Cybernetic Human HRP-4C: A humanoid robot with … Human HRP-4C: A humanoid robot with human-like proportions Shuuji KAJITA, Kenji KANEKO, Fumio KANEIRO, Kensuke HARADA, Mitsuharu

Cybernetic Human HRP-4C: A humanoid robotwith human-like proportions

Shuuji KAJITA, Kenji KANEKO, Fumio KANEIRO, Kensuke HARADA,Mitsuharu MORISAWA, Shin’ichiro NAKAOKA, Kanako MIURA, KiyoshiFUJIWARA, Ee Sian NEO, Isao HARA, Kazuhito YOKOI, Hirohisa HIRUKAWA

Abstract Cybernetic human HRP-4C is a humanoid robot whose body dimensionswere designed to match the average Japanese young female. In this paper, we ex-plain the aim of the development, realization of human-like shape and dimensions,research to realize human-like motion and interactions using speech recognition.

1 Introduction

Cybernetics studies the dynamics of information as a common principle of com-plex systems which have goals or purposes. The systems can be machines, animalsor a social systems, therefore, cybernetics is multidiciplinary from its nature. SinceNorbert Wiener advocated the concept in his book in 1948[1], the term has widelyspreaded into academic and pop culture. At present, cybernetics has diverged intorobotics, control theory, artificial intelligence and many other research fields, how-ever, the original unified concept has not yet lost its glory.

Robotics is one of the biggest streams that branched out from cybernetics, and itsgoal is to create a useful system by combining mechanical devices with informationtechnology. From a practical point of view, a robot does not have to be humanoid;nevertheless we believe the concept of cybernetics can justify the research of hu-manoid robots for it can be an effective hub of multidiciplinary research.

WABOT-1, the world first humanoid robot developed by Kato and his colleaguesin 1973[2], was built as an integrated system having two arms, two legs, a voice

Shuuji Kajita, Kenji Kaneko, Fumio Kanehiro, Kensuke Harada, Mitsuharu Morisawa, Shin’ichiroNakaoka, Kanako Miura, Kiyoshi Fujiwara, Ee Sian Neo, Isao Hara, Kazuhito Yokoi, HirohisaHirukawaAIST, 1-1-1 Umezono, Tukuba, Ibaraki, Japan e-mail: {s.kajita,k.kaneko,f-kanehiro,kensuke.harada,m.morisawa,s.nakaoka,kanako.miura,k-fujiwara,rio.neo,isao-hara,Kazuhito.Yokoi,hiro.hirukawa}@aist.go.jp

1

2 Kajita, Kaneko, Kanehiro, Harada, Morisawa, Nakaoka, Miura, Fujiwara et al.

recognition system etc. Later, their group developed a piano playing humanoid,WABOT-2 in 1985[3]

In the early 1990s, Brooks and his colleague started to build humanoid robotsas physical embodiment of artificial intelligence[4]. Research activities in ATR[5]and the RobotCub project[6] can be considered to have the same intention, namelyhumanoid robotics for cognitive science.

Since the breakthrough on biped walking done by Hirai et al.[7], many researchprojects on biped humanoid robots were conducted. Research was carried on gen-eration of walking motion[8], jogging and running [9, 10], efficient walking[11],human-like walking[12], dynamic whole body balance control[13] and so forth.

There also exists research working on facial expression of humanoid robots[14, 15, 16, 17]. These works target social communication and interaction, which isanother aspect of cybernetics.

In AIST, we have been developing a series of humanoid robots[19, 20]. Cyber-netic human HRP-4C is our latest development, which is a humanoid robot designedto have body dimensions close to average Japanese young female(Fig.1, Table 1).This paper explains the goal of our project and introduce the developed robot sys-tem.

Fig. 1 Cybernetic human HRP-4C

Cybernetic Human HRP-4C: A humanoid robot with human-like proportions 3

Table 1 Principal specifications of HRP-4C

Height 1,580 [mm]Weight(with batteries) 43 [kg]

Total DOF 42 DOFFace 8 DOFNeck 3 DOFArm 6 DOF × 2Hand 2 DOF × 2Waist 3 DOFLeg 6 DOF × 2

CPUs Motion controller Intel Pentium M 1.6GHzSpeech recognition VIA C7 1.0GHz

Sensors Body Posture sensorSole 6-axies force sensor × 2

Batteries NiMH

2 Aim of the development

2.1 User Centered Robot Open Architecture

Fig. 2 User Centered Robot Open Architecture (UCROA)

HRP-4C was developed in the User Centered Robot Open Architecture (UCROA)Project which is one of the projects under the AIST Industrial Transformation Re-search Initiative, a 3-year industry-academia joint project implemented by AISTfrom the fiscal year of 2006. The goal of the UCROA is to show society that it is pos-


sible to develop robot products that meet the specifications required by users com-bining reusable core technologies and developing prototype next-generation robotswhich can be used in practice by 2010 and for which the market is expected to belarge. Three prototype robots were developed in the project (Fig.2).

