SEFRE (Shoulder-Elbow-Forearm Robotics Economic) rehabilitation system is presented in this paper. SEFRE Rehab System is composed of a robotic manipulator and an exoskeleton, so-called Forearm Supportive Mechanism (FSM). The controller of the system is developed as the Master PC consisting of five modules, that is, Intelligent Control (IC), Patient Communication (PC), Training with Game (TG), Progress Monitoring (PM), and Patient Supervision (PS). These modules support a patient to exercise with SEFRE in six modes, that is, Passive, Passive Stretching, Passive Guiding, Initiating Active, Active Assisted, and Active Resisted. To validate the advantages of the system, the preclinical trial was carried out at a national rehabilitation center. Here, the implement of the system and the preclinical results are presented as the verifications of SEFRE.
Aging era is now. Based on Thai Aging Status Report, now the elders are around 12% of Thai population, and the percentage can be double in year 2030 [
An impaired ability plagues their daily life. Thus relieving any of those impairments is always a great help for them. In general, recovering functions of limbs are practicable. Therefore we focus our research on the rehabilitation of arm and leg. Since recently there are an inadequate number of caretakers, so we believe that employing robotic systems in the rehabilitation process is a must.
Robotics enhances a simple device to be the super power tool. Extra enrichments include repeatability, high precision, and customizable movement. A number of medical and rehabilitation robotic systems have been on trial, while some of them are accepted in a certain level [
On one hand, numerous robotic rehabilitation systems have been developed around the globe as some examples are listed in Table
Examples of robotic rehabilitation.
Reference | Target | Key concept |
---|---|---|
Lum et al. [ |
Hand | A rehabilitator in bimanual lifting |
Chiri et al. [ |
Hand | A novel wearable multiphalanges device |
Mao and Agrawal [ |
Hand | A cable driven arm exoskeleton |
Takahashi et al. [ |
Wrist | Robotic device for hand motor therapy |
Krebs et al. [ |
Wrist | A robot for wrist rehabilitation |
Zhang et al. [ |
Elbow | A curved pneumatic muscle based exoskeleton |
Wiegand et al. [ |
Elbow | A lightweight, portable, and active orthosis |
O’Malley et al. [ |
Wrist & forearm | An exoskeleton rehabilitation robot |
Oblak et al. [ |
Wrist & forearm | A universal haptic drive (UHD) |
Hesse et al. [ |
Elbow & wrist | A robotic arm for bilateral training |
Perry et al. [ |
Upper limb | A cable-actuated dexterous powered arm exoskeleton |
Howard et al. [ |
Upper limb | A modular 2D planar manipulandum |
Lam et al. [ |
Upper limb | A haptic device with postural sensors |
Thus a device that is bearable in price and competent in features is needed to expand the deployment of robotics in the rehabilitation process. Setting this as our motto, WEFRE (Wrist-Elbow-Forearm Robotic Economic) Rehab System was firstly developed. This system is aimed at being employed as a household tool [
SEFRE Rehab System is created as a robotic rehabilitation system for all and sundry. The system is composed of three key components: a Shoulder-Elbow-Forearm Rehabilitating Mechanism, an Intelligent Controller, and a Friendly Graphic User Interface. To expedite the development process, a small industrial robot (KUKA KR5 sixx850) is used for motioning shoulder joint. Then a novel exoskeleton so-called “Forearm Supportive Mechanism (FSM)” is integrated to the system. FSM is responsible for moving elbow and forearm. This section provides the understanding of SEFRE in the details of FSM, rehabilitation protocol, control scheme and implementation, and games. (Details of control design in this section was presented at ECTI 2013, Thailand [
While the main task of KUKA is to restore the shoulder motions, FSM is deployed as elbow-forearm trainer. FSM has been created as an independent module that can either work on its own or be controlled by other systems. The control program of FSM thus has been developed separately from the main controller, called “sFSM” (Section
Since FSM must be attached to the patient arm, several criteria need to be considered. These include, for examples, form and material causing no pain or irritation, weight being light to minimize an additional payload to KUKA, and the mechanism suiting for both left and right arms.
As a result, an exoskeleton is a desired form of FSM. This leads SEFRE Rehab System to be a semiexoskeleton robotic rehabilitation system. The first prototype of FSM is shown in Figure
The first prototype of FMS (a) and the configuration of SEFRE Rehab System with a user (b).
After integrating FSM to the robotic manipulator, SEFRE Rehab System is ready to provide an arm therapy to the patient. Figure
Since we were born, our upper limbs are crucial parts for manipulating things all day and night. Dispossessing the ability to move an arm freely is alike of having no arm. Thus one who loses the limb functions needs to reinstate the features. There are several levels of arm disability based on the residue muscle strength. SEFRE is designed to service the patient in any level of muscle weakness. The system also provides the exercise in two types: the individual joint exercise that let the patient to rehabilitate any dysfunction joint, that is, shoulder, elbow, or forearm, separately one by one, and the combined joints exercise, that is, Functional Activity Rehabilitation, that allows the patient to move the arm in a pattern of an activity in a daily life. Figure
Rehabilitation protocol.
