A brief review on lavatory cleaning devices and their feasibility in public toilets in developing countries

Abstract

The purpose of this article is twofold, one is to provide a brief review on various lavatory cleaning devices while the other is to study the feasibility of using these devices in public toilets in developing countries. The article presents a literature review on various lavatory cleaning devices, focusing on various designs available as patent documents and commercially available toilet cleaning robots. The issues that prevent these devices from being deployed in multi-lavatory public toilet complexes in developing countries are discussed. Design considerations of a simple, cost-effective, semi-automated lavatory cleaning robot that may serve as a solution to these issues are also covered in this article.

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Vol:.(1234567890)
International Journal of Intelligent Robotics and Applications (2020) 4:354–369
https://doi.org/10.1007/s41315-020-00143-2
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REGULAR PAPER
A brief review onlavatory cleaning devices andtheir feasibility
inpublic toilets indeveloping countries
R.HariKrishnan1
Received: 7 March 2020 / Accepted: 27 June 2020 / Published online: 8 July 2020
© Springer Nature Singapore Pte Ltd. 2020
Abstract
The purpose of this article is twofold, one is to provide a brief review on various lavatory cleaning devices while the other is
to study the feasibility of using these devices in public toilets in developing countries. The article presents a literature review
on various lavatory cleaning devices, focusing on various designs available as patent documents and commercially available
toilet cleaning robots. The issues that prevent these devices from being deployed in multi-lavatory public toilet complexes
in developing countries are discussed. Design considerations of a simple, cost-effective, semi-automated lavatory cleaning
robot that may serve as a solution to these issues are also covered in this article.
Keywords Service robotics· Automation· Toilet cleaning· Public toilets· Sanitation
1 Introduction
The need for sanitation of public toilets is a common and
important issue. Public bathrooms carry a large number of
bacteria, fungi and viruses. These germs can spread from
the toilet seat to body parts of the user and also to other sur-
faces to which the person is in contact with, spreading infec-
tious diseases to other people (Gerhardts etal. 2012; Ahmed
2018). Human excreta is a main source of transmission of
many classical diseases including urinary, anal and vaginal
infections (Greed 2006) and studies have shown that toilet
seats are always contaminated with faecal bacteria (Mendes
and Lynch 1976). Faecal borne bacteria such as Escherichia
coli (E. coli), Shigella sonnei, Streptococcus, Staphylococ-
cus, Salmonella, Yersinia and viruses such as norovirus,
rotavirus, adenovirus, Torque teno virus spread from toilet
surfaces (Gerhardts etal. 2012; Greed 2006; Mendes and
Lynch 1976; Sassi etal. 2018) and can result in several seri-
ous health issues. Flushing of toilets or cleaning lavatories
using pressurized water jet streams can also result in aero-
solization of the above mentioned bacteria and viruses which
can cause transmission of infectious diseases such as Severe
Acute Respiratory Syndrome (SARS) (Gerhardts etal. 2012;
Greed 2006; Mendes and Lynch 1976; Johnson etal. 2013;
Hamilton etal. 2018).
One of the promising approaches to reduce the spreading
of toilet bound infectious diseases is to use anti-microbi-
ally active surfaces in public toilets (Gerhardts etal. 2012;
Greenhalgh and Walker 2017; Querido etal. 2019). Still, the
basic requirement is to perform scheduled periodic cleaning
of public bathrooms (Querido etal. 2019; ASEAN 2016).
In toilets in public places such as schools, universities, hos-
pitals, bus stands, train stations and airports where there are
several lavatories to be kept clean and hygienic, the only
available cleaning equipment is generally limited to a toilet
cleaning brush. Studies show that, among the toilets in pub-
lic places, hospital toilets are considered to be less hygienic
as it would be used by several persons who are suffering
from various diseases including gastrointestinal disorders or
staphylococcal infections (Greed 2006; Mendes and Lynch
1976). More importantly, effective cleaning of lavatories in
public toilets is even more critical for developing countries,
where people affected by toilet bound infectious diseases
may not have economic resources or awareness to receive
appropriate medication (Maiti etal. 2015; Grover and Citro
2011; WHO 2017).
Further, cleaning a lavatory is considered an unpleas-
ant chore and cleaning several such lavatories with just a
brush involves a lot of time and effort. Even though several
designs of lavatory cleaning systems have been proposed
as patents, only a very few devices have been developed
* R. Hari Krishnan
harikrishnan.r@mech.sastra.edu
1 School ofMechanical Engineering, SASTRA Deemed tobe
University, Thanjavur613401, TamilNadu, India

