In the nearly six decades since researchers began to explore methods of creating them, exoskeletons have progressed from the stuff of science fiction to nearly commercialized products. While there ...are still many challenges associated with exoskeleton development that have yet to be perfected, the advances in the field have been enormous. In this paper, we review the history and discuss the state-of-the-art of lower limb exoskeletons and active orthoses. We provide a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.
At moderate to fast walking speeds, the human ankle provides net positive work at high-mechanical-power output to propel the body upward and forward during the stance period. On the contrary, ...conventional ankle-foot prostheses exhibit a passive-elastic response during stance, and consequently, cannot provide net work. Clinical studies indicate that transtibial amputees using conventional prostheses have higher gait metabolic rates than normal. Researchers believe that the main cause for these higher rates is due to the inability of conventional prostheses to provide sufficient positive power at terminal stance in the trailing leg to limit heel strike losses of the adjacent leading leg. In this investigation, we evaluate the hypothesis that a powered ankle-foot prosthesis, capable of providing human-like ankle work and power during stance, can decrease the metabolic cost of transport (COT) compared to a conventional passive-elastic prosthesis. To test the hypothesis, a powered prosthesis is built that comprises a unidirectional spring, configured in parallel with a force-controllable actuator with series elasticity. The prosthesis is shown to deliver the high mechanical power and net positive work observed in normal human walking. The rate of oxygen consumption and carbon dioxide production is measured as a determinant of metabolic rate on three unilateral transtibial amputees walking at self-selected speeds. We find that the powered prosthesis decreases the amputee's metabolic COT on average by 14% compared to the conventional passive-elastic prostheses evaluated (Flex-Foot Ceterus reg and Freedom Innovations Sierra), even though the powered system is over twofold heavier than the conventional devices. These results highlight the clinical importance of prosthetic interventions that closely mimic the mass distribution, kinetics, and kinematics of the missing limb.
We present a bitmap printing method and digital workflow using multi-material high resolution Additive Manufacturing (AM). Material composition is defined based on voxel resolution and used to ...fabricate a design object with locally varying material stiffness, aiming to satisfy the design objective. In this workflow voxel resolution is set by the printer’s native resolution, eliminating the need for slicing and path planning. Controlling geometry and material property variation at the resolution of the printer provides significantly greater control over structure–property–function relationships. To demonstrate the utility of the bitmap printing approach we apply it to the design of a customized prosthetic socket. Pressure-sensing elements are concurrently fabricated with the socket, providing possibilities for evaluation of the socket’s fit. The level of control demonstrated in this study cannot be achieved using traditional CAD tools and volume-based AM workflows, implying that new CAD workflows must be developed in order to enable designers to harvest the capabilities of AM.
•Bitmap printing workflow enables digital fabrication in printer’s native resolution.•Voxel-based design and representation of objects for multi-material printing.•Using 3D printed light guides, deformation of materials can be sensed.
An active ankle-foot orthoses (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop-foot gait. During controlled plantar flexion, a ...biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to minimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plantar flexion movements, and during the swing phase, a torsional spring-damper control lifts the foot to provide toe clearance. To assess the clinical effects of variable-impedance control, kinetic and kinematic gait data were collected on two drop-foot participants wearing the AAFO. For each participant, zero, constant, and variable impedance control strategies were evaluated and the results were compared to the mechanics of three age, weight, and height matched normals. We find that actively adjusting joint impedance reduces the occurrence of slap foot allows greater powered plantar flexion and provides for less kinematic difference during swing when compared to normals. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop-foot gait compared to conventional ankle-foot orthoses having zero or constant stiffness joint behaviors.
Powered ankle-foot prosthesis Samuel Au; Herr, H.
IEEE robotics & automation magazine,
09/2008, Letnik:
15, Številka:
3
Journal Article
Recenzirano
The minimum level of series compliance that adequately protects the transmission from damage during foot collision fails to satisfy bandwidth requirements. As a resolution to this difficulty, ...parallel motor elasticity is used to lower the forces borne by the SEA, enhancing system force bandwidth. To minimize prosthesis cost of transport (COT) and motor or transmission size, we select a parallel stiffness that supplies the necessary ankle stiffness during early stance period dorsiflexion, eliminating the need for SEA during that gait phase. In future investigations, we hope to apply the ankle-foot design to robotic, orthotic, and exoskeletal applications. In the design of biomimetic ankle-foot systems, we feel both series and parallel motor elasticity are of paramount importance.
The role of a routine second transurethral resection in evaluating and managing bladder tumors is defined.
From January to October 1998, 150 patients with new or recurrent bladder tumors underwent ...repeat transurethral resection within 2 to 6 weeks after the initial resection, and the results, including the presence of residual tumor and tumor stage, were compared.
Of the 150 cases 36 (24%) had no and 114 (76%) had residual tumor on repeat transurethral resection. Of 96 cases with superficial (Ta, Tis, T1) bladder tumors 72 (75%) had residual noninvasive tumor and 28 (29%) were up staged to invasive tumor. Among 54 patients with a muscle invasive tumor 12 (22%) had no residual tumor on repeat transurethral resection. Results of the second resection changed tumor treatment in 50 patients (33%).
