Rehabilitation robot cell for multimodal standing-up motion augmentation

The paper presents a robot cell for multimodal standing-up motion augmentation. The robot cell is aimed at augmenting the standing-up capabilities of impaired or paraplegic subjects. The setup incorporates the rehabilitation robot device, functional electrical stimulation system, measurement instrumentation and cognitive feedback system. For controlling the standing-up process a novel approach was developed integrating the voluntary activity of a person in the control scheme of the rehabilitation robot. The simulation results demonstrate the possibility of “patient-driven” robot-assisted standing-up training. Moreover, to extend the system capabilities, the audio cognitive feedback is aimed to guide the subject throughout rising. For the feedback generation a granular synthesis method is utilized displaying high-dimensional, dynamic data. The principle of operation and example sonification in standing-up are presented. In this manner, by integrating the cognitive feedback and “patient-driven” actuation systems, an effective motion augmentation system is proposed in which the motion coordination is under the voluntary control of the user

Fuzzy logic based intention recognition in STS processes

This paper represents a fuzzy logic based classifier that is able to recognise human users' intention of standing up from their behaviours in terms of the force they apply to the ground. The research reported focused on the selection of meaningful input data to the classifier and on the determination of fuzzy sets that best represent the intention information hidden in the force data. The classifier is a component of a robot chair which provides the users with assistance to stand up based on the recognised intention by the classifier

FES-standing and muscle spasms: neurophysiology and biomechanics

Functional Electrical Stimulation (FES) can be used to assist patients with complete paraplegia arising from a traumatic spinal cord injury to stand. In clinical practice the take-up of this technology is poor. It was hypothesised that one potential reason was that the posture during standing was difficult to predict from non-standing biomechanical measures because of the spinal cord's motor responses to standing. In six patients biomecharrical and electrophysiological recordings were made to test whether motor activity arising as a result of standing affected their standing posture. Recordings were made using surface EMG electrodes, force plates and instrumented handles a motion analysis system. No motor activity that affected the posture of the patients was recorded during standing or when the patients changed their hip or ankle angles. The act of standing with FES assistance affected spasms in two of the six patients. In one patient his spasms became regularised to a 16s pattern when standing with FES but when standing without FES and in the second patient his spasms were stopped for periods of up to 7 hours. This prolonged cessation only occurred when standing with FES. Mechanically supported standing produced a short (5 minute) cessation in the activity. The neural activity during the sit-to-stand or steady state standing did not change with increasing experience of standing in one naive subject studied over 6 weeks. The patient used the same strategy for the sit-to-stand as other patients. He improved his performance of this strategy by shortening the phases and the intervals between the phases as well as reducing the safety margin for knee buckling. The spinal cord when removed from descending inputs is capable of generating rhythmical motor outputs in response to changes in sensory inputs. FES may interact with some of this oscillatory activity

Empowering and assisting natural human mobility: The simbiosis walker

This paper presents the complete development of the Simbiosis Smart Walker. The device is equipped with a set of sensor subsystems to acquire user-machine interaction forces and the temporal evolution of user's feet during gait. The authors present an adaptive filtering technique used for the identification and separation of different components found on the human-machine interaction forces. This technique allowed isolating the components related with the navigational commands and developing a Fuzzy logic controller to guide the device. The Smart Walker was clinically validated at the Spinal Cord Injury Hospital of Toledo - Spain, presenting great acceptability by spinal chord injury patients and clinical staf

Feedback Control of an Exoskeleton for Paraplegics: Toward Robustly Stable Hands-free Dynamic Walking

This manuscript presents control of a high-DOF fully actuated lower-limb exoskeleton for paraplegic individuals. The key novelty is the ability for the user to walk without the use of crutches or other external means of stabilization. We harness the power of modern optimization techniques and supervised machine learning to develop a smooth feedback control policy that provides robust velocity regulation and perturbation rejection. Preliminary evaluation of the stability and robustness of the proposed approach is demonstrated through the Gazebo simulation environment. In addition, preliminary experimental results with (complete) paraplegic individuals are included for the previous version of the controller.Comment: Submitted to IEEE Control System Magazine. This version addresses reviewers' concerns about the robustness of the algorithm and the motivation for using such exoskeleton

Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke

Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance—walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint powers, and metabolic power. Compared to walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2= 0.83, P= 0.004) and nonparetic (R2= 0.73, P= 0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in nonparetic limb COM power (R2= 0.80, P= 0.007), not paretic limb COM power (P> 0.05). These findings provide a fundamental understanding of how individuals poststroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.Accepted manuscript2019-03-0

Lessons from New Orleans: A Stronger Role for Public Defenders in Spurring Indigent Defense Reform

Excessive caseloads prevent public defenders from fulfilling their ethical obligations and curtail criminal defendants’ right to the effective assistance of counsel. Despite this ethical and constitutional dilemma, legislators have been reluctant to provide adequate funds for indigent defense. And because of the separation of powers, courts have been unable to force legislators’ hands. Against this backdrop, criminal defendants in states that choose not to adequately fund indigent defense face a serious risk of wrongful conviction. The Orleans Public Defenders Office (OPD) provides a case study of public defenders playing a stronger role in spurring legislative reform. In response to a funding crisis in Louisiana, the OPD refused to take new cases beyond constitutionally permissible workloads. This refusal resulted in criminal defendants being put on waiting lists for representation, which garnered national attention, gave rise to class action lawsuits against the state, and created a threat to public safety. These are governance problems that legislators prioritize over funding indigent defense. The OPD’s refusal to take new cases has been somewhat successful: in response to this crisis, the state legislature has provided additional funds to public defenders’ offices in the state. Public defenders are in a unique position to put pressure on legislators. By refusing to take new cases that would cause their workloads to be excessive, public defenders can both maintain their obligations to the profession and ensure constitutional representation for their clients

Rehabilitation interventions for foot drop in neuromuscular disease

"Foot drop" or "Floppy foot drop" is the term commonly used to describe weakness or contracture of the muscles around the ankle joint. It may arise from many neuromuscular diseases