Development of Robotic Systems for Upper and Lower …ie.utcluj.ro/files/acta/2007/Number4/Papers/P10104.pdf · Based on the biomechanics of the limbs, ... propose a 2 DOF robotic

1st International Conference on Advancements of Medicine and Health Care through Technology, MediTech2007, 27-29th September, 2007, Cluj-Napoca, ROMANIA

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Abstract — In this paper several powered therapeutic devices for the rehabilitation of the upper and lower limbs after injury and illness are presented. The devices guide the patient’s limbs through a series of desired exercises to rehabilitate multiple muscle groups. Based on the biomechanics of the limbs, the design methodology of the proposed devices is presented and their applications for passive or active movements are emphasized. Keywords: rehabilitation, kinetotherapy, five-bar mechanism, Tetrobot, exercisers. 1. INTRODUCTION The actual health insurance system in our country is in a complex reorganization process. Though the financial constrains, the health units seek to improve their endowment for diagnosis, treatment and rehabilitation. Rehabilitation is an important component of the actual medicine that has as objective the reintegration of disabled in family and society. Rehabilitation Engineering is a component of Biomedical Engineering that contains simple devices or complex systems (prosthetics, orthotics, mobility aids, exercisers, rehabilitation robotics, etc), designed for a more efficient rehabilitation process, [4], [20]. Kinetotherapy is defined as an ensemble of procedures which promote motion as a basic element of rehabilitation treatment, [1], [15]. Kinetotherapy aspects are varied, including: walking, running, gym, games, training – using specialized equipment, rehabilitation of walk and prehension, hidro-kinetotherapy, and so on. The kinetic treatment is recommended in the following cases: posttraumatic affections of the locomotor apparatus, diseases of the nervous system and respiratory system, rheumatic illnesses, cardiac, metabolic and nutrition-related diseases, [21], [24]. In massive trauma (stroke, head injury, spinal cord injury) the patient’s motor skills in multiple muscle groups are impaired and the patient loses the full range of motion in the limbs. The passive mobilizations are those movements imposed to a patient’s articulation by an exterior intervention, without its neuromuscular system to be involved. The active

D. Mândru is with the Technical University of Cluj-Napoca,

Romania, phone: +40-264-401-645; fax: +40-264-415-490; e-mail: [email protected]

C. Rusu is with the Technical University of Cluj-Napoca, Romania, phone: +40-264-401-679; fax: +40-264-415-490; e-mail: [email protected]

E. Teuţan is with the Technical University of Cluj-Napoca, Romania, phone: +40-264-401-695; fax: +40-264-415-490; e-mail: [email protected]

I. Lungu is with the Technical University of Cluj-Napoca, Romania, phone: +40-264-401-645; fax: +40-264-415-490; e-mail: [email protected]

movements are the ensemble of exercises performed by the patient, voluntary putting in function his/her neuromuscular system. In order to obtain positive results, the kinetic treatment must be applied methodically and persistently, carefully controlled, aided by technical systems, witch could make it more efficient. Thus, a lot of exercisers were developed and already used. Baker [3] presented a therapeutic wrist rotator for the passive pronation - supination of the forearm. Gallasch et al. [8] proposed a therapeutic exerciser equipped with two angular voice– coil actuators coupled by levers to the upper limb. The development of a rehabilitation machine for upper limb including a wearable muscle suit without metal frame, actuated by McKibben actuators is presented in [17]. Saringer et al. [29] presented a passive motion device including an upper arm support suitably fixed to a drive actuator and an adjustable forearm support. More recently, Solomon et al. [30] described a therapeutic mobilisation and positioning device having a control unit that measures the force. Gao et al. [9] propose a 2 DOF robotic arm used to play arm wrestling game with human for entertainment or physical exercises. Mavroidis et al. [19] described two compact, portable devices for elbow and knee rehabilitation. Kiguchi et al. [16] studied a 3 DOF exoskeleton system attached to the upper limb to assist its motion. Other results are reported in [2], [7], [10], [13]. Similar efforts were conducted in the field of lower limb. Cowans et al. [6] designed an ankle exercise device controlled by the user by successively pushing and pulling a control rod connected with a pivoted leg support. In [5] and [25] two rehabilitation apparatus for lower limb are described. First is based on a coupling between an attendant positioned either behind or in front of a patient on a treadmill. The second is training equipment with possibility to modify the exercise parameters and simultaneously is a computerized measuring apparatus for these parameters. The newest and most modern rehabilitation engineering component is rehabilitation robotics. The rehabilitation robots can be mobile (robotic systems mounted on a

