The 2009 IEEE/RSJ International Conference onIntelligent Robots and Systems
October 11-15, 2009 St. Louis, USA

HELIOS System: A Team of Tracked Robots for Special Urban Searchand Rescue Operations
M. Guarnieri, R. Kurazume, H. Masuda, T. Inoh, K. Takita, P. Debenest, R. Hodoshima, E. Fukushima and S. Hirose

Abstract— Fire brigades and special agencies are often demanded to operate for search and aid of human lives inextremely dangerous scenarios. It is very important to ﬁrst
verify the safety of the environment and to obtain remotely aclear image of the scenario inside buildings or undergroundspaces. Several studies have been addressing the possibility ofusing robotic tools to carry out safe operations.
This contribution presents the development of the HELIOS
team, consisting of ﬁve tracked robots for Urban Search And
Rescue. Two units are equipped with manipulators for theaccomplishment of particular tasks, such as the handling ofobjects and opening doors; the other three units, equipped withcameras and laser range ﬁnders, are utilized to create virtual
3D maps of the explored environment. The three units can moveautonomously while collecting the data by using a collaborative
positioning system (CPS).
After an overview on the speciﬁcations of the team of robots
and with respect to previous publications, detailed information
about the improvements of the robot mechanical design andcontrol systems are introduced. Tests of the CPS system and
HELIOS IX vehicle together with a typical mission experimentare presented and discussed.

I. INTRODUCTION
Teams committed to urban search and rescue operations
have to operate in extreme environments, such as areas
stricken by earthquakes or by terrorist attacks. In thesescenarios, explosions and the collapse of buildings may
always occur. By using mobile platforms with high terrain
adaptability and advanced arrays of sensors, operators canin ﬁrst place size the area of operation and reach dangerous
locations, bringing to the spot cameras and tools.
There are several mobile platforms so far proposed forthese kinds of applications. However these solutions are often
addressing only very speciﬁc problems: machines with only
very high terrain adaptability, robotic tools and or machines
capable to accomplish one task such as the opening of thedoor, the grasping of objects, or the creation of 3D virtual
maps [7]. Moreover when these solutions have to be utilized
for real applications, several issues ranging from the lack ofmobility to the capability of utilizing different platforms together must be addressed. An analysis of the state-of-the-artof the Japanese robotic developments for USAR operations
Guarnieri, Hodoshima, Debenest and Hirose are with Faculty of Mechanical and Aerospace Engineering, Tokyo Institute of Technology, Tokyo, Japan

guarnieri@robotics.mes.titech.ac.jp

Inoh and Takita are with HiBot Corporation, Kamata 2-10-1, Ohta, Tokyo
144-0052, JAPAN, Japan takita@hibot.co.jp
Masuda and Kurazume are with the Graduate School of Information
Science and Electrical Engineering, Kyushu University, Japan

978-1-4244-3804-4/09/$25.00 ©2009 IEEE2795

has been presented in [8]; also, a tentative proposal for aset of machines has been introduced for practical operations
in [9]. However, proposing several types of vehicles withdifferent capabilities can become a problem due to theirlimitations when deploying them in real scenarios.
The HELIOS vehicles team proposed in this contribution
is a system of ﬁve cooperative tracked mobile platforms. The
vehicles can be utilized separately and also together in more
complex missions. Their adaptability to uneven terrain andmobility have been already illustrated in [1] and [2].
Three tracked vehicles called hereafter HELIOS carriersconsist of one parent robot and two child robots as shown in
Figure 1. The parent robot is equipped with a highly precise
laser range ﬁnder. Child robots are quipped with 2D laser
range ﬁnders, a pan-tilt camera, and an image sensor for
acquiring texture images. By making use of the laser range
ﬁnders and corner cubes, the system of the three carriers canmove autonomously in unknown environments, carrying out
the CPS system procedure [4]. Two other units of the teamare called hereafter HELIOS IX and they are utilized for theaccomplishment of speciﬁc tasks in the scenario.