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and commercialized. This paper provides a brief review
on lavatory cleaning devices, focussing on various designs
available as patent documents and commercially available
toilet cleaning robots. Most of these devices serve the pur-
pose of either cleaning only the toilet seat or only the inner
wall of the toilet bowl. An efficient lavatory cleaning device
shall effectively clean both the seat and the inner wall. Also,
most of these expensive devices are meant to be fixed per-
manently on to the toilet commode, serving that commode
alone making the system unaffordable to be employed in a
multi-lavatory public toilet complex. Taking into account of
these limitations and many more, preliminary design con-
siderations that may lead to the development of a semi-auto-
mated lavatory cleaning robot have been discussed towards
the end of this paper. The paper is organized in such a way
that Sect.2 covers literature review and Sect.3 discusses
major challenges and issues to be overcome in the existing
systems, to be used in public toilets. Design considerations
of a semi-automated lavatory cleaning device are discussed
in Sect.4 followed by concluding remarks in Sect.5.
2 Literature review
2.1 Lavatory cleaning equipments inpatent
literature
Several designs of toilet cleaning brushes were proposed by
various inventors. In which, designs proposed by Mayberry
(1982), Miller (1983), Dolah (2001) and Moss (2005) stand
apart as these brushes are electrically powered-motor oper-
ated or have some sort of mechanisms to dispense cleansing
agents. Yehuda etal. had put forward a design of a combina-
tion toilet cleaning device that can be used as a plunger for
grasping and removal of items that may clog the toilet outlet
and also as a toilet cleaning brush (Yehuda and Lebenhartz
2016).
In 1997, a design of a toilet cleaning device with a clean-
ing pad was proposed by Federico etal. (1997). The device
made of plastic, has a handle with a trigger on one side
and a pair of grasper jaws on the other side. Where, one
jaw is fixed (upper) and the other jaw (lower) is hinged to
move towards (close) or away (open) from/to the fixed jaw
when the trigger is manipulated. A cleaning pad made of
biodegradable paper is also part of the design. The pad has
a double-wall, double envelope design with a centre layer
called ‘tongue’. The walls of the pad contain dry detergents.
The user grasps the handle of the device and presses the
trigger moving the lower jaw slightly downwards to open
the jaw. Now the grasper jaws can be inserted into the clean-
ing pad and subsequently the trigger can be released. This
allows the grasper jaws to be clamped down on to the tongue
of the cleaning pad. The pad can now be moistened and the
lavatory can be cleaned by scrubbing the pad on its surface.
As shown in Fig.1, the device has a 15 degree bend between
the handle and its tip which will allow the cleaning pad to
reach the interior surface of the bowel. Even though, most
of the inner corners of the lavatory can be cleaned with this
device, the cleaning process may involve similar time and
effort as that of a manual toilet brush.
Another toilet cleaning system was proposed by Yu in
1998, which can automatically clean the toilet seat before
or after toilet usage (Yu 1998). The system, as shown in
Fig.2, consists of a horizontally rotatable toilet seat placed
on top of a toilet bowl along with a motor and a transmis-
sion mechanism to turn the toilet seat horizontally. A brush
attached to another motor is used to clean the toilet seat
while it is being turned and a water outlet tube is employed
to sprinkle water to the brush for cleaning purpose. A waste
water tank is also included to hold the water falling from the
movable seat after cleaning. Provisions are also provided
in the design to include an electric dryer to dry the wet toi-
let seat after cleaning. To initiate the cleaning process the
control circuit is activated through a switch or an infrared
sensor. Once activated, the toilet seat is moved horizontally
backward towards a slot between the flush tank and the toilet
commode employing associated mechanisms. Underneath
the toilet seat, there is a pair of racks on either side of the
vertical walls of the same. These racks are engaged with
a gear attached to a motor and hence, when the motor is
rotated, the toilet seat is also rotated horizontally. Subse-
quently, the control circuit will energize the second motor
which will rotate the brush over the top surface of the toilet
seat. Water will be sprinkled on the brush and a provision of
a chemical dispenser is also provided to dispense antiseptics
or perfumes to this water outlet. The waste water after the
cleaning is collected in a waste water tank positioned right
under the cleaning brush. Then an electrical dryer is turned
Fig. 1 An illustration of using the device proposed by Federico etal.
to clean a toilet commode (Federico and Gabella 1997)

356 R.H.Krishnan
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on to dry the wet toilet seat. When the toilet seat completes
one complete rotation, the control circuit ceases its opera-
tion stopping all the cleaning and associated processes and
then enters to a stand-by mode. Even though, the system
thoroughly cleans the toilet seat, existence of mechanisms to
turn the toilet seat horizontally make the design complicated.
Moreover, major modification is required in the existing toi-
let bowl to install this system or toilet commodes should be
available commercially with this cleaning system pre-fixed
on to it thereby increasing the cost factor in both the cases.
Such a system is not affordable to be used in public toilets
in developing countries, as each toilet commode in a toilet
complex should be installed with one such cleaning system.
Figure3a shows another apparatus, meant for auto-
matic washing, sanitizing and drying toilet seat, proposed
by Sadegh etal. (1999). The device consists of a pivotally
connected toilet seat cover with three independent tubes to
carry water and hot air. It also consists of a toilet seat, a
water collector means and a control unit. From Fig.3b, c,
it can be observed that there are two water tubes with small
holes located on the interior and exterior rims of the toilet
seat cover to allow the water to reach and wash all areas of
the toilet seat completely. The third tube which carries the
hot air is located on the middle rim and has larger holes to
ensure that the seat is dried properly. The water after clean-
ing the seat will be collected in the water collector means
located at the outer edge of the seat and the collected water
will be drained into the toilet bowel through tubes provided
as illustrated in Fig.3c. Provisions are available in the design
to avoid splashing of water out of the toilet seat onto the floor
while cleaning. The opening and closing of the toilet seat
may be automated by employing a motor controlled by the
control unit. The entire cleaning process is also controlled by
the control unit wherein, the cleaning process starts either by
pressing a button or by triggering a photosensor/proximity
switch provided when the seat cover is closed.
The device is less complicated when compared to the
device proposed by Yu, as it do not have any moving mecha-
nisms to achieve cleaning. One of the major limitation of the
design is that, the inner part of the rim cannot be cleaned
forming a dead zone. As mentioned for the previous system,
several such devices need to be installed to implement this
cleaning scheme in a multi-lavatory public toilet complex.
A similar device was proposed by Pellati (2004). The inven-
tor claims that the design is structurally and constructively
simple as the method followed to feed the disinfectant fluid
and hot air has been simplified, when compared to the previ-
ous designs. This results in improved efficiency and ease of
assembly & maintenance of the device. The device is also
capable of cleaning the dead zones of the toilet seat ring as
well. A design of a minimal energy-consuming device for
cleaning toilet seat was proposed by Blatz etal. (2004). The
device includes associated mechanisms and a mobile clean-
ing unit which can be moved along the upper surface of the
toilet seat making use of water power.
Ermini (2006) had come up with a design of self-sanitiz-
ing toilet seat, which is illustrated in Fig.4. It consists of a
ring-shaped seat, placed over a toilet bowl, on which the user
will be sitting. In the rear part of the seat, close to the wall,
adjacent to/below the conventional water flush tank, there is
a box-like structure bearing a plurality of nozzles. The cas-
ing above the box-like structure includes electronic circuits
for controlling the functioning of these nozzles based on
the status of the sensor provided in the same to detect the
presence of the user. When the sensor triggers the circuit,
the water & gas circuits which are housed inside the casing
Fig. 2 Design of toilet cleaning system as proposed by Yu a side view; b top view; (Yu 1998)