Development of Robotic Systems for Upper and Lower Limbs Kinetotherapy

Dan Mândru, Călin Rusu, Emil Teuţan, and Ion Lungu


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mobile unit, directly controlled by the user; designed for home, but used also in hospitals and rehabilitation centres) or stationary (manipulators mounted on platforms attached to the desktop or user’s bed; could manipulate cutlery, small tools and utensils and could interact with a PC). Depending on the rehabilitation procedure, the rehabilitation robots could be framed in one of the following categories: robotic systems attached to the wheelchairs or to the bed, autonomous wheelchairs, mobile robotic systems for the assistance of the disabled, prosthetic and orthotic robotic systems, and robotic systems for rehabilitation exercises The last ones are designed for active or passive mobilization of upper or lower limbs, being capable of assuring automatic deployment of the rehabilitation exercises. They offer the control opportunities of motion and resisting force’s amplitude. They can adapt to anthropometric dimension and to the morpho-functional residual capability of each patient, and offer flexibility, concerning the exercise variety, [21]. The robotic systems described in this paper are designed as intelligent environment for medical assistance in the field of rehabilitation, because: - permit a large variety of exercises, which can be accomplished automatically, and modified by programming them; - permit the disabled persons’ tele-assistance (the therapist – from the hospital, and the patient – at home); - permit several patients’ control by a single therapist; - can include cameras and sonorous perception systems, for distance communication between the therapist and the patient to be the most natural it can be - a single patient may interacts with several therapists; - with the aid of an adequate equipment, the systems can monitorise the most important of the patient’s biomechanical parameters. 2. ROBOTIC SYSTEM FOR THE UPPER LIMB

The first exerciser was designed to be used in passive and active upper limb’s mobilization, aiming the re-attainment of the shoulder articulations, elbow’s and wrists movement capacity and patient’s motor skills. According to figure 1a, user 1, in the sitting position, has its upper limb linked with mechanical structure 2 (the hand is in direct contact with a handle). The upper limb is mobilized, actively or passively, in the marked plan. Mechanical structure 2 is connected to computer 3. Because the upper limb’s movement is occurring into a plane, it results that the mechanical structure can be based on two degrees of freedom linkages. The mechanical structure presented in figure 1b is a five-bar linkage with the driving joints being placed at the base (elements 4 and 5 are input elements). A similar robotic exerciser is described in [14]. The dimensional synthesis of the five bar linkage is based on its workspace, taking into account the so-called zones of convenient reach (ZCR) of upper limbs, for the sitting position. Thus, the maximum workspace of the mechanical structure is 400 x 600 mm.

The exerciser was designed to responds to the requirements of passive or active motion of the upper limb (backward-forward projection, inner-outer rotation and abduction-adduction), of the forearm (flexion-extension and pronation – supination) and the hand (abduction – adduction and flexion – extension), [26]. In figure 2 is presented the prototype of the symmetric five-bar linkage used for the applications. The lengths of the elements are 272 mm respectively 400 mm and the distance between the two fixed joints is 600 mm. The driving elements are actuated by two DC servomotors with reduction gears. The servomotors are driven by linear voltage amplifiers. These amplifiers receive the command signals from the 12 bits digital to analog converters, which are integrated into a data acquisition and control board compatible with LabView software. The transducers are two precision rotary potentiometers. At every 10 ms a motion controller (software implemented) with feed-forward compensation, processes the information received from the transducers, and establishes the strategy to command the motors, aiming the error’s cancelling.

2.1 Results For the active exercises, the therapist learns the patient about the motions to be executed, and the exerciser displaces trajectories and targets to be accomplished. In this exercise the patient has to displace the mechanism’s

Figure 2. The prototype of the exerciser

a) b)

Figure1. The structure of the upper limb robotic exerciser


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characteristic point on the target circle, with displaying the precision of this task. The application is intended for active exercises. The user interface for this application is presented in figure 3. In order recover the control abilities, it is necessary that the cursor 6 to overlap on the target 4 by moving the mechanism of the exerciser. The target is placed on the circle 1 and its position can be modified. The proximity is marked by indicators 8. The positioning error can be controlled with button 7. The position and radius of the circles 1 and target 4 can be modified using cursors 2 respectively buttons 3 and 5. If the positioning error is into the admissible range the position of the target circle can be automatically changed. This allows various motions in the shoulder, elbow and wrist joints. The results are depicted in figure 4, [27]

.

