Improved Industrial Robot Positional Accuracy for Machining with Bias Correction

Robotic machining has the potential to provide advantages as a substitute for conventional CNC machine tool operations. However, conventional industrial robots are restricted to low accuracy tasks due to their poor positional accuracy. This creates challenges in achieving the tolerances required for machining tasks. Data-based modelling of the positional error data is a potential solution which learns the positional errors in order to compensate and minimise them. There has been some success in improving industrial robot accuracy in research literature, by first calibrating the kinematic model and then using machine learning (ML)-based bias correction to learn the positional errors. However, the limitations of ML-based bias correction applied to the industrial robot positional accuracy problem have not been fully explored with the accuracies required to achieve tight machining tolerances. Mapping the positional errors with a greater resolution of training data, and reducing the burden on bias correction by calibrating the kinematic model with a higher level of calibration, are two examples which have the potential to improve accuracy. This thesis focusses on both training data resolution and bias reduction to maximise outcomes whilst informing trade-offs when using ML-based bias correction in this application. The key finding of this thesis is that substantial gains in accuracy can be achieved using ML-based bias correction and that the accuracy limit can be achieved with practicable amounts of data gathering and processing. Also that calibration prior to bias correction did not significantly improve overall accuracy for the cases investigated. This suggests that data may be better utilised in training the bias corrector rather than for calibration of the physical model. In conclusion, ML-based bias correction methods can provide a solution that provides substantial gains in positional accuracy for conventional industrial robots, bringing them to a level that may facilitate broader adoption in machining applications

Reviews

The following publications have been reviewed by the authors; Programmes of Study for Design & Technology - Reviewed by Jim PattersonManaging Design & Technology in the National Curriculum - Reviewed by David DickinsonFocus on Technology - Reviewed by Ian McLintockAccommodating Technology in Schools - Reviewed byJ.R. MathiasDesigning and Making - Reviewed by Paul SpencerTreasury of Historic Pattern and Design - Reviewed by Geoff SmithDesign & Technology in Process - Reviewed by Jonty CrockettTechnology Through Home Economics - Reviewed by Rhona HumphriesThe Soft Toy Workshop - Reviewed by Margaret Jeavons02 PAGES (Quarterly) - Reviewed by AIf MerricksAdventures in Technology - Reviewed by John EvansDesigning Starts here - Reviewed by Trevor TaylorTechnology Shaping Our World - Reviewed by Alan TruemanIntroducing Design: Technology Across the Curriculum - Reviewed by Norman CassonThe Tapestry Makers - Reviewed by Goeff SmithWoodcut with Rigby Graham - Reviewed by John Lancaste

Maintenance N-acetyl cysteine treatment for bipolar disorder : a double-blind randomised placebo controlled trial

Background N-acetyl cysteine (NAC) is a glutathione precursor that has been shown to have antidepressant efficacy in a placebo-controlled trial. The current study aimed to investigate the maintenance effects of NAC following eight weeks of open-label treatment for bipolar disorder.Method The efficacy of a double blind randomized placebo controlled trial of 2 g/day NAC as adjunct maintenance treatment for bipolar disorder was examined. Participants (n = 149) had a Montgomery Asberg Depression Rating Score of [greater than or equal to]12 at trial entry and, after eight weeks of open-label NAC treatment, were randomized to adjunctive NAC or placebo, in addition to treatment as usual. Participants (primarily outpatients) were recruited through public and private services and through newspaper advertisements. Time to intervention for a mood episode was the primary endpoint of the study, and changes in mood symptoms, functionality and quality of life measures were secondary outcomes.Results There was a substantial decrease in symptoms during the eight-week open-label NAC treatment phase. During the subsequent double-blind phase, there was minimal further change in outcome measures with scores remaining low. Consequently, from this low plateau, between-group differences did not emerge on recurrence, clinical functioning or quality of life measures.Conclusions There were no significant between-group differences in recurrence or symptomatic outcomes during the maintenance phase of the trial; however, these findings may be confounded by limitations. Trial Registration The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12607000074493)