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Fig. 3 a Design of automatic toilet cleaning apparatus invented by Sadegh etal.; b bottom view of the toilet seat cover; c Enlarged section of the
outer edge of the toilet seat in closed position (Sadegh etal. 1999)
Fig. 4 Design of self-sanitizing
toilet seat proposed by Ermini
(2006)

358 R.H.Krishnan
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are activated. As a result, first the upper surface of the seat
is flushed with sanitized water through the nozzles and then
it is provided with hot air to dry the surface. The toilet seat
has a design with the outer edge of the seat having a passage.
The waste water after washing the upper surface of the seat
will flow into this passage without splashing the water on to
the floor. This water will be drained into the bowl through a
channel that connects the outer edge and inner edge of the
toilet seat. A similar device was proposed by Dorra which
consist of a seat cover housing at least one outlet each to
dispense water and gas, a motor pump to induce flow of
water from water source to the water outlet and an air blower
(Dorra 2016). The water and gas outlets are positioned at
the back end of the toilet seat. The seat cover is designed in
such a way that, when closed, water is discharged through
the outlet and the air blown by the blower allows the flow
of this water from back end to the front end of the toilet
seat. This ensures the cleaning of the entire upper surface
of the seat. The seat also include a plurality of Ultraviolet
(UV) light source which may emit UV light after rinsing and
blowing air to anti-microbialy disinfect the toilet seat. To
install the devices put forward by Ermini and Dorra, infra-
structural modification is required in the existing toilets and
these devices are meant to be installed onto a single toilet
commode.
Graves etal. (2009) had proposed a design of a toilet
cleaning apparatus, as illustrated in Fig.5a, that can clean
the toilet seat without spraying water and air drying. The
inventors claim that the design of the device is less complex,
it is less expensive and the apparatus can be fixed on to an
existing toilet commode without any infrastructure modifica-
tions. The device, a seat, is hinged to fit on a toilet commode
between the existing toilet lid and rim of the toilet. There
are two pedal controls, of which, one is used for lowering
and lifting the seat via a pivot drive employing a motor. As
shown in Fig.5b, c, the seat is oval in shape having a top
Fig. 5 a Design of toilet cleaning apparatus proposed by Graves etal.; b bottom view of the toilet seat while the seat is lifted; c partial cross sec-
tional view of bottom part of toilet seat while seat is lifted (Graves and Graves 2009)

