A Novel Spatial Position Prediction Navigation System Makes Surgery More Accurate.

During intravascular interventional surgery, the 3D surgical navigation system can provide doctors with 3D spatial information of the vascular lumen, reducing the impact of missing dimension caused by digital subtraction angiography (DSA) guidance and further improving the success rate of surgeries. Nevertheless, this task often comes with the challenge of complex registration problems due to vessel deformation caused by respiratory motion and high requirements for the surgical environment because of the dependence on external electromagnetic sensors. This article proposes a novel 3D spatial predictive positioning navigation (SPPN) technique to predict the real-time tip position of surgical instruments. In the first stage, we propose a trajectory prediction algorithm integrated with instrumental morphological constraints to generate the initial trajectory. Then, a novel hybrid physical model is designed to estimate the trajectory's energy and mechanics. In the second stage, a point cloud clustering algorithm applies multi-information fusion to generate the maximum probability endpoint cloud. Then, an energy-weighted probability density function is introduced using statistical analysis to achieve the prediction of the 3D spatial location of instrument endpoints. Extensive experiments are conducted on 3D-printed human artery and vein models based on a high-precision electromagnetic tracking system. Experimental results demonstrate the outstanding performance of our method, reaching 98.2% of the achievement ratio and less than 3 mm of the average positioning accuracy. This work is the first 3D surgical navigation algorithm that entirely relies on vascular interventional robot sensors, effectively improving the accuracy of interventional surgery and making it more accessible for primary surgeons.

An Improved Networked Predictive Controller for Vascular Robot Using 5G Networks.

Percutaneous coronary intervention (PCI) has gradually become the most common treatment of coronary artery disease (CAD) in clinical practice due to its advantages of small trauma and quick recovery. However, the availability of hospitals with cardiac catheterization facilities and trained interventionalists is extremely limited in remote and underdeveloped areas. Remote vascular robotic system can assist interventionalists to complete operations precisely, and reduce occupational health hazards occurrence. In this paper, a bionic remote vascular robot is introduced in detail from three parts: mechanism, communication architecture, and controller model. Firstly, human finger-like mechanisms in vascular robot enable the interventionalists to advance, retract and rotate the guidewires or balloons. Secondly, a 5G-based communication system is built to satisfy the end-to-end requirements of strong data transmission and packet priority setting in remote robot control. Thirdly, a generalized predictive controller (GPC) is developed to suppress the effect of time-varying network delay and parameter identification error, while adding a designed polynomial compensation module to reduce tracking error and improve system responsiveness. Then, the simulation experiment verifies the system performance in comparison with different algorithms, network delay, and packet loss rate. Finally, the improved control system conducted PCI on an experimental pig, which reduced the delivery integral absolute error (IAE) by at least 20% compared with traditional methods.

Design and Performance Evaluation of a Novel Vascular Robotic System for Complex Percutaneous Coronary Interventions.

The robotic-assisted percutaneous coronary intervention is an emerging technology with great potential to solve the shortcomings of existing treatments. However, the current robotic systems can not manipulate two guidewires or ballons/stents simultaneously for coronary bifurcation lesions. This paper presents VasCure, a novel bio-inspired vascular robotic system, to deliver two guidewires and stents into the main branch and side branch of bifurcation lesions in sequence. The system is designed in master-slave architecture to reduce occupational hazards of radiation exposure and orthopedic injury to interventional surgeons. The slave delivery device has one active roller and two passive rollers to manipulate two interventional devices. The performance of the VasCure was verified by in vitro and in vivo animal experiments. In vitro results showed the robotic system has good accuracy to deliver guidewires and the maximum error is 0.38mm. In an animal experiment, the interventional surgeon delivered two guidewires and balloons to the left circumflex branch and the left anterior descending branch of the pig, which confirmed the feasibility of the vascular robotic system.

[Characteristics of CO2 Flux in a Mature Apple (Malus demestica) Orchard Ecosystem on the Loess Plateau].

