberg, Ferris, de
which include participation in cognitively and socially Leon, & Crook, 1982).
stimulating leisure activities. To date, only a handful of other assistive tech-
Even though a number of smart home technolo- nologies have been developed to assist individuals in
gies have been developed to assist the elderly with kitchen environments. These technologies can be cate-
ADLs around the home, few have actually focused gorized as either providing cognitive assistance or phys-
on what particularly happens in the kitchen envi- ical assistance. With respect to aids that can be utilized
ronment. Our recent work focuses on the develop- in the kitchen for people with cognitive impairments,
ment of an assistive kitchen environment to enable PDAs and touch screens providing step-by-step meal
the elderly with cognitive impairments to indepen- preparation instructions have been a popular approach
dently carry out regular kitchen activities. Our design such as the Visual Assistant (2011). However, these sys-
aims at incorporating the following two essential fea- tems do not use natural communication modes that
tures of an assistive kitchen system: (1) Cognitive elderly individuals are familiar with and require that
Assistance: which assists users in kitchen activities the items needed for meal preparation be found in
such as remembering the locations of items and the kitchen solely by the user. This latter task can
assisting step-by-step in the meal preparation process, be particularly difficult for someone with cognitive
by using voice and visual prompting interfaces, and impairment as there are a number of cabinets and draw-
(2) Increased Accessibility: which allows easy access to ers in the kitchen. Other systems designed for memory
out of reach items in the kitchen through automated aids also include the Cook’s Collage visual display sys-
devices. tem (Tran, Calcaterra, & Mynatt, 2005), and Archipel
247 Design of an Interactive Assistive Kitchen System
touch screen system (Giroux, Bauchet, Pigot, Lussier- of interest and recipes in order to prepare meals via
Desrochers, & Lachappelle, 2008). The Cook’s Collage a unique user interface and automated cabinet sys-
display system provides to the user a visual summary tem. The automated cabinet has been designed with
of ongoing kitchen activities taking place on a coun- the ability to only lower a single shelf at a time
tertop, as recorded from two webcams, to remind the within the original fixed frame of a cabinet. This is an
user of actions he/she has already performed such as important unique design feature as the system directly
which ingredients were already added and the count provides the location of an item to a user, brings the
for each ingredient used. The Archipel system provides item in closer reach and also prompts the user to
instructions to a user to complete a predefined task retrieve the item. Our aim in developing the assistive
chosen by the user by interfacing to devices placed kitchen system is to provide elderly individuals with
in the environment that use lights or sounds to draw a tool that can aid them in accomplishing instru-
the attention of the user to a particular location in mental ADLs required in a kitchen environment. The
the kitchen. Robot assistants are currently also being system can be integrated into an intelligent environ-
developed to undertake such tasks in the future such ment or with other complementary systems such as
as setting the table, cooking and washing the dishes the Cook’s Collage and Archipel, where context-aware
(Beetz et al., 2008; Asfour et al., 2006). However, it will sensors placed in the kitchen such as cameras, LEDs,
be several years before these robotic systems are readily acoustic devices and RFID tags can be used to aid and
available as well as cost-effective enough to be placed in monitor an individual in additional meal preparation
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the homes of elderly individuals. In addition, a number tasks or other related complex ADLs such as cooking,
of safety concerns also still need to be considered with eating, and washing the dishes.
this technology as the robots will be performing these
tasks autonomously in human occupied environments.
Currently, two popular accessible automated cabi- METHODS
net designs are available for kitchens known as the Assistive Kitchen System Design
DIAGO 504 Adjustable Height Cabinet (2010) and
the VERTI Adjustable Height Shelving (2010). The The design of our initial prototype of the
DIAGO 504 system automatically moves an entire assistive kitchen system consists of two main sub-
cabinet unit down over counter space for a user to systems: (1) user interface, and (2) automated cabinet.