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portion, a bottom portion and a cavity in between. Within
the cavity, there is an arrangement employing a motor with
a pulley and several pulleys placed spaced apart which are
connected via a continuous loop belt. In the bottom portion
of the seat, there is a guide track and both the ends of the
guide track have stoppers which can be tactile switch sen-
sors. A drive attachment is affixed on to and propelled by
the belt which will be guided by the previously mentioned
guide track. Now when the motor is powered on, the belt
is propelled and the drive attachment moves between the
stoppers at the two ends. A cleaning pad with various cleans-
ing agents is attached below the drive attachment and as it
moves, the pad cleans the upper surface of the rim. Once
the drive attachment reaches one end, this will be sensed by
the stopper and ceases the motor power. To move it again in
reverse direction, the pedal control designated for turning on
the motor to move the cleaning pad should be pressed again.
The major advantage of the design is that, no infrastructure
modification is required in the toilet to install the device.
Most of the designs discussed above, other than the toilet
cleaning brushes, pertain to toilet seat cleaning systems and
these devices are not meant for cleaning & sanitizing the
inner surface of a toilet commode. Unlike these devices,
Nunez etal. had patented a design of a toilet bowl self-
cleaner, that can be used to clean the inner surface of the
toilet commode (Nunez and Chavez 2009). The device as
shown in Fig.6 is attached on to the rim of the toilet com-
mode. It consists of a container to hold cleaning solution,
a dispenser to spray cleaning solution, an electric motor
and associated mechanisms to move the device throughout
the length of the toilet rim and a motorized foldable brush.
When the toilet seat is at a lowered position, the device
is turned off. Once when the seat is lifted, the tactile sen-
sor within the device senses this motion and energizes the
motor. This moves the device along the length of the rim at
a predetermined speed. Simultaneously, the dispenser will
spray the cleaning solution and another motor will rotate the
brushing arm that will perform the cleaning and sanitation
of the inner area of the toilet bowl. Another sensor is also
provided to sense the stopping point, so as to stop the device
travelling further along the length of the rim by shutting off
the motor. The device can be fixed on to a single toilet com-
mode to serve that commode alone or a single device can
be used to clean multiple toilet commodes in a public toilet.
Figure7a depicts a design of a toilet bowl cleaning
assembly, attached to a toilet bowl, proposed by Ba-Akeel
and Ghaemi (2011). As shown in Fig.7b, the device has
an elongated housing with an inverted L-shaped telescopic
height adjustable member on top acting as a handle. A rotat-
able cleaning brush mechanism is downwardly attached to
the bottom portion of the housing. The brush mechanism
is equipped with a spring actuated-telescopic central shaft
having a cleaning head at its bottom and it is aligned in the
same axis as that of the housing. The cleaning head has sev-
eral bristles in it which extends downwards from the central
shaft. The brush mechanism is also equipped with a pair of
lateral shafts extending downwards from the central shaft
with an angle as shown in Fig.7b. Each of the lateral shafts
is spring actuated and telescopic, having a bend on its distal
end with several bristles attached to it. A drive mechanism is
mounted inside the housing which includes a motor that will
rotate the central and lateral shafts when the switch provided
in the handle is operated to achieve cleaning of the inner
surface of the bowl. The power required for the functioning
of the drive mechanism is drawn from a battery which is also
included in the housing. The toilet bowl cleaning assembly
is designed to have a cover coupled to the housing between
the handle and the brush mechanism to avoid splashing of
water towards outside while cleaning. The bottom portion of
this cover can be attached to the upper edge of the toilet bowl
using the clips provided. The cover consists of several panels
hinged on to the housing and are expandable outwards from
the housing to increase the diameter at the bottom part of
the cover. The housing also has a fluid chamber which is
coupled to the brush mechanism and it can provide cleans-
ing fluid to the brush mechanism while cleaning. The fluid
can be filled using the inlet provided near the housing and it
will be ejected out through the outlet nozzles provided in the
central and lateral shafts due to centrifugal force caused by
the rotation of the shafts. No infrastructure modification is
required to use this device and it can be used to clean multi-
ple toilet commodes in a toilet complex without the need of
installing it on to each toilet commodes.
Qualls etal. conceived a method to automatically clean
a toilet bowl and the same is illustrated in Fig.8a, b (Qualls
and Jones 2017). As shown in Fig.8b, their design was quite
complicated and had two circular tracks spanning the entire
circumference of the upper – outer surface of a circular
shaped toilet rim, below the seat cover. Out of the two tracks,
Fig. 6 Design of toilet bowl self cleaner proposed by Nunez et al.
(2009)

360 R.H.Krishnan
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the inner track is rigidly fixed or bolted to the inner part of
the rim. The tracks are coupled with each other using motion
transfer balls such as in ball bearings and thus, arresting the
motion of the inner track will allow the outer track to spin
freely. A pair or more of retractable brushes (spiral in shape)
are movably fixed to a vertical to horizontal tension control
guide which is adapted to move along the outer track as it
spins. With the help of a DC motor, making use of suitable
motion transfer mechanisms, the outer track is made to spin.
When the track spins in the clockwise direction, the vertical
to horizontal tension control guide forces the brushes to
engage with and clean the vertical inner walls of the toilet
bowl. In reverse direction, the brushes are forced to retract
horizontally to the upper rim of the toilet bowl. The cleans-
ing solution is dispensed into the bowl through the existing
water pathway between the commode and the flush tank. An
infrared sensor is positioned inside the bowl to detect debris
obstructing the water line. Flushing and opening or clos-
ing of the toilet cover are also automated. The entire device
is microprocessor controlled and the complete cleaning of
Fig. 7 a Toilet bowl cleaning assembly designed by Ba-Akeel etal. attached onto a toilet bowl; b Cross-sectional view of the toilet bowl clean-
ing assembly (Ba-Akeel and Ghaemi 2011)
Fig. 8 a Design of the device proposed by Qualls etal. to automatically clean a toilet bowl; b A cross-sectional perspective top view under the
rim (Qualls and Jones 2017)

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the bowl is achieved through seven timed cycles—close lid
cycle, automatic flushing cycle to flush the bowl with water,
sensing cycle to check for debris, chemical release cycle
to dispense cleansing solution, a cleaning cycle where the
brushes spin vertically in clockwise direction, a cleaning
cycle where the brushes retract and spin horizontally in
counter clockwise direction and open lid cycle. The entire
cleaning process can be controlled by the user using the
human interface panel provided on the flush tank. The major
disadvantage of this system is that, it has a complex design
and moreover, it can only be employed in toilet commodes
with circular shaped rim.
Recently, a design of an antimicrobial self-cleaning toilet
was proposed by Hall etal., which is shown in Fig.9 (Hall
etal. 2018). The invention consists of a steep interior-tita-
nium dioxide coated toilet bowel, a rinsing toilet seat with
lid, a water tank and a helical loop trapway. The rinsing seat
with the lid is hinged on to the upper portion of the toilet
bowl in a manner similar to the attachment of conventional
toilet seat and lid to the toilet commode, but using electrical
motors. The seat is designed to have a cavity, along its inner
circumference, with an array of nozzles to facilitate dispens-
ing of water on to the vertical wall of the toilet bowl in an
oscillatory and overlapping pattern with enough pressure.
Fig. 9 a Design of an antimicrobial self-cleaning toilet proposed by Hall etal. b Rinsing seat with nozzles and UV source placed above rimless
bowl and c Lid and rinsing seat arrangement (Hall etal. 2018)

