六自由度上肢康复机包括手腕使用器.pdf

Proceedings of the IEEE International Conference on Mechatronics Automation Niagara Falls Canada July 2005 0 7803 9044 X 05 20 00 2005 IEEE A 6 DOF Rehabilitation Machine for Upper Limbs including Wrists Using ER Actuators Junji Furusho Chengqiu Li and Yuhei Yamaguchi Graduate school of Engineering Osaka University 2 1 Yamadaoka Suita Osaka Japan furusho mech eng osaka u ac jp Shinya Kimura Kenji Nakayama Takaya Katuragi and Takamichi Oguri Graduate school of Engineering Osaka University 2 1 Yamadaoka Suita Osaka Japan Ushio Ryu and Sadami Suzuki Asahi Kasei Engineering Co Ltd Kohnan 4 chome Minatoku Tokyo Japan Akio Inoue ER tec Co Ltd 2 1 31 Sakuragaoka Minoo Osaka Japan Abstract New training methods and exercises for upper limbs rehabilitation are made possible by application of robotics and virtual reality technology The technologies can make quantitative evaluations and enhance the qualitative effect of training This paper deals with the development of a 6 DOF rehabilitation machine for upper limbs including wrists using ER actuators Robotherapist Index Terms Rehabilitation System Upper Limb Rehabili tation Wrist Rehabilitation Robotics ER Actuator I INTRODUCTION Movements of the upper limbs such as eating and oper ating appliances are complicated various and indispensable for daily activities It therefore is important for the aged to exercise to keep their upper limb function Moreover there are many patients of paralysis caused by stroke For example in Japan more than two hundred and fi fty thousand people have stroke every year and many of them are paralyzed The human brain is capable of an extraordinary degree of plasticity self organization enabling learning and leaving open the possibility for motor recovery 1 Therefore neuro rehabilitation for stroke patients is effective The physical therapy involves one on one interaction with a therapist who assists and encourages the patient through a number of repetitive exercises A robotic therapist can eliminate unnecessary exertion by the therapist quantitatively monitor patient progress and ensure consistency in planning a therapy program The percentage of aged persons in society and their number are increasing and their physical deterioration has become a social problem in many countries Early detection of function deterioration and suffi cient rehabilitation training are necessary not only to decrease the numbers of aged who are bedridden or need nursing care but also to enable the aged to take an active part in society Using apparatus that applies robotic technology and vir tual reality makes new training methods and exercises in This work is supported by New Energy and Industrial Technology Development Organization NEDO under the Ministry of Economy Trade and Industry of Japan rehabilitation possible 2 3 Feeding back the quantitative evaluations to the training by a computer can enhance the qualitative effect of training Therefore some rehabilitation systems using these technologies for upper limbs have been developed However most of them apply training within a two dimensional horizontal plane Many movements how ever in daily activities need to move arms in a vertical direction A system therefore that enables exercise in three dimensions would seem to be more effective for such train ing Although the MIME system 3 using PUMA 560 by VA and Stanford Univ can give training in three dimensions the PUMA 560 is a robot originally developed for industrial use and may not be suffi ciently safe to train the aged and or disabled Furusho et al of Osaka University developed two types of 2 DOF force display systems using ER actuators 4 5 6 and have carried out clinical trials of rehabilitation for upper limbs 6 In these systems ER actuators ensure the mechanical safety Then Osaka University and Asahi Kasei Group joined the 5 year NEDO Project and developed a 3 D rehabilitation apparatus for upper limbs based on this knowledge 5 Then we conducted the clinical evaluation at Hyogo Medical college 7 In the rehabilitation system developed in the 5 year NEDO Project the wrist of the rehabilitation machine is not driven by actuators and rotate freely So the proper rehabilitation for upper limbs including wrists can not be attained Krebs et al of MIT developed a wrist robot 8 for rehabilitation and then have developed a 5 DOF rehabilitation system consisting of MIT MANUS 2 and this wrist robot 9 In this paper we present the development of a 6 DOF rehabilitation machine for upper limbs including wrists using ER actuators in a project for the Practical Application of Next Generation Robots This machine will be exhibited at the 2005 International Exposition held in Aichi Prefecture Japan 1033 Input Rotational Cylinder ER Fluid Electric Field Motor Output Rotational Cylinder Output Torque Input Torque Fig 1 Conceptual Illustration of ER Actuator Fig 2 Multi cylindrical type ER Actuator with Output Torque in Both Rotational Directions Fig 3 Multi cylindrical type ER Clutch II ER ACTUATORS ER fl uid is a fl uid whose rheological properties can be changed by applying an electrical fi eld 10 Fig 1 shows the conceptual illustration of an ER fl uid actuator The ER actuator is composed of an ER clutch and its drive mechanism consisting of a motor and a reduction gear unit The rotational speed of the motor is kept constant The output torque of ER actuator is controlled by the applied electric fi eld The sectional view of ER actuator which is