reach items whereas the VERTI system simultaneously An overview of the overall system is presented in
lowers all the shelves in a cabinet through the open Figure 1. This initial prototype has been designed with
bottom of the cabinet. These systems can be con- the following specific aims: (1) to develop an easy to
trolled by a remote control, or a push button placed use interface to promote natural communications dur-
either beside the cabinets or on the wall. The main ing kitchen tasks, and (2) design a cost-effective and
target consumer for these products are people with easy to use automated cabinet system using existing
limited mobility in their lower body. The Personal
Mobility and Manipulation Appliance (Grindle, Wang, Automated Cabinet
Salatin, Vazquez, & Cooper, 2011) has been designed
for individuals with both lower and upper limb dis-
abilities. The system consists of two robotic arms that
Micro controller
are mounted on a mobile robotic base. Preliminary Speakers
tests have been conducted with this system for tasks
such as opening a refrigerator, retrieving and opening a
container and then putting it in the microwave. Visual Display
Visual Interface and
Speech Synthesizer Databases
Our proposed interactive kitchen system focuses Internet
High-level Control
on providing cognitive assistance as well as increased
accessibility to elderly individuals in order to encour- Microphone Speech Recognition
age as well as aid these individuals in performing and Analysis
instrumental ADLs. In particular, the system provides
an interactive environment to find and retrieve items FIGURE 1 System overview (color figure available online).
M. Ficocelli and G. Nejat 248cabinet components and available off-the-shelf com- Speech Recognition and
ponents. The prototype provides the perfect platform Analysis Module
to obtain feedback regarding functionality, acceptance,
and usability of such a system. User speech is recognized via the Speech
The assistive kitchen system prototype is initiated Recognition and Analysis module. Recognition is
through the detection of close-range sound or when performed utilizing Julius, which is a two-pass large
intentionally verbally prompted by a user. All requests vocabulary continuous speech recognition (LVCSR)
from users are verbal and are registered by the Speech decoder (Lee & Kawahara, 2009). Words are recognized
Recognition and Analysis module, and are also dis- based on their phonemes and their approximate loca-
played visually to the user for verification and recall via tion in an utterance. Speech analysis then compares
the Visual Interface and Speech Synthesizer module. corresponding synsets to its own database of words.
Three specific cases are identified by the system: (1) the The LVCSR software has been customized to sup-
user wants to retrieve an item(s) from the kitchen, port the vocabulary, dialog and action-based context
(2) the user wants a recipe to retrieve the items to needed during the proposed kitchen activities. We have
prepare a meal, and/or (3) the user wants to store an incorporated the person independent VoXForge (2009)
item(s). acoustic model into our module. This acoustic model
The overall system consists of a database that stores is composed of statistical representations, created via
the names of available kitchen items and their locations Hidden Markov Models, for each phoneme in the
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within a cabinet. If the user is requesting to retrieve English language to account for persons with different
items, the user interface then provides the user with accents and speaking styles. The acoustic model has
the location of a required item(s) within a correspond- been trained using 625 unique voices.
ing cabinet. This information is provided to the user
both verbally through a speech synthesizer and non-
Visual Interface and Speech
verbally as text on the display. The interface can also
provide a list of stored items that the user can eas-
Synthesizer Module
ily choose from to retrieve. Once the location of the The Visual Interface and Speech Synthesizer Module
item is determined, the automated cabinet sub-system was developed in a C++ software framework and is
is used to bring the cabinet shelf that the item is used to both visually display the status of the interac-
stored on to an accessible ergonomic height for the tion as well as also provide verbal cues and prompts
user. All shelves have the ability to translate horizon- to the user. The visual display provides information
tally out towards the user to provide easy reach for a regarding the following parameters: (1) Mode: which
requested item. A similar procedure is implemented is used to indicate the activity at hand, that is, item
when a user would like to place items on shelves in retrieval, (2) Item to Get: defines which item of inter-
the cabinet. est that needs to be retrieved at a certain time, that
With respect to recipe finding, a high-level con- is, a can of chicken soup or a plate, (3) Recipe:
trol module looks up a specific recipe name for the Defines the recipe name for the meal preparation
user. Two recipe-searching approaches are incorpo- task, (4) Items: Outlines all the items needed for the
rated: an internal database search and an online search recipe, and (5) Cabinet shows on which of the three
using ehow-recipes (http://www.ehow.com/recipes/). shelves in the cabinet a particular item is located.
