Effective Collision Detection Research Articles

Flexible control and trajectory planning of medical two-arm surgical robot.

This paper introduces the flexible control and trajectory planning medical two-arm surgical robots, and employs effective collision detection methods to ensure the safety and precision during tasks. Firstly, the DH method is employed to establish relative rotation matrices between coordinate systems, determining the relative relationships of each joint link. A neural network based on a multilayer perceptron is proposed to solve FKP problem in real time. Secondly, a universal interpolator based on Non-Uniform Rational B-Splines (NURBS) is developed, capable of handling any geometric shape to ensure smooth and flexible motion trajectories. Finally, we developed a generalized momentum observer to detect external collisions, eliminating the need for external sensors and thereby reducing mechanical complexity and cost. The experiments verify the effectiveness of the kinematics solution and trajectory planning, demonstrating that the improved momentum torque observer can significantly reduce system overshoot, enabling the two-arm surgical robot to perform precise and safe surgical tasks under algorithmic guidance.

Multi-Objective Point Motion Planning for Assembly Robotic Arm Based on IPQ-RRT* Connect Algorithm

Six-axis industrial assembly robotic arms are pivotal in the manufacturing sector, playing a crucial role in the production line. The IPQ-RRT* connect motion planning algorithm for the robotic arm is proposed to improve the assembly process by reducing the time of motion planning and improving the assembly efficiency. The new IPQ-RRT* connect algorithm improves the original PQ-RRT* algorithm applied to UAVs in two dimensions by adding a node-greedy bidirectional scaling strategy. An obstacle detection range is set on the node-greedy bidirectional scaling strategy, in which the existence of obstacles is judged, and different sampling strategies are used according to the judgment results to get rid of obstacles faster, while bidirectional sampling can further improve the operation efficiency of the algorithm. In addition, effective collision detection is realized by combining the hierarchical wraparound box method. Finally, the Bezier curve is utilized to smooth the trajectory of the assembly robotic arm, which improves the trajectory quality while ensuring that the assembly robotic arm does not collide with obstacles. This paper takes the actual assembly process of an intelligent assembly platform as an example and proves the feasibility and effectiveness of the algorithm through simulation experiments and real I5 assembly robotic arm experiments.

Quadrotor UAV: Collision Resilience Behaviors

In this paper, a safety control scheme for quadrotor is proposed to guarantee collision resilience like flying insects. The direction and magnitude of contact wrench are quantitatively analyzed subject to the compliant contact wrench model. A nonlinear disturbance observer (NDO) is developed to estimate the contact wrench imposed on quadrotor, and based on the observer, effective collision detection can be guaranteed. Subsequently, a tilt-torsion decomposition based attitude controller is developed to prioritize the correction of horizontal posture over yaw error. The attitude error is separated into roll-pitch portion and yaw portion. Reasonable roll and pitch torques can be generated by allocating a higher gain for roll-pitch portion, allowing the quadrotor to recover from collisions promptly. Simulation and flight experiments are carried out to demonstrate the effectiveness of the proposed collision resilience control scheme.

An Asymmetric Collision-Free Optimal Trajectory Planning Method for Three DOF Industrial Robotic Arms

To improve the speed and dynamic adaptability of robotic arm trajectory planning, a collision-free optimal trajectory planning method combining non-uniform adaptive time meshing and bounding box collision detection was proposed. First, the dynamics and objective function of the asymmetric industrial robotic arm with three degrees of freedom (DOF) was formulated in the form of the dynamic optimization problem. Second, the control vector parameterization (CVP) was improved to enhance the computational performance of the problem. The discrete grid was adaptively adjusted according the trend of control variables. Then, a quick and effective collision detection strategy was used to avoid obstacles and to speed up calculation efficiency. The non-collision constraint is built by transforming the collision detection into the distance between two points, and then is combined into the dynamic optimization problem. The solution of the new optimization problem with the improved CVP leads to the higher calculation performance and the avoidance of obstacles. Lastly, the Siemens Manutec R3 robotic arm is taken as an example to verify the effectiveness of the planning method. The approach not only reduces computation time but also maintains accurate calculations, so that optimal trajectory can be selected from symmetric paths near the obstacles. When weights were set as λ1 = λ2 = 0.5, the solution efficiency was improved by 33%, and the minimum distance between the robotic arm and obstacle could be 0.08 m, which ensured that there was no collision.

