54 research outputs found
Application of Compensation Algorithms to Control the Movement of a Robot Manipulator
This article presents an application-oriented method for the structural synthesis of control systems for multichannel linear objects. It provides a general form, based on the compensation for object dynamics and disturbances. The algorithm is based onalgebraic transformations of the mathematical model of the object and reference systems. The
general procedure for the synthesis of a control algorithm is presented by the example of a SISO first-order object. Parametric robustness and correspondence of the system behavior to its own reference filters were derived. The possibility of applying this method to control non-linear objects presented in the form of "State Dependent coefficient (SDC)" is ascertained. A simplified example is given by the synthesis of the motion control of a one-link manipulator with a drive, described by a second-order nonlinear equation. Control of a two-link manipulator represented by its linearized equation is demonstrated. The
convenience of the proposed synthesis method for controlling multi-channel objects under certain simplifications allowed by the specifics of the use of objects is shown. The
numerical example shows the independence of the system through individual channels, a zero static error in all the modes of operation and the correspondence of the system
behavior to given dynamics
Observation-Based Data Driven Adaptive Control of an Electromechanical Device
The model-based approach in control engineering
works well when a reliable plant model is available. However, in
practice, reliable models seldom exist: instead, typical âlevelsâ
of limited reliability occur. For instance,
Computed Torque
Control (CTC)
in robotics assumes almost perfect models. The
Adaptive Inverse Dynamics Controller (AIDC)
and the
Slotine Li
Adaptive Robot Controller (SLARC)
assume absolutely correct
analytical model form, and only allows imprecise knowledge
regarding the actual values of the model parameters. Neglecting
the effects of dynamically coupled subsystems, and allowing
the action of unknown external disturbances means a higher
level of corrupted model reliability. Friction-related problems
are typical examples of this case. In the traditional control
literature, such problems are tackled by either drastic ârobustâ
or rather intricate âadaptiveâ solutions, both designed by the
use of
Lyapunovâs 2
nd
method
that is a complicated technique
requiring advanced mathematical skills from the designer. As
an alternative design methodology, the use of
Robust Fixed Point
Transformations (RFPT)
was suggested, which concentrates on
guaranteeing the prescribed details of tracking error relaxation
via generation of iterative control signal sequences that converge
on the basis of
Banachâs Fixed Point Theorem
. This approach
is essentially based on the fresh data collected by observing the
behavior of the controlled systems, rather than in the case of the
traditional ones. For the first time, this technique is applied for
order reduction in the adaptive control of a strongly nonlinear
plant with significant model imprecisions: the control of a DC
motor driven arm in dynamic interaction with a nonlinear
environment is demonstrated via numerical simulations
Vision-based real-time position control of a semi-automated system for robot-assisted joint fracture surgery
Purpose: Joint fracture surgery quality can be improved by robotic system with high-accuracy and high-repeatability fracture fragment manipulation. A new real-time vision-based system for fragment manipulation during robot-assisted fracture surgery was developed and tested. Methods: The control strategy was accomplished by merging fast open-loop control with vision-based control. This two-phase process is designed to eliminate the open-loop positioning errors by closing the control loop using visual feedback provided by an optical tracking system. Evaluation of the control system accuracy was performed using robot positioning trials, and fracture reduction accuracy was tested in trials on ex vivo porcine model.Results: The system resulted in high fracture reduction reliability with a reduction accuracy of 0.09mm (translations) and of (Formula presented.) (rotations), maximum observed errors in the order of 0.12mm (translations) and of (Formula presented.) (rotations), and a reduction repeatability of 0.02mm and (Formula presented.). Conclusions: The proposed vision-based system was shown to be effective and suitable for real joint fracture surgical procedures, contributing a potential improvement of their quality
Space Science Opportunities Augmented by Exploration Telepresence
Since the end of the Apollo missions to the lunar surface in December 1972, humanity has exclusively conducted scientific studies on distant planetary surfaces using teleprogrammed robots. Operations and science return for all of these missions are constrained by two issues related to the great distances between terrestrial scientists and their exploration targets: high communication latencies and limited data bandwidth.
