An assistive tabletop keyboard for stroke rehabilitation

We propose a tabletop keyboard that assists stroke patients in using computers. Using computers for purposes such as paying bills, managing bank accounts, sending emails, etc., which all include typing, is part of Activities of Daily Living (ADL) that stroke patients wish to recover. To date, stroke rehabilitation research has greatly focused on using computer-assisted technology for rehabilitation. However, working with computers as a skill that patients need to recover has been neglected. The conventional human computer interfaces are mouse and keyboard. Using keyboard stays the main challenge for hemiplegic stroke patients because typing is usually a bimanual task. Therefore, we propose an assistive tabletop keyboard which is not only a novel computer interface that is specially designed to facilitate patient-computer interaction but also a rehab medium through which patients practice the desired arm/hand functions. © 2013 Authors

Comparing "pick and place" task in spatial Augmented Reality versus non-immersive Virtual Reality for rehabilitation setting.

Introducing computer games to the rehabilitation market led to development of numerous Virtual Reality (VR) training applications. Although VR has provided tremendous benefit to the patients and caregivers, it has inherent limitations, some of which might be solved by replacing it with Augmented Reality (AR). The task of pick-and-place, which is part of many activities of daily living (ADL's), is one of the major affected functions stroke patients mainly expect to recover. We developed an exercise consisting of moving an object between various points, following a flash light that indicates the next target. The results show superior performance of subjects in spatial AR versus non-immersive VR setting. This could be due to the extraneous hand-eye coordination which exists in VR whereas it is eliminated in spatial AR

Measuring human arm’s mechanical impedance for assessment of motor function

Assessment of motor function has remained a challenge for years. This is because of the complexity of human brain and the subjective nature of the assessment. On the other hand the assessment has lots of applications such as assessment of functional capabilities in post-stroke rehabilitation for which several scoring methods such as Fugl-Meyer or NIH stroke scale already exist but in general they are subjective or qualitative while for clinic purpose these methods are widely used. Hence, this thesis aims to develop a new tool for assessment of human’s motor function with a focus on the upper limb. For that purpose, Simultaneous Sensing cum Actuating technology (SSA) will be used for measuring force, velocity, and mechanical impedance of the limb. Impedance measured at the hand point while the upper limb is performing a motion task is an indicator of quality of the limb’s function. Here an electrical motor is used as sensor-actuator which carries a mechanical load (human’s limb); because the motor plays the role of a sensor as well, if we calibrate the “Transduction Matrix” of the motor, we can measure the mechanical impedance of the load through measuring the electrical impedance of the operating motor. A number of apparatuses are designed and fabricated (one-DoF rotary and one-DoF linear). Experimental and theoretical procedures are conducted to obtain the transduction matrix for the DC motor and linear motor mechanisms. In the experimental process, the systems operate with a set of pre-known loads and the angular velocity is continuously measured. Concurrently, voltage and current signals are recorded. Correlation of electrical input and the mechanical output gives the transduction matrix. The theoretical procedure, involves popular torque-to-current and angular velocity-to-voltage models as well as a transient mathematical model for the DC motor that altogether they provide the transduction matrix model. Then the arm’s mechanical impedance is measured for a number of subjects (8 distinct individuals) in several conditions. It is shown that while performing the one-dimensional rotary task, the subjects adjust their arm’s mechanical impedance to synchronize their arm’s movement with the rotation of the wheel. Their impedance is measured in 30 consequent trials to investigate their adaptation; the subjects minimized their impedance as they learned the task. More over it is shown that the value of mechanical impedance becomes more consistent with practice. Use of the linear motor and the transduction matrix provided measurement of impedance during reaching motion. Four distinct subjects are tested and for all subjects the impedance decreases and it converges to probably a minimum value required for doing the task. Since it is practically not possible for human subjects to have zero impedance at their arm, they decreases the impedance to reach to a lower level than the beginning of the trials which confirms that the mechanical impedance of the arm will be optimized while adapting the reaching task. In order to measure the mechanical impedance in form of a complex number, sinusoidal perturbation is applied to the arm using the DC motor. Using Hilbert transform and correlating the vibration of hand and the force applied by the motor real/imaginary parts of the mechanical impedance of human arm are separated. The experiment is done for two different postures (proximal and distal) and the results are compared. The results show that for human’s hand/arm system damping increases with frequency. The imaginary part of mechanical impedance that contains mass and stiffness increases with frequency; at 5 Hz the impedance was negative and it increased at 6, 7, 8 Hz until approached zero near 10 Hz. This suggests that the system’s resonance frequency is around 10 Hz. Further experiments presenting EMG vs. mechanical impedance shows a correlation between the impedance and the EMG. In both impedance graphs and EMG graphs it was observed that the magnitude of the signals increased when the arm was stiffened; this comparison validates the impedance measurement method. Finally, to verify the effect of postures on the impedance of human arm, a primitive model is employed. The model compares the results of a series of simulated end-point stiffness to the experimental studies done by other researchers. The compassion shows in most postures the model can fairly simulate the reality.Doctor of Philosophy (MAE