N-acetilcisteína para o tratamento de episódios de depressão maior no transtorno bipolar

Objetivo: Neste relato, avaliamos o efeito da N-acetilcisteína (NAC) adjuvante em sintomas depressivos e desfechos funcionais no transtorno bipolar. Para isso, conduzimos uma análise secundária de todos os pacientes com critérios diagnósticos para um episódio depressivo em um ensaio clínico randomizado comparando NAC adjuvante com placebo no transtorno bipolar. Método: Ensaio clínico randomizado comparando NAC adjuvante com placebo para episódios depressivos no transtorno bipolar durante 24 semanas. Desfechos funcionais e sintomáticos foram coletados no período. Resultados: Dezessete participantes estavam disponíveis para esta análise. Tamanhos de efeito grandes foram encontrados para sintomas depressivos e desfechos funcionais. Oito dos dez participantes no grupo da NAC tiveram resposta clínica ao fim do tratamento. O mesmo ocorreu em apenas um dos sete que receberam placebo. Discussão: Esses resultados indicam que a NAC adjuvante pode ser útil para episódios de depressão maior no transtorno bipolar. Estudos desenhados para confirmar esta hipótese são necessários.Objective: In this report, we aimed to evaluate the effect of add-on N-acetylcysteine (NAC) on depressive symptoms and functional outcomes in bipolar disorder. To that end, we conducted a secondary analysis of all patients meeting full criteria for a depressive episode in a placebocontrolled trial of adjunctive NAC for bipolar disorder. Method: Twenty-four week randomised clinical trial comparing adjunctive NAC and placebo in individuals with bipolar disorder experiencing major depressive episodes. Symptomatic and functional outcome data were collected over the study period. Results: Seventeen participants were available for this report. Very large effect sizes in favor of NAC were found for depressive symptoms and functional outcomes at endpoint. Eight of the ten participants on NAC had a treatment response at endpoint; the same was true for only one of the seven participants allocated to placebo. Discussion: These results indicate that adjunctive NAC may be useful for major depressive episodes in bipolar disorder. Further studies designed to confirm this hypothesis are necessary

N-acetyl cysteine for depressive symptoms in bipolar disorder - a double blind, randomized, placebo-controlled trial

Background: Treatment-resistant subthreshold depression is a major problem in bipolar disorder. Both depression and bipolar disorderare complicated by glutathione depletion. We hypothesized that treatment with N-acetyl cysteine (NAC), a safe, orally bioavailable precursor of glutathione, may improve the depressive component of bipolar disorder.Methods: A randomized, double-blind, multicenter, placebo-controlled study of individuals (n 75) with bipolar disorder in the maintenance phase treated with NAC (1 g twice daily) adjunctive to usual medication over 24 weeks, with a 4-week washout. The two primary outcomes were the Montgomery Asberg Depression Rating Scale (MADRS) and time to a mood episode. Secondary outcomes included the Bipolar Depression Rating Scale and 11 other ratings of clinical status, quality of life, and functioning.Results: NAC treatment caused a significant improvement on the MADRS (least squares mean difference [95% confidence interval]: 8.05 [13.16, 2.95], p .002) a n d most secondary scales at end point. Benefit was evident by 8 weeks on the Global Assessment of Functioning Scale and Social and Occupational Functioning Assessment Scale and at 20 weeks on the MADRS. Improvements were lost after washout. There was no effect of NAC on time to a mood episode (log-rank test: p .968) and no significant between-group differences inadverse events. Effect sizes at end point were medium to high for improvements in MADRS and 9 of the 12 secondary readouts.Conclusions: NAC appears a safe and effective augmentation strategy for depressive symptoms in bipolar&nbsp; disorder.<br /

Effects of N-acetylcysteine on substance use in bipolar disorder : a randomized placebo controlled clinical trial

