The use of data logging systems for capturing wheelchair and user behavior has increased rapidly over the past few years. Wheelchairs ensure more independent mobility and better quality of life for people with motor disabilities. Especially, for people with complex movement disorders, such as dyskinetic cerebral palsy (DCP) who lack the ability to walk or to handle objects, wheelchairs offer a means of integration into daily life. The mobility of DCP patients is based on a head-foot wheelchair steering system. In this work, a data logging system is proposed to capture data from human-wheelchair interaction for the head-foot steering system. Additionally, the data logger provides an interface to multiple Inertial Measurement Units (IMUs) placed on the body of the wheelchair user. The system provides accurate and real-time information from head-foot navigation system pressure sensors on the wheelchair during driving. This system was used as a tool to obtain further insights into wheelchair control and steering behavior of people diagnosed with DCP in comparison with a healthy subject.
Introduction: Power wheelchairs (PW) with head/foot steering systems are used as an alternative to joysticks in children with severe dyskinetic cerebral palsy (DCP). Mobility training programs are unstandardized to date, and insight on dystonia, choreoathetosis, and mobility performance may lead to greater independent mobility. Objective: To map the presence and severity of dystonia and choreoathetosis during PW mobility in DCP and their relation with mobility performance. Methods: Ten participants with DCP performed four PW mobility tasks using a head/foot steering system. Dystonia and choreoathetosis in the neck and arm regions were evaluated using the Dyskinesia Impairment Mobility Scale (DIMS). PW mobility performance was assessed using time-on-task and the number of errors during performance. The Wilcoxonsigned rank test and the Spearman's correlation coefficients were used to explore differences and correlations. Results: Median levels of dystonia (83.6%) were significantly higher (p<0.01) than median levels of choreoathetosis (34.4%). Positive significant correlations were found between the Arm Proximal DIMS and the PW mobility experience (rs=-0.92, p<0.001), and between the Arm Distal DIMS and the number of errors (rs=0.66, p=0.039) during mobility performance. Conclusions: Dystonia is more present and severe during PW mobility than choreoathetosis. The hypertonic hallmark of dystonia may mask the hyperkinetic hallmark of choreoathetosis, resulting in lower median levels. Results may suggest that with an increase in driving experience, children with DCP adopt deliberate strategies to minimize the negative impact of arm overflow movements on mobility performance, however, future research with bigger sample size and additional outcome measures is strongly encouraged.
The majority of individuals with dyskinetic cerebral palsy cannot use powered mobility with a joystick, due to the lack of manual abilities by the severe presence of dystonia and choreoathetosis. Reliable measurements of these movement disorders is indispensable for good evaluation towards evidence–based insights during powered mobility. This study aimed to develop and assess the Dyskinesia Impairment Mobility Scale (DIMS), a video–based tool to measure presence and severity of dystonia and choreoathetosis during powered mobility. DIMS was measured for the neck and arms region during five mobility tasks. Interrater reliability, test–retest reliability, internal consistency and concurrent validity of the DIMS were assessed. Interrater reliability coefficients ranged between 0.68 and 0.87 for the total DIMS, and the dystonia and choreoathetosis subscales. Test–retest reliability was moderate to excellent (range 0.51–0.93) while Cronbach’s alpha was good (range 0.69–0.81) for the total scale and subscale scores. Concurrent validity showed during mobility tasks significant correlations with rest postures in the arm region, and with requested but voluntary activity in the neck region. The DIMS reliably measures the presence and severity of the movement disorders during powered mobility, increasing insights into the underlying mechanisms of independent mobility. This scale may therefore be a promising tool to evaluate mobility training.
In this paper a novel head-foot wheelchair steering system based on force sensor arrays (FSAs) for people diagnosed with dyskinetic cerebral palsy (DCP) is introduced. The user applies pressure on FSAs placed on the head, and foot supports of the electrically powered wheelchair (EPW), based on his/her intention to accelerate, brake, steer right or left. The microcontroller-based electronic system acquires and translates the mean voltage generated by the applied force into wheelchair control signals. In such a system, FSAs are integrated into the head support of the wheelchair using support materials and textiles for the comfort of the user, having an effect on the sensor readings. This work aims to explore the effect of integrating FSAs into the head support of the wheelchair using support material and textiles. Four different sensor integration approaches were examined and compared to baseline readings of a non-integrated FSA. It was found that when a maximum force of 80 N is applied to a single sensing element (sensel) the support material decreases the mean voltage by approximately 70%, and the sensor integration into textile has shown increases between 5.2 and 14.9% compared to the support material. Furthermore, when force is applied over multiple sensels, the support material accounts for a reduce in the mean voltage ranging from approximately 3 to 32%. The addition of textile has exhibited peak decrease in the mean voltage up to roughly 41% for the tested integrations.
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