Time-Optimization of Trajectories Using Zero-Clamped Cubic Splines and Their Analytical Gradients

Planning smooth trajectories through a sequence of waypoints under nonconvex constraints is challenging due to the coupling between coefficient optimization and time allocation. Existing gradient-based spline trajectory optimization methods tend to be susceptible to local minima and poor initializations, or restrained by complicated gradient computations. We propose a sampling augmented bilevel optimization (SABO) approach that integrates gradient-based optimization with correlated spatio-temporal sampling for improved robustness and optimality. Through temporal normalization, the closed-form solution of coefficient optimization becomes an explicit function of segment durations, while the Hessian becomes linear in their powers, enabling analytic bilevel gradient computation without using finite differences or linearized constraints. Correlated mutations are subsequently performed around the gradient-induced solution to further explore the constrained spatio-temporal space, with sample projection and covariance matrix adaptation to guide sampling towards low-cost, feasible regions. Simulations show that SABO outperforms existing methods in terms of optimality and robustness. We validate SABO in flight experiments conducted on a quadrotor.

As full automation is often not achievable in flexible production, collaborative robot systems offer potential for an increase in productivity for manual systems. These systems however pose great challenges concerning planning and engineering. We define main requirements for industrial human robot collaboration simulation. It is found that current simulation systems in research and industry cannot sufficiently support the digital planning of such systems. We introduce a framework for a human-in-the-loop system capable of simulation and virtual commissioning of industrial collaborative robot systems. For this, we implement a combined virtual reality, motion capturing and object tracking architecture into an industry standard robot simulation software. We validate our system on real use cases from power electronics production implementing real safety controllers and evaluate the fulfillment of the defined requirements.

The ROSA (Robotic Surgical Assistant) Knee system (Zimmer Biomet, Warsaw, IN) for total knee arthroplasty (TKA) can be considered as collaborative robotics, where the surgeon remains in charge of the procedure and collaborates with a smart robotic tool, to perform the surgery with a high accuracy and reproducibility. The aim was to describe: (1) its concept and surgical technique; (2) its advantages and potential limits; (3) the early experience with this system. The goal during its development phase was to keep the surgeon active and at the center of the operation: the surgeon handles the saw and performs the cuts while the robotic arm places and holds the guide at the right place. The ROSA knee platform assists the surgeon for the distal femoral cut, the femoral component sizing and positioning, the tibial cut and the ligament balance. This robotic system has two options: image-based with 3D virtual model; or image-less, based on intraoperative landmarks acquisition. All the classic surgical techniques can be used: measured resection, gap balancing, functional alignment, kinematic alignment. Some techniques recently developed are more ROSA-specific: Robotic personalized TKA, ROSA-FuZion technique. Its advantages as compared to other available systems include: radiographs in standing position, collaborative robotic system where the robot completes the surgeon skills, "off-the-shelf" implants, predictive robotic with concept of machine learning incorporated into the system. Two cadaveric studies have reported the high accuracy and reproducibility of this device. This robotic system is recent and currently no clinical series has enough follow-up to report clinical outcomes. The ROSA knee system is a robotically assisted semi-autonomous surgical system with some specific characteristics. The aim of this collaborative robotic system is to improve the accuracy and reliability of the bone resections and the ligament balancing, without replacing the steps well performed by the surgeon.

Robotics in Simulated COVID-19 Patient Room for Health Care Worker Effector Tasks: Preliminary, Feasibility Experiments

Аннотация. В работе сформирован ряд предложений по совершенствованию разработанного алгоритма для распределения работ в коллаборативной робототехнической системе (КРТС) и назначения участников КРТС на выполнение операций технологического процесса. Реализован учет пространственной модели рабочего пространства (размещения рабочих мест), изменения объекта воздействия (изделия) и использования дополнительных ресурсов, случайного поведения и ошибок людей, накопления усталости и снижения эффективности их работы со временем, а также динамического переназначения участников КРТС на выполнение операции в случае внезапного выхода из строя кобота или потери трудоспособности человеком. Также предложен модифицированный алгоритм минимизации целевой функции (решения оптимизационной задачи) на этапе подбора состава и назначения исполнителей на выполнение операции, учитывающий значения эффективности доступных участников КРТС и минимизирующий их состав.

The use of collaborative robots in the industrial domain has significantly grown in the last years, allowing humans to operate in the same workspace occupied by robots without any physical barriers. Understandably, the safety of the human operator has been a major concern both for researchers and regulatory bodies. The power and force limited modality of robots is of particular interest in that sense, being used in order to bound the energy of eventual collisions when a close physical interaction with humans is necessary. Such an interaction modality allows the robotic system to operate without the use of barriers, but a measurement of the force and pressure occurring due to a contact must be provided as part of the risk assessment. However, the precise procedure to follow in order to reliably provide such measures is still unclear for users and system integrators willing to self-assess the safety of their own collaborative robotic system. In this work, the repeatability and reliability of such testing procedures and measures are analyzed with an interlaboratory comparison approach, with the aim to establish the degree of variability possibly encountered when performing the same test under slightly different conditions.

Problem-Solving Skill Development in Learning Factories Through Collaborative Robotic Systems

Mobile manipulator is a robot for the next generation of processes. The mobile manipulator can increase process efficiency by being combined with the collaborative robot system. However, due to worker safety issues, simultaneous control of the mobile manipulator is still difficult. In this paper, we present the designing path of collision avoidance of a mobile manipulator for the safety of workers. By monitoring the position and velocity of a worker modeled as a cylinder, the mobile manipulator designs a path to avoid the worker using reinforcement learning. We learned the robot using simulation, and we checked the mobile and manipulator move to the destination by avoiding the worker.

