Collision Detection Algorithm Research Articles

Collision Detection on Industrial Robots in Repetitive Tasks Using Modified Dynamic Time Warping

SUMMARYThis paper presents a non-model-based collision detection algorithm for robots without external sensors and with closed control architecture. A reference signal of repetitive motion is recorded from the robot operation. To detect collisions, the reference is compared with measurements from the robot. One of the key contributions is a novel approach to optimal matching of compared signals, which is ensured by the newly developed modified Dynamic Time Warping (mDTW) method presented in this paper. One of the main improvements of the mDTW is that it enables comparing a signal with the most similar section of the other signal. Partial matching also enables online application of time warping principles and reduces the time and computation resources needed to perform matching. In addition to mDTW, two complementary decision rules are developed to identify collisions. The first rule, based on the absolute difference between compared matched samples, uses statistically determined thresholds to perform rapid detection of unambiguous collisions. The second rule is based on Eigen values of the covariance matrix of matched samples, and it employs its higher sensitivity to detect collisions with lower intensity. Results from experimental validation of the proposed collision algorithm on two industrial robots are shown.

Optimization of trajectory durations based on flow rate scaling for a 4-DoF semi-automated hydraulic rockreaker

In order to increase the overall efficiency of mines as well as improve worker safety, efforts continue to be made toward the automation of various mining operations. Rock breaking, whereby large pieces of ore are broken down into smaller pieces prior to being sent to a jaw crusher, is one such operation. In this paper, a trajectory planning algorithm destined for use in a semi-automated rockbreaker system is described. The algorithm’s development is driven by the objective of minimizing the duration of rockbreaker motions. Paths between initial and final configurations are fully prescribed in the rockbreaker’s task space to allow for the (future) seamless integration of collision detection algorithms. The time parameterization of these paths is then performed using motion profiles that ensure continuity at the acceleration level. Continuous flow rate scaling of the trajectory is applied in order to fully exploit the flow rate capacities of the rockbreaker’s hydraulic pump and proportional valves, resulting in near time-optimal trajectories. The proposed trajectory planning algorithm is shown to lead to significant decreases in trajectory durations compared to other proposed approaches.

Implementation of three-dimensional physical reflective boundary conditions in mesh-free particle methods for continuum fluid dynamics: Validation tests and case studies

Mesh-free particle methods applied to continuum fluid dynamics still use fictitious, ghost or virtual particles, and/or molecular dynamics concepts in the treatment of the boundaries. The aim of this paper is to present the implementation of the physical reflective boundary conditions (RBC), based on Newton’s restitution law and the foundations of analytical geometry, in the treatment of contours in a three-dimensional (3D) domain. In a previous paper [C. A. D. Fraga Filho, “An algorithmic implementation of physical reflective boundary conditions in particle methods: Collision detection and response,” Phys. Fluids 29, 113602 (2017)], RBC validation tests and simulation results were presented for a two-dimensional (2D) domain. The current work presents the validation of the collision detection and response algorithm employed for the RBC and its application in two cases (hydrostatics and hydrodynamics) in a 3D domain. Following an analysis of the simulation results, the applicability of the RBC to 3D continuum fluid dynamic problems is verified. In the hydrostatics case, a still liquid (Newtonian, incompressible, uniform, and isothermal) inside an immobile reservoir is studied. The fluid flow is modeled using an improved Smoothed Particle Hydrodynamics (SPH) formulation utilizing a modified concept of pressure. The simulation results are excellent, showing complete agreement with the analytical solution and the nonmotion of the particles throughout the simulation time. In the hydrodynamics case, 3D dam break flow modeling is carried out using the standard SPH formulation. Results provided by the RBC and standard SPH modeling are compared with the literature data demonstrating good agreement with the experimental findings.

A Robot Gripper With Variable Stiffness Actuation for Enhancing Collision Safety

This article presents the design of a two-finger variable stiffness gripper and demonstrates how the adjustable compliance of the fingers can enhance manipulation safety and robustness during collisions. The compliance between actuators and fingers are generated by using repulsive magnets as preloaded nonlinear springs such that by adjusting the air-gaps between the magnets, the position and stiffness of the fingers can be controlled simultaneously. The capability of the proposed design in collision detection and reaction is demonstrated via two collision scenarios. In the first experiment, a momentum-based collision detection algorithm in the context of compliant grasping is investigated. In the second experiment, an optimal reaction strategy is developed that exploits the adjustable stiffness characteristics of the gripper to improve safety during collisions. The experimental results of the two scenarios indicate the effectiveness of the proposed gripper in enhancing collision safety.