In the individual joint exercise, five therapy modes are provided based on each Muscle Strength Level (MSL).
Passive mode provides complete support to produce a joint motion of the target joint within the selected range of motion (ROM). The movement is carried out by SEFRE without any effort from the patient.
This mode is used for the patient with MSL 0 who does not have any residue muscle strength, that is, any patient who completely lost the muscle strength by a disease or an accident.
In this mode, a joint motion must be initiated by an acting force from the patient; then the motion is carried out by SEFRE as in Passive mode. This is a motivation mode that encourages the patient to try to use the regain muscle force.
This mode is used for the patient with MSL 1-2 who begins to recover some muscle strength. This could be a next step of rehabilitation process after the patient did exercises of the Passive mode in a period of time.
The AA mode provides for a patient who can insert a target guiding force to the system in some period of time. After the guiding force is less than the target level, SEFRE continues the motion as in Passive mode.
This mode is used for the patient who recovers and reaches the muscle strength in level 3 who wishes to train oneself to gain more and more strength.
This mode is similar to AA except that SEFRE only moves when the guiding force is more than or equal to the target level. This is a weight-training for the patient who almost completely recovers oneself.
This mode is used for the patients with MSL 4-5 who has high level of muscle strength. The patient who practices in this mode has ability to do the daily activities almost similar to a healthy person.
This is a special mode that is available only for the individual joint exercise. In this mode, a joint motion is carried out by SEFRE as in Passive mode. The additional step is a pause for a short period of time at either end of the desired path. This mode let ROM of the joint be increased by stretching the joint at either end.
This mode is used for the patients with MSL 0–5 who has a spastic problem.
This is a special mode that is available only for the functional activity exercise. For the functional activity option, the patient can exercise based on a typical arm movement, for example, reaching forward or feeding oneself. Four first therapy modes are provided the same as in the previous exercise type, that is, P, IA, AA, and AR. And in PG mode, a desired moving path is defined by a doctor or a caretaker, that is, a special reaching pattern; then this new customized path can be added for practicing in Passive mode.
This mode is used for the patient with MSL 0 who does not have any residue muscle strength who requires additional special movement paths.
SEFRE is targeted as an intelligent device that any caretaker or even patients themselves can use the tool enjoyably with no sweat. A number of key components thus have been evolved: Intelligent Control System providing effective rehabilitation to all, Friendly GUI and Games pleasing and entertaining the patients (Section
Overview of control system for SEFRE Rehab System: (a) scheme and (b) layout.
The control system is divided into four modules: Master PC, Robot Manipulator (KUKA), Safety Sensor Hardware (SS), and FSM (Figure
The Master PC has been developed as an Intelligent Controller. The controller is decomposed into five submodules: Intelligent Control (IC), Patient Communication (PC), Training with Game (TG), Progress Monitoring (PM), and Patient Supervision (PS). Each has a key task as follows: IC: the intelligent control unit, PC: the interface unit between the patient and the system, TG: the games management unit, PM: the rehabilitation monitoring unit, PS: the analyzing and supervising unit.
IC is responsible for generating commands based on the configured rehabilitation options. To conduct such a task, the communication protocol between IC and other modules, that is, KUKA, FSM, GUI, and Games, is executed as shown in Figure
SEFRE state diagram.
The protocol has four components: Robot Pose, Robot State, Changing State, and Clicked Button. To change the robot state when a button on the GUI is clicked, IC must send a corresponding signal to the robot after receiving the signal based on the Clicked Button. Consequently, this results in a new pose of the manipulator; that is, Robot Pose and Robot State are changed. This concept opens the door for assembling the other modes to the system by modifying IC only; neither KUKA nor FSM needs to be reprogrammed.
There are five communication paths to be managed by IC for conducting the rehabilitation process.
IC inspects safety of the system in different patterns based on the state in Figure
sFSM is an autonomous controller to control only FSM module, which is created separately from IC. Two servomotors that are deployed for FSM have two operation modes. Both are joint mode and wheel mode, which are used for controlling motor position and velocity, respectively. Due to mechanical design of FSM, one motor is operated in wheel mode, which requires an additional control algorithm. The algorithm composed of a round-counting function as an encoder and PID (Proportional-Integral-Derivative) control function. This customized algorithm supports sFSM to control the position of the joint while the motor is operated in wheel mode.
Force Sensing is an essential part of the system because the sensors empower SEFRE to sense any effort from the patient. Each force sensor is selected based on its special properties that are consistent with the sensing task. Three types of force sensors, namely, six-axis force torque sensor, load cell, and Force Sensing Resistor (FSR), are integrated with SEFRE.
As a remark, since forearm and elbow rotate around their own axis, so we simplified our system by using load cell and FSR instead of other complicated sensors.
In every state, IC plays a vital role in synchronizing between KUKA and FSM to make various desired motions, for example, reaching forward, to be a concurrent and natural motion. This section informs the synchronization process between both modules of each rehab mode.
According to the synchronization flowchart in Figure
Synchronization procedures between IC, FSM, and KUKA.
Synchronization can be classified based on two major modes: Passive and Active.