Fig. 1.

Total system of HELIOS IXs and carriers

HELIOS IX, introduced in [1], consists of two tread
units connected to a base that acts mainly as a manipulator
for task based operations. The arm end-effector offers highmaneuverability for precise handling operations, making useof a special hybrid parallel linkage consisting of only 2 active
DOFs. Two CCD cameras are installed on the platform:
one with a 360◦ degrees view directly connected at theend effector for grasping operation, and another utilizedfor driving the robot and for inspecting the environment,
installed at the extremity of a 2 DOF arm.
The next section will introduce the speciﬁcations that weredeﬁned for this development. The following section will
introduce in detail the improvements and the control system of each robot. Several experiments are then introduced
and presented together with conclusions and future works
discussions.
A. Speciﬁcations
For this development the following speciﬁcations list wasdeﬁned by the NEDO sponsor of the project (NEDO is thelargest public R&D management organization for promoting
the development of advanced industrial, environmental, newenergy and energy conservation technologies in Japan):• The system can be only remotely controlled by wirelesscommunication;• The map of the explored buildings must be realized
together with the eventual presence of stairs and doors;• Robots must have a minimum speed of 5km/h;• The types of environment to be explored are civil, suchas: subways, tunnels, airports, ofﬁces and malls;• The environment may be crowded with people andseveral obstacles;• Eventually doors must be opened;• The luminosity of the environment is unknown;• The system can utilize only the onboard power;• Video of the explored buildings must be also taken;
II. M ECHANICAL S OLUTIONS AND C ONTROLA RCHITECTURE I MPROVEMENTS
This section will introduce the proposed system in detail.
All machines make use of brushless motors to avoid explosions in case of environments ﬁlled with gases.

TABLE IHELIOS IX S PECIFICATIONS
Item
Mass
Width
LengthArm (extended)
Gripper Payload
Track unit (width)
Track unit (height)
Speed on ﬂat ground

HELIOS IX
40kg
490mm
570mm
1220mm
8kg
160mm
202mm
over 7km/h

Carrier
18kg
490mm
570mm
NaN
NaN
160mm
202mm
over 7km/h

HELIOS IX. The arm length was extended 200mm in order
to be able to reach the door knobs/handles when operating
inside buildings. In this way it was possible to open space
for the installation of a corner cube utilized for the vehicle
tracking system. Besides, the gripper, that presented with theﬁrst prototype a pitch range of ±50◦ , has been improved inorder to obtain a ±90◦ . The two active links have been infact shifted backward with respect to the end effector in order
to allow the rotation of the gripper. In addition the camera
arm has been shifted forward on the forearm, so that it may
be rotated together with the end-effector.
B. HELIOS Carrier
Each HELIOS Carrier consists of a simple tracked basecomposed by two of the same treads of HELIOS IX. Two
extra motors are utilized for the tail mechanism, previously
introduced in [2] for the autonomous control of the vehicle onstairs and for the pan control of the sensing devices. Figure
3 shows the PAN actuation and the sensors installed on the
carrier.

A. HELIOS IX

Fig. 3.

Fig. 2.

HELIOS IX lifting a 7kg chair

The mechanical design of HELIOS IX vehicle shown in
Figure 2 was presented in details in [1]. This section will
depict a few improvements that were introduced after several
tests with the ﬁrst prototype. Table I shows the dimensions of2796

PAN control and devices on the child carriers

Each track, as in the case of HELIOS IX is equipped with
its own motor driver controlled by an SH2 based microcontroller and batteries. These are connected by CANbus to one
main HiBot SH2 Tiny installed in the main body, which isinterfacing by serial communication the lower system witha small laptop pc also housed inside the body. One extra
SH2 Tiny inside the CANbus network is instead utilized forthe control of the tail and the pan mechanism. In the main
body is installed also one extra battery and one router forthe network communication introduced in the next section.

