Including Collision Detection Research Articles

Simulating Fish Motion through a Diagonal Reversible Turbine

Utilization of unharnessed hydro-power necessitates designing fish-friendly hydraulic machinery. Towards this effort, the present work investigates various methods for tracking fish motion, ranging from particle tracking methods to accurate, but computationally expensive, body tracking methods, such as immersed boundaries and overset meshes. Moreover, a novel uncoupled 6-Degree of Freedom tracking technique is proposed, based on an approximated pressure field around the tracked body of interest, using steady-state flow field data, and including collision detection to walls. The proposed method shows promising results in terms of accuracy, being comparable to the more computationally expensive fully coupled methods at a tiny fraction of the execution time. The new method reveals location of fish–blade impact, as well as statistics of forces, pressure and flow shear that a passing fish is subjected to, both in the normal and reverse operation of the turbine. The low computational cost of the proposed method renders it attractive for optimization studies.

ASIC Design and Implementation of the Real-Time Collision Detection for Machine Tool Automation

Collision detection of two objects plays an essential role for the machine tool automation. Although the collision detection of two objects has been studied in applications like virtual reality, the collision detection for the machine tool requires high precision to avoid overcut damage to the high-cost machine tools. The current collision detection for machine tools is under the soft-ware based computer numerical control (CNC), the low computation capability of which refrains the CNC based approach from real-time collision detection. In this paper, we consider the design of application specific integrated circuit (ASIC) to enhance the collision detection for machine tool automation. Because the bounded objects are represented by meshed triangles, we consider the separating axis theorem (SAT) based detection algorithm. Furthermore, by considering high precision required by machine tool applications, the proposed algorithm includes collision detection of either non-coplanar or coplanar triangles. Following the collision detection algorithm, we design hardware architecture with parallel processing to provide higher throughput rate over the architecture reported in our conference paper. The VLSI implementation results under the TSMC TN40G (45nm) CMOS technology reveal that our architecture requires 1,212K gates and provides detection throughput 38.46M per second for collision detection of two triangles, while operating at 500 MHz. For two objects represented by 400 and 400 meshed triangles, respectively, our hardware architecture can provide collision detection in 0.96 ms, which is smaller than the 1 ms required for real-time processing of collision detection of two objects.

Coupling of an SPH-based solver with a multiphysics library

A two-way coupling between the Smoothed Particle Hydrodynamics-based (SPH) code with a multiphysics library to solve complex fluid-solid interaction problems is proposed. This work provides full access to the package for the use of this coupling by releasing the source code, completed with guidelines for its compilation and utilization, and self-contained template setups for practical uses of the novel implemented features, is provided here. The presented coupling expands the applicability of two different solvers allowing to simulate fluids, multibody systems, collisions with frictional contacts using either non-smooth contact (NSC) or smooth contact (SMC) methods, all integrated under the same framework. The fluid solver is the open-source code DualSPHysics, highly optimised for simulating free-surface phenomena and structure interactions, uniquely positioned as a general-purpose Computational Fluid Dynamics (CFD) software with a GPU-accelerated solver. Mechanical systems that comprise collision detection and/or multibody dynamics are solved by the multiphysics library Project Chrono, which uses a Discrete Element Method (DEM). Therefore, this SPH-DEM coupling approach can manage interactions between fluid and complex multibody systems with relative constraints, springs, or mechanical joints. Program summaryProgram title: DualSPHysics-ChronoCPC Library link to program files:https://doi.org/10.17632/g2cc37dw4f.1Licensing provisions: DualSPHysics and DSPHChronoLib under GNU Lesser General Public License (LGPL); Project Chrono under BSD-3-Clause License.Programming language: C++ and CUDANature of problem: The simulation of turbulent free-surface flows in interaction with complex fixed or floating structures is essential to address typical marine and coastal engineering problems. The Smoothed Particle Hydrodynamics (SPH) method is particularly suitable for solving this type of nonlinear problems. However, this type of application usually requires mechanical restrictions between the different structural elements (spherical joints, hinges, or springs), as well as the correct simulation of collisions between solid objects. In these cases, it is necessary to combine the SPH method with other numerical methods that allow performing these multiphysics simulations.Solution method: DualSPHysics-Chrono is a two-way coupling between an SPH solver and a multiphysics library that combines fluid simulation using a Lagrangian approximation and interactions between solids using Discrete Element Method (DEM). DualSPHysics solver is a GPU-optimized implementation of the SPH method that allows efficient simulation of fluid-structure interaction problems. Whereas Project Chrono is a DEM implementation for simulating multibody dynamics that includes collision detection and numerous mechanical constraints to solve complex mechanisms. The coupling of DualSPHysics and Project Chrono combines the capabilities of both models under a free software framework.Additional comments including restrictions and unusual features: The SPH solver includes a version implemented with CUDA (Compute Unified Device Architecture) to exploit the parallelism of NVIDIA graphics processing units (GPUs).

