93 research outputs found
The coupling effect in bilateral tele-impedance: Beneficial or detrimental for unstructured environment interaction?
No full textTele-impedance augments classical teleoperation by enabling the human operator to actively command remote robot stiffness. Hereby, an essential strategy used by humans to successfully interact with the unstructured environment complements remote robot-environment interaction. However, literature lacks awareness of benefits and disbenefits of currently used stiffness command interfaces (SCIs) in bilateral tele-impedance. In this paper, we introduce a term called the coupling effect. The coupling effect pertains to the coupling between human initiated commanded stiffness and force-feedback from the master robot. It is hypothesized that, whenever the operator’s commanded stiffness and the master device are coupled, like in muscle activity based SCIs, force-feedback can invoke changes in the commanded stiffness due to human reflexes. Although the coupling effect takes away some degree of the operator’s control over the commanded stiffness, these involuntary changes can be either beneficial (e.g. during position tracking) or detrimental (e.g. during force tracking) to the task performance on the remote robot side. In an experimental study 16 participants perform position and force tracking tasks by using both an EMG based coupled type and an external device based decoupled type of SCI. Our results demonstrate a benefit of the coupling effect by showing lower absolute position error during the unexpected force perturbation when a coupled SCI was is in the position task. The coupling effect does not affect reference stiffness tracking in the force task during the process of establishing contact compared to maintaining reference force when a coupled SCI is used. The decoupled SCI is beneficial for tracking reference force in the force task and tracking reference stiffness for both tasks. We conclude that—when using bilateral tele-impedance—one should be aware of the coupling effect, which is beneficial for rejecting a disturbance in a position tracking task but detrimental for establishing contact in a force tracking task.Mechanical Engineering | BioMechanical Desig
Aerial Transport System Design: Design of an Aerial Transport System for last mile parcel distribution with Unmanned Aerial Vehicles
No full textMechanical, Maritime and Materials EngineeringMarine and Transport TechnologyTransportation Engineerin
The Force-Feedback Coupling Effect in Bilateral Tele-Impedance
No full textIn this paper, we introduce and explore a concept called coupling effect, which pertains to the influence of force feedback on the commanded stiffness that is voluntarily controlled by the operator through the stiffness interface during bilateral tele-impedance. The degree of coupling effect depends on the type of interface used to control the impedance of the remote robot. In case of muscle activity based stiffness command interfaces, the force feedback can invoke involuntary changes in the commanded stiffness due to human reflexes. These involuntary changes can be either beneficial (e.g., during position tracking) or detrimental (e.g., during force tracking) to the task performance on the remote robot side. To investigate the coupling effect in different types of stiffness command interfaces (i.e., coupled and decoupled), we conduct an experimental study in which participants are asked to perform position and force tracking tasks. The results show that in both position and force tracking tasks a lower tracking error of the reference stiffness is obtained with a decoupled interface (p<0.001). However, the unexpected force perturbation yields lower absolute position error when using a coupled interface (p=0.0091), which indicates a specific benefit of the coupling effect. Finally, a lower absolute force error is found in the force tracking task by using the decoupled interface (p<0.001), which indicates a specific downside of the coupling effect. Accepted Author ManuscriptHuman-Robot Interactio
Analysis of Coupling Effect in Human-Commanded Stiffness During Bilateral Tele-Impedance
No full textTele-impedance augments classic teleoperation by enabling the human operator to actively command remote robot stiffness in real-time, which is an essential ability to successfully interact with the unstructured and unpredictable environment. However, the literature is missing a study on benefits and drawbacks of different types of stiffness command interfaces used in bilateral tele-impedance. In this article, we introduce a term called coupling effect, which pertains to the coupling between human-commanded stiffness going to the remote robot and force feedback coming from the remote robot. We hypothesize that, whenever the operator&#x0027;s commanded stiffness and force feedback are subject to coupling effect (e.g., muscle activity based stiffness command interfaces), force feedback can invoke involuntary changes in the commanded stiffness due to human reflexes. Although the coupling effect takes away some degree of the operator&#x0027;s control over the commanded stiffness, these involuntary changes