If a recipe is not found in the database, the Google In addition, the visual interface displays three more
RSS (Really Simple Syndication) reader is utilized to textboxes which include the verbal request from the
extract RSS feed information from the eHow—Recipes user as recognized by the speech recognition mod-
website. Once the recipe is found, the system can com- ule (User Input), the speech spoken by the system
municate the items that are needed for the recipe to a (System Output) and guides for answering the sys-
user one at a time. The automated cabinet sub-system tem’s questions (Answer Guide). The Answer Guide
runs simultaneously in order to help the user retrieve is used to provide users with options, including pro-
these items. The following sub-sections will discuss the viding activity/food options based on the time of the
development of the sub-systems and modules of the day. For example, in the morning, the system may
assistive kitchen system. ask what the user would like to eat for breakfast and
249 Design of an Interactive Assistive Kitchen System(a) Automated Cabinet
Item Retrieval The automated cabinet requires that adjustments be
Plate
made directly to an existing kitchen cabinet in order
for all three shelves to be automated one at a time to
an accessible height. The cabinet can be placed at a
System height at which the bottom shelf is within the optimum
reach envelope of the user. The top two shelves have
Answer Guide
also been designed to translate vertically downwards to
User Input an acceptable height within this reach envelope using
I would like a plate
a lifting mechanism. Each shelf will de-couple from
(b) the shelf supports and lock into the lifting mechanism.
Item Retrieval
At the required height, all shelves have the ability to
translate horizontally out towards the user to provide
Plate easy reach for a requested item. Figure 3 illustrates the
steps utilized to bring the top shelf of the automated
cabinet to an acceptable height.
System
Okay, let’s get a PLATE The overall movement of each shelf is controlled
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Answer Guide by three major elements which are the ‘shelf roller
mechanism’ that rolls the shelf horizontally in and
User Input
I would like a plate out, the ‘lifting mechanism’ used to raise/lower a shelf
as needed, and the ‘coupling and de-coupling mech-
FIGURE 2 Visual display (color figure available online). anism’ used to couple/de-couple a shelf with respect
to the shelf supports and also lock/disengage the shelf
to/from the lifting mechanism. One of the main design
the Answer Guide could provide food options such as criteria is to ensure that all the components needed for
cereal, bread, and so forth. This information, similar this application can fit within the cabinet space.
to the other parameters, is also verbally presented to
the user via the speech synthesizer in addition to being
displayed in the textbox under the heading Answer The shelf roller mechanism
Guide. In order to provide the horizontal translation
An example scenario using the Visual Display is motion of all three shelves, a DC motor driven roller
shown in Figure 2. In particular, a user tells the sys- system is designed to be placed underneath each shelf.
tem that he/she would like a plate, the system’s Mode Namely, a shelf roller mechanism consisting of a motor
parameter indicates the item retrieval sub-task and the driven roller can move the shelf horizontally in both
Item to Get parameter states that the item of interest is directions. To aid the motion of the shelf, four free-
a plate. The system confirms this action and identifies rolling rollers are distributed along the width of the
that this item is on the bottom shelf (i.e., shelf #3). shelf and placed at the same height as the driving
(a) (b) (c)
FIGURE 3 (a) Lifting arm raised to required shelf position, (b) shelf de-coupled into lifting arm, and (c) desired shelf lowered to an
acceptable height (color figure available online).
M. Ficocelli and G. Nejat 250roller to assist the horizontal motion by minimizing shelf has machined tapered edges in order to easily
friction and keeping the shelf in a stable configura- slide into the tapered openings in the locking riders.
tion. The advantage of this actuation system is that it Once the shelf has rolled into the riders, the riders then
is compact, cost-effective and can be placed directly start moving outwards until the shelf is completely
underneath each shelf. In order to design an appro- de-coupled from the shelf supports. When the shelf is
priate motorized roller system, the minimum motor commanded to be inserted back to its original position,
power (in watts) required to move an individual shelf the locking riders will start to move in the opposite
with various kitchen items placed on top of it needs to direction until the driving roller from the shelf roller
be determined: mechanism makes contact with the shelf. The motor
torque required to move the shelf during coupling and
WL nwμdv × 103 1 decoupling is:
Pmr = (2k + μr) + + Fp v,
367D 102D η
(1) Fp + Ffr
Tls = , (3)
2π Ps nls
where W is the combined weight of the items on the
shelf and the shelf itself, L is the total length of all where Ffr is the friction forces internal to the leadscrew
the rollers, and D is the roller diameter; k is the rolling mechanism, Fp is the resistive forces encountered when
friction factor (in meters), μ is the coefficient of fric- moving the shelf into and out of the riders, Ps is the
leadscrew pitch, and ηls is the leadscrew efficiency. Ffr
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tion at the roller shaft and the bearing interface, and r
is the roller journal radius (d is the journal diameter); can be defined as:
n is the number of rollers supporting the total weight
of the shelf and items, w is the weight of the rotat- Ffr = μls W cos(γ ), (4)
ing part of each roller, v is the linear velocity of the
shelf moving across the rollers, and η is the efficiency where γ = 0◦ for horizontal motion and μls is the
of the drive system. Lastly, Fp is the resistive forces in coefficient of friction in the leadscrew mechanism.
