Trajectory Guidance Research Articles

Trajectory approach to the Schrödinger–Langevin equation with linear dissipation for ground states

The Schrödinger–Langevin equation with linear dissipation is integrated by propagating an ensemble of Bohmian trajectories for the ground state of quantum systems. Substituting the wave function expressed in terms of the complex action into the Schrödinger–Langevin equation yields the complex quantum Hamilton–Jacobi equation with linear dissipation. We transform this equation into the arbitrary Lagrangian–Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation is simultaneously integrated with the trajectory guidance equation. Then, the computational method is applied to the harmonic oscillator, the double well potential, and the ground vibrational state of methyl iodide. The excellent agreement between the computational and the exact results for the ground state energies and wave functions shows that this study provides a synthetic trajectory approach to the ground state of quantum systems.

Redundancy optimization strategy for hands-on robotic surgery.

During hands-on cooperative surgery, the use of a redundant robot allows to address encumbrance issues in the Operating Room (OR), which can occur due to the presence of large medical instrumentation, such as the surgical microscope. This work presents a new Null Space Optimization (NSO) strategy to constraint the position of the manipulator's elbow within predefined range of motions, according to the spatial requirements of the specific procedure, also taking into account the physical joint limits of the robotic assistant. The proposed strategy was applied to the 7 degrees of freedom (dof) lightweight robot LWR4+. The performance of the NSO was compared to two state-of-the-art null space optimization strategies, i.e. damped posture and fixed optimal posture, over a pool of three non-expert users in both strict (20deg) and negligible (100deg) angular encumbrance limitations. The NSO strategy was proved versatile in providing wide elbow mobility together with safe distance from relevant continuity null space boundaries, guaranteeing smooth guidance trajectories. Future works would be performed in order to evaluate the potential feasibility of NSO in a real surgical scenario.

Single-Camera Closed-Form Real-Time Needle Tracking for Ultrasound-Guided Needle Insertion

Many common needle intervention procedures are performed with ultrasound guidance because it is a flexible, cost-effective and widely available intra-operative imaging modality. In a needle insertion procedure with ultrasound guidance, real-time calculation and visualization of the needle trajectory can help to guide the choice of puncture site and needle angle to reach the target depicted in the ultrasound image. We found that it is feasible to calculate the needle trajectory with a single camera mounted directly on the ultrasound transducer by using the needle markings. Higher accuracy is achieved compared with other similar transducer-mounted needle trackers. We used an inexpensive, real-time and easy-to-use tracking method based on an automatic feature extraction algorithm and a closed-form method for pose estimation of the needle. The overall accuracy was 0.94 ± 0.46 mm.

TU-AB-201-04: Optimizing the Number of Catheter Implants and Their Tracks for Prostate HDR Brachytherapy

Purpose: In prostate HDR brachytherapy, interstitial implants are placed manually on the fly. The aim for this research is to develop a computer algorithm to find optimal and reliable implant trajectories using minimal number of implants. Methods: Our new algorithm mainly uses these key ideas: (1) positive charged static particles are uniformly placed on the surface of prostate and critical structures such as urethra, bladder, and rectum. (2) Positive charged kinetic particles are placed at a cross-section of the prostate with an initial velocity parallel to the principal implant direction. (3) The kinetic particles move through the prostate, interacting with each other, spreading out, while staying away from the prostate surface and critical structures. The initial velocity ensures that the trajectories observe the curvature constraints of typical implant procedures. (4) The finial trajectories of kinetic particles are smoothed using a third-degree polynomial regression, which become the implant trajectories. (5) The dwelling times and final dose distribution are calculated using least-distance programming. Results: (1) We experimented with previously treated cases. Our plan achieves all prescription goals while reducing the number of implants by 41%! Our plan also has less uniform target dose, which implies a higher dose is delivered to the prostate. (2) We expect future implant procedures will be performed under the guidance of such pre-calculated trajectories. To assess the applicability, we randomly perturb the tracks to mimic the manual implant errors. Our studies showed the impact of these perturbations are negligible, which is compensated by the least distance programming. Conclusions: We developed a new inverse planning system for prostate HDR therapy that can find optimal implant trajectories while minimizing the number of implants. For future work, we plan to integrate our new inverse planning system with an existing needle tracking system.