capable of producing output torque in both directions are given in Fig 2 The input rotational parts of Fig 2 Part I and Part II possess cylindrical structure The input rotational PartI is rotated clockwise through a gear by an electric motor and the input rotational Part II is rotated counterclockwise through a series of gears by the same motor The input torque is transferred to the rotating cylindrical section of the output axis via the particle type ER fl uid fi lled in the rotating cylinder Both the input axis cylinders and the output axis cylinder serve as electrodes and output torque is controlled by the electric fi eld applied between the electrodes The output cylinder is made of aluminum alloy in order to reduce the moment of inertia of the output axis Fig 3 shows a ER clutch with cylindrical structure An actuator using ER fl uid is effective for human coexistent mechatronics systems like rehabilitation systems Fig 4 Human Machine Coesistent Mechatronics HMCM System using ER Actuators Fig 5 Rehabilitation System NIOH 1 Fig 6 Rehabilitation System NIOH 2 for upper limbs 4 Fig 4 shows a conceptual illustration of Human Machine Coexistent Mechatronics HMCM System using ER Actuators Merits of ER actuators in applications to Human Machine Coexistent Mechatronics HMCM system are as follows 1 From the Viewpoints of the Characteristics of Opera tion a Since ER actuators have good back drivability the operator can easily operate HMCM system from its end effector b When HMCM system is driven by the operator from its end effector HMCM system can be moved quickly over the rotational speed of the input cylinder of the ER clutch 2 From the Viewpoints of Performances in Force Display System a Quick force response property originated from the low inertia property of ER actuator and the rapid response of ER fl uid make the force presentation with high fi delity possible b Force display systems with large force presentation ability can be realized safely 1034 Fig 7 Passive type Force Display System Fig 8 EMUL in Rehabilitation III REHABILITATION ANDFORCEDISPLAYSYSTEMS USINGER FLUIDS Furusho Lab of Osaka University has been developing rehabilitation systems and force display systems using ER fl uids since 1993 11 Fig 5 shows the 2 DOF rehabilitation systems NIHO 1 using ER actuators shown in Fig 2 4 12 The rehabilita tion training system was installed in a hospital for testing purpose 13 patients volunteered to participate in several experiments for evaluation of upper limb s physical capability and for rehabilitation training The patients suffered from arm paralysis due to a damaged spinal cord or clogged brain artery Fig 6 shows the 2 DOF rehabilitation system NIHO 2 using ER actuators shown in Fig 3 5 13 Fig 7 shows a passive force display using ER brakes 14 Passive force displays using brakes to present resistance force against operator s force are quite safe 14 15 Furusho Lab is going to examine a passive force display on rehabilitation for upper limbs Fig 8 shows the 3 D rehabilitation system for upper limbs using ER actuators EMUL 7 EMUL was developed in a 5 year NEDO project and evaluated for stroke patients by using Fugel Meyer assessment 16 Motricity Index 17 and Ueda Stage 18 in the clinical testing The good results were obtained in the evaluation Fig 9 Hand grip of EMULFig 10 Drawing of the 1st Prototype Fig 11 Movement of Link 2 IV THE1STPROTOTYPE OF6 DOF REHABILITATION SYSTEM Fig 12 Movement of Link 3 In the 3 DOF rehabilitation system EMUL the proper rehabilitation for upper limbs including wrists can not be attained since EMUL has the free rotation wrist as shown in Fig 9 So we have developed a 6 DOF machine using ER actuators in a project for the Practical Application of Next Generation Robots In this chapter we present the develop ment of the 1st prototype machine using servo motors Fig 10 shows drawings of the 1st prototype machine The mechanism of the prototype machine is as in the following 1 It has 2 DOF the horizontal rotation and 1 DOF for the vertical movement in the arm part 1035 Fig 13 Wrist Part and Link 3 of the 1st Prototype Fig 14 Side View of the Link 3 2 Actuators and belt pulley reduction systems for the arm motion are set on the base in order to reduce the inertia of the moving parts The vertical rotation part adopts a parallel link mechanism consisting of link 2 1 and link 2 2 as shown in Fig 10 This makes the gravity effect compensation by counter balance weight in all posture possible see Fig 11 3 Link 3 driven by the spatial link mechanism rotates in the horizontal plane as shown in Fig 12 4 Actuators for the wrist motion are mounted on link 1 in order to reduce the inertia of the moving parts The motor torques are transmitted to the wrist by using universal joints driving shafts and wire pulley system see Fig 13 5 Fig 14 shows the wire pulley system for the wrist Fig 15 shows the pathways of wires for roll pitch yaw a Roll b Pitch Fig 15 Wires for Roll Pitch and Yaw Rotation c Yaw Fig 16 Twist of Wire rope Fig 17 The 6 DOF Rehabilita tion System Robotherapist Fig 18 ER Actuator respectively 6 The roll motion of the wrist causes the relative rotation between the part A and the part B of Fig 14 As the result of this relative rotation the driving wires for the pitch and yaw motions are twisted as shown in Fig 16 In order to reduce the variation of wire length caused by this roll motion these wires are placed near the roll axis as possible V 6 DOF REHABILITATIONMACHINE