Proceedings of the 2006 IEEE/RSJInternational Conference on Intelligent Robots and Systems

October 9- 15, 2006, Beijing, China

Dental Patient RobotHideaki Takanobu Akihisa OkinoKogakuin University Okino Industries, Ltd. / Waseda University

Nishi-shinjuku, Shinjuku, Tokyo, Japan Kamikawa, Kodamagun, Saitama Pref. Saitama, Japantakanobugieee.org a okino@d3 .dion.ne.jp

Atsuo Takanishi Mutsumi Madokoro, Yoshikazu Miyazaki, Koutarou MakiWaseda University Department ofOrthodontics, School ofDentistry

Ohkubo, Shinjuku, Tokyo, Japan Showa Universitytakanishi(wasedajp Hatanodai, Shinagawa, Tokyo, Japan

Abstract - Presently, the simple head model (hereinafterreferred to as phantom forpractical training) with dentition modelsis usedfr dental therapy training. We suggested the patient robotfor dental therapy training (hereinafter referred to as patient robot)as one of the practical applications of the humanoid robottechnology, and we actually developedbpatient robots. One of themis the general modelprovided with 14 degrees offteedom (DOE) inaddition to a tongue and lips that may interfere with treatment,allowing reflection ofany change in simple expression. Also, activemotions of the neck or hand allow various impediments so as tointerfere with the actual potential treatment. The robot allowedtrainees to do dental therapy training closer to the actual practiceinvolving avoidance o these risks.

Key words - robot, dental robotics, dental therapy education,patient model, phantom

1. Clinical training in dental therapy and patient robot Fig. 1 Phantom for practical trainingThe practical training in dental therapy education for (Dental model for therapeutic training)

treatment is now performed using the head and dentitionmodel with a simple structure and functions called phantomfor practical training (Figs. 1 and 2), there are considerabledifferences between the actual patient treatment and thatmodel. However, the trainees become dentists throughpractical experiences only with this phantom for practicaltraining in the present circumstances.

We suggest the patient robot as an influential means ofsettling the current state. Practical experiences in the sensitive......and sophisticated interventions would actually be essentialusing therapeutic instruments as well as presentation andjudgment of information on images obtained by computergraphics and so on. It seems to be an important factor in thepractical training that trainees can also experience the sense oftension and realism like treating a patient. To achieve these...............goals, the patient robot with unprecedented multi-functions, a......shape closer to man, and presence is required.

2. Feasibility study on the patient robot with humanoid Fig. 2 Therapeutic trainingrobot

Before developing the patient robot, the possibility andusability of the patient robot are verified using a model of the

1-4244-0259-X/06/$20.00 C)2006 IEEE1273

head and upper body of "Cybot." This is provided with somedegree of freedom capable of executing various motions, suchas closing and opening of the mouth, pull-up or pull-downand horizontal tension around the upper or lower lip,movements of the eyelids and eyes, rotation and inclination ofthe neck, and up-and-down movements of shoulders. Thismimics the patient robot and is placed on a chair for treatmentto verify the appearance and conditions during the practicaltraining.

3. Prototype patient robot3.1 Target specifications

Prototype patient robot with only the head of which hadreduced degree of freedom was fabricated as a robot fordental therapy training. This robot was provided a tonguehaving 3 degrees of freedom, a skin texture close to man, anda degree of freedom for closing and opening of the jaw.Because these DOF are driven by low-pressure compressedair, the robot is not in danger of damage by applying externalforce so as to interfere with any motion under the operatingconditions while feeling moderate reactive force only on thehand that restrains it, and it is possible to make this robot asafe and simple structure. A small silent air-pump was used asan air-pressure source and the actuators were controlled bysmall electromagnetic valves in the robot. The degree-of-freedom configuration of this robot is shown in Table 1, andthe appearance of the patient robot in Figs. 3 and 4. Fig. 3shows a skull with the skin removed, and Fig. 4 the state withthe flexible skin attached.

3.2 Motion test and assessmentsThe robot was presented to experienced dentists engaged

in dental education to get their impressions and assessments.Since actual cutting, drilling, etc. with the robot were notassumed, no fastener means of the head necessary for thetherapeutic training was provided, and the water drainagespray was not provided. However, positive assessments ofthe features missing in the conventional training phantomwere obtained, including the most impeditive tongue from theview of the dentists during treatment, limitation of the mouthopening extent, and elasticity of the lips just as man.

Table 1 Configuration of the first patient robotItem DOF Motion

Protrusion andTongue 3 retrusion

Tip up and downExpansion

Jaw 1 Open and close

r 1g. 3 Prototype patient robot without sKin

1274

Table 2 DOF configurations of patient robot

uber Item DOF Motion

I Eyeball 1 (Active) Right and Left2 Eyelid 1 (Active) Open and Close3 Jaw 1 (Active) Open and Close

Protrusion and Retraction4 Tongue 3 (Active) Tip Up and Down

Expansion5 Throat 1 (Active) Open and Close

Nod6 C 3 (Active) Rotation(Head) ITilt

7 Chest 1 (Active) reath8 Shoulder 3x2 (Passive) l

9 Elbow 1 (Active) Bend and Stretch

10 ight Wrist 1 (Active) p and DownI I Left Elbow 1 (Passive) l12 Left Wrist 1 (Passive) l13 aist 1 (Passive) l14 ip Point 3x2 (Passive)

15 nee I x2 (Passive)

16 Ankle 3x 2(Passive)

DOF-Joint* :3-DOF Activeo :1-DOF Activeo :3-DOF Passiveo :1-DOF Passive

Fig. 5 DOF Configuration of the patient robot

1275

4. Patient robot4.1 Target specifications

To make the practical training closer to the clinicalsetting, objectives in the realizable training by the patientrobot are as follows:(1) Obstacle to treatment due to unexpected motions of the

tongue during treatment unavoidable in the dentaltherapy and their response;

(2) Observation of the patient's expression;(3) Quick avoidance of danger due to sudden motions of the

neck;(4) Actual cutting training of the dentition model including

water spray;(5) Response to the sweeping motion by the patient's hand

mainly due to pain;(6) Simple voice recognition and voice synthesis;(7) Improvement of realism by motion-simulated breathing;(8) Whole body model capable of using the chair for

patients in the clinical setting;(9) Segmentalization for ease to transfer.The degree-of-freedom configuration is shown in Table 2,and a simplified diagram of the body of the second patientrobot considering these objectives is shown in Fig. 5.