C. HELIOS carriers sensing system

Parent robotz

The parent vehicle is equipped with a highly precise laser
range ﬁnder (GPT-9000A, TOPCON LTD), a pan-tilt camera(VB-C50i, Canon Inc.), and an attitude sensor (MD900T, Applied Geomechanics Inc.) as shown in Figure 4. Child robots
as seen before are equipped with corner cubes, 2D laser range
ﬁnders (TOP-URG, Hokuyo Automatic Co.,LTD), a pan-tilecamera, and an image sensor for acquiring texture images.
The highly precise laser range ﬁnder and corner cubes areused for the positioning of robots by CPS. The speciﬁcationof the laser range ﬁnder is shown in Table II.

x

y

1

1

r1

0

0

2

ψ1

φ1

2

Child robots(2) Robot 0 measures
the position of robot 1.

(1) Robot 1 and 2 move.
1
2 r
2

0

0

ψ2

2

φ2

(3) Robot 0 measures
the position of robot 2.

Fig. 6.

r2
φ2

ψ2

r1
ψ1

1
φ1

(4) Robot 0 moves andmeasures the positionof robots 1 and 2.

Cooperative Positioning System (CPS)

GPT-9000A

The 2D laser range ﬁnder installed on the child robots
are used for taking 3D geometrical information of theenvironment. The sensor can acquire 2-dimensional slit-likerange data within the range of 20m and 270 degrees, as
shown in Table III. The 2D laser range ﬁnder was placedon the rotating table, presented earlier, so that the laser slit
is vertical to the ground. By rotating the table around thevertical axis while scanning with the 2D laser range ﬁnder,
360◦ 3D range images can be acquired in 39 seconds. Figure
7 shows an example of obtained 3D and 2D maps.

Attitude sensor
Pan-tilt camera

Fig. 4.

TOP-URG

Parent robot

TABLE IIS PECIFICATIONS OF THE TOTAL STATION , GPS-9000A

Image sensor
Corner cubes

GPT-9000A (TOPCON Ltd.)Range
1.3 ∼ 3000 [m]Resolution (distance)
0.2 [mm]3”
Resolution (angle)
Precision (distance)± 2+2ppm [mm]±5”Precision (angle)

Pan-tilt camera

TABLE IIIS PECIFICATION OF THE LASER RANGE FINDER , TOP-URG
Fig. 5.

Child robot

The basic procedure of CPS is shown in Figure 6. The
laser range ﬁnder can measure the relative positions of thechild robots from the parent robot. Considering that the initial
position of the parent robot is measured or deﬁned beforehand, these are the steps followed by the CPS algorithm:(1) Child robots 1 and 2 are moved and stopped.
(2) The parent robot measures the distance, azimuth, andelevation angles to child robot 1 and identiﬁes its
position.
(3) The position of child robot 2 is identiﬁed in the same
way as in Step 2.
(4) The parent robot moves and stops. The distances,azimuth, and elevation angles to child robots 1 and 2
are then measured, and the position of the parent robot
is calculated using the triangular surveying technique.
(5) Steps 1 through 4 are repeated until the target position
is reached.

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TOP-URG (Hokuyo Automatic Co.,LTD)Range
30 [m]
270◦
Field of view
Resolution (distance)
1 [mm]
0.25◦
Resolution (angle)
Precision (distance)± 30 [mm]D. HELIOS IX and Carriers Control System
Although the basic control system of Helios IX was notchanged with respect to the previous publication, many improvements were added to the controllability of the vehicle.
The graphic interface using the feedback data from themachine shows three different 3D virtual views of the robot
for remote control as pictured in Figure 8. Also, images
acquired with the two CCD cameras can be included in the
GUI by user selection. The following modes were also added:• Direct control of each actuator of the robot;• Simple inverse kinematics control for the manipulator;

3D map(Different colors indicate different range data)

2D mapFig. 9.

Fig. 7.

