Asif Hussain

Quantitative motor assessment of upperlimb after unilateral stroke: A preliminary feasibility study with H-Man, a planar robot

This paper presents the results of a preliminary assessment study to investigate baseline performance measures and differences between control and stroke participants during reaching tasks in three directions. H-Man, planar robot is, used for this purpose. Thirteen healthy and two chronic stroke patients with upper limb motor impairment participated in the study. Assessment of performance was made through three task parameters (smoothness of movement, peak velocity, and time to peak velocity). The results from healthy subjects indicate no significant difference between different directions, however significant differences are observed in stroke participants across different directions for smoothness measure (Spectral Arc Length). All the three measures show significant differences between control and Stroke participants for corresponding directions.

Role of EMG as a complementary tool for assessment of motor impairment

Due to the aging population and increase in the number of neurological injuries, the demand for physical therapy has increased. As a result, in recent years robotic devices have been introduced to address the neuro-rehabilitation needs and have been proved to augment the recovery process. Results from a preliminary assessment study on a planar reaching task are presented in this paper. H-Man, a novel upper limb rehabilitation planar robot is employed for the study with ten healthy control subjects - divided into young and aged adults (to understand the effect of aging) and two chronic stroke patients with motor impairment. The assessment of performance was made through kinematic task parameters (smoothness of movement and time to peak velocity) and EMG signal measure (Integrated Average Value) from the upper limb muscles. This revealed significant differences between the groups. The results of the study indicated the potential use of EMG-based metric as a complementary measure to generally-used end effector robotic metrics to track the recovery process.

Self-Paced Reaching after Stroke: A Quantitative Assessment of Longitudinal and Directional Sensitivity Using the H-Man Planar Robot for Upper Limb Neurorehabilitation

Technology aided measures offer a sensitive, accurate and time-efficient approach for the assessment of sensorimotor function after neurological insult compared to standard clinical assessments. This study investigated the sensitivity of robotic measures to capture differences in planar reaching movements as a function of neurological status (stroke, healthy), direction (front, ipsilateral, contralateral), movement segment (outbound, inbound), and time (baseline, post-training, 2-week follow-up) using a planar, two-degrees of freedom, robotic-manipulator (H-Man). Twelve chronic stroke (age: 55 ± 10.0 years, 5 female, 7 male, time since stroke: 11.2 ± 6.0 months) and nine aged-matched healthy participants (age: 53 ± 4.3 years, 5 female, 4 male) participated in this study. Both healthy and stroke participants performed planar reaching movements in contralateral, ipsilateral and front directions with the H-Man, and the robotic measures, spectral arc length (SAL), normalized time to peak velocities (TpeakN), and root-mean square error (RMSE) were evaluated. Healthy participants went through a one-off session of assessment to investigate the baseline. Stroke participants completed a 2-week intensive robotic training plus standard arm therapy (8 × 90 min sessions). Motor function for stroke participants was evaluated prior to training (baseline, week-0), immediately following training (post-training, week-2), and 2-weeks after training (follow-up, week-4) using robotic assessment and the clinical measures Fugl-Meyer Assessment (FMA), Activity-Research-Arm Test (ARAT), and grip-strength. Robotic assessments were able to capture differences due to neurological status, movement direction, and movement segment. Movements performed by stroke participants were less-smooth, featured longer TpeakN, and larger RMSE values, compared to healthy controls. Significant movement direction differences were observed, with improved reaching performance for the front, compared to ipsilateral and contralateral movement directions. There were group differences depending on movement segment. Outbound reaching movements were smoother and featured longer TpeakN values than inbound movements for control participants, whereas SAL, TpeakN, and RMSE values were similar regardless of movement segment for stroke patients. Significant change in performance was observed between initial and post-assessments using H-Man in stroke participants, compared to conventional scales which showed no significant difference. Results of the study indicate the potential of H-Man as a sensitive tool for tracking changes in performance compared to ordinal scales (i.e., FM, ARAT).

Preliminary feasibility study of the H-Man planar robot for quantitative motor assessment

Current robotic rehabilitation devices have a high cost-to-benefit ratio, which prevents their large scale adoption by the clinical rehabilitation community. This paper first presents H-Man, a low cost planar robot, as a quantitative assessment and training tool. This is followed by a preliminary study to investigate baseline performance measures for motor assessment during reaching tasks as a step toward replacing conventional ordinal scales with continuous quantitative scales. Thirteen healthy and one participant with upper limb motor impairment participated in the study and performed reaching tasks with their dominant and non-dominant hands in three directions. The results from healthy subjects indicate no significant difference between different directions for both limbs and also between corresponding directions of dominant and non-dominant limbs (p > 0.05, all cases). However, differences in measures can be observed for the impaired subject.