Compliant Control of Single Tendon-Sheath Actuators Applied to a Robotic Manipulator

Tendon-sheath actuators (TSAs), similar to Bowden cable-based series elastic actuators (SEAs), have a wide range of applications in robots. However, when applying them to manipulators, force sensors cannot be mounted due to limited space. Therefore, this paper proposes a new method for compliant control based on a dual encoder, and the existing transmission model was improved by considering the joint torque. To validate the proposed method, experimental setups composed of a motor, a tendon-sheath component, a robotic joint, force sensors, and position sensors are established. The transmission processes are interpreted clearly through a position control mode. Parameter identifications without external disturbance force are conducted to acquire the ideal transmission model, and the error value between the experiment data and the fitted curve is measured. The availability of the presented scheme is verified by compliant control experiments, including collision detection and hand guiding, and the frequency characteristics of the actuator are analyzed. The results show that the function can be realized without force and torque sensors during the whole process.

CAMA: Contact‐Aware Matrix Assembly with Unified Collision Handling for GPU‐based Cloth Simulation

AbstractWe present a novel GPU‐based approach to robustly and efficiently simulate high‐resolution and complexly layered cloth. The key component of our formulation is a parallelized matrix assembly algorithm that can quickly build a large and sparse matrix in a compressed format and accurately solve linear systems on GPUs. We also present a fast and integrated solution for parallel collision handling, including collision detection and response computations, which utilizes spatio‐temporal coherence. We combine these algorithms as part of a new cloth simulation pipeline that incorporates contact forces into implicit time integration for collision avoidance. The entire pipeline is implemented on GPUs, and we evaluate its performance on complex benchmarks consisting of 100 – 300K triangles. In practice, our system takes a few seconds to simulate one frame of a complex cloth scene, which represents significant speedups over prior CPU and GPU‐based cloth simulation systems.

Simulation of Collision Situations in RobotStudio

The article deals with the problem of the collision condition of robotic device, which is possible to be revealed by spatial simulation. In addressing the collision condition, RobotStudio program was used. It includes collision detection functions. Collision detection function automatically monitors objects and indicates the collision, which may arise during the operation of the robot. In my case, collision condition occurs between the stationary part, which is a component part and moving part, which is a burner.

A motion planning method for simulating a virtual crowd

A model of motion planning for agent-based crowd simulation is one of the key techniques for simulating how an agent selects its velocity to move towards a given goal in each simulation time step. If there is no on-coming collision with other agents or obstacles around, the agent moves towards the designated goal directly with the desired speed and direction. However, the desired velocity may lead the agent to collide with other agents or obstacles, especially in a crowded scenario. In this case, the agent needs to adjust its velocity to avoid potential collisions, which is the main issue that a motion planning model needs to consider. This paper proposes a method for modelling how an agent conducts motion planning to generate velocity for agent-based crowd simulation, including collision detection, valid velocity set determination, velocity sampling, and velocity evaluation. In addition, the proposed method allows the agent to really collide with other agents. Hence, a rule-based model is applied to simulate how the agent makes a response and recovers from the collision. Simulation results from the case study indicate that the proposed motion planning method can be adapted to different what-if simulation scenarios and to different types of pedestrians. The performance of the model has been proven to be efficient.

Theoretical models of planetary system formation: mass vs. semi-major axis

Planet formation models have been developed during the last years in order to try to reproduce the observations of both the solar system, and the extrasolar planets. Some of these models have partially succeeded, focussing however on massive planets, and for the sake of simplicity excluding planets belonging to planetary systems. However, more and more planets are now found in planetary systems. This tendency, which is a result of both radial velocity, transit and direct imaging surveys, seems to be even more pronounced for low mass planets. These new observations require the improvement of planet formation models, including new physics, and considering the formation of systems. In a recent series of papers, we have presented some improvements in the physics of our models, focussing in particular on the internal structure of forming planets, and on the computation of the excitation state of planetesimals, and their resulting accretion rate. In this paper, we focus on the concurrent effect of the formation of more than one planet in the same protoplanetary disc, and show the effect, in terms of global architecture and composition of this multiplicity. We use a N-body calculation including collision detection to compute the orbital evolution of a planetary system. Moreover, we describe the effect of competition for accretion of gas and solids, as well as the effect of gravitational interactions between planets. We show that the masses and semi-major axis of planets are modified by both the effect of competition and gravitational interactions. We also present the effect of the assumed number of forming planets in the same system (a free parameter of the model), as well as the effect of the inclination and eccentricity damping.