Apples (Malus demestica) in the Loess Plateau region are grown in the largest apple orchards in the world and China, playing an important role in the improvement of the ecological environment. However, there is little research on the scale of the ecological system of the apple orchard in the Loess Plateau region. In this study, the CO2 flux of a mature apple orchard in the Loess Plateau region was observed using an eddy covariance technique in the Shannxi Province. Based on the observation data sets observed from January 2016 to December 2016, a quantitative analysis of the apple orchard net ecosystem exchange (NEE), ecosystem respiration (Reco), total ecosystem primary productivity (GPP) changes at different time scales, changes in main meteorological factors, the effects of soil temperature (Ts) and air temperature (Ta) at different levels, and PAR on NEE were discussed. The results showed that during the study period, the apple orchard ecosystem NEE monthly totals were positive (as a carbon source) in the non-growing season in December, January, February and March, were negative (a carbon sink) in the growing season from April to November, and functioned as a strong carbon sink year round. The maximum peak NEE (absolute value) monthly average daily change appeared in August[-17.08 µmol ·(m2 ·s)-1], and the smallest peak appeared in November[-4.47 µmol ·(m2 ·s)-1] during the growing season. The NEE monthly average daily change value during the non-growing season is very weak, though the change is not obvious. GPP, Reco, and NEE maximum daily total values were 11.12, 5.04, and -7.34 g ·(m2 ·d)-1, respectively. GPP, Reco, and NEE maximum monthly total values were 238.97, 105.38, and -144.44 g ·(m2 ·month)-1, respectively, as GPP and NEE maintained high cumulative values that were relatively stable from May through August. The annual GPP, Reco, and NEE were 1223.2, 525.2, and -698.0 g ·(m2 ·a)-1. The observations show that the mature apple orchard ecosystem in the Chinese Loess Plateau has a relatively high carbon sequestration capacity. Nighttime ecosystem respiration Reco.n was positively correlated with the soil temperature and air temperature at different levels, and the correlation coefficients were Ts-5 cm > Ts-10 cm > Ta-4 m > Ta-8 m, The photosynthetic active radiation (PAR) can explain more than 80% of the daytime NEE changes.

[Variation characteristics of soil moisture in apple orchards of Luochuan County, Shaanxi Province of Northwest China].

To have an overall understanding on the soil moisture characteristics in the apple orchards of Luochuan County can not only provide theoretical basis for selecting apple orchard sites, choosing the best root-stock combination, and improving the soil water management, but also has reference importance in increasing the productive efficiency of our apple orchards. In this study, a fixed-point continuous monitoring was conducted on the overall soil moisture environment and the variation characteristics of soil moisture in the County apple orchards differed in age class, stand type, and tree type (standard or dwarfed). For the apple orchards in the County, the rhizosphere (0-200 cm) soils of most apple trees were water-deficient, and the deficit in 0-60 cm soil layer was less than that in 60-200 cm layer. During growth season, the water storage in 0-60 cm soil layer had the same variation trend as the rainfall pattern. The relative soil moisture content in most orchards was less than 60% , and seasonal drought was quite severe. The coefficient of variation of soil moisture content decreased with soil depth. With the increasing age of the orchards, soil water storage decreased. At the same planting density, the orchards with dwarfed trees had more water storage in 0-5 m soil layer than the orchards with standard trees. However, when the orchards were planted with dwarfed trees at a higher density, the soil water storage in the orchards with dwarfed trees was lesser than that in the standard orchards. The mature orchards on highland had the highest soil moisture content, followed by the mature orchards on flat land, and on terraced land. Tree density had great effects on the soil moisture content. When the tree density was the same, planting dwarfed trees could decrease the water consumption, and increase the soil moisture content significantly. To decrease the planting density through the removal of trees would be an effective way to maintain the soil water balance of apple orchards, and achieve the sustainable development of the orchards.