Predictive Maintenance: An Autoencoder Anomaly-Based Approach for a 3 DoF Delta Robot

Performing predictive maintenance (PdM) is challenging for many reasons. Dealing with large datasets which may not contain run-to-failure data (R2F) complicates PdM even more. When no R2F data are available, identifying condition indicators (CIs), estimating the health index (HI), and thereafter, calculating a degradation model for predicting the remaining useful lifetime (RUL) are merely impossible using supervised learning. In this paper, a 3 DoF delta robot used for pick and place task is studied. In the proposed method, autoencoders (AEs) are used to predict when maintenance is required based on the signal sequence distribution and anomaly detection, which is vital when no R2F data are available. Due to the sequential nature of the data, nonlinearity of the system, and correlations between parameter time-series, convolutional layers are used for feature extraction. Thereafter, a sigmoid function is used to predict the probability of having an anomaly given CIs acquired from AEs. This function can be manually tuned given the sensitivity of the system or optimized by solving a minimax problem. Moreover, the proposed architecture can be used for fault localization for the specified system. Additionally, the proposed method can calculate RUL using Gaussian process (GP), as a degradation model, given HI values as its input.

Successful surgical correction of an extreme form of ectopic penis

Reported here is the successful multi-staged repair of a rare case of complete penoscrotal transposition with ectopic penis. The need to evaluate for associated anomalies is discussed.

Dribbling diversion in Y-V glanuloplasty modified Mathieu repair

INTRODUCTION

Aim of the study was to determine the impact of an indwelling transurethral catheter on surgical outcome and postoperative micturation in Y-V glanuloplasty modified Mathieu repair for primary hypospadias.

MATERIALS AND METHODS

Fifty-nine consecutive boys underwent Y-V glanuloplasty modified Mathieu repair for primary distal hypospadias in our institution. The first 37 patients (group A) had catheterless repair. Due to significant painful postoperative urination, the next 22 children (group B) had an indwelling transurethral catheter (5 Fr feeding tube) for 24-48 hours. Adjunct caudal analgesia and penile block was given in both groups. Pain during postoperative voiding, urinary retention, meatal stenosis and fistula formation was statistically analysed with Wilcoxon's signed rank test.

RESULTS

All patients in group A had distressing painful first micturation (p < 0.05). Eight children did not pass urine for more than 8 hours. Five (13.5 %) patients had urinary retention, 3 of whom required catheterisation (p < 0.05). Six (16 %) boys developed meatal stenosis and a further 5 (13.5 %) had urethrocutaneous fistula. In group B all patients had easy micturation after removal of the catheter. Only 1 boy developed a urethrocutaneous fistula and none of the boys in this group presented with meatal stenosis.

CONCLUSION

An indwelling transurethral catheter obviates urinary retention and avoids distressing postoperative micturation. It minimises the chance of urethrocutaneous fistula and meatal stenosis in Y-V glanuloplasty modified Mathieu repair.

Does the type of bladder augmentation influence the resolution of pre-existing vesicoureteral reflux? Urodynamic studies

AIMS

The type of bladder augmentation on pre-existing vesicoureteral reflux (VUR) was assessed. The effects of urodynamic changes on the resolution of VUR following augmentation cystoplasty performed with various gastrointestinal segments were examined. It was queried whether elimination of high-pressure bladder is sufficient to resolve pre-existing reflux.

METHODS

A retrospective record review of patients who underwent bladder augmentation between 1987 and 2004. Patients were divided into two groups. Group I included patients who had a simultaneous augmentation and ureteral reimplantation. Group II included patients with reflux in whom only a bladder augmentation was performed. Pre-and post-augmentation urodynamic results were compared in both groups. The outcome of VUR and the role of various gastrointestinal (GI) segments on the resolution of VUR were studied.

RESULTS

Sixty-three patients underwent bladder augmentation during the study period. Twenty-six of them had VUR before augmentation. There were 10 patients in Group I and 16 patients in Group II. In Group I, VUR ceased in all patients, while in group II, VUR resolved in 14 patients and persisted in two patients. Small and large bowel segments used for augmentation had no effect on the resolution of VUR but the results of gastrocystoplasties were less favorable. Urodynamically there was no significant difference between the various augmentation cystoplasties.

CONCLUSIONS

Bladder augmentation alone without simultaneous antireflux repair is usually sufficient for the resolution of pre-existing reflux. The various GI segments used for augmentation have no effect on urodynamic results and the resolution of VUR.

Congenital posterior urethral polyps in childhood. A case report

We describe a 3-year-old boy who presented with dysuria and urinary retention. The diagnostic work-up (USS, MRI, urethrocystoscopy), suggested a polypoid lesion at the bladder base, originating from the verumontanum. Histology showed the lesion to be a fibroepithelial polyp. A rare cause of urinary retention in childhood must be considered in the differential diagnosis.

Paraurethral cysts in female neonates. Case reports

Paraurethral or Skene's duct cysts are a rare congenital abnormality in the female neonate and are characterized by a round, yellow or orange-coloured cystic mass on either side of the urethra meatus. In the past 17 y we have treated six cases of paraurethral cysts in our unit. All patients underwent incision and unroofing of the cyst resulting in complete healing. The diagnosis and therapeutic options for this rare lesion are reviewed.

CONCLUSION

Paraurethral cysts are not as rare as suggested in the literature. Excision, marsupialization and needle aspiration of the cyst are all effective methods of treatment. However, spontaneous resolution has also been reported. It is suggested that the least aggressive therapy should be used.

[Fibroepithelial polyp causing ureteropelvic obstruction in childhood]

The fibroepithelial polyp is a benign tumour that occurs as a rare intraluminal mass within the urinary tract. Most commonly it is located within the ureter or ureteropelvic junction. The authors present 3 cases of fibroepithelial polyp causing obstruction of the ureteropelvic junction. Dismembering pyelonplasty resulted in disappearance of the hydronephrosis, and the postoperative course was uneventful.

[Pulmonary hydatidosis. Contribution of x-ray computed tomography]

33 patients with pulmonary hydatidosis were followed by CT scan imaging. 53 hydatid cysts were found in 31 of them. The remaining two were cases of metastatic hydatidosis, the primary affection was cardiac located with multiple small bilateral cysts. The observed cysts were single in 27 cases and multiple in 4, totalizing 26 cysts. Among the 27 single cysts, 15 were found to be complicated while 8 cysts were complicated among the four cases of multiple hydatidosis. This paper gives the most important signs observed by CT scan imaging in 33 cases examined during 6 months in the Central Service of Radiology Avicenne CHU, Rabat.