scholarly journals Closed-loop control of ankle plantarflexors and dorsiflexors using an inverted pendulum apparatus: A pilot study

2013 ◽  
Vol 21 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Michael Same ◽  
Hossein Rouhani ◽  
Kei Masani ◽  
Milos Popovic
Keyword(s):  
Control Strategy ◽  
Pid Control ◽  
Closed Loop ◽  
Inverted Pendulum ◽  
Performance Metrics ◽  
Settling Time ◽  
Voluntary Control ◽  
Lower Limbs ◽  
Quiet Stance ◽  
Cord Injury

Considerable demand exists for a device to facilitate hands-free, stable stance in individuals with neurological disorders such as spinal cord injury (SCI) and stroke. In this regard, applying functional electrical stimulation (FES) to muscles of the lower limbs in closed loop has shown promise. In particular, it has been suggested that a PID control strategy could offer functional benefits to stability by mimicking the neurological control strategy employed in able-bodied stance. In this proof of concept study, we tested this assertion by examining the potential of a PID control strategy with gravity compensation to effectively maintain balance during quiet stance by regulating FES-induced contractions of the ankle plantarflexors and dorsiflexors in able-bodied individuals. A novel Inverted Pendulum Standing Apparatus (IPSA) was employed to simulate quiet stance whilst minimizing the voluntary control of able-bodied subjects. Quiet and perturbed standing trials were performed in 3 able-bodied subjects. Performance metrics including those pertaining to stability during quiet stance (root mean square difference), perturbation rejection capabilities (settling time, peak deviation), and ability to transition from an offset initial position (settling time), were examined. For all 3 subjects and for all of the metrics examined, our results showed that the proposed closed-loop controlled FES system improved performance in comparison to voluntary control. These results indicate that the PID plus gravity control strategy used in this study offers meaningful benefits over voluntary control in terms of standing stability. Thus, the controller could potentially be applied to the problem of improving or restoring standing ability in some neurologic patient populations.

Study on the Effect of Fuzzy PID Air-Fuel Ratio Closed Loop Control of a Natural Gas Engine

2014 ◽  
Vol 577 ◽  
pp. 372-377 ◽  
Author(s):  
Yue Li ◽  
En Zhe Song ◽  
Zhan Hu Zhang ◽  
Guo Feng Zhao ◽  
Shuai Huang
Keyword(s):  
Control Strategy ◽  
Pid Control ◽  
Closed Loop ◽  
Feedback Signal ◽  
Closed Loop Control ◽  
Loop Control ◽  
Gas Engine ◽  
Fuel Ratio ◽  
Cng Engine ◽  
Self Tuning

The air-fuel ratio (AFR) control becomes an important research direction in gas engine. This article conducts air-fuel ratio (AFR) closed loop control research in a CNG engine. The injection pulse width of gas is controlled by a controller, oxygen sensor signal as a feedback signal. In order to make the engine can achieve the anticipated air-fuel ratio under different conditions; we adopt fuzzy self-tuning PID control strategy based on feed forward control. We transformed a 2135G diesel engine into the single fuel gas engine. Experimental investigation on the effect of air-fuel ratio closed loop control .Experimental results shows that, fuzzy self-tuning PID control strategy can control CNG engine air-fuel ratio working in the good condition.

scholarly journals Double Closed-Loop Compound Control Strategy for Magnetic Liquid Double Suspension Bearing

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1195
Author(s):  
Jianhua Zhao ◽  
Yongqiang Wang ◽  
Xuchao Ma ◽  
Sheng Li ◽  
Dianrong Gao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Electromagnetic Force ◽  
Closed Loop ◽  
Static Characteristic ◽  
Magnetic Liquid ◽  
Initial Current ◽  
Electromagnetic System ◽  
Initial Flow ◽  
Hydrostatic Force ◽  
Position Feedback

