Search for a Stationary Target

2016 ◽  
pp. 9-48
Author(s):  
Lawrence D. Stone ◽  
Johannes O. Royset ◽  
Alan R. Washburn
Keyword(s):  
Stationary Target

Adjustable impact-time-control guidance law against non-maneuvering target under limited field of view

2021 ◽  
pp. 095441002110129
Author(s):  
Jun-Yong Lee ◽  
Hyeong-Guen Kim ◽  
H Jin Kim
Keyword(s):  
Field Of View ◽  
Control Technique ◽  
Moving Target ◽  
Time Error ◽  
Stationary Target ◽  
Impact Time ◽  
Maneuvering Target ◽  
Time Control ◽  
Guidance Law ◽  
Intercept Point

This article proposes an impact-time-control guidance law that can keep a non-maneuvering moving target in the seeker’s field of view (FOV). For a moving target, the missile calculates a predicted intercept point (PIP), designates the PIP as a new virtual stationary target, and flies to the PIP at the desired impact time. The main contribution of the article is that the guidance law is designed to always lock onto the moving target by adjusting the guidance gain. The guidance law for the purpose is based on the backstepping control technique and designed to regulate the defined impact time error. In this procedure, the desired look angle, which is a virtual control, is designed not to violate the FOV limit, and the actual look angle of the missile is kept within the FOV by tracking the desired look angle. To validate the performance of the guidance law, numerical simulation is conducted with different impact times. The result shows that the proposed guidance law intercepts the moving target at the desired impact time maintaining the target lock-on condition.

Differentiating Laparoscopic Skills of Trainees with Computer Vision Based Metrics

2021 ◽  
Vol 65 (1) ◽  
pp. 304-308
Author(s):  
Shiyu Deng ◽  
Chaitanya Kulkarni ◽  
Tianzi Wang ◽  
Jacob Hartman-Kenzler ◽  
Laura E. Barnes ◽  
...  
Keyword(s):  
Computer Vision ◽  
Transfer Task ◽  
High Sensitivity ◽  
Video Data ◽  
Machine Learning Algorithms ◽  
Fixation Rate ◽  
Skill Levels ◽  
Stationary Target ◽  
Practice Trials ◽  
Context Dependent

Context dependent gaze metrics, derived from eye movements explicitly associated with how a task is being performed, are particularly useful for formative assessment that includes feedback on specific behavioral adjustments for skill acquisitions. In laparoscopic surgery, context dependent gaze metrics are under investigated and commonly derived by either qualitatively inspecting the videos frame by frame or mapping the fixations onto a static surgical task field. This study collected eye-tracking and video data from 13 trainees practicing the peg transfer task. Machine learning algorithms in computer vision were employed to derive metrics of tool speed, fixation rate on (moving or stationary) target objects, and fixation rate on tool-object combination. Preliminary results from a clustering analysis on the measurements from 499 practice trials indicated that the metrics were able to differentiate three skill levels amongst the trainees, suggesting high sensitivity and potential of context dependent gaze metrics for surgical assessment.

Neuronal Responses Related to Smooth Pursuit Eye Movements in the Periarcuate Cortical Area of Monkeys

1998 ◽  
Vol 80 (1) ◽  
pp. 28-47 ◽  
Author(s):  
Masaki Tanaka ◽  
Kikuro Fukushima
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Cortical Area ◽  
Eye Position ◽  
Smooth Pursuit Eye Movements ◽  
Neuronal Responses ◽  
Stationary Target ◽  
Pursuit Eye Movements ◽  
Preferred Direction ◽  
Eye Velocity

Tanaka, Masaki and Kikuro Fukushima. Neuronal responses related to smooth pursuit eye movements in the periarcuate cortical area of monkeys. J. Neurophysiol. 80: 28–47, 1998. To examine how the periarcuate area is involved in the control of smooth pursuit eye movements, we recorded 177 single neurons while monkeys pursued a moving target in the dark. The majority (52%, 92/177) of task-related neurons responded to pursuit but had little or no response to saccades. Histological reconstructions showed that these neurons were located mainly in the posterior bank of the arcuate sulcus near the sulcal spur. Twenty-seven percent (48/177) changed their activity at the onset of saccades. Of these, 36 (75%) showed presaccadic burst activity with strong preference for contraversive saccades. Eighteen (10%, 18/177) were classified as eye-position–related neurons, and 11% (19/177) were related to other aspects of the stimuli or response. Among the 92 neurons that responded to pursuit, 85 (92%) were strongly directional with uniformly distributed preferred directions. Further analyses were performed in these directionally sensitive pursuit-related neurons. For 59 neurons that showed distinct changes in activity around the initiation of pursuit, the median latency from target motion was 96 ms and that preceding pursuit was −12 ms, indicating that these neuron can influence the initiation of pursuit. We tested some neurons by briefly extinguishing the tracking target ( n = 39) or controlling its movement with the eye position signal ( n = 24). The distribution of the change in pursuit-related activity was similar to previous data for the dorsomedial part of the medial superior temporal neurons ( Newsome et al. 1988) , indicating that pursuit-related neurons in the periarcuate area also carry extraretinal signals. For 22 neurons, we examined the responses when the animals reversed pursuit direction to distinguish the effects of eye acceleration in the preferred direction from oppositely directed eye velocity. Almost all neurons discharged before eye velocity reached zero, however, only nine neurons discharged before the eyes were accelerated in the preferred direction. The delay in neuronal responses relative to the onset of eye acceleration in these trials might be caused by suppression from oppositely directed pursuit velocity. The results suggest that the periarcuate neurons do not participate in the earliest stage of eye acceleration during the change in pursuit direction, although most of them may participate in the early stages of pursuit initiation in the ordinary step-ramp pursuit trials. Some neurons changed their activity when the animals fixated a stationary target, and this activity could be distinguished easily from the strong pursuit-related responses. Our results suggest that the periarcuate pursuit area carries extraretinal signals and affects the premotor circuitry for smooth pursuit.