In the second application, the patient can move a circle, representing the position of his arm attached to the mechanical structure of the exerciser, into a labyrinth. The patient must pass through the corridors of the labyrinth as quickly as possible with as few collisions as possible. A similar application is presented in [15]. The user interface is depicted in figure 5

For passive exercises, the exerciser interacts with the upper limb, moving it through the marked points and along the desired trajectories. The user’s interface for passive motions is presented in figure 6. The characteristic point of the mechanism is programmed to move along an arbitrary trajectory 2. Its form and position in the workspace could be modified, using table 1. The coordinates of characteristic point and the values from the transducers are marked by indicators 4. Hereby, the range of motions performed by the patient’s limb is controlled, and the desired anatomical movements could be selected.

The speed and the direction of motion are possible to be controlled by moving the cursor along the programmed trajectory. By interpolation of the x, y values from table 1, it’s possible to obtain a wide variety of trajectories. One example is presented in figure 7. 3. ROBOTIC SYSTEM FOR THE LOWER LIMB The ankle joint, with an important role in the human lower limb structure, representing the link between the human body and the ground during current biomechanical activities (statically, walking, running, etc.), facilitates the following types of motions, (Figure 8), [1], [24]:flexion – extension of the foot with an amplitude of maximum 60o, of which 25o count for the dorsal flexion and 35o for plantar flexion or extension (fig. 8a); supination and pronation with an amplitude of maximum 90o, of which maxim 30o for supination and maximum 60o for pronation or tibias inclination (fig. 8b); abduction and

Figure 3. The user interface for the first application

Figure 4. Different target positions

Figure 5. The user interface for the second application

Figure 6. The user interface for passive exercises

Figure 7. Trajectory for passive motions


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adduction, with an amplitude of maximum 70o, which motion at this level can be compensated by the internal and external rotation at the hip joint (fig. 8c).

a b c

Figure 8. The biomechanics of the distal extremity of the lower limb

Following, an original powered device for ankle kinetic treatment is proposed. Its peculiarity consists in actuation system based on a tetrahedral module so-called Tetrobot. This highly redundant robotic mechanism was originally proposed by Hamlin and Sanders [11], [12]. Tetrobot is a complex mechanism which belongs to a class of modular reconfigurable parallel robotic systems. The elements within the structure of a Tetrobot are connected together using mechanisms of the type presented in figure 9a. The links in the Tetrobot structure are connected to one another at spherical joints. In figure 9b is presented the way in which several elements (three elements for the presented case) are connected to a common rotation centre. Using these mechanisms placed at the top of the octohedronal, tethraedical, etc., cells, different structures of Tetrobots can be developed. Such a structure is presented in figure 9c.

a b c

Figure 9. The structure of Tetrobot The device (fig. 10a) includes a foot engaging element 2, which can move in a spherical pattern. The actuation is provided by the tethraedical module 1, rigid connected in B to the support plate. In passive exercises the foot is moved only by external forces given by tethraedical module 1. But this equipment can be used for active exercises, also. In this case, the patient moves her or his foot while being resisted by external forces given by tethraedical module 1. The notations in figure 10a are: V1, V2, V3 – actuators, m1 – inversion – eversion motion, m2 – flexion (dorsi - / plantarflexion) motion, m3 – abduction – adduction motion. Figure 10b shows the workspace of the tethraedical module equipped three DC motors (24 V variable reluctance), whose rotor has a driving screw at one end which provides a translation motion through a slide nut length which assure the dimensional changes of these tetrahedron edges, as shown in figure 11a. The position of mobile platform rotation axes is fixed in relation with the axes of biomechanical motions, as in figure 11b.

a b

Figure 10. The scheme of the ankle exerciser

a b Figure 11. The actuation system and the axis of the platform

Figure 12. The mobilization schemes

Figure 13. The trajectory of the characteristic point

Figure 14. The relative position of the platform

b) supina


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Since the mobile platform perform motions over circular paths about axes OX and OY respectively, of certain amplitudes, the motion of characteristic point A will be modelled about two circular trajectories at angular speed ωx respectively ωy within planes XOZ and YOZ. The dimensions of the mobile platform on which the patient’s foot rests (man/woman) are stated in conformity with [18], thus: for men – the mobile platform is 450x240 [mm] and for women – 360x200 [mm]. In our research the tetrahedral module has following characteristics: the base of a equilateral triangle of side 500 mm and faces, isosceles triangles of edge 769.7 mm (680+84.7) where 84.7 mm represents the mounting height L1 for the plane joint hinge, [32] Figure 13 shows the path trajectory of the characteristic point A, which must be modelled, so that it provides the control of three motors for its passage. Two situations are considered with the motion of passing the trajectory of angle Δα=60o; one of maximum time t1=5s and another of minimum time t2=2s. These values along with the position of the tetrahedron with respect to the movable platform, (Figure 14) are employed for determining the variation law l1(t), l2(t), l3(t) for the control of three motors of the tetrahedral module. With these motion laws and an adequate control algorithm one can provide the motion of the platform and of the patient’s foot, respectively in this flexion – extension motion. Likewise, considering a different plane of motion we can determine the laws of motion for the case of supination-pronation motion. 4. ROBOTIC SYSTEM FOR THE WRIST A new type of hand exercisers was proposed by the authors in their previously work, [22], (Figure 15). It consists in a pivoting hand support S able to conduct both flexion-extension and abduction–adduction due to its universal joint with the base, spherical joint in point A and a cylindrical joint between the platform S and A.