As a new type of suspension bearing, the magnetic liquid double suspension bearing (MLDSB) is mainly supported by electromagnetic suspension and supplemented by hydrostatic support. At present, the MLDSB adopts the regulation strategy of “electromagnetic-position feedback closed-loop, hydrostatic constant-flow supply” (referred to as CFC mode). In the equilibrium position, the external load is carried by the electromagnetic system, and the hydrostatic system produces no supporting force. Thus, the carrying capacity and supporting stiffness of the MLDSB can be reduced. To solve this problem, the double closed-loop control strategy of “electromagnetic system-force feedback inner loop and hydrostatic-position feedback outer loop” (referred to as DCL mode) was proposed to improve the bearing performance and operation stability of the MLDSB. First, the mathematical models of CFC mode and DCL mode of the single DOF supporting system were established. Second, the real-time variation laws of rotor displacement, flow/hydrostatic force, and regulating current/electromagnetic force in the two control modes were plotted, compared, and analyzed. Finally, the influence law of initial current, flow, and controller parameters on the dynamic and static characteristic index were analyzed in detail. The results show that compared with that in CFC mode, the displacement in DCL mode is smaller, and the adjustment time is shorter. The hydrostatic force is equal to the electromagnetic force in DCL mode when the rotor returns to the balance position. Moreover, the system in DCL mode has better robustness, and the initial flow has a more obvious influence on the dynamic and static characteristic indexes. This study provides a theoretical basis for stable suspension control and the safe and reliable operation of the MLDSB.

scholarly journals Acute-onset paraplegia as an unexpected complication under general anesthesia in supine position during abdominal endovascular aneurysm repair: a case report

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Atsushi Morio ◽  
Hirotsugu Miyoshi ◽  
Noboru Saeki ◽  
Yukari Toyota ◽  
Yasuo M. Tsutsumi
Keyword(s):  
Spinal Cord ◽  
General Anesthesia ◽  
Supine Position ◽  
Spinal Cord Ischemia ◽  
Endovascular Aneurysm Repair ◽  
Acute Onset ◽  
Lower Limbs ◽  
Canal Stenosis ◽  
Cord Injury ◽  
Aneurysm Repair

Abstract Background Acute onset paraplegia after endovascular aneurysm repair (EVAR) is a rare but well-known complication. We here show a 79-year-old woman with paraplegia caused by static and dynamic spinal cord insult not by ischemia after EVAR. Case presentation The patient underwent EVAR for abdominal aortic aneurism under general anesthesia in the supine position. She had a medical history of lumbar canal stenosis. After the surgery, we recognized severe paraplegia and sensory disorder of lower limbs. Although the possibility of spinal cord ischemia was considered at that time, postoperative magnetic resonance imaging (MRI) revealed burst fracture of vertebra and compressed spinal cord. Conclusions Patients with spinal canal stenosis can cause extrinsic spinal cord injury even with weak external forces. Thus, even after EVAR, it is important to consider extrinsic factors as the cause of paraplegia.

scholarly journals Disseminated Cryptococcosis revealed by transverse myelitis in Immunocompetent patient: a case report and review of the literature

BMC Neurology ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Fangfang Qu ◽  
Zhenzhen Qu ◽  
Yingqian Lv ◽  
Bo Song ◽  
Bailin Wu
Keyword(s):  
Spinal Cord ◽  
Amphotericin B ◽  
Transverse Myelitis ◽  
Immunocompetent Patient ◽  
Lower Limbs ◽  
Coxsackie Virus ◽  
Gadolinium Contrast ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Cord Injury

Abstract Background Transverse myelitis (TM) is due to inflammatory spinal cord injury with bilateral neurologic involvement, which is sensory, motor, or autonomic in nature. It may be associated with autoimmune disease, vaccination, intoxication and infections. The most common infection cause of TM is Coxsackie virus and Mycoplasma pneumoniae. The cryptococcosis is rare. We present the case of disseminated cryptococcosis revealed by transverse myelitis in an immunocompetent 55-year-old male patient. The literature review is also stated. Case presentation The 55-year-old man suffered from gradual numbness, weakness in both lower limbs and finally paralyzed in the bed. The thoracic spine Computed tomography (CT) was normal, but multiple nodules in the lung were accidentally discovered. Thoracic Magnetic Resonance Imaging (MRI) showed diffused thoracic spinal cord thickening and extensively intramedullary T2 hyper intensity areas. Gadolinium contrast enhanced T1WI showed an intramedullary circle-enhanced nodule at 9th thoracic level. Diagnosis was made by histological examination of the bilateral lung biopsy. The patient was treated successfully with systemic amphotericin B liposome and fluconazole and intrathecal dexamethasone and amphotericin B liposome. Conclusions This is a patient with disseminated cryptococcosis involving the lung, spinal cord and adrenal glands, which is rare in the absence of immunodeficiency.

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