Gesture-based human-robot interface for dual-robot with hybrid sensors

PurposeThe purpose of this paper is the research of a novel gesture-based dual-robot collaborative interaction interface, which achieves the gesture recognition when both hands overlap. This paper designs a hybrid-sensor gesture recognition platform to detect the both-hand data for dual-robot control.Design/methodology/approachThis paper uses a combination of Leap Motion and PrimeSense in the vertical direction, which detects both-hand data in real time. When there is occlusion between hands, each hand is detected by one of the sensors, and a quaternion-based algorithm is used to realize the conversion of two sensors corresponding to different coordinate systems. When there is no occlusion, the data are fused by a self-adaptive weight fusion algorithm. Then the collision detection algorithm is used to detect the collision between robots to ensure safety. Finally, the data are transmitted to the dual robots.FindingsThis interface is implemented on a dual-robot system consisting of two 6-DOF robots. The dual-robot cooperative experiment indicates that the proposed interface is feasible and effective, and it takes less time to operate and has higher interaction efficiency.Originality/valueA novel gesture-based dual-robot collaborative interface is proposed. It overcomes the problem of gesture occlusion in two-hand interaction with low computational complexity and low equipment cost. The proposed interface can perform a long-term stable tracking of the two-hand gestures even if there is occlusion between the hands. Meanwhile, it reduces the number of hand reset to reduce the operation time. The proposed interface achieves a natural and safe interaction between the human and the dual robot.

Hardware-efficient interval analysis based collision detection and avoidance for mobile robots

Collision detection and avoidance is challenging when the mobile robot is moving among multiple dynamic obstacles. A hardware-efficient architecture supporting parallel implementation is presented in this work for low-power, faster and reliable collision-free motion planning. An approach based on interval analysis is developed for designing an efficient hardware architecture. The proposed architecture achieves parallelism which can be combined with any robotic task involving multiple obstacles. Interval arithmetic is used for representing the pose of the robot and the obstacle as velocity intervals in a fixed time period. These intervals correspond to sub-intervals such as arcs and line-segments. In particular, the collision detection problem for dynamic objects involves the computation of line segment-arc intersections and segment-segment intersections. The intersection of these boundary curves is carried out in a hardware-efficient manner so that it avoids complex arithmetic computations such as multiplication, division etc and exploits parallelism. We develop several results on intersection of these sub-intervals for collision detection and use them to obtain a hardware-efficient collision detection algorithm that requires only shift and add-type of computations. The algorithm is further used in developing a hardware-efficient technique for finding an exhaustive set of solutions for avoiding collision of the robot with dynamic obstacles. Simulation results in MatLab and experiments with a Field Programmable Gate Array (FPGA)-based robot show that a variety of collision avoidance techniques can be implemented using the proposed solution set that guarantees collision avoidance with multiple obstacles.

Multi-Scale Flow Field Mapping Method Based on Real-Time Feature Streamlines

Traditional static flow field visualization methods suffer from many problems, such as a lack of continuity expression in the vector field, uneven distribution of seed points, messy visualization, and time-consuming calculations. In response to these problems, this paper proposes a multi-scale mapping method based on real-time feature streamlines. The method uses feature streamlines to solve the problem of continuity expression in flow fields and introduces a streamline tracking algorithm which combines adaptive step length with velocity matching to render feature streamlines in a real-time and multi-scale way. In order to improve the stability and uniformity of the seed point layout, this method uses two different point placement methods which utilize a global regular grid distribution algorithm and feature area random distribution algorithm. In addition, this method uses a collision detection algorithm to detect and deal with the unreasonable covering between streamlines, which alleviates visual confusion in the resulting drawing. This method also uses HTML5 Canvas to render streamlines, which greatly improves the drawing speed. Therefore, use of this method can not only improve the uniformity of the seed point layout and the speed of drawing but also solve the problems of continuity expression in the vector field and messy visualization.

An enhanced sweep and prune algorithm for multi-body continuous collision detection

Multi-body collision detection is a key and important technology in societies of computer graphics, system simulation, virtual reality, etc. and has been widely used in various graphics applications. To deal with the collision detection problem in large-scale multi-body scenes, we in this paper proposed a robust and efficient algorithm based on the kinetic “sweep and prune” technique and the event-driven mechanism. Our algorithm first culls redundant detection calculations in finding object pairs that do not collide in the scene with very large number of moving objects and then automatically generates events to predict the object collisions, which probably take place in near future. All the events are pushed into an optimized priority queue to drive the proposed algorithm. By introducing a hybrid bounding box hierarchy in the event processing process, the algorithm can detect the positions where the object pairs collide. Based on our finding that event blocking is an important factor affecting the robustness of the algorithm, we further propose several techniques to alarm blockings to be occurred or relieve the system from blocking state. Experimental results show that our algorithm has good stability and robustness, and it can improve the operating efficiency of multi-body continuous collision detections in an efficient way.