the free-rolling rollers that must be overcome by the Alternatively, Fp can be defined as:
motor driven roller:
Fp = μw W , (5)
Fp = F1 + F2 + F3 , (2)
where μw is the coefficient of sliding friction. The min-
where, imum power rating, in watts, for an appropriate motor
can be found using:
k μr nwv2
F1 = W , F2 = (W + wn) , F3 = .
R R gL pls = Tls ωls , (6)
F1 is the resistance to rolling of the shelf on the free- where ωls is the angular velocity of the leadscrew, which
rolling rollers, F2 is the frictional resistance in the can be found from the required linear velocity, vls , of
free-rolling rollers’ bearings, F3 is the resistance due to the shelf, that is, ωls = 2π pls vls . Herein, pls is the pitch
sliding of the shelf on the free-rolling rollers and the of the thread in the leadscrew defined in rev/m (rev/ft).
force required to impart kinetic energy to those roller.
R is the roller radius and g is gravity.
Lifting mechanism
A lead-screw-based linear track actuator is used to
Shelf coupling and de-coupling translate vertically and individually the top two shelves
mechanism to an acceptable reach range (bottom shelf’s height).
In order to lower the top two shelves and bring A lifting arm can be connected to the linear track actu-
forward the bottom shelf; each shelf will need to ator on one side and a guide mechanism on the other
de-couple from the shelf supports and lock into the side. For translation of the shelf, the lifting arm must
lifting mechanism. To achieve this, two locking riders stay parallel to the shelf supports with minimal deflec-
are placed on the lifting arm, one at each end. Each tion. A pulley system ensures the arm is straight and
251 Design of an Interactive Assistive Kitchen Systemtwo free rolling bearings in the guide system restrict composed of eight states, Figure 4(a). Each FSM action
the motion of the arm to the vertical axis. In order to represents a set of actions performed by the system
determine the minimum required motor power, first in order to achieve a specific state. The FSM initi-
the motor torque required to lift the shelf vertically is ates from the Standby state. An input command is
determined: provided from the Speech Recognition and Analysis
module to retrieve/store an item or find a recipe. The
Fg + Ffr Enter Search action is then performed to achieve the
Tla = , (7)
2π Ps nls Search state. Since the FSM we utilized was devel-
oped using a heterogeneous design approach, it allows
where the force due to gravity is Fg = W sin γ , and for a hierarchy in the FSM design. In particular, the
γ is 90◦ for vertical motion. Ffr consists of the sliding Search state is refined into logical sub-states forming
friction forces of the guide and pulley system. The min- a sub-FSM as shown in Figure 4(b). Once the Search
imum power rating, in watts, for an appropriate motor state is entered, the sub-FSM initiates from its own
can then be determined to be: Standby state. From this state, the system can per-
form an item location search or a recipe search using
Pla = Tla ωls , (8) the corresponding database or also the online option
for the latter. For example, it can move to the Search
where ωls can be found from the required linear vertical Recipe Database State via the Search for Stored Recipe
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velocity of the shelf. action. If the recipe is found in the database, the
The minimum required power for the motors of all sub-FSM returns to its Standby state via the Return
three systems are multiplied by a 1.5 safety factor. action. The Return action sends the recipe items to
the Visual Interface and Speech Synthesizer module
to display and verbally state to the user. If the recipe
High-Level Control Architecture is not in the recipe database, the sub-FSM moves to
We utilize a finite-state machine (FSM) approach the Search Internet for Recipe state via the Search
to design the high-level controller for the assistive for On-line Recipe action. Within this state, the RSS
kitchen system. The FSM is a mathematical abstrac- reader is used to obtain the corresponding recipe from
tion consisting of a set of states and actions which the internet. Once the recipe is found, the sub-FSM
match the system’s output behavior to a given user returns to its Standby state via the Return action, while
input. The FSM for the assistive kitchen system is also sending the recipe items to the Visual Interface
(a)
(b)
Item
received Search
Shelf #3 Shelf #3
in out Shelves
Database
Shelf #3
Fault Return Shelf
returned Fault
Shelf #1 Search for Number
returned Fault Item
Shelf #1 Shelf #2
Standby Return
up up Search
Fault Shelf #2
Standby Internet for
returned
Search for Recipe
Item Fault Fault Enter Fault Item On-line
received search received Search for Recipe
Stored Return
Shelf #1 Shelf #2 Recipe
Search
down Item on Item on down
Search
Shelf #1 Shelf #2
Recipe
Database
Item on
Shelf #3
FIGURE 4 (a) FSM for the Assistive Kitchen System, and (b) sub-FSM for the Search state.