362 R.H.Krishnan
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This ensures that the entire inner surface of the bowl is
cleaned efficiently. The water for rinsing comes from a
remote water source which can be controlled independently
from the flush water tank. The flush water tank incorporated
in the design also facilitates in storing water and once dis-
pensed, the water will be flushed through the helical loop
trapway. A range of sensors is employed in the device and
with the help of a microprocessor the device operates auto-
matically. For example, the sensors detect whether the user is
sitting on the toilet seat and once the user finishes toileting,
the action will be detected and subsequently the toilet lid
will be closed automatically to flush. If the user intends to
urinate by standing in front of the commode, the associated
sensors will detect the user and the processor in turn will
open the lid to facilitate the same. Sensors are also incorpo-
rated in the toilet seat to measure the weight of the user and
determine the volume of water to be dispensed through the
dispensing seat. The bowl is coated with titanium dioxide
and also includes an array of UV light source on the upper
circumference of the rimless bowl. This light source is capa-
ble of emitting UV rays of about 520nm. After flushing, the
ultraviolet light sources will be turned ON automatically
to activate the antimicrobial properties of titanium dioxide.
2.2 Commercial toilet cleaning devices
Even though several designs of lavatory cleaning devices
have been proposed in patent documents, there exist only
three predominant market players in this segment.
2.2.1 SpinX‑ Toilet cleaning robot
SpinX is a fully autonomous toilet cleaning robot developed
by SpinX Robotics, Inc., Israel (SpinX World’s 2019). The
robot, shown in Fig.10, is designed to clean the toilet seat
and bowl in 90s. The robot consists of a robotic arm with a
spinning cleaning brush as end-effector, that can reach every
nook and corner of the internal wall of the toilet bowl and
an array of water jets for rinsing the toilet seat followed by
hot air blowers for drying the same. These mechanisms are
incorporated inside a specially designed toilet lid and can
be fixed on to a conventional standard western toilet com-
mode by removing the existing toilet lid. The robot can be
either battery operated or plugged on to the power socket.
To initiate cleaning, the lid should be gently pushed down-
wards resulting in smooth and gentle closing of the lid and
subsequently a button is pressed. The robot makes use of
a dynamic toilet bowl scanning system employing a smart
sensor/array of sensors that can scan the inner surface of
the toilet bowl. This enables the robotic arm to reach and
scrub the inner walls of the bowl, irrespective of size, shape
or model of toilet commode used. Once after scanning, the
robotic arm hidden inside the lid cover expands downwards
with a spinning brush to clean the inner wall. Water mixed
with detergents or disinfectants will be dispensed as a jet
stream from the distal end of the robotic arm towards the
inner wall for both cleaning the wall and for self-cleaning of
the spinning brush. After cleaning the wall and self-cleaning
of the brush, the robotic arm will be tucked itself inside the
lid. Meanwhile, the toilet seat is also rinsed by dispensing
water jets through an array of nozzles provided underneath
the lid and later the seat is dried by blowing compressed air.
The company claims that, the robot is compactable to fit in
98% of western toilet commodes available in market and it’s
rechargeable lithium-ion battery can serve up to 50 cleaning
cycles (Chang 2017; Mlot 2017).
2.2.2 Giddel toilet cleaning robot
Giddel is a patent pending (D’Souza etal. 2019), portable
toilet cleaning robot developed by Altan Robotech Inc.,
USA (Robotech 2019). It can be suspended over the toi-
let using the mounting bracket provided, so that it’s body
does not come in contact with the bowl or the water. This
battery operated codeless robot has a rotary body with a
telescopic robotic arm with a brush at its end that can reach
and clean toilet bowl of a variety of sizes & shapes. The
robot is designed to have a triple joint configuration of two
rotary and one linear joints and this results in its dexterity
to scrub top, under and inside portions of the rim along with
the entire vertical wall of the bowl down to the drain. The
cleaning is performed in three different motions—circular
or radial motion, sinusoidal or wavy pattern and vertical
motion towards the drain. Giddel’s software is designed
in such a way that, with the help of tactile feedback, the
Fig. 10 SpinX toilet cleaning robot attached to a toilet bowl; Image
Courtesy: SpinX Robotics, Inc