Coordination of reach-to-grasp in physical and haptic-free virtual environments

BackgroundVirtual reality (VR) offers unprecedented opportunity as a scientific tool to study visuomotor interactions, training, and rehabilitation applications. However, it remains unclear if haptic-free hand-object interactions in a virtual environment (VE) may differ from those performed in the physical environment (PE). We therefore sought to establish if the coordination structure between the transport and grasp components remain similar whether a reach-to-grasp movement is performed in PE and VE.MethodReach-to-grasp kinematics were examined in 13 healthy right-handed young adults. Subjects were instructed to reach-to-grasp-to-lift three differently sized rectangular objects located at three different distances from the starting position. Object size and location were matched between the two environments. Contact with the virtual objects was based on a custom collision detection algorithm. Differences between the environments were evaluated by comparing movement kinematics of the transport and grasp components.ResultsCorrelation coefficients, and the slope of the regression lines, between the reach and grasp components were similar for the two environments. Likewise, the kinematic profiles of the transport velocity and grasp aperture were strongly correlated across the two environments. A rmANOVA further identified some similarities and differences in the movement kinematics between the two environments - most prominently that the closure phase of reach-to-grasp movement was prolonged when movements were performed in VE.ConclusionsReach-to-grasp movement patterns performed in a VE showed both similarities and specific differences compared to those performed in PE. Additionally, we demonstrate a novel approach for parsing the reach-to-grasp movement into three phases- initiation, shaping, closure- based on established kinematic variables, and demonstrate that the differences in performance between the environments are attributed to the closure phase. We discuss this in the context of how collision detection parameters may modify hand-object interactions in VE. Our study shows that haptic-free VE may be a useful platform to study reach-to-grasp movements, with potential implications for haptic-free VR in neurorehabilitation.

A fully Lagrangian meshfree framework for PDEs on evolving surfaces

We propose a novel framework to solve PDEs on moving manifolds, where the evolving surface is represented by a moving point cloud. This has the advantage of avoiding the need to discretize the bulk volume around the surface, while also avoiding the need to have a global mesh. Distortions in the point cloud as a result of the movement are fixed by local adaptation. We first establish a comprehensive Lagrangian framework for arbitrary movement of curves and surfaces given by point clouds. Collision detection algorithms between point cloud surfaces are introduced, which also allow the handling of evolving manifolds with topological changes. We then couple this Lagrangian framework with a meshfree Generalized Finite Difference Method (GFDM) to approximate surface differential operators, which together give a method to solve PDEs on evolving manifolds. The applicability of this method is illustrated with a range of numerical examples, which include advection-diffusion equations with large deformations of the surface, curvature dependent geometric motion, and wave equations on evolving surfaces.

Collision detection Based on OBB Simplified modeling

This paper has analysed the most common algorithm of collision detection based on Oriented Bounding Box(OBB) simplified modeling. After that, in order to improve the efficiency of traditional collision detection algorithm in practical applications, an improved OBB collision detection algorithm is proposed.Moreover, a collision detection algorithm and the double robot coordinated motion model were built by matlab software, at the same time, a trajectory where two robots can collide with each other was built. In addition, the two algorithms were compered by changing the calculation accuracy in robot trajectory planning. Finally, the results show that the algorithm can greatly improve the efficiency of collision detection in dual robot systems.

지능로봇] 6-DOF 메니퓰레이터의 전류 분석을 통한 충돌 감지 알고리즘

본 논문에서는 DC 모터와 다이나믹셀이 혼합 적용된 6-DOF 메니퓰레이터의 제어 및 Joint의 전류 데이터 분석을 통한 충돌 감지 알고리즘을 제안한다. 논문에 사용된 6-DOF 메니퓰레이터는 3차 다항식 형태의 Path planning 와 PD 제어기를 사용하여 제어를 진행하게 되고 이때 발생하게 되는 전류 데이터를 이용하여 Frequency spectrum 분석을 진행하게 된다. 이후 충돌 시 발생하게 되는 임펄스 성격의 전류 데이터를 주파수 대역 및 Amplitude를 바탕으로 기준치 이상일 경우 충돌로 판별한다. 또한 충돌 방향을 도출하기 위해 방위를 표현하는 3축 중 충돌이 발생할 수 없는 z 축을 제외한 x, y 축에 해당하는 Joint1, Joint2의 전류 데이터를 이용하여 충돌 방향을 도출한다. 논문의 실험 및 결론에서는 실제 실험을 통하여 제안된 충돌 감지 알고리즘의 유효성 및 타당성을 검증한다.