Trajectory Guidance Law for MAV Based on MEMS Sensor/GPS

This paper studies a new trajectory guidance logic system for Bank-To-Turn fixed-wing (BTT) micro air vehicle (MAV) based on MEMS sensor / GPS , and introduce the method of estimating the navigation information from MEMS sensors and GPS. a nonlinear guided logic based on literature is utilized to get the desired roll angle , and a total energy controller is utilized in the longitudinal loop. Based on the kinematic model of the coordinated turning of MAV, the system can ensure that the aircraft stably track a flight plan segment. Flight tests on MAV prove the feasibility of the trajectory guidance logic system.

A biased competition theory of cytotoxic T lymphocyte interaction with tumor nodules.

The dynamics of the interaction between Cytotoxic T Lymphocytes (CTL) and tumor cells has been addressed in depth, in particular using numerical simulations. However, stochastic mathematical models that take into account the competitive interaction between CTL and tumors undergoing immunoediting, a process of tumor cell escape from immunesurveillance, are presently missing. Here, we introduce a stochastic dynamical particle interaction model based on experimentally measured parameters that allows to describe CTL function during immunoediting. The model describes the competitive interaction between CTL and melanoma cell nodules and allows temporal and two-dimensional spatial progression. The model is designed to provide probabilistic estimates of tumor eradication through numerical simulations in which tunable parameters influencing CTL efficacy against a tumor nodule undergoing immunoediting are tested. Our model shows that the rate of CTL/tumor nodule productive collisions during the initial time of interaction determines the success of CTL in tumor eradication. It allows efficient cytotoxic function before the tumor cells acquire a substantial resistance to CTL attack, due to mutations stochastically occurring during cell division. Interestingly, a bias in CTL motility inducing a progressive attraction towards a few scout CTL, which have detected the nodule enhances early productive collisions and tumor eradication. Taken together, our results are compatible with a biased competition theory of CTL function in which CTL efficacy against a tumor nodule undergoing immunoediting is strongly dependent on guidance of CTL trajectories by scout siblings. They highlight unprecedented aspects of immune cell behavior that might inspire new CTL-based therapeutic strategies against tumors.

Robust Model Predictive Control of Unmanned Aerial Vehicles Using Waysets

This paper introduces a new formulation of model predictive control for robust trajectory guidance of unmanned aerial vehicles. It generalizes the ubiquitous concept of waypoints to waysets, in order to provide robustness to bounded state disturbances in the presence of obstacles. Using a variable horizon formulation of model predictive control, it shows how wayset guidance combined with constraint tightening can guarantee robust recursive feasibility and finite-time completion of a control maneuver. Simulations on a point mass fixed-wing unmanned aerial vehicle model moving through a field of obstacles with wind disturbances demonstrate significant computational benefits from using waysets when compared to existing mixed-integer optimization methods that employ long prediction horizons. Using the controller’s robustness to mitigate linearization error, an additional example implements the strategy on a simulated quadrotor, demonstrating how waysets can be used to control more complex nonlinear systems.

Multi‐model direct generalised predictive control for automatic train operation system

The authors propose a novel multi-model direct generalised predictive control based on predictive function control (PFC) algorithm for automatic train operation system. The proposed method facilitates autonomous driving of a train through a given guidance trajectory. Firstly, they present a multi-model architecture based on fuzzy c-means clustering algorithm. In order to obtain the optimal number of sub-linear models, they apply Xie–Beni cluster validity index. In this regards, the multi-model set is established off-line. Secondly, the proper sub-linear model is selected as the predictive model by using switching performance index at each time slot. The control variables are calculated by direct generalised predictive controller based on PFC. The control algorithm is simple, and can reduce the on-line computation time by directly identifies the unknown parameters in the controller. It can avoid recursively solving the Diophantine equations. The calculation of compensation value becomes simple by introducing PFC. Finally, simulation results are provided to show the effectiveness of the proposed scheme.