1. Logistics support robot2. Personal service robot3. Cybernetic human

For the logistics support robot, we developed a robotic system for warehouses. Forthe personal service robot, a small manipulator system to assist daily life of hand-icapped people was developed. The third subject of the UCROA is the cybernetichuman, whose concept is explained in the next subsection.

2.2 Concept of Cybernetic human

A humanoid robots attract many people, because of its human-like appearance andbehavior. Although a robot with very human-like appearance is called an “android”in general, we coined a new term Cybernetic human to define a humanoid robot withthe following features.

1. Have the appearance and shape of a human being2. Can walk and move like a human being3. Can interact with humans using speech recognition and so forth

Such robots can be used in the entertainment industry, for example, exhibitionsand fashion shows. It can be also used as a human simulator to evaluate devices forhumans.

As the successor of our previous humanoid robots HRP-2 and HRP-3[19, 20],we call our new humanoid robot HRP-4C, “C” stands for cybernetic human.

3 Realization of human-like shape and dimensions

3.1 Target specifications

To determine the target shape and dimensions of HRP-4C, we used the anthropomet-ric database for Japanese population, which was measured and compiled by Kouchiet al.[18]. The database provides the dimensions of the following four differentJapanese groups.

1. Young male: aged 19-27, average 20.5 years old, 110 samples2. Young female: aged 19-27, average 20.2 years old, 107 samples3. Aged male: aged 60-82, average 68.6 years old, 51 samples


4. Aged female: aged 60-80, average 66.9 years old, 50 samples

Considering the entertainment applications like fashion show, we picked the averageyoung female data. Figure 3 shows part of the dimensions provided by the database.

Sta

ture

: 1586

[mm]

Supra

ste

rnal heig

ht: 1

281

Wais

t heig

ht: 9

93

Ilia

c s

pin

e h

eig

ht: 8

50

Sym

physeal heig

ht: 7

89

La

tera

l e

pic

on

dyle

he

igh

t: 4

29

Tro

chante

rion h

eig

ht: 8

01

Crista

l heig

ht: 9

44

Chest circumference: 830

Waist circumference: 659

Upper arm circumference: 253

Forearm circumference: 228

Thigh circumference: 543

Calf circumference: 351

Head breadth: 156

Head length: 181

Tota

l head h

eig

ht: 2

31

Fig. 3 Anthropometric data of average young Japanese female [18]

In the early stage of design, we explored the possible choice and arrangementof mechanical and electric devices by scaling up and down Fig.3 to have the staturebetween 145cm and 160cm. In our final design, HRP-4C is 158cm tall which is veryclose to the average of the young female, 158.6cm.

3.2 Joint configuration

To obtain graceful motion of females, we asked a professional walking model toperform walking, turning, sitting on chair, and other motions. The positions of 86markers attached to her body were captured by Vicon Motion Systems, a 3D opticalmotion capture device (Fig.4). This data was used to evaluate the different jointconfigurations proposed for HRP-4C structure. By calculating joint angles to realizethe captured motion, the necessary movable range was estimated. In addition, we


Fig. 4 Motion capturing of professional walking model (Walking Studio Rei)

estimated the motor power during biped walking to determine the appropriate legjoint configuration.

x

y

z

(a)

(b)

Fig. 5 Joint configuration of HRP-4C body (The head and hands are omitted)

Figure 5 shows the joint configuration we finally decided on for HRP-4C. In thisdrawing, the joints for head and hands are omitted. It has the following characteristiccompared with our former humanoid robots, HRP-2 and HRP-3.


• Roll axes of waist and neck were added to realize human-like behavior (Fig.5arrow (a))

• Slanted links of forearm and thigh to mimic human (Fig.5 arrow (b))• Use of standard hip joint structure to realize natural waist line (For HRP-2 and

HRP-3, we used cantilever type hip joint[19, 20])

3.3 Design of the body mechanism

Figure 6 shows the designed body mechanism of HRP-4C (right) and HRP-2 (left).By comparison, we see that HRP-4C realized much smaller chest and hip as wellas slender extremities. To realize this body mechanism, we adopted the followingtechnologies.

• PCI-104 single board computer and peripheral boards for the whole body motioncontrol

• Distributed network motor drivers• Development of slim ankle mechanism

For further details of the body mechanism and electronics, see our next report[21].