Parallel algorithms for simulating interacting carriers in nanocommunication

Diffusion-based molecular communication (DMC) with interacting carrier molecules allows exploring a variety of new communication paradigms. Simulating these interactions on a network scale is however hard from an analytic point of view, and continuous detection of which couples of particles may interact is a computationally expensive task. This work proposes different algorithms that allow detecting which particles are interacting. Hierarchical grid based approaches are explored and designed to maximally exploit the parallelism offered by multiple-graphics processing units (multi-GPU) systems. An implementation of the proposed algorithm is compared to some of our previous work in this domain and to a state-of-the-art collision detection library and nanosimulator. Performance tests indicate a speedup of up to a factor 100 compared to the collision detection algorithm implemented in the nanosimulator, and a factor 77 relative to the collision detection library.

Parameterization of proximal humerus locking plate impingement with in vitro, in silico, and in vivo techniques

Locked plating of displaced proximal humeral fractures is common, but rates of subacromial impingement remain high. This study used a multidisciplinary approach to elucidate the relationships between common surgical parameters, anatomic variability, and the likelihood of plate impingement. The experiment was completed in 3 phases. First, a controlled in vitro experiment was conducted to simulate impingement. Second, a dynamic in silico musculoskeletal model modeled changes to implant geometry, surgical techniques, and acromial anatomy, where a collision detection algorithm was used to simulate impingement. Finally, in vivo shoulder kinematics were recorded for 9 activities of daily living. Motions that created a high likelihood of impingement were identified. Of simulated impingement events, 73.9% occurred when the plate was moved proximally, and 84% occurred when acromial tilt was 20° or 25°. Simulations of impingement occurred at cross-body adduction angles between 10° and 50°. Impingement occurred at an average of 162.0° ± 14.8° abduction with 10 mm distal plate placement, whereas the average was 72.1° ± 11.4° with 10 mm proximal placement. A patient may encounter these shoulder angles when performing activities such as combing one's hair, lifting an object overhead, and reaching behind one's head. Proximal implant placement and decreases in acromial tilt play major roles in the likelihood of impingement, whereas plate thickness and humeral head center of rotation should also be considered. Careful preoperative planning that includes these factors could help guide operative decision making and improve clinical outcomes.

Optimization of the geometric parameters of the EAST articulated maintenance arm (EAMA) with a collision-free workspace determination in EAST

An EAST Articulated Maintenance Arm (EAMA), upgraded based on an articulated inspection arm (AIA), which was successfully operated in Tore Supra in 2008, was developed for the purpose of the inspection and maintenance of damaged internal components during plasma discharges without breaking the East Advanced Superconducting Tokamak (EAST) ultra-high vacuum condition. However, the coupling structure and high redundancy of the EAMA, due to the requirement of coverage ratio and the limitation of the EAST environment, produces a limited accuracy in positioning control. Therefore, the optimal design of the geometric parameters plays a vital role in the EAMA’s performance. In this paper, the main characteristics of the EAMA system are investigated to formulate the optimization into a multi-objective problem. Furthermore, an approach based on the Monte Carlo method, integrated with a dedicated collision detection algorithm in the EAST environment, is elaborated on, which is utilized to calculate the collision-free workspace of the EAMA. With the knowledge of the workspace, the coverage ratio is obtained by a progressive meshing technique. Finally, several groups of geometric parameters are sampled to calculate the corresponding value of the objective functions, and the optimized combination of the geometric parameters is obtained by comparing the results.

Validity of a Microsensor-Based Algorithm for Detecting Scrum Events in Rugby Union.