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bowl’s curvature is measured and the arm is provided with
3D coordinates for reaching all surfaces that need cleaning.
The robot has a heavy duty anti-microbial, electrically safe
plastic housing which can even withstand acidic environ-
ment in the toilet. Provisions of inbuilt reservoir and pump
are also incorporated in the robot to rinse the bowl with
water mixed with disinfectants (Arar 2018; Wetzel 2019).
Figure11 shows Giddel robot being attached to a toilet bowl.
2.2.3 Toibot
An Israeli start up has come up with a battery operated toilet
cleaning robot christened Toibot (2019). The small sized
robot that follows a toothed plastic track positioned around
the rim, below the toilet seat. It has a uniquely designed,
elastic, replaceable brush that can reach any point in the
toilet bowl. The robot moves in 3 axes i.e. moving around
the toilet rim following the track and up and down motion of
the brush connected to a motorized arm mechanism which
may resemble a motion similar to the steel tape extending
and retracting from a retractable measuring tape. In addition
to this, the brush also spins about its own axis to achieve
effective and efficient cleaning. The robot also comes with
disinfectant tablets which can be inserted into the device in
the slot provided. Once the robot is switched on, the robot
will clean the inner wall of the toilet bowl following the
above mentioned motions and ceases its operation automati-
cally once one rotation is made around the rim successfully.
3 Challenges andissues
The devices mentioned in Sect.2 are evaluated based on
three major aspects- functionality and efficiency, afford-
ability and water resources that they require to perform
cleaning. As mentioned in the introduction section, clean-
ing public lavatories with a brush or brush like equipment
is a humongous task which involves a lot of time and effort.
Using electrically powered brushes may reduce the physical
effort of scrubbing the bowl, but the time involved in clean-
ing will be the same as that of conventional cleaning. Also,
it will be difficult to ensure that every corner of the bowl is
cleaned while using such equipment. While the designs put
forward by Yu, Sadegh etal., Pellati, Blatz etal., Ermini,
Dorra and Gravis etal. are meant for merely cleaning the
toilet seat, designs of Nunez etal., Ba-Akeel etal., Quallas
etal. and Hall etal. are meant only for cleaning the toilet
bowl. In commercial devices, Giddel toilet cleaning robot
and Toibot are also employed for cleaning the inner part of
the bowl and not the toilet seat. An efficient toilet cleaning
device should effectively clean both the toilet seat and the
inner wall of the bowl. SpinX toilet cleaning robot satisfies
this requirement, as it effectively cleans the bowl as well as
the toilet seat. Still, it has its own disadvantages when it is
being used in public toilets having several lavatories to be
cleaned, especially in developing countries.
The SpinX toilet cleaning robot is not yet commercially
released in the market and the retail price of the device is
expected to be around $350 (Marquis 2017) which would be
unaffordable, as this robot is meant to be fixed to a single toi-
let commode. As public toilets house several numbers of toi-
let commodes, equal number of SpinX robots are needed to
be installed which would be a financial burden for the opera-
tors, both government and private, in a developing country
like India. The case is same with the designs proposed by
Yu, Sadegh etal., Pellati, Blatz etal., Ermini, Dorra, Graves
etal., Qualls etal. and Halls etal. Giddel Toilet cleaning
robot costs around $399.99 (Giddel Toilet Cleaning Robot
Kit 2019), but the advantage is that a single robot can be
employed to clean multiple toilet commodes. Toibot is also
not commercially released into the market and it may cost
between $99 and $149 (Toibot 2019) which is comparatively
more economical than SpinX and Giddel. Toibot also has the
disadvantage that the service of one unit of robot is restricted
to a single toilet commode. Moreover, most of the toilet
seat cleaning devices, bowel cleaning devices and the com-
mercial devices discussed in this paper have a complicated
design and remove the intervention of humans completely,
while cleaning. Hence, a low-cost semi-automated lavatory
cleaning device may serve as a solution against the costly
fully autonomous system. Table1 provides a comparison of
toilet cleaning devices discussed in Sects.2.1 and 2.2.
The devices discussed in Sect.2 wash the toilet seat/bowl
with water. None of the research works reported in litera-
ture clearly specifies the quantity of water needed by the
devices to clean. Shortage of water resources is a serious
issue around the world and researchers recommend reuse of
treated sewage water as a solution to this (Ren etal. 2019).
Even though, this treated water can be used for toilet clean-
ing purposes, toilet cleaning devices should be designed to
Fig. 11 Giddel robot attached to toilet commode (D’Souza et al.
2019)

364 R.H.Krishnan
1 3
Table 1 Comparison of toilet cleaning devices
Sl. no System Purpose Cleaning strategy Limitations in using in public toilets
1 Federico and Gabella (1997) Cleaning toilet seat and inner surface of the
bowl
● Toilet brush with handle & trigger on one
side and grasping jaw on the other side
● The cleaning pad that can be held by the
grasping jaw can be scrubbed onto the toilet
surface to clean
● The cleaning may involve similar time and
effort as that of a manual toilet brush
2Yu (1998) Cleaning toilet seat ● Automatic washing, scrubbing and drying of
a horizontally rotating toilet seat
● Existence of mechanisms to turn the toilet seat
horizontally makes the design complicated
● Major modification is required in the existing
toilet infrastructure to install the device or toi-
let bowls should be available with the cleaning
mechanisms pre-fixed onto it
● A single device can service only one toilet
commode. Hence, may not be economically
affordable
● Cannot be used for cleaning inner surface of
the bowl
3 Sadegh etal. (1999) Cleaning toilet seat ● Automatic rinsing of the toilet seat with
water or disinfectant fluid and drying of the
seat using hot air
● Inner part of the rim cannot be cleaned form-
ing a dead zone
● The system is meant to be installed onto a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl
4 Pellati, 2004 (2004) Cleaning toilet seat ● Automatic rinsing of the toilet seat with
water or disinfectant fluid and drying of the
seat using hot air, reaching the dead zone
areas
● The system is meant to be installed onto a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl
5 Blatz etal. (2004) Cleaning toilet seat ● A mobile cleaning unit comprising of a
sponge, wiper and a container to carry
disinfectant fluid is moved along the upper
surface of the toilet seat making use of water
power and associated mechanisms
● There may be areas on the toilet seat where
the mobile cleaning unit cannot reach forming
a dead zone
● The system is meant to be installed onto a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl
6 Ermini (2006) Cleaning toilet seat ● When the sensor is triggered, the seat is
flushed by sanitized water and then, hot air is
provided to dry the surface
● Infrastructural modification is required to
install the device
● The device is meant to be installed on to a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl

365
A brief review onlavatory cleaning devices andtheir feasibility inpublic toilets indeveloping…
1 3
Table 1 (continued)
Sl. no System Purpose Cleaning strategy Limitations in using in public toilets
7 Graves and Graves (2009) Cleaning toilet seat ● A cleaning pad with various cleansing
agents is attached below a drive attachment
that is fixed below a seat cover and when the
peddle provided is operated, the drive attach-
ment moves so that the pad cleans the upper
seat/rim surface
● The device is meant to be installed on to a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl
8 Nunez and Chavez (2009) Cleaning inner surface of toilet bowl ● A device with a motorized foldable brush,
that is movably fixed on to the rim of the
toilet
● The device is designed to move along the
rim automatically, spraying cleaning solution
and simultaneously brushing the inner wall
of the bowl
● Cannot be used for cleaning the toilet seat
9 Ba-Akeel and Ghaemi (2011) Cleaning inner surface of toilet bowl ● A battery operated device with an outer
cover, a telescopic central shaft with a brush
at its end and a pair of lateral shafts with
brushes extending from central shaft
● When turned on, the brushes rotate within
the commode, without splashing the water
outside the bowl, cleaning the entire inner
wall of the bowl
● Cannot be used for cleaning the toilet seat
10 Dorra (2016) Cleaning toilet seat ● Automatically discharges water through
the outlet provided and blows air to allow
the flow of this water from back end to the
front end of the toilet seat cleaning the upper
surface of the seat
● Later the seat is anti-microbially disinfected
using UV rays
● Infrastructural modification is required to
install the device
● The device is meant to be installed on to a
single toilet commode
● Cannot be used for cleaning inner surface of
the bowl
11 Qualls and Jones (2017) Cleaning inner surface of toilet bowl ● The device with circular tracks and a pair of
retractable brushes with vertical-horizontal
tension control guide is fixed to the rim
● First the bowl is flushed with water, then
cleansing solution is dispensed, later the
brushes rotate in clockwise direction to clean
the vertical wall and finally, the brushes
retract and spin horizontally in counter
clockwise direction
● Complex design
● Can be used only in toilet commodes with
circular shaped ring
● The device is meant to be installed on to a
single toilet commode
● Cannot be used for cleaning the toilet seat

366 R.H.Krishnan
1 3
Table 1 (continued)
Sl. no System Purpose Cleaning strategy Limitations in using in public toilets
12 Hall etal. (2018) Cleaning inner surface of toilet bowl ● Automatically senses whether the user has
completed toileting and closes the lid. It then
dispenses water to the vertical wall of the
bowl in an oscillatory and overlapping pat-
tern with enough pressure through nozzles in
the bottom side of the toilet seat
● Later the seat is anti-microbially disinfected
using UV rays
● Specifically designed for rimless commodes
● Toilet commodes should be available commer-
cially with this cleaning mechanisms pre-fixed
onto it
● Cannot be used for cleaning the toilet seat
13 SpinX- Toilet cleaning robot (2019) Cleaning toilet seat and inner surface of the
bowl
● The robot scans the inner surface of the bowl
with the sensor(s)
● The arm with a spinning brush extends out
from the lid to clean the wall
● Water mixed with detergents or disinfect-
ants will be dispensed as a jet stream from
the distal end of the robotic arm towards the
inner wall
● The toilet seat is also rinsed by dispens-
ing water jets through an array of nozzles
provided underneath the lid
● Later the seat is dried by blowing com-
pressed air
● Not affordable
● A single device can service only one toilet
commode
14 Giddel Toilet Cleaning Robot (2019) Cleaning inner surface of toilet bowl ● The battery operated, portable robot can be
suspended over the toilet and the telescopic
robotic arm with a brush at its end can clean
the toilet bowl
● The inbuilt reservoir and pump will rinse the
bowl with water mixed with disinfectants
● Not affordable
● Cannot be used for cleaning the toilet seat
15 Toibot (2019) Cleaning inner surface of toilet bowl ● The device with an arm having an elastic
brush attached to it follows a track positioned
around the rim
● The device moves around the rim and simul-
taneously the brush moves up and down
cleaning the entire inner bowl surface
● The brush also spins in its own axis
● Cannot be used for cleaning the toilet seat
● A single device can service only one toilet
commode