M. Ficocelli and G. Nejat 252and Speech Synthesizer module. The sub-FSM is also
utilized to identify the location of items via the Search
Shelves Database state. It enters this state using the
Search for Item action. Within this state, a search algo-
rithm is used to find the corresponding shelf the item
is stored on. Once an item’s location is found, the
Return Shelf Number action returns the sub-FSM to
the Standby state and sends this shelf number to the
Visual Interface and Speech Synthesizer module to
communicate to the user. The master FSM can then FIGURE 5 Overview of automated cabinet system (color figure
lower the appropriate shelf to allow the user to retrieve available online).
the item by using the corresponding Item on Shelf
action. For example, if the item is located on shelf TABLE 1 Cabinet specifications
#2 (middle shelf), the Item on Shelf #2 action is per-
Cabinet height 77 cm (30.3 inches)
formed and the system enters the Shelf #2 Down state
in which the appropriate signal is sent to the micro- Cabinet width 76 cm (29.9 inches)
processor to move this shelf from its position in the Shelf length 28 cm (11 inches)
Shelf width 56 cm (22 inches)
cabinet into the reach envelope of the user. When the
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Mass of shelf 2.27 kg (5 lbs)
system has confirmed that the user has removed the Shelf load capacity 11.4 kg (25 lbs)
requested item from the shelf, the system performs the Maximum shelf 3cm/s (1.18 inches/s)
Item Received action to move Shelf #2 back to its travelling speed
original position via the Shelf #2 Up state, in which
the corresponding signal is sent to the microprocessor
to move the shelf up and back into its original posi- TABLE 2 Motor selection
tion in the cabinet. The FSM then performs the Shelf Power
#2 returned action and moves the FSM back to the Mechanism Motor output (W)
Standby state, where it waits for the next input. Similar
The shelf roller ZHENGKE ZGA 42 RH 5
actions and states exist for shelves #1 (top shelf) and
mechanism
#3 (bottom shelf). If the search request was to find a Shelf coupling and ZHENGKE ZGA 42 RH 5
recipe, once the items in the recipe have been found, de-coupling
the FSM sequentially repeats the aforementioned pro- mechanism
cedure to retrieve all the necessary items. It should be Lifting mechanism Firgelli Automations 13
noted that if there is any fault detected when moving FA-200-TR-24
(Linear Actuator)
the shelves of the cabinet via the onboard sensors, the
FSM will move back to its Standby state using the Fault
action. Once the Fault is cleared, the FSM moves back
to its previous state via the same path and continues its As previously mentioned, the user will be able to ask
previous actions. for kitchen items already stored on the shelves of the
cabinet through the Speech Recognition and Analysis
module. The item retrieval and storage search will look
Automated Cabinet Prototype
through its database of stored items to identify the
Development item and its location. Once the location of the item
Based on the aforementioned design, we have devel- is known, it will send a signal to the microcontroller
oped a physical prototype of the cabinet, Figure 5. in order to lower and/or move forward the specified
The specifications of this cabinet are presented in shelf on which the item sits. During this time the
Table 1. Based on the specifications in Table 1 and the user will also be provided with information about the
motor requirements in Equations (1)–(8), the motors actions taken by the overall system through the Visual
presented in Table 2 were chosen for the automated Interface. When an item is placed onto the shelf, the
cabinet. shelf is moved back to its initial location.