Design: Kawada Industries. Inc.

15

80

Fig. 6 HRP-2 and mechanism of HRP-4C


3.4 Design of appearance

After the mechanical design of the leg part of HRP-4C was completed, we startedto consider the design of appearance. Figure 7 shows the proposed appearances ofHRP-4C. Fig.7(a) is a metallic robot with womanly form, (b) is a human-like designwith artificial skin and a dress to cover the mechanical parts, (c) is a conventionalhumanoid robot design and (d) is a design as a mannequin.

(a) (b) (c) (d)

Fig. 7 Proposed designs for HRP-4C

One of the problems of the design like Fig.7(b) is when the degree of similaritypasses a certain level, it can make people feel strange or even fearful. This effect wasnamed the uncanny valley by Mori[22]. He also pointed out that it can be amplifiedby the difference of motion pattern between the robot and human. This is serious foran entertainment robot.

Considering the uncanny valley and the impact as the entertainment robot, thefinal design was decided to be between (a) and (b), that is metallic robot body witha human-like face (Fig.8). We also decided to make the robot face not so real.


Fig. 8 Final design for HRP-4C

3.5 Head and hands

To realize a head size close to the average young female (Fig.3) and achieve weightreduction, we limited the numbers of degrees of freedom (DOF) of the head. Asthe minimum DOF to create facial expression we chose the movements shown inTable 2. Since each pair of the eyebrows, eyelids, eyeballs pan and eyeballs tilt areactuated by one servomotor, HRP-4C cannot perform some facial expressions likewinking. Figure 9 shows the face of HRP-4C. Despite the above noted limitations,HRP-4C can perform effective facial expressions like smile, surprise, anger etc.

Table 2 Head joints of HRP-4C

Joint name DOF Joint name DOFEyebrows 1 Mouth 1Eyelids 1 Upper lip 1

Eyeballs pan 1 Lower lip 1Eyeballs tilt 1 Cheek 1

Total 8


Fig. 9 Face of HRP-4C

We designed the hand of HRP-4C to create motion which is used in dance perfor-mance. Its DOF was again limited to the minimum (Table 3). The four fingers fromthe index to the little fingers are driven by one servomotor and the thumb is drivenby another. The size of the hand became bigger than the average young female, dueto the selected servomotors.

Table 3 Hand joints of HRP-4C

Joint name DOFIndex, middle, third and little fingers 1

Thumb 1Total 2

4 Towards human-like motion and walking

We developed a couple of algorithms to generate human-like motion and walkingfrom the mocap data obtained in 3.2[23, 24]. Figure 10 shows HRP-4C performinga 90 degree turn which was created from the captured human motion. We developeda new control software to stabilize a humanoid robot motion with stretched knee.Currently, the reliability of the controller is not enough, and we are improving it.

We also have developed a software tool to manually program HRP-4C. It can beused to quickly create the motion of HRP-4C through an interactive user interface[25].


t=3.1[s] t=4.1[s]

t=5.05[s] t=6.16[s]

Fig. 10 90 degree turn based on captured motion

5 Interaction using speech recognition

We used the open source speech recognition engine Julian[26]. It runs on the CPUembedded in the head of HRP-4C. To realize robust recognition against ambientnoise, an operator uses a wireless Bluetooth microphone to send voice commands.

The recognition result is transmitted to the motion control software running onthe other CPU in the body of HRP-4C via RT middleware[27]. Figure 11 shows anoperator speaking the voice command “Look surprised!” and HRP-4C demonstrat-ing the surprise motion.


Fig. 11 HRP-4C responding to the voice command ”Look surprised!”

6 Conclusions and future work

In this paper, we gave an overview of the development of our new humanoid robot,cybernetic human HRP-4C. The robot has the appearance and shape of a humanbeing, specifically, an average young Japanese female. It can perform biped walkusing its own battery and it can interact with humans using speech recognition.

The software of HRP-4C is still under development for the project was carriedout with a tight schedule. One of the urgent goal is to realize a reliable human-likebiped walking with stretched knees.

Acknowledgments

We would like to thank Dr. Junji Ito, director of AIST, for his generous help ob-taining the financial support to the project. Moreover, we also thank Dr. MasaahiMochimaru, Dr. Kei Aoki and other members of the Digital Human Research Cen-ter, who kindly helped our motion capturing experiment. Without the help of abovementioned people, the development of HRP-4C was not possible.


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Documents

Cybernetic Human HRP-4C: A humanoid robot with … Human HRP-4C: A humanoid robot with human-like proportions Shuuji KAJITA, Kenji KANEKO, Fumio KANEIRO, Kensuke HARADA, Mitsuharu