Search

Serial robots have been successful in numerous applications; however, their limited motion accuracy hinders the potential for high precision robotic machining. Among the many sources of error in robot movement, non-linearities at robot joints, namely backlash and stiction/friction, are yet to be thoroughly investigated and addressed. When a robot joint reverses, backlash-induced excitation switches direction and stiction induces localized errors that occur over a short duration. Together, backlash and stiction from joint reversal lead to significant positional errors. This paper closes the research gap by proposing feedforward backlash and stiction compensation with a focus on suppressing errors during joint reversals. The controllers are designed using experimental studies of robot joints and the nominal tool centre point (TCP) trajectories. Based on the robot kinematics, the strategy interpolates the nominal trajectories to ensure accurate identification of joint reversals along the path, and therefore provides optimal error compensation with minimum latency. The performance of the controller is evaluated in single axis tests for suppressing backlash in static conditions and in multi-axis path tests for suppressing backlash and stiction in continuous motions. The experimental results show that the feedforward compensation greatly improves the robot accuracy during joint reversal, reducing errors by more than 70%. [ABSTRACT FROM AUTHOR]

Community learning disability nursing has been faced with considerable changes over recent years. In the early part of the 1990s, some commentators believed that it was a specialism in decline. The aim of the present study was to describe the way in which community nurses, learning disabilities (CNLDs), work within National Health Service (NHS) trusts in England, the other professionals whom they relate to, the client group whom they serve, their qualifications and their working practices. A postal questionnaire enquiring about these themes was returned by CNLD managers from 136 out of the 170 NHS trusts which were identified (81%).

Abstract Background In 2004, the Malawian Ministry of Health declared a human resource crisis and launched a six year Emergency Human Resources Programme. This included salary supplements for key health workers and a tripling of doctors in training. By 2010, the number of medical graduates had doubled and significantly more doctors were working in rural district hospitals. Yet there has been little research into the views of this next generation of doctors in Malawi, who are crucial to the continuing success of the programme. The aim of this study was to explore the factors influencing the career plans of medical students and recent graduates with regard to four policy-relevant aspects: emigration outside Malawi; working at district level; private sector employment and postgraduate specialisation. Methods Twelve semi-structured interviews were conducted with fourth year medical students and first year graduates, recruited through purposive and snowball sampling. Key informant interviews were also carried out with medical school faculty. Recordings were transcribed and analysed using a framework approach. Results Opportunities for postgraduate training emerged as the most important factor in participants’ career choices, with specialisation seen as vital to career progression. All participants intended to work in Malawi in the long term, after a period of time outside the country. For nearly all participants, this was in the pursuit of postgraduate study rather than higher salaries. In general, medical students and young doctors were enthusiastic about working at district level, although this is curtailed by their desire for specialist training and frustration with resource shortages. There is currently little intention to move into the private sector. Conclusions Future resourcing of postgraduate training opportunities is crucial to preventing emigration as graduate numbers increase. The lesser importance put on salary by younger doctors may be an indicator of the success of salary supplements. In order to retain doctors at district levels for longer, consideration should be given to the introduction of general practice/family medicine as a specialty. Returning specialists should be encouraged to engage with younger colleagues as role models and mentors.