Figure 15. The scheme of the hand kinetotherapy exerciser

To describe the three possible trajectories in plane P2 denoted by 1Γ , 2Γ or 3Γ , a set of parallel mechanisms were proposed, systematized by number and type of the actuators, resulting 15 different variants. The hand exerciser is used for people who have limited hand mobility. Progressive resistance in different levels of density allow each exercise to be helpful to the patient. It helps improve muscle tone, blood circulation, strength,

dexterity and range of motion using isometric and resistive movements while the hand is positioned for optimal functioning.

a b

c d

Figure 16. Two different variants (a,b), upper (c) and side view (d) of the layout for the wrist exerciser

Figure 17.The 3 D model and the prototype of the wrist

robotic exerciser The variant given in figure 16a was investigated in [23]. In [15] a prototype based on structural scheme in figure 16b, is developed. The geometrical characteristics are based on anthropometric data regarding the hand and the wrist biomechanics (fig. 16c,d). The prototype actively moves the hand in flexion-extension and abduction-adduction with controllable amplitude and speed. Two stepper motors, reducers and belt transmissions were used. The electronic module was developed and tested. The sensors and the actuators are controlled by a Atmega 8535 microcontroller. Based on Delphi software, an interface was proposed. 5. CONCLUSIONS There is a real need for a robotic systems which allow a therapist to rehabilitate multiple patients at once, train therapists, permit remote sessions or autonomous recapitulation of a session, do not require the therapist’s attention at all times during therapy, and quantify the patient’s progress, permitting the exercises to be tailored to the patient and maximizes the rate of recovery.


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Limbs injuries are a frequent problem. The aim of this paper is to present a compilation of robotic systems for accelerating the rehabilitation procedures of upper and lower limbs. Conceptual design, mechanical structures, hardware realizations and user interfaces are presented. A 2 DOF exerciser was developed allowing active or passive complex motions of upper limbs taking into account individual needs. The mechanical structure is composed of a five bar linkage actuated by two actuators. The exerciser offers the control opportunities of exercises parameters. It can adapt to anthropometric dimension and to the morpho-functional residual capability of each patient offering a more flexibility, concerning the exercise variety. The system can be used in the early stage of therapy, when passive exercises are preferred; in this case, it moves the upper limb with the muscles remaining passive. In the next stage of rehabilitation (which is active-assistive moving phase), the device offers external assistance to the muscles moving the joints for a neuromuscular control reestablishment. An important feature of equipment for lower limb consists in its potential of being used in automatic exploitations regime, in accordance with various exercises using an adequate interface. The actuation system of the proposed device is represented by a 3 DOF modular structure Tetrobot type, thus a wide range of ankle motion is possible performing a spherical motion of the foot. Such a device does not require a user to place his / her weight on their foot to exercise, strengthen or rehabilitate an ankle. It can accommodate users of various sizes while can be commanded to exercise particular muscles, tendons and ligaments. There are several drawbacks and limitation in our developed prototypes, thus our efforts are focussed on improvements of the mechanical structures and actuation systems and developing new control strategies according with the requirements of several new exercises. 6. REFERENCES [1] Baciu, C., - Aparatul locomotor (anatomie funcţională, biomecanică semiologie clinică, diagnostic diferenţial), Ed. Medicală, Bucureşti, 1981. [2] Bardorfer, A., et al., Post-Stroke Upper Limb Rehabilitation, Movement Quality and Motor Assessment, IFMBE International Conference, 2002. [3] Baker, E., Therapeutic wrist rotator, U.S. Patent no. 5.788.607, 1998. [4] Bronzino, J.D. (ed.), Biomedical Engineering Handbook, CRC Press & IEEE Press, Hartford, 1995. [5] Borsheim, J.T., Therapeutic and rehabilitation apparatus, U.S. Patent no. 6.666.798 B2, 2003. [6] Cowans, J. et al., Ankle exercise device, U.S. Patent no. 6.206.807 B1, 2001. [7] Furusho, J., et al., A 6-DOF Rehabilitation Machine for Upper Limbs, IEEE International Conference on Mechatronics and Automation, 2005. [8] Gallasch, E., Taferner, H.P., Fend, M., Stiffness controlled voice coil actuator for muscoskeletal studies, International Conference ACTUATOR 2000, Bremen, 2000.