Lane Change Assistance with Haptic Instruction and Trajectory Guidance

Lane Change Assistance with Haptic Instruction and Trajectory Guidance

Hybrid Re-entry Guidance for Reusable Launch Vehicle

A hybrid re-entry guidance approach, based on the nominal trajectory guidance method and predictor-corrector guidance, is proposed for the reusable launch vehicle (RLV). This approach generates a feasible re-entry trajectory which consists ofpre-entry phase, optimized bank angle phase and predictor-corrector phase. With the help of quasi-equilibrium glide condition (QEGC), the angle's constraints are transformed from re-entry constraints in optimized bank angle phase, and then guidance command is optimized using sequential quadratic program (SQP).In predictor-corrector phase, downrange errors are repeatedly calculated to updateconstant bank angle profiles.A bank reversal strategy based upon an azimuth error deadbandis designed to control crossrange. Simulationswith nominal and dispersion conditions demonstrategood performance of the guidance method.

Design of Fuzzy Neural Network Guidance Law Based on TakagiSugeno for UAV

Guidance of unmanned aerial vehicle (UAV) in three-dimensional space was studied in this paper. We designed a three-dimensional fuzzy neural network guidance law with the fuzzy rules of Takagi-Sugeno that based on proportional guidance principle and put the characteristics of the fuzzy neural network control into use. We decomposed the 3-D tracking trajectory into two two-dimensional planes and guided respectively, and took the influence of target mobility for guidance trajectory into consider. The design of guidance law was using the principle of proportional guidance, based on the Takagi-Sugeno type fuzzy inference, we took horizontal line of approaching velocity of missile-to-target, vertical line of sight angle velocity and sight angle velocity as inputs of fuzzy neural network, and yaw and pitch acceleration commands of UAV are the outputs, then we simulated the seeker tracking process against the target doing uniform motion in a straight line, curve movement and uniform circular motion respectively for UAV. Verified by simulation in this paper, the effect of the design of guidance law is ideal, and the proposed law is superior to the others and has good effect in response to the maneuvering target, and guidance trajectory is smoother.

Guidance and control for satellite in-orbit-self-assembly proximity operations

In this paper, the autonomous in-orbit-self-assembly of multiple satellites is exploited in close proximity operations. Guidance and control algorithms are developed based on the closed-form analytical solution of relative motion equations that is completely explicit in time in a general Keplerian orbit. The guidance algorithm is based on a modified version of the inbound glideslope transfer that was used in the past for rendezvous and proximity operations of the space shuttle with other vehicles. The control algorithm is based on a discrete multipulse technique that was used to track the guidance trajectory efficiently while avoiding collisions between satellites during maneuvers. These algorithms are general, and can translate each satellite in the assembly in any direction and decelerate while approaching the desired target location in the final assembly configuration. Numerical nonlinear simulations that illustrate the performance and accuracy of the proposed algorithms are performed in a cubic formation assembly.

Wide-bore 1.5 T MRI-guided deep brain stimulation surgery: initial experience and technique comparison

ObjectWe report results of the initial experience with magnetic resonance image (MRI)-guided implantation of subthalamic nucleus (STN) deep brain stimulating (DBS) electrodes at the University of Wisconsin after having employed frame-based stereotaxy with previously available MR imaging techniques and microelectrode recording for STN DBS surgeries. MethodsTen patients underwent MRI-guided DBS implantation of 20 electrodes between April 2011 and March 2013. The procedure was performed in a purpose-built intraoperative MRI suite configured specifically to allow MRI-guided DBS, using a wide-bore (70cm) MRI system. Trajectory guidance was accomplished with commercially available system consisting of an MR-visible skull-mounted aiming device and a software guidance system processing intraoperatively acquired iterative MRI scans. ResultsA total of 10 patients (5 male, 5 female)—representative of the Parkinson Disease (PD) population—were operated on with standard technique and underwent 20 electrode placements under MRI-guided bilateral STN-targeted DBS placement. All patients completed the procedure with electrodes successfully placed in the STN. Procedure time improved with experience. ConclusionOur initial experience confirms the safety of MRI-guided DBS, setting the stage for future investigations combining physiology and MRI guidance. Further follow-up is required to compare the efficacy of the MRI-guided surgery cohort to that of traditional frame-based stereotaxy.