Objective: To evaluate the effect of N-acetylcysteine (NAC) on substance use in a double-blind, placebo-controlled trial of NAC in bipolar disorder. It is hypothesised that NAC will be superior to placebo for reducing scores on the Clinical Global Impressions scale for Substance Use (CGI-SU).Methods: Participants were randomised to 6-months of treatment with 2 g/day NAC (n = 38) or placebo (n = 37). Substance use was assessed at baseline using the Habits instrument. Change in substance use was assessed at regular study visits using the CGI-SU.Results: Amongst the 75 participants 78.7% drank alcohol (any frequency), 45.3% smoked tobacco and 92% consumer caffeine. Other substances were used by fewer than six participants. Caffeine use was significantly lower for NAC-treated participants compared with placebo at week 2 of treatment but not at other study visits.Conclusion: NAC appeared to have little effect on substance use in this population. A larger study on a substance using population will be necessary to determine if NAC may be a useful treatment for substance use.<br /

A preliminary investigation on the efficacy of N-acetyl cysteine for mania or hypomania

Objective: Oxidative imbalance has emerged as a treatment target in bipolar disorder. As very limited data are available on the clinical use of antioxidants for mania, we report here results from a post hoc and exploratory subgroup analysis of a randomized, placebo-controlled trial of N-acetyl cysteine (NAC). Methods: This was a placebo-controlled, randomized, clinical trial assessing the effect of NAC over 24 weeks in mania or hypomania. Symptomatic and functional outcomes were collected over the study period. Results: Fifteen participants were available for this report; two participants in each group failed to complete all assessments. Within-group analyses pointed to an improvement in the NAC group on manic symptoms and worsening in the placebo group on depressive symptoms at endpoint. Conclusions: Although the sample size was small, these results indicated within-group efficacy for this glutathione precursor as compared to placebo. Future trials specifically designed to demonstrate the efficacy of NAC in mania are needed

N-acetilcisteína para o tratamento de episódios de depressão maior no transtorno bipolar

Objetivo: Neste relato, avaliamos o efeito da N-acetilcisteína (NAC) adjuvante em sintomas depressivos e desfechos funcionais no transtorno bipolar. Para isso, conduzimos uma análise secundária de todos os pacientes com critérios diagnósticos para um episódio depressivo em um ensaio clínico randomizado comparando NAC adjuvante com placebo no transtorno bipolar. Método: Ensaio clínico randomizado comparando NAC adjuvante com placebo para episódios depressivos no transtorno bipolar durante 24 semanas. Desfechos funcionais e sintomáticos foram coletados no período. Resultados: Dezessete participantes estavam disponíveis para esta análise. Tamanhos de efeito grandes foram encontrados para sintomas depressivos e desfechos funcionais. Oito dos dez participantes no grupo da NAC tiveram resposta clínica ao fim do tratamento. O mesmo ocorreu em apenas um dos sete que receberam placebo. Discussão: Esses resultados indicam que a NAC adjuvante pode ser útil para episódios de depressão maior no transtorno bipolar. Estudos desenhados para confirmar esta hipótese são necessários.Objective: In this report, we aimed to evaluate the effect of add-on N-acetylcysteine (NAC) on depressive symptoms and functional outcomes in bipolar disorder. To that end, we conducted a secondary analysis of all patients meeting full criteria for a depressive episode in a placebocontrolled trial of adjunctive NAC for bipolar disorder. Method: Twenty-four week randomised clinical trial comparing adjunctive NAC and placebo in individuals with bipolar disorder experiencing major depressive episodes. Symptomatic and functional outcome data were collected over the study period. Results: Seventeen participants were available for this report. Very large effect sizes in favor of NAC were found for depressive symptoms and functional outcomes at endpoint. Eight of the ten participants on NAC had a treatment response at endpoint; the same was true for only one of the seven participants allocated to placebo. Discussion: These results indicate that adjunctive NAC may be useful for major depressive episodes in bipolar disorder. Further studies designed to confirm this hypothesis are necessary