[9] Gao, Z., et al., Design, Fabrication and Application of Arm Wrestling Robot, International Conference on Mechatronics and Automation, Luoyang, China, 2006., [10] Gregorio, P. et al.: Hand controller, U.S. Patent no. 6.781.569, 2004. [11] Hamlin, G., Sanderson, A.C., Tetrobot a modular approach to Reconfigurable Parallel Robotics, Kluwer Academic Publishers, Boston, 1998. [12] Hamlin, G., Sanderson, A.C: A Novel Concentric Multilink Sferical Joint with Parallel Robotics Applications, IEEE Int. Conf. on Robotics and Automation, pp. 1267-1272, 1994. [13] Hassler, A., Therapeutic and training device for the shoulder joint, U.S. Patent no. 6.824.498, 2004. [14] Hogan, N., Interactive Robotic Therapist, U.S. Patent no. 5.466.213, 1995. [15] Husea, A., Development of a wrist kinetotherapy device, Diploma Project, Technical University of Cluj-Napoca, 2007. [16] Kiguchi, K., et al., Design and Control of an Exoskeleton System for Human Upper-Limb Motion Assist, International Conference on Advanced Intelligent Mechatronics, 2003. [17] Kobayashi, H., et al., Development on Muscle Suit – Realization of Abduction Motion, International Conference on Advanced Intelligent Mechatronics, 2003. [18] Kroemer, K., Ergonomics- How to design for ease and efficiency, Pretince Hall Englewood Cliffs, 1995. [19] Mavroidis, C., et al., Smart portable rehabilitation devices, ASME 2005 International Design Engineering Technical Conferences, Long Beach, California, 2005. [20] Mândru, D., Ingineria protezării şi reabilitării, Editura Casa Cărţii de Ştiinţă, Cluj-Napoca, 2001. [21] Mândru, D., Rusu, C., Noveanu, S., Research concerning the development of a robotic system for rehabilitation exercises, Mecatronica, nr. 2, 2004. [22] Mândru, D., Stan, S., The systematization of the robotic systems for hand kinetotherapy, Proceedings of the Scientific Conference with International Participation, Inter-Ing 2005, Tg-Mures, pp. 333 – 338, 2005. [23] Mandru, D., Stan, S., Exerciser for Wrist Kinetotherapy, in Acta Technica Napocensis, 49, vol. II, pp. 325 – 330, 2006. [24] Papilian. V. Anatomia omului, vol I, (Aparatul locomotor), Editura Didactică şi pedagogică, Bucureşti, 1982. [25] Peterson, K., et al., Method and an apparatus for joint-controlled training of motoric units, U.S. Patent no. 5.330.417, 1990. [26] Rusu C., Mândru D., Mătieş V., A two degree of Freedom Robotic exerciser for Rehabilitation, The 9th IFToMM Int. Symposium on Theory of Machines and Mechanisms, 2005. [27] Rusu, C., Mândru, D., Măties, V., Upper limb exerciser, 5th European Symp. on Biomedical Engineering, Patras, 2006. [28] Rusu, C., Brisan, C., Consideration concerning training of the human muscles using robotic methods, The Annual Symposium of the Institute of Solid Mechanics, SISOM 2006, Bucharest, 2006. [29] Saringer, J.,et al., Continuous motion device for upper extremity therapy, U.S.Patent 5.951.499, 1999. [30] Solomon, A., et al., Control device for the mobilization of joints, U.S. Patent no. 6.743.187, 2004. [31] Stan, S., Diplomarbeit, Analyse und Optimierung der strukturellen Abmessungen von Werkzeugmaschinen mit Parallelstruktur, IWF-TU Braunschweig, 2003. [32] Teutan, E.: Contributions regarding the study of the Tetrobot structures type. Applications in engineering, PHD Thesis, Technical University of Cluj-Napoca, 2006.

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Development of Robotic Systems for Upper and Lower …ie.utcluj.ro/files/acta/2007/Number4/Papers/P10104.pdf · Based on the biomechanics of the limbs, ... propose a 2 DOF robotic