Commercially available microtechnology devices containing accelerometers, gyroscopes, magnetometers, and global positioning technology have been widely used to quantify the demands of rugby union. This study investigated whether data derived from wearable microsensors can be used to develop an algorithm that automatically detects scrum events in rugby union training and match play. Data were collected from 30 elite rugby players wearing a Catapult OptimEye S5 (Catapult Sports, Melbourne, Australia) microtechnology device during a series of competitive matches (n = 46) and training sessions (n = 51). A total of 97 files were required to "train" an algorithm to automatically detect scrum events using random forest machine learning. A further 310 files from training (n = 167) and match-play (n = 143) sessions were used to validate the algorithm's performance. Across all positions (front row, second row, and back row), the algorithm demonstrated good sensitivity (91%) and specificity (91%) for training and match-play events when the confidence level of the random forest was set to 50%. Generally, the algorithm had better accuracy for match-play events (93.6%) than for training events (87.6%). The scrum algorithm was able to accurately detect scrum events for front-row, second-row, and back-row positions. However, for optimal results, practitioners are advised to use the recommended confidence level for each position to limit false positives. Scrum algorithm detection was better with scrums involving ≥5 players and is therefore unlikely to be suitable for scrums involving 3 players (eg, rugby sevens). Additional contact- and collision-detection algorithms are required to fully quantify rugby union demands.

Research on Path Planning of Substation X-Robot

In this paper, according to the environment of the robot in the substation, firstly, the D-H mathematical modeling of the UR10 manipulator is built and the forward and inverse kinematics of the UR10 manipulator are solved by studying the basic knowledge of the manipulator. Secondly, aiming at the problems existing in the traditional artificial potential field method, the improved artificial potential field method is studied and the principle that the link of the manipulator can not collide with obstacles is studied. The collision detection algorithm is added and the collision detection of cylindrical bounding box is designed. Then according to the starting position of the end of the manipulator and the position of the obstacle, the moving path of the end of the manipulator is determined. Finally, the improved artificial potential field method is used in MATLAB to simulate the moving path of the UR10 manipulator, and field tests are carried out to verify the effectiveness of the improved artificial potential field method and collision detection of cylindrical bounding box in the path planning. These methods can make the robot reach the designated detection position perfectly in the process of walking in the substation and also avoid the collision between the manipulator and the obstacle (substation electrical equipment and building, etc.). The application of X-ray detection equipment in substation becomes more intelligent.

A Physical Layer Algorithm for Estimation of Number of Tags in UHF RFID Anti-Collision Design

A priori knowledge of the number of tags is crucial for anti-collision protocols in slotted UHF RFID systems. The number of tags is used to decide optimal frame length in dynamic frame slotted ALOHA (DFSA) and to adjust access probability in random access protocols. Conventional researches estimate the number of tags in MAC layer based on statistics of empty slots, collided slots and successful slots. Usually, a collision detection algorithm is employed to determine types of time slots. Only three types are distinguished because of lack of ability to detect the number of tags in single time slot. In this paper, a physical layer algorithm is proposed to detect the number of tags in a collided slot. Mean shift algorithm is utilized, and some properties of backscatter signals are investigated. Simulation results verify the effectiveness of the proposed solution in terms of low estimation error with a high SNR range, outperforming the existing MAC layer approaches.

Tool Path Planning Optimization for Multi-Tool Additive Manufacturing

Additive manufacturing (AM) has revolutionized the way industries manufacture and prototype products. A significant drawback that prevents 3D printing from being widely implemented in large-scale production is cycle time. This issue has been improved by allowing multiple collaborating printheads to print different parts of the same object simultaneously. However, little formal research has been done to support the aforementioned approach, and current implementations have room for improvement in terms of both makespan and mechanical properties. A new toolpath optimization methodology is proposed in this research to fill this need. The objectives are to create a collision-free infill toolpath for each printhead while maintaining the mechanical performance and geometric accuracy of the printed object. The methodology utilizes the combination of tabu search and novel collision detection and resolution algorithms, TS-CCR. The performance of the TS-CCR is analyzed and compared with the current industry standard.

A Decision Support System for Managing the Water Space

A novel decision support system comprising of several interference identification algorithms for the detection of hazardous (i.e., risk to life, assets, and/or mission) voyages and water space allocations in maritime operations is proposed. Given a specified spatio-temporal region for each polygonal or ellipsoidal object, the objective is to identify interference, defined as overlap, among the assigned regions. The challenge is to fuse information on bathymetry, obstacles, and planned spatial assignments to identify conflicts among any combination of polygons or ellipses. We briefly review data structures for the representation of spatio-temporal regions computationally, and efficient algorithms for collision detection. Specifically, we propose a two-phase solution approach to interference identification using time-parameterized R-trees, linear programming, and quadratic programming. The proposed interference detection algorithms can detect overlaps among thousands of polygons and elliptic regions. The resulting decision support tool, conflict identification, is part of a larger system for water space planning.