Collision detection for six-DOF serial robots force/position hybrid control based on continuous friction model

In this work, an effective and practical robot collision detection algorithm is proposed, with the aim of addressing the safety problem of industrial robot force/position hybrid control application conditions. First, a robot force/position hybrid control collision detection scheme was designed, and a collision detection model based on dynamics was established. Then, given the problem of large joint friction force identification error caused by the discontinuous joint speed of the robot force control, the continuous friction model was used to identify and address the joint friction problem through the least square method. Finally, experiments were carried out on a light industrial manipulator. According to the different collision directions of the robots during the experiment, a collision detection method was proposed to monitor the torque changes of the position control joints and the force control joints. Experimental results prove that the continuous friction model is more accurate and effective for joint friction compensation than other methods. The proposed method can achieve effective collision detection with force and position control direction thresholds of 8 and 4 N·m, respectively. The practicability and simplicity of the algorithm that can streamline the process of robot collision detection, the simplified model of the collision detection process only detects the torque change in the position control direction, which has a certain engineering reference value.

Collision-aware interactive simulation using graph neural networks

Deep simulations have gained widespread attention owing to their excellent acceleration performances. However, these methods cannot provide effective collision detection and response strategies. We propose a deep interactive physical simulation framework that can effectively address tool-object collisions. The framework can predict the dynamic information by considering the collision state. In particular, the graph neural network is chosen as the base model, and a collision-aware recursive regression module is introduced to update the network parameters recursively using interpenetration distances calculated from the vertex-face and edge-edge tests. Additionally, a novel self-supervised collision term is introduced to provide a more compact collision response. This study extensively evaluates the proposed method and shows that it effectively reduces interpenetration artifacts while ensuring high simulation efficiency.

Ship domain model for ships with restricted manoeuvrability in busy waters

AbstractShip domain is an important theory in ship collision avoidance and an effective collision detection method. First, several classical ship domain models are used in experiments. The results show that the alarm rate is too high in busy waters, leading to greatly reduced practicality of the model. Potential collision risk cannot be detected effectively, especially for a ship with restricted manoeuvrability, which is usually regarded as an overtaken ship due to its navigation characteristics. Therefore, it is necessary to fully consider the interference of other ships to ships with limited manoeuvrability in an encounter situation. A novel ship domain model for ships with restricted manoeuvrability in busy waters is proposed. Considering the navigation characteristics of a ship with restricted manoeuvrability and the influence of the ship–ship effect, an algorithm to determine the boundary of the ship domain model is given by force and moment equations. AIS trajectory data of the North Channel of the Yangtze River Estuary are used to perform a comparative experiment, and four classical ship domain models are employed to perform comparative experiments. The results show that the alarm rates of the novel ship domain model are 7⋅608%, 15⋅131%, 55⋅785% and 7⋅608% lower than those of the other four classical models, and this outcome can effectively reduce the high false alarm rate produced by other models in this environment.

Optimal path planning for automated dimensional inspection of free-form surfaces

Structural dimensional inspection is vital for the process monitoring, quality control, and fault diagnosis in the mass production of auto bodies. Comparing with the non-contact measurement, the high-precision five-axis measuring machine with the touch-trigger probe is a preferred choice for data collection. It can assist manufacturers in making accurate inspection quickly. As the increase of free-form surfaces and diverse surface orientations in product design, existing inspection approaches cannot capture some new critical features in the curvature of products in an efficient way. Therefore, we need to develop new path planning methods for automated dimensional inspection of free-form surfaces. This paper proposes an optimal path planning system for automated programming of measuring point inspection by incorporating probe rotations and effective collision detection. Specifically, the methodological contributions include: (i) a dynamic searching volume-based algorithm is developed to detect potential collisions in the local path between measurement points; (ii) a local path generation method is proposed with the integration of the probe trajectory and the stylus rotation. Then, the inspection time matrix is proposed to quantify the measuring time of diverse local paths; (iii) an optimization approach of the global inspection path for all critical points on the product is developed to minimize the total inspection time. A case study has been conducted on an auto body to verify the performance of the proposed method. Results show that the collision-free path for the free-form auto body could be generated automatically with off-line programming, and the proposed method produces about 40% fewer dummy points and needs 32% less movement time in the auto body inspection process.