To serve various patients who have different conditions of muscle weakness, the exercises are also grouped into two modes: Passive and Active, as explained in the rehabilitation protocol. Therefore, games are designed deliberately to match the patient condition in each mode.
Games nowadays are mostly suitable for Active mode due to they must allow the players to experience the social interactions [
The crucial factors that separate games in Passive mode from the others are the event conditions and scoring.
To play the transportation game in Figure
Games for Passive mode.
For the fruit collection game in Figure
Also, there should not be any negative score because this condition might discourage the patients from playing the game.
Pre-Active mode is an Active mode with an assigned path. This mode suits anyone who has enough muscle strength to motion a decayed arm along a preprogrammed path.
Pre-Active Transportation game is derived from a game in Passive mode. Due to the fact that patient may not notice the magnitude of acting force, it is necessary to add a force indicator in every Active game. The indicators, which represent the force magnitudes in colors, are shown as arrows at both sides of the window in Figure
Games for Active mode.
For the Slot Machine Game in Figure
To verify the advantages of SEFRE, we have carried out an intensive clinical trial at the national rehabilitation center of Thailand.
The main objective of the preclinical trial is to validate the operation and the safety of the system through the rehabilitation in Passive mode. Since a small group of subjects can give a preliminary result to forward the work [ Before they began the trial and signed the contract, the details of the trial protocol were precisely explained. Then the personal information and medical background were recorded. During the 5-day trial, the subjects received the conventional therapy for two hours per session, one session per day. In each session, they must be rehabilitated by SEFRE for 15 minutes. In this trial, every subject was verified with two assessments, namely, the muscle tone assessment and Passive ROM (PROM) assessment. Both assessments were carried out two times: before the first day and after the fifth day.
Also, the subjects must fill in the questionnaire to evaluate the impression of SEFRE Rehab System. The actual trial period of all subjects for each day is shown in Figure
Trial period of all subjects on each day.
SEFRE provides the exercise for the patients in several movements as shown in Figures
Example movements of SEFRE Rehab System: shoulder extension-flexion.
Example movements of SEFRE Rehab System: shoulder abduction-adduction.
Example movements of SEFRE Rehab System: elbow extension-flexion.
Example movements of SEFRE Rehab System: forearm pronation-supination.
Examples of subjects for the preclinical trial are shown in Figure
SEFRE clinical trial result of 3 subjects: PROM.
Day | Shoulder E-F | Elbow E-F | Forearm P-S |
---|---|---|---|
1st | WNL | WNL | WNL |
5th | WNL | WNL | WNL |
SEFRE clinical trial result of 3 subjects: muscle tone.
Day | S001 | S002 | S002 |
---|---|---|---|
1st | 1 | 1 | 1 |
5th | 1 | 1 | 1 |
Examples of SEFRE clinical trial.
Based on these results, the next phase is to certify the system in Active mode. Also, the number of subjects and the trial period must be extended. Moreover, to assure that the system can support and unite with the conventional therapy protocol, the subjects must be divided into two groups, that is, the control and experiment groups. Thus, the work we present here is still in an initiating step; nevertheless, we believe that our research must be a great achievement to rehabilitation domain when SEFRE is accomplished.
SEFRE Rehab System is composed of a robotic manipulator and an exoskeleton, that is, FSM (Forearm Supportive Mechanism). The main controller of the system is the Master PC that consists of five modules, that is, Intelligent Control (IC), Patient Communication (PC), Training with Game (TG), Progress Monitoring (PM), and Patient Supervision (PS). Based on these modules, SEFRE Rehab System is able to provide six arm therapy modes: Passive (P), Passive Stretching (PS), Passive Guiding (PG), Initiating Active (IA), Active Assisted (AA), and Active Resisted (AR). These allow SEFRE to be the robotic rehabilitation system for everybody, for example, a patient without any residue muscle strength or a healthy person who has temporary muscle deficiency problem. To validate the advantages of the system, the preclinical trial was carried out by providing the rehabilitation in Passive mode for three subjects who aged 40–68 years. The results of this intensive trial, that is, three subjects were trialed for five sessions, show that all subjects and relatives felt safe when they were rehabilitated by SEFRE. Moreover, the muscle tone and PROM assessments verified the system for retaining the physical condition of the upper limb. Thus the next phase is to validate the system in Active mode, which we believe that this must be a great benefit to the rehabilitation field when the system is completed.
Furthermore, to achieve the motto of SEFRE, an affordable robotics rehabilitation system, a small industrial robot with ATI mini45 module, must be replaced with a customized novel mechanism that lower the producing cost of the system. This is our next key milestone to complete SEFRE as the Shoulder-Elbow-Forearm Robotics Economic rehabilitation system.
The authors declare that they have no competing interests.
The authors would like to thank Dr. Wasuwat Kitisomprayoonkul from The Thai Red Cross Rehabilitation Center, Dr. Daranee Suwapan from Sirindhorn National Medical Rehabilitation Center, and their OTs and PTs for allowing them to do an intensive preclinical test of SEFRE Rehab System there and Mr. Nassaree Benalie to support them to complete the trial.