An example of obtained 3D and 2D maps

Fig. 8.

HELIOS IX User Graphic Interface

Semi-automation of the stairs climbing motion by using
the onboard attitude sensor for stability control.
The vehicle can be controlled using both: a normal game
console joypad and a pair of Nintendo Wii controllers
installed in a control box as shown in Figure 9 and 10. It
consists of a touch monitor, a computer and batteries.
Wii input devices were introduced in order to test an
intuitive control of the 6 degrees of freedom installed in
the manipulator. As shown in Figure 9 two Wii remotecontrollers and one Wii Nunchuck are utilized. Using the data
extracted from the Nunchuck attitude sensors, it is possible
to obtain the roll and pitch attitude of the operator wrist.
Yaw, as well as Y,X, and Z coordinates, are instead
extracted by tracking (with the infrared camera of controllerA) the position of two infrared LEDs that were installedon the Nunchuck front panel. Controller B is utilized forthe mode selections and for the feedback vibration whengrasping an object by the end effector. In order to avoid
sudden unwanted motions of the vehicle, the data collectedby the attitude sensors are sent to the robot only if the operator keeps pressed one particular controller button according
to the selected mode. When gripper mode is selected, the•2798

Input device controller for HELIOS IX

wrist position of the user drives directly the end-effector. In
manipulator mode, the wrist position (x,y,z) in the space isutilized for the inverse kinematics control of the manipulator.
The analog joystick is instead utilized when controllingthe vehicle crawlers and when the user directly actuates
separately each motor.
HELIOS carriers are simultaneously controlled by one
control box shown in Figure 10. The operator can easily
switch the display mode between 3D and 2D (Figure 7). In
3D mode, the acquired 3D models are virtually displayed on
the screen and the virtual robots move in the 3D model. The
operator can check the movements of the robots (including
the two HELIOS IX vehicles) from the panoramic view.
The snap shots taken by cameras can be attached along themoving path as shown in Figure 11. On the other hand,in the 2D mode, the operator can plan search and rescue
missions and send movement commands to the actual robot
by indexing the target positions with a touch pen on thescreen.

2D and 3D maps

Camera images
Controller

Fig. 10.

Control box

E. WiFi Communication
The network utilized for the communication between the
robots and the operator is based on the IEEE802.11n network
by 5GHz dual band routers. Each vehicle is equipped with

Snap shots

Fig. 11.

3D model with snap shops

Fig. 12.

Door opening tests

Fig. 13.

Door opening tests

one router. For the ﬁrst tests of HELIOS system, a totalof 5 access points equipped with a small slim battery weredisplaced on different ﬂoors during ﬁeld tests. In future
works the displacement of each access point device will bealso addressed by using the carriers for their positioning.
Each router ﬁrmware was changed in order to allow eachvehicle (i.e. movable router) to connect to the strongest signalrouter in the network while moving in the environment.
III. T ESTS
A typical operation utilizes ﬁrst two HELIOS Carriers tostart to analyze the environment and to send to the user 3D
images of the scenario. In the meantime, one unit of HELIOS
IX can be also deployed by using the onboard cameras andthe carrier cameras as external points of view for controllingthe vehicle. Eventually, tasks like opening doors, removing
objects and obstacles up to 8kg can be carried out with it.
The parent robot carrier is then deployed and the automatic
3D analysis of the environment can be carried out.
A second unit of HELIOS IX can be deployed for additional tasks of search and rescue. The control of this second
unit can be effectively carried out by using the informationof the 3D environment and the tracking system offered by
the parent carrier.
The new HELIOS IX control system based on Wii controllers was tested in different situations. Several handlingtasks were carried out. Although when operating with theteam of robots it is possible to make use of the carrier
cameras to view and control HELIOS IX, this ﬁrst partpresents tests carried out with using only the on-board
cameras.
Figure 12 shows the opening of a door with knob. The
gripper eye camera while approaching the knob is reported
in Figure 12-1 .
The time to accomplish these kinds of operations isdependent on the familiarity (i.e. training) that the user has
with the control of the robot. The positioning of the machinewith respect to the door is also very important. By using theanalog joystick on the nunchuck, once the door is opened, it
is possible to control the base assigning the velocity vector
direction and amplitude of the vehicle and push or pull thedoor as shown in Figure 13. The use of the Wii has been
proven to be very effective and intuitive in this kind of task.
On the carriers sensing equipments, several modelingexperiments were carried out in a large hall area. Figure 14