253 Design of an Interactive Assistive Kitchen SystemPROTOTYPE TESTING PROTOCOL the workplace. However, it has been designed so that it
can be adapted to any technology of interest. For exam-
Preliminary experiments were conducted to evalu-
ple, Heerink, Krosë, Wielinga, and Evers (2009) revised
ate the performance of the overall proposed assistive
the model to measure users’ acceptance of assistive
kitchen system. An interaction scenario between par-
robots. This included adding additional new constructs
ticipants and the kitchen system was developed, where
such as Trust and Perceived Adaptability as well as
each participant asked the system to locate an item,
incorporating the Perceived Ease of Use and Perceived
retrieve that item, and then restore the item. This list
Usefulness constructs from the Technology Acceptance
included common items that potentially can be found
Model (TAM) (Davis, 1989). These additional con-
on kitchen shelves such as cans of soup and tuna, tea
structs haven been shown to be important constructs
boxes, small cereal boxes and cracker boxes. The cabi-
for users of assistive technology. The model was tested
net was placed approximately 137 cm (54 inches) from
with elderly participants and the assistive robot iCat
the ground, and the laptop controlling the system and
in a long-term care facility. In our own study, eight of
displaying the interface was placed on a table near the
the revised UTAUT constructs (for a total of 24 ques-
cabinet (as shown in Figure 5). The height of the cabi-
tions) which we found to be directly applicable to the
net was chosen to reflect the average floor-to-bottom
quality of life of elderly users were used to measure the
of cabinet height of wall kitchen cabinets in North
acceptance and use of the assistive kitchen system on a
America. The food items were distributed on the three
5-point Likert scale ranging from 1 (not at all) to 5 (very
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shelves. The shelves were lowered and brought forward
much). The constructs and corresponding questions are
at a height of approximately 142 cm (56 inches) from
presented in Table 3.
the floor. Fifteen healthy participants (10 within the
ages of 20–35, and 5e within the ages of 56–68) took
part in the experiments (mean = 38.13; std. dev. = RESULTS AND DISCUSSIONS
17.75). Six of the participants were females (three of
whom were from the older cohort) and nine were males
Preliminary Performance Testing
(two of whom were from the older cohort). None of Results of the system performance experiments are
the participants had any prior experience with assistive presented in Table 4. It can be seen that the system was
technologies for kitchen environments. All participants successful at selecting and executing the appropriate
could speak English, however, for four of the par- behaviors throughout the interactions with the partici-
ticipants, English was not their first language. The pants. The number of trials represents the total number
participants were given a tutorial on how the system of opportunities that existed for each of the behaviors
operates prior to testing. Each participant interacted of the system.
with the system a total of five times. The acoustic model we utilized for speech recog-
A detailed analysis was conducted on the per- nition was not trained to be participant-dependent
formance of the Speech Recognition and Analysis and thus, inherently, as a general limitation to per-
Module, Visual Interface Module and Automated son independent speech recognition techniques, it may
Cabinet. In addition to the performance experiments, experience difficulty correctly recognizing different
acceptance of the interactive system by elderly users pronunciations of the same words. This was evident in
was also measured via a questionnaire. In particular, a the achieved success rate of 93% amongst the 15 par-
modified version of the Unified Theory of Acceptance ticipants. In particular, the six failures are a result of
and Use of Technology (UTAUT) scale (Venkatesh, the system not being able to correctly recognize cer-
Morris, Davis, & Davis, 2003) was provided to the five tain words spoken by two male non-native English
older participants to complete after their interactions speakers, one from the older cohort and one from the
were finished. younger cohort. Our findings are consistent with previ-
The UTAUT combines eight previous models of ous research that has found that English speech recog-
technology acceptance into one model incorporat- nition systems have more trouble recognizing words
ing measurable factors such as Behavioral Intention, spoken by males than females (Goldwater, Jurafsky, &
Anxiety, and Attitude. The UTAUT was first developed Manning, 2010). The two words spoken by these two
to measure technology acceptance and predict usage in participants that were the most difficult for the system
M. Ficocelli and G. Nejat 254TABLE 3 Modified UTAUT constructs TABLE 4 System performance results
Anxiety (ANX)∗ : Expected system No. of No. of Success
1. When using the kitchen system, I am afraid to make behavior trials failures rate
mistakes with it
Recognize speech input 80 6 93%
2. When using the kitchen system, I am afraid to break
Displays item location 75 0 100%
something
Rolls shelf out/in 150 0 100%
3. I find the kitchen system scary
De-couples/couples shelf 150 7 95%
4. I find the kitchen system intimidating
(on the first try)
Attitude towards using the system (ATT): Lifts/lowers shelf 150 0 100%
5. I think it’s a good idea to use the kitchen system
6. The kitchen system would make my life more
interesting to recognize were “want” and “tea.” Even though 93%
7. It’s good to make use of the kitchen system
is a high success rate, we would like to see success rates
Facilitating Conditions (FC): of 100% for our particular application. To address this
8. I have everything I need to make good use of the
limitation for our future work, we have been focusing
system
9. I know enough of the system to make good use of it on the utilization of acoustic models that are opti-
mized specifically for older adults (Anderson et al.,
Behavioral Intention to use the system (BI):
10. I think I’ll use the kitchen system during the next few 1999). Furthermore, if the users are known in advance,
which is true for personal home settings, we can also
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months
11. I am certain to use the kitchen system during the next train the speech recognition system for the identified
few months users.