367
A brief review onlavatory cleaning devices andtheir feasibility inpublic toilets indeveloping…
1 3
use less water for cleaning. Another important issue that
needs to be considered while designing such a device is to
ensure that all electronics sub-systems are enclosed properly
in waterproof chambers to avoid damage due to contact with
water or moisture (Krishnan and Pugazhenthi 2014). Consid-
eration of the weight of the toilet cleaning device may have
been rendered irrelevant for devices mentioned in literature
because these are to be fixed on to the toilet commode and
aimed to be employed in domestic toilets. However, this
parameter becomes an important design consideration for
devices intended to be used in public toilets.
Squatting toilet commodes are used widely in most of the
Asian and African countries (Krishnan 2019). None of the
devices discussed in Sect.2, except the brush like equipment
can be employed to clean squatting type toilet commodes.
Hence, developing a single device that shall clean and sani-
tize both western and squat type toilet commodes can be
thought off. With such a device, public toilets housing both
western and squat type commode can be cleaned without
the need for separate devices for the two types. The semi-
automated device shall ease the cleaning process keeping
purchasing cost to a minimum and such a device shall curtail
the role of man power only to a small extent so that it does
not result in unemployment leading to a win–win situation.
4 Design considerations
ofasemi‑automated lavatory cleaning
device
Maneuverability is an important factor for the semi-auto-
mated lavatory cleaning device under consideration, as it is
meant to be used in places where there are several numbers
of lavatories. The design should be in such a way that, the
user can easily push or pull the device to maneuver it above a
toilet commode. The device should be accommodated inside
a toilet cubicle of minimum size 0.9m (L) × 0.75m (W)
(MoHUA 2018) housing a sitting type western toilet bowl
with dimensions ~ 0.393m (H) × 0.425 (L) × 0.365 (W) or
a squat commode with dimensions ~ 0.585m (L) × 0.460m
(W) with a depth of 0.250m. Also, as mentioned in Sect.3,
the weight of the device is an important design criterion. The
user should be able to push or pull the device to manoeu-
vre it within the restroom and at the same time, the device
should be sturdy enough as it should not vibrate much or
move during the cleaning process.
The device is expected to clean the toilet seat, rim, inner
edge of the rim and the inner vertical wall of a western toilet
bowl as well as the foot placement area, inner edge of the
rim & inner bowl surface of a squat type commode. It shall
have brushes with proper mechanisms for scrubbing the sur-
faces of the toilet commode and shall also have nozzles to
sprinkle water mixed with cleansing agents, in order to rinse
the cleaning surfaces. Provisions to blow hot air so as to dry
the cleaned surfaces can also be incorporated in the device
under consideration. As mentioned in Sect.1, aerosolization
of the germs while cleaning or flushing may lead to respira-
tory diseases and hence the device shall be designed to clean
the toilet bowl in an enclosure preventing the aerosolized
germs from spreading into the toilet environment. Provisions
to scan the inner surface of the toilet bowl can also be incor-
porated, as in SpinX toilet cleaning robot, but with low-cost
sensors so that the brush mechanism can reach every corner
of the bowl irrespective of its size and shape.
As the device is expected to be employed in a public toilet
with several numbers of lavatories and as these lavatories
have to be cleaned frequently, the power for its functioning
can be drawn from the power socket via wires with proper
insulation to avoid possible electric shock due to water or
moisture contact. A Switch Mode Power Supply (SMPS)
can be employed in the device to convert the alternative
current (AC) to required direct current (DC). Using battery
power source may not be feasible as the batteries need to
be charged frequently. The device shall also have a simple
user interface that shall help the user to operate the device
with ease.
In addition to this, an Internet of Things (IoT) based sani-
tation monitoring and compliance system can be embedded
into the proposed toilet cleaning device to ensure timely
cleanliness of the lavatories in public toilets. The sanita-
tion monitoring and compliance system may include Radio
Frequency Identification (RFID) tags having unique identi-
fication codes attached to each toilet commode. The lava-
tory cleaning device may employ an RFID reader which will
align with the RFID tag of the commode when the device
is manually aligned over the commode before starting the
cleaning process. The reader scans the RFID tag and updates
a cloud database with information such as public toilet ID,
lavatory ID, time of cleaning, cleaning duration, whether
the cleaning was successfully completed and so on. The
information updated in the database will help the concerned
authorities to monitor and ensure timely cleanliness of pub-
lic toilets and cleaning activities of the sanitary workers.
Employing a camera and a deep learning algorithm,
implementation of a commode cleanliness classification
system can be thought off to classify the cleanliness lev-
els into three categories- ‘dirty’, ‘satisfactory’ and ‘clean’.
After the device is aligned on to the commode, the camera
captures the image of the inner wall and the deep learning
algorithm will suggest the cleanliness level to the device.
The device, based on the suggested level will automatically
choose and perform a cleaning sequence in order to clean the
commode. For example, if the suggested level is ‘dirty’, the
cleaning sequence will involve rinsing the wall with more
water and rigorous scrubbing using the brush. On the other
hand, if the suggested level is ‘clean’, the cleaning sequence

368 R.H.Krishnan
1 3
will use less water and normal scrubbing of the inner wall.
Once the cleaning sequence is completed, the camera will
again capture the image of the inner wall and the learning
algorithm will again classify the cleanliness level for con-
firmation of cleanliness. If again the level is not as desired,
the cleaning sequence will continue. By implementing this
smart cleanliness classification system, both cleanliness of
the lavatory and optimal use of water & other resources can
be ensured. Finally, after incorporating the above mentioned
functionalities and features in the design, the device shall
cost below $200 when commercialized, making it affordable
for the developing world.
5 Conclusion
Cleaning toilet commode is an unpleasant task and cleaning
public toilets housing several such commodes make the task
back-breaking. This article presents a brief review on vari-
ous lavatory cleaning devices, focussing on designs avail-
able as patent documents and commercially available toilet
cleaning robots. The devices discussed in the article and
the commercial toilet cleaning robots- Giddel and Toibot,
either clean only the toilet seat or wash only the toilet bowl.
SpinX is the only robot that satisfies both the requirements
but it is not affordable to be used in public toilets in devel-
oping countries, as each of the toilet commode in a public
toilet may require individual robot fixed on to it. A manu-
ally manoeuvrable device that can clean multiple toilet com-
modes of both sitting and squatting type and that satisfies the
discussed design criteria is the need of the hour. This cost
effective, semi-automated toilet cleaning robot may serve as
a fast and easy solution to effectively clean public toilets in
developing countries without completely removing human
intervention.
Funding Not applicable.
Compliance with ethical standards
Conflict of interest The author has no potential conflict of interests.
Availability of data and material Not applicable.
Code availability Not applicable.
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Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
R. Hari Krishnan is serving as an
Assistant Professor (Research) at
SASTRA Deemed to be Univer-
sity, India. He received his M.Sc.
in Electronics from Mahatma
Gandhi University, India, and M.
Tech. in Embedded Systems
from Hindustan Institute of
Technology and Science, India,
in 2009 and 2010, respectively.
He received his Ph.D. from SAS-
TRA Deemed to be University in
2017. His research interests
include assistive & rehabilitative
robotics, service robotics,
embedded systems and
mechatronic systems. He is a member of IEEE, IEEE Robotics & Auto-
mation Society and The Robotics Society of India (TRS).