Optimal control of a universal rotating magnetic vector for petal-shaped capsule robot in curve environment

Steering control of a capsule robot in curve environment by magnetic navigation is not yet solved completely. A petal-shaped capsule robot with less steering resistance based on multiple wedge effects is presented, and an optimization method with two processes for determining the orientation of a pre-applied universal magnetic spin vector is proposed. To realize quick and non-contact steering swimming, a fuzzy comprehensive evaluation method for optimizing the steering driving angle is presented based on two evaluation indexes including the average steering speed and the average steering trajectory deviation, achieving the initial optimal orientation of a universal magnetic spin vector. To further reduce robotic magnetic vibration, a main target method for optimizing its final orientation, which is used for fine adjustment, is employed under the constrains of the magnetic moments. Swimming experimental results in curve pipe verified the effectiveness of the optimization method, which can be effectively used to realize non-contact steering swimming of the petal-shaped robot and reduce its vibration.

Mars Science Laboratory Flyaway Guidance, Navigation, and Control System Design

This paper describes the flyaway guidance, navigation, and control system design that was successfully used during the landing of NASA’s Mars Science Laboratory on Mars on 5 August 2012. One of the most challenging phases of the Mars Science Laboratory mission is the entry, descent, and landing that starts with the Mars atmospheric entry and ends with the rover Curiosity landing on Mars and the descent stage with the sky crane crashing to the surface. Because the two-way signal’s communication time between Earth and Mars is about 26 min and the fact that the end-to-end entry, descent, and landing takes about 7 min, the lander must be controlled completely autonomously. At the last step of the landing, the rover is lowered to the surface by using a new sky crane, which resides on the descent stage of the lander. The sky crane slowly descends toward the Martian surface as the rover is lowered. Once the touchdown is detected, the onboard control system flies the descent stage as far away as possible from the rover. This phase of the landing is called the “flyaway.” The flyaway is the last phase, and its main goals are to move the sky crane, which may contain unused propellant, to a safe distance and to avoid plume impingement on the sensitive science instruments on the rover during the flyaway maneuver. The coupled attitude and translational motion is planned, that is, rotational and translational trajectories are time profiled by the onboard guidance algorithm. The trajectories obey the control authority constraints, due to maximum torque and force, while maximizing the divert distance. These guidance trajectories are tracked by using feedback control laws that provide robustness to any model uncertainties and disturbances forces and torques. Simulation results predicted that a desirable performance would be achieved in terms of the flyaway distance and the plume avoidance. Finally, the actual landing on Mars on 5 August 2012 was extremely successful, and the results were consistent with predictions.

The Design Research of Millimeter-Wave Homing Empty - Empty Ammunition Ballistics

The millimeter-wave terminal guidance ammunition monitoring scanning field is small. The modified design is in order to improve the search section trajectory guidance. This study established seeker search area to capture the target model, which leads to the missile engine unpowered glide distance formula after flameout. At the millimeter-wave terminal on the missiles contraction section ballistic. Each missile is designed for the flat road, the swash decline ballistic programs. Flat missile road program scans and does not shrink. Its flight speed falls and declines rapidly, has different gliding distance and terminal velocity. After the missile engine is flameout, its start-gliding speed is great. Ramp fell ballistic program enhances the air-air (or air-ground) guided missile’s gliding ability, helping to improve range. But shortcomings are that target tracking scanning domain contracts. Using the seeker optical axis in the pitch direction can achieve accurate positioning with the height precession. Two ballistic designs can both meet the target seeker’s scanning, thus effectively improve the striking precision.

Communication-Based Train Control (CBTC) Systems With Cooperative Relaying: Design and Performance Analysis

A communication-based train control (CBTC) system is an automated train control system using bidirectional train-ground communications to ensure the safe operation of rail vehicles. CBTC systems have stringent requirements for communication availability and latency. Most existing CBTC train-ground communication systems work in the infrastructure mode without train-train communications. Due to unreliable wireless communications and frequent handoffs, existing CBTC systems can severely affect train control performance, train operation efficiency, and the utility of the railway. In this paper, we use recent advances in cooperative relaying to enable train-train communications and, consequently, enhance the train control performance of CBTC systems. Trains act not only as end communication points but as relays for other trains as well. Unlike existing works on cooperative relaying, in this paper, linear quadratic cost for the train control performance in CBTC systems is considered as the performance measure. We jointly consider cooperative relaying and handoff decision issues in CBTC systems. Moreover, to mitigate the impacts of handoff latency on the train control performance, we propose an optimal guidance trajectory calculation scheme in the train control procedure that takes full consideration of the tracking error caused by handoff latency. Simulation results show that the train control performance can be substantially improved in our proposed CBTC system with cooperative relaying.