Parallel cloth simulation with effective collision detection for interactive AR application

In this paper, we present a parallel cloth simulation with an efficient collision detection algorithm for interactive AR applications. In the first step of the proposed method, a set of sphere colliders is automatically defined for the 3D moving object colliding with a cloth model for the effective collision detection even on low-end devices. In the second step, the collision detection and handling between a set of sphere colliders and a cloth model are performed in parallel. We propose an efficient collision handling method based on a sphere to prevent the penetration of cloth into the object which can be happened due to the low mesh resolution of the cloth model. The proposed method was implemented as a plugin for Unity which is widely used for the real-time game development. Comparative experimental tests with the cloth object basically provided by Unity was performed in order to analyze the performance of the proposed method. As a result, we confirmed that the proposed method can reduce the cumbersome work to manually build colliders on a 3D model, and can effectively express more accurate and plausible behavior of the cloth that collides with the object.

UMan: A Low-Impedance Manipulator for Human–Robot Cooperation Based on Underactuated Redundancy

This paper revisits the concept of underactuated manipulator in order to significantly improve physical human–robot cooperation for the assembly industry. The main focus is to achieve intuitive and minimum effort fine manipulation, regardless of the payload's shape and weight. An underactuated manipulator—referred to as uMan—based on a macro–mini architecture is designed with a novel passive mini mechanism, which aims at minimizing the impedance, eliminating the nonlinear impedance, and decoupling the human and robot dynamics. A specific control strategy is developed to achieve these objectives, while handling the underactuated nature of the robot for cooperative and autonomous assistance. Experimental validations are provided to assess the ease of fine manipulation using a peg-in-hole task to demonstrate the safety of the device using an effective collision detection and to establish the viability of the concept for practical industrial assembly tasks.

The Research and Application of Data Glove in Virtual Interaction System

The virtual reality technology is used in the mine training simulation areas, which can overcome the limitations of traditional training methods effectively. It can also improve the quality of mine training simulation greatly, reduce training costs, and the users can achieve safe and convenient training. In this paper, a dynamic collision detection algorithm is proposed based on the prediction of the movement direction of a virtual hand, and it is the effective collision detection algorithm using data glove in the mine training simulation system. Compared with the traditional static collision detection algorithm in the performance, the dynamic algorithm is proposed to solve the collision detection between one simulation solid model and another one, and to achieve the function that a virtual hand grip and rotate virtual objects in the virtual environment. The dynamic collision detection algorithm can be extended to other simulation systems.

VGIS-COLLIDE: an effective collision detection algorithm for multiple objects in virtual geographic information system

Collision detection is an important component in simulation applications which are based on virtual geographic information system (VGIS). In this paper, an effective collision detection algorithm for multiple objects in VGIS, VGIS-COLLIDE, is presented. The algorithm firstly integrates existing quadtree, which is the global hierarchical structure of VGIS, with axis-aligned bounding box of object to perform the broad-phase of collision detection. After that, exact collision detection between two objects which have passed the broad-phase of collision detection is performed. The algorithm makes no assumption about input primitives or object's motion and is directly applicable to all triangulated models. It can be applicable to both rigid and deformable objects without preprocessing. The performance of the algorithm has been demonstrated in several environments consisting of a high number of objects with hundreds of thousands of triangles.

Cooperative Wireless Medium Access Exploiting Multi-Beam Adaptive Arrays and Relay Selection

Cooperative transmission among wireless network nodes can be exploited to resolve collisions and thereby enhance the network throughput. Incorporation of multi-beam adaptive array (MBAA) at a base station/access point (destination) receiver has been shown to improve the network performance. In this paper, we propose an efficient cooperative wireless medium access scheme that exploits novel relay selection methods in a network equipped with MBAA at the destination receiver. Unlike existing techniques that require the estimation of angles-of-arrival (AoAs), the proposed scheme uses the spatial correlation among users for simpler but more effective collision detection and resolution. We present two useful relay selection methods based on channel gain and spatial correlation. It is shown that the joint use of an effective relay selection method and an MBAA in a wireless network can significantly improve the uplink throughput. The throughput of the proposed scheme and its upper bound are analytically derived. Numerical and simulation results have demonstrated significant performance enhancement achieved by the proposed cooperative wireless medium access scheme.

An approach to time-optimal, smooth and collision-free path planning in a two robot arm environment

SummaryAn approach to time-optimal smooth and collision-free path planning for two industrial robot arms is presented, where path planning and joint trajectory generation are integrated. A suitable objective function, combining the requirements of time optimality and path smoothness, is proposed, which is subject to the continuity of joint trajectories, limits on their rates of change and collision-free constraints. Fast and effective collision detection for the arms is achieved using the Kuhn- Tucker conditions along with the convexity of the distance function and relying on geometrical relationships between cylinders. Nonlinear optimization is used to solve this path planning problem. The feasibility of this method is illustrated both by simulation and by experimental results.