can be either beneficial (e.g., during position tracking) or detrimental (e.g., during force tracking) to the task performance on the remote robot side. We examined the coupling effect in an experimental study with <formula><tex></tex></formula> participants, who performed position and force tracking tasks by using both coupled type (muscle activity based) and decoupled type (external device based) of interface. The results demonstrate a benefit of the coupling effect when the remote robot is operating in presence of unexpected force perturbations, where lower absolute error in position tracking task was observed. On the other hand, the decoupled type of interface is beneficial for force tracking tasks on the remote robot side, such as establishing or maintaining a stable contact with objects. However, the coupling effect negatively influences the commanding of reference stiffness to the remote robot in both position and force tracking tasks for the coupled type of interface, compared to the decoupled type of interface, which is not affected.Accepted Author ManuscriptHuman-Robot Interactio
Two new treatments for haemorrhoids. Doppler-guided haemorrhoidal artery ligation and stapled anopexy
No full textThe role of endorectal ultrasound in therapeutic decision-making for local vs. transabdominal resection of rectal tumors
No full textINTRODUCTION: In rectal tumors, preoperative biopsies frequently fail to diagnose an invasive carcinoma. Endorectal ultrasound is considered a useful adjunct in preoperative staging of rectal tumors. However, feasibility of endorectal ultrasound and its role in therapeutic decision-making in presumed rectal adenomas is sparsely studied. METHODS: Endorectal ultrasound was performed in 268 tumors referred for local excision because biopsies showed tubulovillous adenoma. Feasibility of endorectal ultrasound was studied and ultrasound staging was compared with definite histopathologic findings. RESULTS: In 231 tumors, endorectal ultrasound was technically feasible (86 percent). Median distance from the dentate line was 11 cm in nonassessable tumors and 7 cm in assessable tumors (P<0.001). In 21 tumors, endorectal ultrasound was not conclusive, mainly in tumors being recurrent or after recent endoscopic manipulation (P<0.001). With endorectal ultrasound the rate of preoperative missed carcinomas could be reduced from 21 to 3 percent (P<0.01). In diagnosing tubulovillous adenomas, sensitivity and specificity of endorectal ultrasound was 89 and 86 percent, respectively. CONCLUSIONS: Endorectal ultrasound is technically feasible in almost all presumed rectal adenomas, referred for local excision. Proper endorectal ultrasound interpretation is possible in 78 percent of all presumed rectal adenomas. Endorectal ultrasound is very reliable in diagnosing tubulovillous adenomas, and therapeutic decision-making regarding local excision vs. radical surgery based on endorectal ultrasound is valid
Laparoscopic Rectovaginopexy for Neorectal Prolapse After Transanal Total Mesorectal Excision
No full textIncisional Negative-Pressure Wound Therapy for Perineal Wounds After Abdominoperineal Resection for Rectal Cancer, a Pilot Study
No full textImplementation of a New High-Volume Circular Stapler in Stapled Anopexy for Hemorrhoidal Disease: Is Patient’s Short-Term Outcome Affected by a Higher Volume of Resected Tissue?
No full text<b><i>Background:</i></b> Stapled anopexy is a safe technique for the treatment of hemorrhoids but carries a higher risk of recurrence, which might be caused due to the limited volume of resected tissue. In this study, we investigated the introduction of a high-volume circular stapling device; in particular whether an increased amount of resected tissue could affect patients’ short-term postoperative outcome. <b><i>Methods:</i></b> Between 2011 and 2015, stapled anopexy was performed for hemorrhoids and/or anal prolapse in 141 patients (<i>n</i> = 25 conventional PPH-3<sup>©</sup>-stapler versus <i>n</i> = 116 high-volume CHEX<sup>©</sup>-stapler). In this prospectively collected dataset, operation details and short-term postoperative outcome were compared. <b><i>Results:</i></b> With the high-volume stapler, a significantly higher amount of tissue was resected: 9.8 g (range 6.2–11.4) vs. 6.4 g (range 4.9–8.8) with the conventional stapler, <i>p</i> &#x3c; 0.01. Postoperative short-term outcome did not differ in terms of readmission and complication rates. In all 5 patients who underwent a redo operation for residual hemorrhoids or prolapse, the high-volume stapler was used in the primary operation. <b><i>Conclusion:</i></b> A high-volume stapling device for stapled anopexy was introduced safely with a significantly higher amount of resected tissue without a worse short-term outcome. However, it remains unclear whether higher stapling volumes may lead to improved long-term outcome with less reinterventions.</jats:p
The effect of neoadjuvant short-course radiotherapy and delayed surgery versus chemoradiation on postoperative outcomes in locally advanced rectal cancer patients – A propensity score matched nationwide audit-based study
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