Despite the proven successes of in-situ science being conducted using teleprogrammed robotic assets such as Spirit, Opportunity, and Curiosity rovers on the surface of Mars, future planetary field research may substantially overcome latency and bandwidth constraints by employing a variety of alternative strategies that could involve: 1) placing scientists/astronauts directly on planetary surfaces, as was done in the Apollo era; 2) developing fully autonomous robotic systems capable of conducting in-situ field science research; or 3) teleoperation of robotic assets by humans sufficiently proximal to the exploration targets to drastically reduce latencies and significantly increase bandwidth, thereby achieving effective human telepresence.
This third strategy has been the focus of experts in telerobotics, telepresence, planetary science, and human spaceflight during two workshops held from October 3â7, 2016, and July 7â13, 2017, at the Keck Institute for Space Studies (KISS). Based on findings from these workshops, this document describes the conceptual and practical foundations of low-latency telepresence (LLT), opportunities for using derivative approaches for scientific exploration of planetary surfaces, and circumstances under which employing telepresence would be especially productive for planetary science. An important finding of these workshops is the conclusion that there has been limited study of the advantages of planetary science via LLT. A major recommendation from these workshops is that space agencies such as NASA should substantially increase science return with greater investments in this promising strategy for human conduct at distant exploration sites
Space Science Opportunities Augmented by Exploration Telepresence
Since the end of the Apollo missions to the lunar surface in December 1972, humanity has exclusively conducted scientific studies on distant planetary surfaces using teleprogrammed robots. Operations and science return for all of these missions are constrained by two issues related to the great distances between terrestrial scientists and their exploration targets: high communication latencies and limited data bandwidth.
Despite the proven successes of in-situ science being conducted using teleprogrammed robotic assets such as Spirit, Opportunity, and Curiosity rovers on the surface of Mars, future planetary field research may substantially overcome latency and bandwidth constraints by employing a variety of alternative strategies that could involve: 1) placing scientists/astronauts directly on planetary surfaces, as was done in the Apollo era; 2) developing fully autonomous robotic systems capable of conducting in-situ field science research; or 3) teleoperation of robotic assets by humans sufficiently proximal to the exploration targets to drastically reduce latencies and significantly increase bandwidth, thereby achieving effective human telepresence.
This third strategy has been the focus of experts in telerobotics, telepresence, planetary science, and human spaceflight during two workshops held from October 3â7, 2016, and July 7â13, 2017, at the Keck Institute for Space Studies (KISS). Based on findings from these workshops, this document describes the conceptual and practical foundations of low-latency telepresence (LLT), opportunities for using derivative approaches for scientific exploration of planetary surfaces, and circumstances under which employing telepresence would be especially productive for planetary science. An important finding of these workshops is the conclusion that there has been limited study of the advantages of planetary science via LLT. A major recommendation from these workshops is that space agencies such as NASA should substantially increase science return with greater investments in this promising strategy for human conduct at distant exploration sites
A development of assistant surgical robot system based on surgical-operation-by-wire and hands-on-throttle-and-stick
BACKGROUND: Robot-assisted laparoscopic surgery offers several advantages compared with open surgery and conventional minimally invasive surgery. However, one issue that needs to be resolved is a collision between the robot arm and the assistant instrument. This is mostly caused by miscommunication between the surgeon and the assistant. To resolve this limitation, an assistant surgical robot system that can be simultaneously manipulated via a wireless controller is proposed to allow the surgeon to control the assistant instrument. METHODS: The system comprises two novel master interfaces (NMIs), a surgical instrument with a gripper actuated by a micromotor, and 6-axis robot arm. Two NMIs are attached to master tool manipulators of da Vinci research kit (dVRK) to control the proposed system simultaneously with patient side manipulators of dVRK. The developments of the surgical instrument and NMI are based on surgical-operation-by-wire concept and hands-on-throttle-and-stick concept from the earlier research, respectively. Tests for checking the accuracy, latency, and power consumption of the NMI are performed. The