Various motions of the patient robot, for instance, suddenmotions of the neck and tongue, are possible during operatingthe program prepared by PC, or a third party, e.g., aninstructor leading the practical training, can accordinglyintervene to give commands for various motions of the robot.

4.2 Drive systemThe drive source of the actuators in the robot uses low-

pressure compressed air, by which diaphragm actuatorsdeveloped for the robot and cylinders are operated. Theseactuators are controlled by electromagnetic valves opened andshut by signals from PC or outside manually. Water sprayedin cutting and drilling the teeth is drained out of the robotthrough an intra-oral drain. The face skin is made of specialrubber predominantly composed of vinyl chloride, attached tothe skeletal surface built in the robotic drive mechanism. Thisrubber skin backed with fibers represents directions/sites easyto stretch comparatively and hard to stretch like a human face.Replacement of this skin only allows representing different-age patients, sexuality, or characteristic patients. The rightarm has air actuators and moves like a sweeping motion. Theskin of this robot (e.g., its legs, left arm, and trunk), exceptfor the face, uses sponge material for cost reduction andweight reduction. In the dentition model for directlyconducting the therapy training including cutting and drilling,the presently widely-used commercial teeth and jaw unit isused for this robot with minor modification.

rig. o uvuid sensor

Rubber

Strain gage

Fig. 7 Teeth sensor

4.3 Control systemThe patient robot is controlled by a general-purpose PC.

Voice recognition and voice synthesis are simply made withcommercial hardware and software. This allows the trainees

1276

to give simple instructions to the patient in words and alsoallows the patient to put out a signal in words or other vocalsignal, e.g., growl.

4.4 Function of the robotLaying down this robot on the chair used for clinical

treatment allows the dentists to train in the position ofperforming treatment. The basic functions were verified.(1) Water drainage

The robot also showed the same function as theconventional training phantom with the intra-oraldraining function. Elasticity and tension closer to manon the lips and cheeks made conventionally unnaturallarge mouth-opening or treating from an unlikelydirection impossible. The practical training -

considerably close to the actual treatment - becamepossible even with this function alone.

(2) Uvula and tooth sensorUvula and teeth sensor were installed the the robot thatsimulate the vomit and pain as in Fig. 6, 7.

(3) HandIn case of the emergency, the only motion patient can dois rising up the hand. This robot also has hands as in Fig.8.

(4) Camera and target trackingEye camera in the right eye tracks the target during thetraining. For example, children hate the dental doctordue to the metal color of the devices used by thre doctor.This robot simulated the patient's eyeball motion byusing the image tracking system as in Fig. 9.

(5) TongueProtrusion and retrusion, up and down movements, andexpansion of the tongue were verified. The tongue is amajor impediment in treatment, and even risk factor insome cases. Addition of this tongue made thetherapeutic training closer to the actual possible practiceas mentioned above. Also, this robot has uvula sensor.

(6) Neck motionUp and down and right and left movements of the headof the robot were verified. As mentioned above, itbecame possible to represent the quick response to riskaversion against a sudden movement and the sense oftension during the practical training with this robot.

(7) ExpressionThe "scowling face" due to pain, blinking, and transferof the patient's line of sight were verified. This allowsthe trainees to exercise the necessity to always payattention to communication with the patient as well asthe affected area.

(8) Voice recognitionThis robot is controlled by voice recognition system asin Fig. 10

Fig. 9 Target tacking by camera

Fig. 10 Voice recognition

1277

4. 5 Assessments15 students of the department of dentistry and 2 dental

doctors have tested this robot as in Fig. 11.In result, some student didn't recognize the patient robot

hand go up. Dental doctor said that this patient robot is closerto the human patient than the phantom.

5. Conclusion(1) The idea and specification of the patient robot for the

dental therapy training were suggested.(2) The patient robot based on the aforementioned

suggestion was developed.

6. Future prospectsThe patient robot is desirable to resolve the following

challenges including the decrease in cost to become actuallywidely available:(1) Easy replacement of consumptions of dentition or oral

tissue and so on, maintenance, and improvement indurability;

(2) Development in the popular type training model with thehead only possible replacing the current phantom forpractical training, and the advanced functioning of thegeneral robot;

(3) Development in the robotic control program consideringthe patient's psychology: the emotion-generatingsoftware of the robot considered the patient's stress andchanges in feeling with treatment, and development inthe software to simulate -as much as possible - variousresponses including the individual differences in thepatient's character.

AcknowledgmentA part of the present study received scientific research

fund (study on objective skill audit procedure aimed atintroducing the practical examinations to the national dentalexaminations, 14150901) from the Ministry of Health, Labourand Welfare, Japan.

Reference[1] H. Takanobu, T. Yajima, T. Nakazawa, A. Takanishi, A.

Ohtsuki, and M. Ohnisi, "Quantification of masticatoryefficiency with a mastication robot" IEEE InternationalConference on Robotics and Automation (ICRA'98), pp.1635-1640, 1998.

(d) new patient robotFig. 11 Test by the dental doctor at real dental hospital

1278