Many patients with bladder tumors have tumor present after an initial transurethral resection. Routine repeat resection is advised to control noninvasive tumors and to detect residual tumor invasion.
This study presents the first long-distance tracks of fin whales (
Balaenoptera physalus
) equipped with satellite transmitters off the Antarctic Peninsula. Southern Hemisphere fin whales were ...severely depleted by twentieth century industrial whaling, yet recently, they have returned to historical feeding grounds off the northern Antarctic Peninsula, forming large aggregations in austral summers. To date, our knowledge only extended to summer behaviour, while information regarding migration routes and the location of breeding and wintering grounds are lacking. During the austral autumn of 2021, we deployed nsatellite transmitters on four fin whales at Elephant Island. Two transmitters stopped working while the animals were still at the feeding grounds, while two continued to transmit during the transition from feeding activity to migration. Both migrating animals left the feeding ground on 15 April 2021, travelling northward into the Pacific and up along the Chilean coast. The most northerly position received before all tags stopped transmitting on 1 May 2021 was at 48°S. These tracks provide initial evidence of seasonal migratory routes and a first indication toward possible locations of winter destinations. This information, even if preliminary, is critical for investigations of population connectivity, population structure and the identification of breeding grounds of Southern Hemisphere fin whales.
To determine the 10-year outcome of patients with muscle-invasive bladder cancer treated by transurethral resection (TUR) alone.
Of 432 newly evaluated patients with muscle-invasive bladder cancer, ...151 were treated by standard radical cystectomy or by definitive TUR, if restaging TUR of the primary tumor site showed no (T0) or only non-muscle-invasive (T1) residual tumor. Patients were followed-up every 3 to 6 months thereafter for a minimum of 10 years and up to 20 years. Primary end points of the study were disease-specific survival, survival with a bladder, frequency of recurrent invasive tumors in the bladder, and survival after salvage cystectomy.
The 10-year disease-specific survival was 76% of 99 patients who received TUR as definitive therapy (57% with bladder preserved) compared with 71% of 52 patients who had immediate cystectomy (P: = .3). Of the 99 patients treated with TUR, 82% of 73 who had T0 on restaging TUR survived versus 57% of the 26 patients who had residual T1 tumor on restaging TUR (P: = .003). Thirty-four patients (34%) relapsed in the bladder with a new muscle-invasive tumor, 18 (53%) were successfully treated with salvage therapy via cystectomy, and 16 patients (16%) died of disease.
Radical TUR for muscle-invasive bladder cancer is a successful bladder-sparing therapeutic strategy in selected patients who have no residual tumor on a repeat vigorous resection of the primary tumor site.
Magnetomicrometry Taylor, C R; Srinivasan, S S; Yeon, S H ...
Science robotics,
08/2021, Letnik:
6, Številka:
57
Journal Article
Recenzirano
Odprti dostop
We live in an era of wearable sensing, where our movement through the world can be continuously monitored by devices. Yet, we lack a portable sensor that can continuously monitor muscle, tendon, and ...bone motion, allowing us to monitor performance, deliver targeted rehabilitation, and provide intuitive, reflexive control over prostheses and exoskeletons. Here, we introduce a sensing modality, magnetomicrometry, that uses the relative positions of implanted magnetic beads to enable wireless tracking of tissue length changes. We demonstrate real-time muscle length tracking in an in vivo turkey model via chronically implanted magnetic beads while investigating accuracy, biocompatibility, and long-term implant stability. We anticipate that this tool will lay the groundwork for volitional control over wearable robots via real-time tracking of muscle lengths and speeds. Further, to inform future biomimetic control strategies, magnetomicrometry may also be used in the in vivo tracking of biological tissues to elucidate biomechanical principles of animal and human movement.
Records of marine debris in and attached to stranded harbour porpoises (Phocoena phocoena), harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) were studied comprising information on ...6587 carcasses collected along the German coast between 1990 and 2014, the decomposition state allowed for necropsy in 1622 cases.
Marine debris items were recorded in 31 carcasses including 14 entanglements (5 harbour porpoises, 6 harbour seals, 3 grey seals) and 17 cases of ingestion (4 harbour porpoises, 10 harbour seals, 3 grey seals). Objects comprised general debris (35.1%) and fishing related debris (64.9%). Injuries associated with marine debris included lesions, suppurative ulcerative dermatitis, perforation of the digestive tract, abscessation, suppurative peritonitis and septicaemia.
This study is the first investigation of marine debris findings in all three marine mammal species from German waters. It demonstrates the health impacts marine debris can have, including severe suffering and death. The results provide needed information on debris burdens in the North and Baltic Seas for implementing management directives, such as the Marine Strategy Framework Directive (MSFD).
•0.5 % of all carcasses collected between 1990–2014 showed external or internal marine debris findings.•A high share of fishing related debris was found (64.9% of all findings).•Injuries associated with marine debris included lesions, perforation of the digestive tract and septicaemia.•This study demonstrate the health impacts marine debris can have on marine mammals, including severe suffering and death.•This is the first assessment of marine debris impacts on marine mammals from German waters.
PDF