Simultaneous Sensing and Actuating Compliance- Adaptive Apparatus for Upper Limb Rehabilitation

Abstract—Full or partial loss of functionality of the upper limbs is usually associated with strokes, spinal cord injury and many other similar injuries. Traditional rehabilitation treatment however is extremely labor intensive and are usually only available at hospital. However a lot of studies have shown that through the use of repetitive robotic practice can help the patients to recover. In this paper, a 4-bar linkages mechanism is designed and constructed as the upper limb rehabilitation apparatus which provided a set of motions for upper limb rehabilitation and a sensor-less method of assessing the patient arm using motor. The concept of using the input electrical impedance for monitoring the output mechanical impedance is then experimentally tested and justified in experiments. Index Terms—Simultaneous sensing cum actuating, dc motor, electrical impedance, mechanical impedance, robotic rehabilitation, 4-bar mechanism. I

Comparing "pick and place" task in spatial Augmented Reality versus non-immersive Virtual Reality for rehabilitation setting.

Introducing computer games to the rehabilitation market led to development of numerous Virtual Reality (VR) training applications. Although VR has provided tremendous benefit to the patients and caregivers, it has inherent limitations, some of which might be solved by replacing it with Augmented Reality (AR). The task of pick-and-place, which is part of many activities of daily living (ADL's), is one of the major affected functions stroke patients mainly expect to recover. We developed an exercise consisting of moving an object between various points, following a flash light that indicates the next target. The results show superior performance of subjects in spatial AR versus non-immersive VR setting. This could be due to the extraneous hand-eye coordination which exists in VR whereas it is eliminated in spatial AR

Choice of Human–Computer Interaction Mode in Stroke Rehabilitation

Background and Objective. Advances in technology are providing new forms of human–computer interaction. The current study examined one form of human–computer interaction, augmented reality (AR), whereby subjects train in the real-world workspace with virtual objects projected by the computer. Motor performances were compared with those obtained while subjects used a traditional human–computer interaction, that is, a personal computer (PC) with a mouse. Methods. Patients used goal-directed arm movements to play AR and PC versions of the Fruit Ninja video game. The 2 versions required the same arm movements to control the game but had different cognitive demands. With AR, the game was projected onto the desktop, where subjects viewed the game plus their arm movements simultaneously, in the same visual coordinate space. In the PC version, subjects used the same arm movements but viewed the game by looking up at a computer monitor. Results. Among 18 patients with chronic hemiparesis after stroke, the AR game was associated with 21% higher game scores (P = .0001), 19% faster reaching times (P = .0001), and 15% less movement variability (P = .0068), as compared to the PC game. Correlations between game score and arm motor status were stronger with the AR version. Conclusions. Motor performances during the AR game were superior to those during the PC game. This result is due in part to the greater cognitive demands imposed by the PC game, a feature problematic for some patients but clinically useful for others. Mode of human–computer interface influences rehabilitation therapy demands and can be individualized for patients