Application of Virtual Reality Techniques in Design of Ergonomic Manufacturing Workplaces

This paper presents possibilities of application of the immersive VR and the haptic technologies during the complex process of design and virtual prototyping of the manufacturing workplaces characterized with a high level of ergonomic quality. Two case studies are presented: a workplace for stud welding and a set of two workplaces, for hole drilling and manual assembly. In the first case study, haptic device with force feedback effect was used to improve ergonomics of main operator activities. In the second case study, immersive approach was used, namely Head-Mounted Device, tracking and gesture recognition systems, to test and improve ergonomics of the whole workplace. Application of VR techniques allows to present the virtual prototype of the workplace in its real operation environment, limiting the need for use of real mock-ups. Therefore, Virtual Reality allows to conduct a number of analyses related to designed prototypes, such as: dimensions of devices and possibilities of adjustment to height of the human operator, and arrangement of control and signaling devices according to the rules of ergonomic design. To conduct these analyses, full interaction between user and workplace must be programmed, including collision detection, kinematics of the devices and possibilities of activating their various functions in relation with other objects in the virtual scene.

Gaze movements and spatial working memory in collision avoidance: a traffic intersection task

Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and represented in spatial working memory. In a virtual reality traffic intersection task, subjects are confronted with a two-lane intersection where cars are appearing with different frequencies, corresponding to high and low traffic densities. Under free observation and exploration of the scenery (using unrestricted eye and head movements) the overall task for the subjects was to predict the potential-of-collision (POC) of the cars or to adjust an adequate driving speed in order to cross the intersection without collision (i.e., to find the free space for crossing). In a series of experiments, gaze movement parameters, task performance, and the representation of car positions within working memory at distinct time points were assessed in normal subjects as well as in neurological patients suffering from homonymous hemianopia. In the following, we review the findings of these experiments together with other studies and provide a new perspective of the role of gaze behavior and spatial memory in collision detection and avoidance, focusing on the following questions: (1) which sensory variables can be identified supporting adequate collision detection? (2) How do gaze movements and working memory contribute to collision avoidance when multiple moving objects are present and (3) how do they correlate with task performance? (4) How do patients with homonymous visual field defects (HVFDs) use gaze movements and working memory to compensate for visual field loss? In conclusion, we extend the theory of collision detection and avoidance in the case of multiple moving objects and provide a new perspective on the combined operation of external (bottom-up) and internal (top-down) cues in a traffic intersection task.

Effects of stand-off bursts on rubble-pile targets: Evaluation of a hazardous asteroid mitigation strategy

We explore the aftereffects of stand-off burst mitigation on kilometer-scale rubble pile asteroids. We use a simple model of X-ray energy deposition to calculate the impulse transferred to the target, in particular to burst-facing blocks on the target surface. The impulse allows us to estimate an initial velocity field for the blocks on the outer side of the target facing the burst. We model the dynamics using an N-body polyhedron program built on the Open Dynamics Engine, a “physics engine” that integrates the dynamical equations for objects of general shapes and includes collision detection, friction, and dissipation.We tested several different models for target objects: rubble piles with different mass distributions, a “brick-pile” made of closely fitting blocks and zero void space, and a non-spherical “contact binary” rubble pile. Objects were bound together by self-gravity and friction/inelastic restitution with no other cohesive forces. Our fiducial cases involved objects of m=3.5×1012kg (corresponding to a radius of 0.7km for the bulk object), an X-ray yield of 1megaton, and stand-off burst distances of R=0.8–2.5km from the target center of mass.Kilometer-scale rubble piles are robust to stand-off bursts of a yield (Y∼1megaton) that would be sufficient to provide an effective velocity change (Δv∼0.05ms−1). Disaggregation involving some tens of percent of the target mass happens immediately after the impulse; the bulk of the object re-accretes on a few gravitational timescales, and the final deflected target contains over 95% (typically, 98–99%) of the original mass. Off-center components of the mitigation impulse and the target mass distribution cause a small amount of induced spin and off-axis components of velocity change. The off-axis velocity component amounts to an angular deviation of ∼ 0.05–0.1 radians from the nominal impulse vector, which may be important for mitigation planning.