12. I’m planning to use the kitchen system during the next The main mechanical issue that was noted during
few months
testing was that the shelf’s tapered edges sometimes
Perceived Adaptability (PA): failed to completely slide into the locking riders, mak-
13. I think the kitchen system can be adaptive to what I
ing it difficult during these instances to reliably decou-
need
14. I think the kitchen system will only do what I need at ple the shelf from the shelf supports. Namely, as the
that particular moment locking riders started to move away from the cabinet
15. I think the kitchen system will help me when I consider to de-couple a shelf, the shelf would not move the
it to be necessary required distance in order to de-couple from the shelf
Perceived Ease of Use (PEU): supports. This scenario occurred in 7 out of the 150 tri-
16. I think I will know quickly how to use the kitchen als on the system’s first try at de-coupling the shelf.
system However, the system was able to de-couple the shelf
17. I find the kitchen system easy to use
either on the second or third try. Although de-coupling
18. I think I can use the kitchen system without any help
19. I think I can use the kitchen system when there is was achieved on subsequent tries by the system, this
someone around to help me issue is being addressed by installing electromagnets on
20. I think I can use the kitchen system when I have a the locking riders and corresponding metal strips on
good manual the sides of the shelves. These electromagnets can then
Perceived Usefulness (PU): be energized only during coupling/de-coupling of the
21. I think the kitchen system is useful to me shelves.
22. It would be convenient for me to have the kitchen Once the participants were finished interacting with
system
the system, they were each asked if there were any other
Trust (TU): features they would like to see incorporated into the
23. I would trust the instructions of the kitchen
system. Sixty-seven percent of the participants stated
system
24. I would follow the instructions the kitchen system that pictures of available items and/or video clips
gives me of various meal preparation activities could also be
∗ Scores on negative questions such as for Anxiety have reverse scores,
included in the visual display.
where a stronger agreement leads to a lower score. The current initial prototype allowed us to test our
conceptual design focusing on such aspects as speech
recognition, visual interface and the mechanical design
of the automated cabinet for accessibility. We are in
255 Design of an Interactive Assistive Kitchen Systemthe process of adding additional sensors to individ- be automated. Furthermore, sensors could be placed
ual shelves for directly monitoring a particular item’s at the different shelf locations in the refrigerator and
placement or retrieval off of a shelf. This will help us freezer to also guide the user to an appropriate shelf on
update the database as needed as well as monitor that which a particular item is on. In addition to optimizing
items are properly placed on corresponding shelves. the internal modules of the system, the overall system
Each shelf can be divided into grids and force sensors can be integrated within an intelligent environment,
can be used for each grid in order to detect a change where environmental sensors placed in the kitchen can
in weight locally on the shelf as well as in the total be used along with the proposed system to aid and
weight of the shelf to determine if items have been monitor an individual in sequential ADLs related to
placed onto or retrieved from the shelf. Cameras and meal preparation, cooking, eating and cleaning up.
feature recognition algorithms can also be used to visu-
ally identify a particular item on a shelf and its exact
location. Long-term use items such as plates, cups and
Modified UTAUT
utensils can have RFID tags placed on them in order to The modified UTAUT questionnaire was completed
identify their exact locations. For our initial prototype, by all five older participants (mean = 61.40; std. dev. =
the system had asked a user to confirm that an item 5.13). Cronbach’s alpha (Santos, 1999) was determined
had been removed from or placed onto a shelf. for each of the constructs in order to verify inter-
As our proposed automated cabinet has been reliability between the questions for the participant
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designed to be incorporated within an original fixed group. The alpha values are presented in Table 5.
