154092 research outputs found
Sort by
Control of an Archimedes Drive based actuator for wearable robotics
No full textArchimedes drive is a composite friction planetary traction drive invented by IMSystems. Its frictiontraction gifts higher efficiency to Archimedes Drive; while, it also brings higher nonlinearity (such ascreep) to the system. The creep is a microslip phenomenon triggering velocity loss. In collaborationwith IMSystems, this EngD design project is called for designing an actuator control strategy withoutany torque sensor to implement on the Archimedes-based actuator for IMSystems. Our control goalis to achieve accurate low frequency (0Hz-20Hz) torque control between [0, 15]Nm for the passive armorthoses and low-back exoskeletons (wearable robotics projects 7-8 https://www.wearablerobotics.nl/).Note that the motor is equipped with a current controller. Therefore, this project only considers therelationship between motor input and drive output torque.To comprehend this nonlinear system better, a series of experiments were conducted to identify thedominated dynamic behaviors. Simulation results show that the plant model, based on system identification,can reflect real-world scenarios, even if some intricate nonlinear dynamics are not captured by ourmodel. Leveraging this dynamics model, two controller strategies have been developed for tracking performanceand disturbance rejection. The tracking controller emphasizes reference tracking with minimaldisturbances, while the robust controller is designed for constant reference tracking under time-varyingdisturbances.Despite the theoretical design, the simulations and experimental results revealed that the creep torqueestimator is unable to function as expected due to its excessive sensitivity. Therefore, a low-gain feedbackcontroller is necessary to limit the potential error during the dynamic reference tracking simulation, whichconstrains the system’s performance bandwidth. On the other hand, thanks to the reliable estimationof constant torque, the slide-mode control simulation exhibited sufficient robustness against time-varyingdisturbances. However, during experiments, the creep torque estimator failed to predict even a constanttorque, thereby rejecting the possibility of testing the feedback controller. Consequently, the final implementationof the tracking and robust controller in the setup integrates solely of the feedforward controland compensator, achieving a bandwidth of 3 Hz. Meanwhile, the robustness experiments maintain onlymarginal stability. For future work, to ensure the implementation of a closed-loop feedback controller,equipping a high-resolution analog encoder and a single-axis gyro is recommended
Holistic assessment of cancer-related fatigue after breast cancer:Working towards monitoring and personalized treatment advice
No full textCancer-related fatigue (CRF) is one of the most reported late and long-term effects after breast cancer. CRF is a complex, multidimensional symptom that severely impairs quality of life (QoL). When CRF persists for more than three months after completion of breast cancer treatment, treatment for CRF is required to reduce its impact. Treatment with different treatment concepts, e.g., physical activity and psychological, are available and have shown effectiveness on group level. However, the treatments are not available for everyone or do not lead to improvement of CRF for every individual. Effective treatment should target the underlying perpetuating factors and align with the patient’s preferences for treatment attributes. Patients express strong unmet needs in the management of CRF, emphasizing the need for personalized treatment advice in addition to efficacy and availability. Therefore, the overall aim was to holistically assess the individual’s needs, the experience of CRF, and the preferences for CRF treatment attributes. To assess the individual’s needs and experience of CRF, we developed the first holistic assessment of cancer-related fatigue (HA-CRF) questionnaire. Additionally, we developed a survey to assess preferences for CRF treatment attributes. Both questionnaires were developed based on extensive input from both (former) patients with breast cancer and healthcare professionals, and a thorough literature review. The HA-CRF showed good face and excellent content validity, and provided useful suggestions for implementation into the daily life of breast cancer survivors. The data collected with the HA-CRF questionnaire, and the preference survey could inform decision rules to develop a personalized treatment advice for CRF. Monitoring CRF and the personalized treatment advice has the potential to support breast cancer survivors and facilitate shared decision-making by aligning treatment referral with individual needs and preferences
A Protocol for Validation of Ground Penetrating Radar Solutions for Subsurface Utility Mapping
No full textPeri-urban Lake Ecosystem Governance:the dynamics of actor-resource interaction
No full textThis study investigates the dynamics of actor-resource interactions in peri-urban lake ecosystems in Ahmedabad, focusing on how diverse governance actors—state, civil society, private, and community—perceive and utilize lake ecosystem services. Through spatial, temporal, and empirical analyses, the research reveals that governance outcomes are shaped by overlapping actor values, competing interests, and cross-scale interactions, offering insights for more inclusive and effective lake management
Governability of peri urban lakes:Socio-ecological Dynamics of Governance
No full textThe poster presents a framework for analysing the governability of peri-urban lake ecosystems by integrating spatial, ecological, and governance dimensions. It emphasizes actor-network mapping, ecological thresholds, and co-constructed impact indicators to address fragmented governance and socio-ecological transformations in the majority world