ROBOTHERAPIST Fig 17 shows a photo of Robotherapist This system is driven by ER actuators Fig 18 shows the ER actuator for the arm motion The mechanism of the grip handle and the wrist was changed to the cantilever type from the both Fig 19 Wrist Part of Robotherapist 1036 Fig 20 Composition of 6 DOF Rehabilitation System Fig 21 Construction of Wrist Part side support type Fig 19 shows the mechanism of the grip handle and the wrist Fig 20 shows the conceptual illustration of the total system The gravity composition is required in the cantilever type grip handle as shown in Fig 21 When we adopt such mechanism the weight near the grip handle increases and the performance as a force display system and the safety property as Human Machine Coexistent system are deteriorated So we placed the balance weight in the ER actuator box as shown in Fig 22 We are developing rehabilitation training software which requires the dexterity of upper limbs including wrists Fig 23 Fig 24 and Fig 25 show a part of training software Fig 22 Arrangement of balance weight Fig 23 Virtual Hitting Fig 24 Virtual SprinkleFig 25 Virtua Wipe VI CONSIDERATION ABOUTSAFETY A rehabilitation system for upper limbs which has large working area can be regarded as a kind of robots In such a human coexistent robot system where an operator must be in contact with or close to the robot the safety securing system is necessary in order that an operator can use the robot safely 19 In industrial robots an operator cannot access a robot except for teaching in order to avoid hazardous conditions Fig 26 shows the structure of safety in human coexistent robots ER actuators have the following merits from the viewpoint of safety a The maximum driving speed of the output shaft of the ER actuator is restricted by the rotational speed of the input shaft of the ER clutch Therefore when the rotational speed of the input shaft is set slow HMCM systems using ER actuators are safe for operators b The inertia of the output part can be made very small So in the case of unexpected accidents the impact force caused by the inertia of the actuator can be reduced Since International Safety Standards for human coexistent robots have not been established yet we have no other choice but to use the ISO and domestic standards for machines working close to human beings see Table I The developed rehabilitation system can assure these standards of Table I by the usage of ER actuators and the mechanical design as follows 1 The items a and b of Table I are satisfi ed by setting the rotational speed of the input cylinder slow 2 The item c is satisfi ed by using a 60 watt motor for the drive of the input rotational cylinder 3 Risk Reduction by Design item d is realized by mechanical limitation of each joint mechanical gravity compensation and the usage of ER actuators Safety from the viewpoint of Information Safety from the viewpoint of Control Safety from the viewpoint of Mechanism and Actuators Safety from the viewpoint of Operation Condition Fig 26 Structure for Securing Safety in Human Coexistent Robots VII CONCLUSIONS We have developed a 6 DOF rehabilitation machine for upper limbs including wrists as in the following 1 The 1st prototype machine using servo motors was developed for the purpose of confi rming a novel mech anism for the rehabilitation system 1037 TABLE I INTERNATIONAL ANDDOMESTICSAFETYSTANDARDS a End effector Speed is less than 0 25 m s ISO10218 Manipulating industrial robots Safety b Low Energy PropertyISO14121 Safety of machinery Principles of risk as sessment c Actuator Power is less than 80 W JAPAN JIS B 8433 1983 General Code for Safety of Industrial Robots d Risk Reduction by DesignISO12100 Safety of machinery Basic conceptsCgen eral principles for design 2 Then the 6 DOF rehabilitation machine for upper limbs including wrists using ER actuators Robothera pist has been developed based on the knowledge ob tained from the development of the prototype machine 3 we are developing the rehabilitation software upper limbs including wrists at present REFERENCES 1 Carr Janet and Roberta Shepherd Neurological Rehabilitation Opti mizing Motor Performance Butterworth Heinemann Boston 1998 2 H I Krebs B T Volpe M L Aisen and n Hogan Increasing produc tivity and quality of care Robot aided neuro rehabilitation Jurnal of Rehabilitation reseach and development vol 37 no 6 pp 639 652 2000 3 C G Burgar P S Lum P C Shor and H M V der Loos Devel opment of robots for rehabilitation therapy The palo alto va stanford experience Jurnal of Rehabilitation Reseach and Development vol 37 no 6 pp 663 673 2000 4 J Furusho and M Sakaguchi New actuators using ER fl uid and their applications to force disply devices in virtual reality and medical treat ments Proc of the International Conferance on Electro Rheological Fluids Magneto Rheological Suspensions and their Applications 755 763 1997 Int J of modern physics B vol 13 no 14 15 16 pp 2151 2159 1999 5 J Furusho K Koyanagi U Ryu A Inoue and K Oda Development of rehabilitation robot system with functional fl uid devices for upper limbs International Journal of Human friendly Welfare Robotic System vol 32 no 6 pp 23 27 2003 6 J Furusho Mechatronics system using ER fl uids review paper J of Japan Hydraulics and Pneumatic Society vol 32 no 6 pp 390 395 2001 In Japanese 7 J Furusho K Koyanagi Y Imada Y Fujii K Nakanishi K Domen K Miyakoshi U Ryu S Takenaka A Inoue A 3 D Rehabilitation system for Upper Limbs Developed in a 5 year NE