Design and Performance Enhancements in Communication-Based Train Control Systems With Coordinated Multipoint Transmission and Reception

A communication-based train control (CBTC) system is an automated train control system that uses bidirectional train–ground communications to ensure the safe operation of rail vehicles. CBTC systems have stringent requirements for communication availability and latency. Due to unreliable wireless communications and frequent handoffs, existing CBTC systems can severely affect train control performance, train operation efficiency, and the utility of railways. In this paper, we use recent advances in coordinated multipoint transmission and reception (CoMP) to enhance the train control performance of CBTC systems. With CoMP, a train can communicate with a cluster of base stations (BSs) simultaneously, which is different from the current CBTC systems, where a train can only communicate with a single BS at any given time. In addition, unlike the existing works on CoMP, in this paper, the linear quadratic cost for the train control performance in CBTC systems is considered the performance measure. We jointly consider the BS cluster selection and handoff decision issues in CBTC systems. Moreover, in order to mitigate the impacts of communication latency on train control performance, we propose an optimal guidance trajectory calculation scheme in the train control procedure that takes full consideration of the tracking error caused by handoff latency. Simulation results show that train control performance can be substantially improved in our proposed CBTC system with CoMP.

Using XperGuide Planning Software to Safely Guide Catheter Access to the Cavernous Sinus via Transorbital Puncture

Many techniques for accessing the cavernous sinus have been described, from a transfemoral venous approach to a direct surgical exposure and cannulation of the superior ophthalmic vein. The cavernous sinus can be accessed safely through direct transorbital puncture and cannulation of a preceding venous confluence with an 18-gauge angiocatheter. This technique is performed under constant fluoroscopy using bony landmarks. The use of XperGuide software allows the operator to obtain an intraprocedural computed tomography and to identify the optimum needle entry point and trajectory to avoid at-risk structures such as the optic nerve in this case. This trajectory is then superimposed onto the real-time fluoroscopic image, and the guidance trajectory is followed during needle insertion. The patient is a 66-year-old woman who spontaneously developed a left-sided cavernous sinus syndrome. She was found to have an indirect carotid cavernous fistula on angiography. Because of tortuosity and occlusion of venous access points to the cavernous sinus, access via transorbital puncture was preferred. The XperGuide system was used to avoid the at-risk structures, and coils were safely deployed within the cavernous sinus after successful cannulation with this guidance system. The patient had complete resolution of her fistula and experienced no complications from the procedure. The XperGuide software guidance system is helpful during direct transorbital puncture of the cavernous sinus because it allows better monitoring of real-time needle location along a safe trajectory selected by the operator to avoid damaging local soft tissue structures.

Individual Driver Modeling via Optimal Selection of Steering Primitives

A shared lane keeping assistance system supports the driver in the steering task. In contrast to an autonomous system, the shared system works in parallel with the driver by applying an additional torque on the steering wheel. This means the system and the driver perform the steering task in cooperation. As the driver is still part of the control loop a driver model is required to predict the steering behavior of the actual driver. In this paper we introduce a new lateral steering model which is suited to characterize individual drivers. This model describes, in contrast to other models, the neuromuscular system, limbs and its control for a specific driver by using a set of dynamic primitives (so called movemes). These movemes build a gray-box model for the neuromuscular system. The steering wheel angle is the predicted output of the moveme model. In order to generate a steering angle trajectory suited for the desired maneuver, the steering model switches between these movemes. Therefore, the central component of the driver model is a framework which determines the optimal switching sequence of the movemes. For this task an optimal control strategy is introduced. The approach is validated using a simulation of an ISO-double lane change with movemes which were identified from a set of real driver trajectories. The results show that the steering trajectories of the driver model highly correspond with the recorded driver trajectories.