gripping force, reaction time, and durability are assessed to validate the surgical instrument. The workspace is calculated for estimating the clinical applicability. A simple peg task using the fundamentals of laparoscopic surgery board and an in vitro test are executed with three novice volunteers. RESULTS: The NMI was operated for 185Â min and reflected the surgeonâs decision successfully with a mean latency of 132Â ms. The gripping force of the surgical instrument was comparable to that of conventional systems and was consistent even after 1000 times of gripping motion. The reaction time was 0.4Â s. The workspace was calculated to be 8397.4Â cm(3). Recruited volunteers were able to execute the simple peg task within the cut-off time and successfully performed the in vitro test without any collision. CONCLUSIONS: Various experiments were conducted and it is verified that the proposed assistant surgical robot system enables collision-free and simultaneous operation of the dVRKâs robot arm and the proposed assistant robot arm. The workspace is appropriate for the performance of various kinds of surgeries. Therefore, the proposed system is expected to provide higher safety and effectiveness for the current surgical robot system
Burden of intracerebral haemorrhage in Europe: forecasting incidence and mortality between 2019 and 2050
Background: Anticipating the burden of intracerebral haemorrhage is crucial for proactive management and building resilience against future health challenges. Prior forecasts are based on population demography and to a lesser extent epidemiological trends. This study aims to utilise selected modifiable risk factors and socio-demographic indicators to forecast the incidence and mortality of intracerebral haemorrhage in Europe between 2019 and 2050. Methods: Three intracerebral haemorrhage risk factors identified in the Global Burden of Diseases, Injuries, and Risk Factors study (GBD 2019)âhigh systolic blood pressure, high fasting plasma glucose, and high body mass indexâwere utilised to predict the risk-attributable fractions between 2019 and 2050. Disease burden not attributable to these risk factors was then forecasted using time series models (autoregressive integrated moving average [ARIMA]), incorporating the Socio-demographic Index (SDI) as an external predictor. The optimal parameters of ARIMA models were selected for each age-sex-country group based on the Akaike Information Criterion (AIC). Different health scenarios were constructed by extending the past 85th and 15th percentiles of annualised rates of change in risk factors and SDI across all location-years, stratified by age and sex groups. A decomposition analysis was performed to assess the relative contributions of population size, age composition, and intracerebral haemorrhage risk on the projected changes. Findings: Compared with observed figures in 2019, our analysis predicts an increase in the burden of intracerebral haemorrhage in Europe in 2050, with a marginal rise of 0.6% (95% uncertainty interval [UI], â7.4% to 9.6%) in incident cases and an 8.9% (â2.8% to 23.6%) increase in mortality, reaching 141.2 (120.6â166.5) thousand and 144.2 (122.9â172.2) thousand respectively. These projections may fluctuate depending on trajectories of the risk factors and SDI; worsened trends could result in increases of 16.7% (8.7%â25.3%) in incidence and 31.2% (17.7%â48%) in mortality, while better trajectories may lead to a 10% (16.4%â2.3%) decrease in intracerebral haemorrhage cases with stabilised mortality. Individuals aged â„80 years are expected to contribute significantly to the burden, comprising 62.7% of the cases in 2050, up from 40% in 2019, and 72.5% of deaths, up from 50.5%. Country-wide variations were noted in the projected changes, with decreases in the standardised rates across all nations but varying crude rates. The largest relative reductions in counts for both incidence and mortality are expected in Latvia, Bulgaria, and Hungaryâranging from â38.2% to â32.4% and â37.3% to â30.2% respectively. In contrast, the greatest increases for both measures were forecasted in Ireland (45.7% and 74.4%), Luxembourg (45% and 70.7%), and Cyprus (44.5% and 74.2%). The modelled increase in the burden of intracerebral haemorrhage could largely be attributed to population ageing. Interpretation: This study provides a comprehensive forecast of intracerebral haemorrhage in Europe until 2050, presenting different trajectories. The potential increase in the number of people experiencing and dying from intracerebral haemorrhage could have profound implications for both caregiving responsibilities and associated costs. However, forecasts were divergent between different scenarios and among EU countries, signalling the pivotal role of public health initiatives in steering the trajectories. Funding: TheEuropean Union's Horizon 2020 Research and Innovation Programme under grant agreement No.754517. TheNational Institute for Health and Care Research (NIHR) under its Programme Grants forApplied Research (NIHR202339)
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