frame of a standard cabinet, it can be integrated into In general, an alpha greater than 0.7 is considered
a number of cabinets in the kitchen and controlled by to be acceptable for this type of study (Nunnally &
the same high-level controller. The user interface can Bernstein, 1978). From Table 5 we can see that the
be updated to present the information not only of the alpha value for trust is the only one below 0.7. This can
shelf that an item is on but also the appropriate cabinet be a result of the small number of questions (i.e., 2) for
or drawer based on an updated database which stores this particular construct as well as the speech recogni-
the names of available kitchen items, their locations tion results. There were two instances for this particular
in the kitchen as well as within a respective cabinet group that the speech recognition and analysis mod-
or drawer. In order to direct a person to a particular ule was unable to register the particular item the user
cabinet or drawer of interest in the kitchen, context- wanted.
aware sensors can be used. For example, light/LED The descriptive statistics for the individual questions
sensors can be affixed to the outside of cabinets or of the modified UTAUT scale are presented in Table 6.
drawers and light up or blink when a particular item Based on the results, it is worth noting that, overall, the
of interest is in these locations. Our automated cab- participants found the assistive kitchen system to be
inet system can then bring the appropriate shelf the useful and easy to use on their own. Furthermore, they
item is on within the reach envelope of the person. also experienced little anxiety towards it. In particular,
We can also automate drawers to slide out along their they were not intimidated or afraid of using the new
guides when an item of interest is in them. If a kitchen
consists of a combination of both automated and stan- TABLE 5 Cronbach’s alpha
dard cabinets and drawers, for the standard cabinets for constructs
and drawers, we can still incorporate context-aware sen- Modified UTAUT
sors to aid users to identify the appropriate cabinet construct Alpha
or drawer location for a particular item. The system ANX 0.78
can also prompt a user to obtain an item from a par- ATT 0.95
ticular shelf in a standard cabinet, however, the shelf FC 0.77
itself will not be automated. In addition to cabinets BI 0.85
and drawers, the kitchen also includes storage appli- PA 0.79
PEU 0.71
ances such as a refrigerator and a freezer. To date, there
PU 0.89
are refrigerators that are being manufactured that have TU 0.63
manually sliding shelves, which could potentially also
M. Ficocelli and G. Nejat 256TABLE 6 Descriptive statistics for modified UTAUT results identify the advantages of the assistive kitchen system
Question # Min Max Mean Std. dev. during the initial short interactions in order for them
to want to use the system again in the future.
1 3 4 3.6 0.54
2 3 5 4.2 0.83
3 4 5 4.6 0.55
4 3 5 4.2 0.83 CONCLUSION
5 3 4 3.4 0.54 In this paper, we present the design of an assistive
6 3 4 3.4 0.54
kitchen system to assist elderly individuals with cogni-
7 3 5 3.6 0.89
8 4 5 4.4 0.54
tive impairments to complete ADLs such as retrieving
9 3 4 4 0.7 and storing items, and obtaining recipes for meal
10 2 4 3.4 0.89 preparation. An initial prototype was developed con-
11 2 5 3.4 1.14 sisting of a user interface and automated cabinet to
12 3 5 4.2 0.83 test the functionality and feasibility of the proposed
13 3 5 3.8 0.83
design. In addition, a modified UTAUT scale was used
14 3 5 4.2 0.83
15 3 5 4 0.70
to measure acceptance and potential use of the pro-
16 3 4 3.8 0.44 posed system by a group of older adults. The results
17 3 5 4 0.70 from the modified UTAUT, though only focusing on a
18 3 5 4.2 0.83 small sample of older adults, show promise for the use
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19 3 5 4 1 of the system for the outlined kitchen ADLs, and moti-
20 3 5 4.2 0.83
vate further development and testing of the proposed
21 3 5 4.2 0.83
22 4 5 4.4 0.54
system for the intended population. Our future work
23 3 5 4 1 will consist of optimizing and adding additional func-
24 2 5 3.8 1.09 tionalities to the prototype in order to conduct large
scale studies with user group participants.
TABLE 7 Correlation
Pearson
Independent Dependent correlation Sig.
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