171 research outputs found
Dundee Discussion Papers in Economics 135:Treatment intensity and provider remuneration: dentists in the British National Health Service
Dundee Discussion Papers in Economics 163:Measuring access to health services: general dental services in Scotland
Dundee Discussion Papers in Economics 143:Theoretical approaches to managing sickness absenteeism
Dundee Discussion Papers in Economics 162:The existence and nature of physician agency: evidence of stinting from the British NHS
Dundee Discussion Papers in Economics 117:Sickness, absenteeism, âpresenteeismâ and sick pay
Dundee Discussion Papers in Economics 218:Recruitment and retention incentives in health labour markets: an analysis of participation in NHS Scotland following dental vocational training
Dundee Discussion Papers in Economics 143:Theoretical approaches to managing sickness absenteeism
Dundee Discussion Papers in Economics 217:The effect of activity-based payment on dentistsâ activity: evidence from a natural experiment in the UK national health service
Dundee Discussion Papers in Economics 117:Sickness, absenteeism, âpresenteeismâ and sick pay
Preliminary results on noncollocated torque control of space robot actuators
In the Space Station era, more operations will be performed robotically in space in the areas of servicing, assembly, and experiment tending among others. These robots may have various sets of requirements for accuracy, speed, and force generation, but there will be design constraints such as size, mass, and power dissipation limits. For actuation, a leading motor candidate is a dc brushless type, and there are numerous potential drive trains each with its own advantages and disadvantages. This experiment uses a harmonic drive and addresses some inherent limitations, namely its backdriveability and low frequency structural resonances. These effects are controlled and diminished by instrumenting the actuator system with a torque transducer on the output shaft. This noncollocated loop is closed to ensure that the commanded torque is accurately delivered to the manipulator link. The actuator system is modelled and its essential parameters identified. The nonlinear model for simulations will include inertias, gearing, stiction, flexibility, and the effects of output load variations. A linear model is extracted and used for designing the noncollocated torque and position feedback loops. These loops are simulated with the structural frequency encountered in the testbed system. Simulation results are given for various commands in position. The use of torque feedback is demonstrated to yield superior performance in settling time and positioning accuracy. An experimental setup being finished consists of a bench mounted motor and harmonic drive actuator system. A torque transducer and two position encoders, each with sufficient resolution and bandwidth, will provide sensory information. Parameters of the physical system are being identified and matched to analytical predictions. Initial feedback control laws will be incorporated in the bench test equipment and various experiments run to validate the designs. The status of these experiments is given
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