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shows the total view of the 3D model of the hall. The sizeof the hall is about 60 m × 25 m.

60m

Fig. 14.

The 3D model of the hall

Figures 15(a) and 15(b) show the comparison of the accuracy of the obtained 2D maps by CPS and dead reckoning
method using the rotation of crawlers. The number of thelaser measurements was 10 for the dead reckoning, and 9
for CPS. The total distance covered by the robot was 54
m and 42 m, respectively. As seen from these ﬁgures, themap created by dead reckoning curved due to the error
accumulation, while the map by CPS is quite accurate evenafter several movements. The Figures illustrate the collected
data overlapped to the ﬂoor map image.
Figure 16 illustrates a few frames of one mission experi-(a)Fig. 15.

(b)Precise 2D map by CPS and by Dead Reckoning

ment carried out between two ﬂoors of a building. The video
attached with the submission of this contribution illustrates
the test. First the HELIOS child carriers are deployed fromthe ﬁrst to second ﬂoor, to create a 3D map of the area asin Figure 16-1. Along the stairs, operators supply a simple
forward command while the machines are autonomously
controlling the tail mechanism in order to move smoothly
on stairs (Figure 16-2).
In Figure 16-3 after the virtual map is created, HELIOSIX is deployed. The control of the robot is made easier byusing images coming from the child robots network cameras.
Last, in Figure 16-4, the parent carrier robot is taken to theupper ﬂoor for robot tracking and for the CPS system.

IV. C ONCLUSION AND F UTURE WORKS
Several experiments were carried out by using separately
each machine to conﬁrm their features. Other tests with thewhole team of robots were also performed in real conditions:in one of the Tokyo subways stations, inside a building halland in different ﬂoors. A more intuitive control device basedon Wii Nintendo controllers has been also conﬁrmed to beeffective when handling objects or opening doors with HELIOS IX. In this case, the use of camera views coming fromthe carrier robots displaced around HELIOS IX was proved
to be useful for fast operations. The vehicles can reach over
7km/h in speed (a feature useful when deploying the vehicles
from a remote spot); however, when utilizing the automatic
tracking system, due to the GPT-9000A speciﬁcations and to
avoid measurement errors, the speed had to be set to 2km/h.
The creating of large 3D maps can be time-demanding
and critical for real rescue operations. However, this canbe addressed by carefully planning the deployment of eachrobot. After part of the 3D map has been generated, one
HELIOS IX can be in fact operated while carriers accomplish
the realization of the remaining map.
Future improvements on the motion automation are to
be addressed in order to obtain a more effective control of
HELIOS IX. Also, further development on the control box
units should be considered in order to allow one single user tocontrol the whole team of robots. In the mission experimentshown previously, two users were operating respectively thetwo HELIOS IXs and the three HELIOS Carriers.
V. ACKNOWLEDGMENTS
The authors acknowledge the NEDO and the JSPS organizations for sponsoring this research.
R EFERENCES

Fig. 16.

Typical mission application

By using the 3D virtual map, the operator can move within
the GUI inside the environment and can eventually deﬁne or
locate spots to be conﬁrmed as shown in Figure 16-5. In thiscase the second ﬂoor was not illuminated and HELIOS IX
was using the on board LEDs to remove an object from asmall bag located in the ﬂoor in Figure 16-5. In Figure 16-6
the parent robot carrying out the robot tracking is marked.

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