A heuristic model for the simulation of the deformation of elastic and spongy material for virtual reality applications

This paper presents a practical algorithm for the simulation of interactive deformation in a 3D polygonal mesh model. The algorithm combines the conventional simulation of deformation using a spring-mass-damping model, solved by explicit numerical integration, with a set of heuristics to describe certain features of the transient behaviour, to increase the speed and stability of solution. In particular, this algorithm was designed to be used in the simulation of synthetic environments where it is necessary to model realistically, in real time, the effect on non-rigid surfaces being touched, pushed, pulled or squashed. Such objects can be solid or hollow, and have plastic, elastic or fabric-like properties. The algorithm is presented in an integrated form including collision detection and adaptive refinement so that it may be used in a self-contained way as part of a simulation loop to include human interface devices that capture data and render a realistic stereoscopic image in real time. The algorithm is designed to be used with polygonal mesh models representing complex topology, such as the human anatomy in a virtual-surgery training simulator. The paper evaluates the model behaviour qualitatively and then concludes with some examples of the use of the algorithm.

Design of a 6 degree of freedom anthropomorphic robotic jaw

We have created a 6 DOF robotic jaw capable of producing, in real-time, the complex set of motions described by the human jaw during speech or mastication. The jaw is designed to fit within a larger robotic human figure such as the head, neck and torso of the 25 DOF Infanoid. [Kozima, Hideki: Infanoid: A Babybot that Explores the Social Environment, K. Dautenhahn et al. (eds.), Socially Intelligent Agents: Creating Relationships with Computers and Robots, Kluwer Academic Publishers, pp. 157–164, 2002]. The produced mechanical prototype has been designed to accommodate a prosthesis mandible with dentures. The mechanism could fit within the skull of the average man; where it would occupy less than 1/3 of the skull cavity. Two TMJs (temporomandibular joints) support the prosthesis, where each is driven by a 3 DOF parallel manipulator. In order to combine the motion of both manipulators each TMJ is capable of 3 DOF. The system is controlled via a USB port using software that models the human skull including collision detection mechanisms. The jaw allows for linear control, zero-backlash, and up to three times exaggerated mobility ranges making it also suitable for speech research, facial gesture affect research and dentistry applications.

The GJK Distance Algorithm: An Interval Version for Incremental Motions

The tracking of distance between two convex polyhedra is commonly used in the field of robotics, including collision detection or path planning. One of the well-known algorithms in this area is the distance algorithm developed by Gilbert, Johnson and Keerthi. Although this algorithm is widely-used in robotics, up till now, there has been no verification of the computed results. This paper will present an interval version for tracking the distance between convex polyhedra using the C++ library PROFIL/BIAS.

A computer-controlled conformal radiotherapy system. III: Graphical simulation and monitoring of treatment delivery

Safe and efficient delivery of radiotherapy using computer-controlled machines requires new procedures to design and verify the actual delivery of these treatments. Graphical simulation and monitoring techniques for treatment delivery have been developed for this purpose. A graphics-based simulator of the treatment machine and a set of procedures for creating and manipulating treatment delivery scripts are used to simulate machine motions, detect collisions, and monitor machine positions during treatment. The treatment delivery simulator is composed of four components: a three-dimensional dynamic model of the treatment machine; a motion simulation and collision detection algorithm, user-interface widgets that mimic the treatment machine's control and readout devices; and an icon-based interface for creating and manipulating treatment delivery scripts. These components are used in a stand-alone fashion for interactive treatment delivery planning and integrated with a machine control system for treatment implementation and monitoring. A graphics-based treatment delivery simulator and a set of procedures for planning and monitoring computer-controlled treatment delivery have been developed and implemented as part of a comprehensive computer-controlled conformal radiotherapy system. To date, these techniques have been used to design and help monitor computer-controlled treatments on a radiotherapy machine for more than 200 patients. Examples using these techniques for treatment delivery planning and on-line monitoring of machine motions during therapy are described. A system that provides interactive graphics-based tools for defining the sequence of machine motions, simulating treatment delivery including collision detection, and presenting the therapists with continual visual feedback from the treatment machine has been successfully implemented for routine clinical use as part of an overall system for computer-controlled conformal radiotherapy treatment, and is considered a necessary part of the routine treatment methodology.