‘Feel the Painting’: a clinician-friendly approach to programming planar force fields for haptic devices

Haptic force fields are widely used in studies on motor adaptation, motor retention, and motor recovery in both healthy and impaired subjects. In the main paradigm the hand is guided or perturbed along specific paths or channels in order to investigate different aspects underlying the human motor control. Programming such fields for complex haptic environments can be very challenging and is often not feasible for clinicians and therapists. The aim of this paper is to introduce a more intuitive and clinician-friendly programming method capable of transforming a 2D drawing (stored as an image) into a haptic environment or planar force field. By considering the image intensity as a position-dependent potential field, the energy function is approximated through locally weighted projection regression (LWPR). Robot forces are then computed through the gradient of the regressed potential. The proposed method is validated with a two degrees-of-freedom planar manipulandum, the H-Man, and a preliminary shape recognition experiment involving blindfolded healthy subjects.

Proprioceptive assessment in clinical settings: Evaluation of joint position sense in upper limb post-stroke using a robotic manipulator

Proprioception is a critical component for motor functions and directly affects motor learning after neurological injuries. Conventional methods for its assessment are generally ordinal in nature and hence lack sensitivity. Robotic devices designed to promote sensorimotor learning can potentially provide quantitative precise, accurate, and reliable assessments of sensory impairments. In this paper, we investigate the clinical applicability and validity of using a planar 2 degrees of freedom robot to quantitatively assess proprioceptive deficits in post-stroke participants. Nine stroke survivors and nine healthy subjects participated in the study. Participants’ hand was passively moved to the target position guided by the H-Man robot (Criterion movement) and were asked to indicate during a second passive movement towards the same target (Matching movement) when they felt that they matched the target position. The assessment was carried out on a planar surface for movements in the forward and oblique directions in the contralateral and ipsilateral sides of the tested arm. The matching performance was evaluated in terms of error magnitude (absolute and signed) and its variability. Stroke patients showed higher variability in the estimation of the target position compared to the healthy participants. Further, an effect of target was found, with lower absolute errors in the contralateral side. Pairwise comparison between individual stroke participant and control participants showed significant proprioceptive deficits in two patients. The proposed assessment of passive joint position sense was inherently simple and all participants, regardless of motor impairment level, could complete it in less than 10 minutes. Therefore, the method can potentially be carried out to detect changes in proprioceptive deficits in clinical settings.

Interactive robot assistance for upper-limb training

This chapter presents a systematic interaction control framework for robot-assisted training in neurologically impaired individuals. The human-robot relationship is considered as the interaction of two agents with respective control described by a cost function, which enables us to express and implement various interaction strategies. Implementation of this method for training arm reaching in chronic stroke survivors exhibits smooth motion guidance, neither disrupting movement nor preventing the inter-trials variability critical to learning. The human-robot interaction is further analyzed by using differential game theory with an algorithm to identify the human user’s behavior, providing stable, reactive and adaptive movement assistance demonstrated in simulations

A modular sensorized handle for the training of functional tasks with planar neurorehabilitation setups

In the past few years, rehabilitation technology has been one of the emerging fields in the robotics area. H-Man, a 2D planar robot, was developed for upper extremities neurorehabilitation. The current design allows elbow and shoulder motor function recovery. To further expand its use to distal components of upper limb physiotherapy, a modular end-effector capable of measuring grip force and vertical displacement is developed to be implemented on the manipulandum. The grip force measurement yields results with less than 1N (3%) mean error and 0.6N (2%) standard deviation, demonstrating the feasibility of the end effector.

Instrumentation of a hand-held power tool for capturing dynamic interaction during finishing tasks

Implementing human like performance in industrial applications is a challenging task. This paper presents a concept to capture the relationship between a grinding tool and a workpiece for future robotic implementation. A grinding tool has been instrumented with force sensors to measure 3D forces and torques, and consequently the contact point and its features have been studied during a grinding task. The results show that the contact point between the tool and the workpiece can be precisely estimated and the results have been validated using 3D motion capture. The contact point and the contact ellipses have been traced on a workpiece. The results of this study are promising and the proposed algorithms and features of the tool can be implemented in a variety of applications. In the near future instrumented tools may be used by robots during industrial tasks in order to improve their performance and allow constant feedback based on the contact point and 3D forces.

Community-based neurorehabilitation in underserved populations

Despite the fact that stroke is the leading cause of long-term adult disability and a primary cause of death, one of the major problems in national healthcare systems is the inability to provide quality post-stroke rehabilitation. Geographical barriers, socioeconomic position, race, education, and cost all contribute to health care disparities. These disparities may not only obstruct access to the most appropriate rehabilitative care, but may contribute to psychological problems, reduced quality of life, and unsuccessful return to meaningful community participation. Information and communications technology (ICT) when combined with robotic technology can enhance the accessibility of rehabilitation in low-resource, capacity-constrained settings. In this paper we introduce a low cost, limited supervision, portable robot (H-Man) designed for upper extremity rehabilitation. A usability and feasibility study indicates that out-patient robotic treatment with the H-Man leads to positive improvements in arm movement, and that the system is usable and well accepted by key stakeholders. This paper also introduces an implementation strategy to assess the effectiveness, benefits and barriers of using the H-Man robot for community-based neurorehabilitation in underserved populations, such as those that live in low income neighborhoods or in rural areas.