Nonlinear dynamic image-based visual servoing of a quadrotor

2015 ◽  
Vol 3 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Geoff Fink ◽  
Hui Xie ◽  
Alan F. Lynch ◽  
Martin Jagersand
Keyword(s):  
Visual Servoing ◽  
Lateral Position ◽  
Control Law ◽  
Stationary Target ◽  
Dynamic Image ◽  
Change Of State ◽  
Dependent Change ◽  
Exponentially Stable ◽  
Aerial Vehicle ◽  
Error Dynamics

This paper proposes a dynamic image-based visual servoing (IBVS) control law for a quadrotor unmanned aerial vehicle (UAV) equipped with a single fixed on-board camera facing downward. The motion control problem is to regulate the relative lateral position of the vehicle to a stationary target located on the ground. The control law is termed dynamic as it is based on the dynamics and kinematics of the vehicle. The proposed design uses a nonlinear input-dependent change of state coordinates and its error dynamics are proven to be locally exponentially stable with an estimate provided for the region of attraction. Experimental and simulation results demonstrate the method's ease of on-board implementation, performance, and robustness. The simulation and experimental results include a comparison with an established dynamic IBVS method. This comparison shows the proposed method can provide similar performance with the benefit of reduced complexity.

Model Predictive Control-Based Probabilistic Search Method for Autonomous Ground Robot in a Dynamic Environment

2015 ◽  
Author(s):  
Chang Liu ◽  
Shengbo Eben Li ◽  
J. Karl Hedrick
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Gaussian Function ◽  
Dynamic Environment ◽  
Gaussian Mixture ◽  
Search Method ◽  
Stationary Target ◽  
Probability Map ◽  
Probabilistic Search ◽  
Binary Sensor

Target search using autonomous robots is an important application for both civil and military scenarios. In this paper, a model predictive control (MPC)-based probabilistic search method is presented for a ground robot to localize a stationary target in a dynamic environment. The robot is equipped with a binary sensor for target detection, of which the uncertainties of binary observation are modeled as a Gaussian function. Under the model predictive control framework, the probability map of the target is updated via the recursive Bayesian estimation and the collision avoidance with obstacles is enforced using barrier functions. By approximating the updated probability map using a Gaussian Mixture Model, an analytical form of the objective function in the prediction horizon is derived, which is promising to reduce the computation complexity compared to numerical integration methods. The effectiveness of the proposed method is demonstrated by performing simulations in dynamic scenarios with both static and moving obstacles.

Multiple image processing to enhance stationary target detection

1992 ◽  
Author(s):  
Michael B. Sechtin ◽  
Michael C. Burl
Keyword(s):  
Image Processing ◽  
Target Detection ◽  
Stationary Target ◽  
Multiple Image

scholarly journals Effect of grip size and grip strength on pistol marksmanship in police officers: A pilot study

2021 ◽  
Vol 26 (1) ◽  
pp. 61-72
Author(s):  
Robin Orr ◽  
Anthony Rofe ◽  
Ben Hinton ◽  
Jay Dawes ◽  
Gianpiero Greco ◽  
...  
Keyword(s):  
Pilot Study ◽  
Grip Strength ◽  
Police Officers ◽  
Influencing Factor ◽  
Hand Grip Strength ◽  
Stationary Target ◽  
Hand Grip ◽  
Significant Relationships ◽  
Hand Size ◽  
Self Defence

Police officers may be required to use their firearms in self-defence. The purpose of this study was to evaluate the relationships between hand grip size and strength with pistol shooting accuracy in police officers. Twelve (age = 38.08 ± 6.24 years; height = 174.42 ± 7.33 cm) police officers had their hand sizes (palm width and hand span) and hand grip strength measured. Handgrip dynamometer was set at a Glock 17 pistol's grip width (50 mm). The officers fired 10 rounds from their service pistols at a stationary target. Independent samples t-tests were performed to identify differences between the sexes. Correlations were used to investigate relationships between measures of hand size, strength, and marksmanship. Alpha levels were set at p < 0.05. Male officers were significantly stronger (p = 0.01) and had a bigger hand width (p = 0.03), but not hand span. There were no significant differences in marksmanship between the sexes. Neither hand size nor grip strength had a significant impact on marksmanship even though there were strong and significant relationships between hand size (span and MCP) and grip strength. A V-shaped curve appears to exist between grip strength and marksmanship and hand span and marksmanship, with a potential influencing factor being the standard sizing of the pistol grip.

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