The development of the notion of virtual fixture originated the broader concept of robot haptic guidance, meaning a recent technology to support motor learning. It has been applied in many areas, namely on automotive assembly, medical rehabilitation and training of healthy people. The implementation of virtual fixtures depends on the robot mechanical and drive system, namely the type of actuators and transmissions. If non-backdriven transmissions are used the operator controls the robot through the forces he / she exerts on the robot handle (which are measured by a force transducer incorporated at the robot end-effector). These robots usually use motors with large reduction ratios and are admittance controlled. In this paper we implement haptic guidance in an impedance type three degree-of-freedom (dof) heavy robot. An admittance low-level controller is firstly designed based on an IP (Integral, Proportional) velocity controller. Two types of virtual fixtures are implemented and the effectiveness of the proposed approach is illustrated experimentally.KeywordsCollaborative robotic systemvirtual fixturesadmittance control

The aim of this paper is to develop a robotic system which can navigate in an indoor environment and charge several electrical devices. Several algorithms such as Travel Salesman Problem, Probabilistic Roadmap and Fuzzy C-means Clustering are used for development of such a system. The testbed is constructed by Arduino Uno, Arduino WIFI Shield, Go-between Shield by Mayhew Lab and Polulu Zumo robot for Arduino Ver.1.2. All the algorithms are coded by MathWorks MATLAB and Simulink. The core of the wireless charging robot is to optimize the best performance for single robot to charge multiple devices. Owing to the computation restriction of the mobile robot, the calculation will be done on remote server and communicate with the robot through Wi-Fi connection. By this, the computation load on mobile robot can be reduced as well as improving the efficiency. A real-time feedback system is also built to promote accuracy in actual environment. After the development of improved stability and flexibility, the robot can be brought to real life as an interactive and collaborative robotic system.

Pursuit eye movements correlate with perceived motion in both velocity and direction, even without retinal motion. Cortical cells in the monkey medial temporal region generate signals for initiating pursuit eye movements and respond to retinal motion for perception. However, recent studies suggest multiple motion processes, fast and slow, even for low-level motion. Here we investigated whether the relationship with pursuit eye movements is different for fast and slow motion processes, using a motion aftereffect technique with superimposed low- and high-spatial-frequency gratings. A previous study showed that the low- and high-spatial-frequency gratings adapt the fast and slow motion processes, respectively, and that a static test probes the slow motion process and a flicker test probes the fast motion process (Shioiri & Matsumiya, 2009). In the present study, an adaptation stimulus was composed of two gratings with different spatial frequencies and orientations but the same temporal frequency, moving in the orthogonal direction of ±45° from the vertical. We measured the directions of perceived motion and pursuit eye movements to a test stimulus presented after motion adaptation with changing relative contrasts of the two adapting gratings. Pursuit eye movements were observed in the same direction as that of the motion aftereffects, independent of the relative contrasts of the two adapting gratings, for both the static and flicker tests. These results suggest that pursuit eye movements and perception share motion signals in both slow and fast motion processes.

In this paper, we develop a novel path-constrained and collision-free optimal trajectory planning algorithm for robot manipulators in the presence of obstacles for the following problem: Given a desired sequence of discrete waypoints of robot configurations, a set of robot kinematic and dynamic constraints, and a set of obstacles, determine a time and jerk optimal and collision-free trajectory for the robot passing through the given waypoints with constant speed. Our approach in developing the robot path through the waypoints relies on the orthogonal collocation method where the states are represented with Legendre polynomials in the Barycentric form; the transcription process efficiently converts the continuous-time formulation of the optimal control problem (both time and jerk optimal) into a discrete non-linear program. In addition, we provide an efficient method for avoiding robot self-collisions (of joints and links) and collisions with workspace obstacles by modeling them as the union of spheres and cylinders in the workspace. The resulting collision free optimal trajectory provides smooth and constrained motion for the robot passing through all the waypoints in the given prescribed sequence. The proposed method is validated using numerical simulations and experiments on a six degree-of-freedom robot.

Drum corps color guard experts spend years developing skills in spinning rifles, sabers, and flags. Their expertise provides a unique window into factors that govern sensitivity to the speed of rotational and radial motion. Prior neurophysiological research demonstrates that rotational and radial motion register in the Medial Superior Temporal (MST) region of the primate visual system. To the extent that shared neural events govern rotational and radial speed sensitivity, one would expect expertise on either task to transfer to the other. One similarly would expect shared neural events to generate correlations between rotational and radial speed sensitivity. We evaluated these predictions via visual speed sensitivity tests on drum corps color guard experts, drum corps low brass experts, and other age-matched control participants. Displays comprised bilaterally presented plaid patterns that rotated, radiated, or both. Participants reported which side contained faster motion. The data revealed a modest but reliably reproducible and specific group-by-task interaction; color guard speed sensitivity exhibited a rotational motion advantage and radial motion disadvantage. Additionally, rotational and radial speed sensitivity failed to predict each other significantly. Overall, the findings match predictions that follow from a dissociation between the neural events governing rotational and radial speed sensitivity.

A promising direction in the development of robotics is collaborative robotics under control of artificial intelligence systems. Such socio-cyber-physical systems are able to provide a synergistic effect in implementation of weakly determined technological processes. Nevertheless, there is a low degree of efficiency of known methods for integrating human factor models within robotic process` digital twin, as well as the lack of unified methodologies for developing models themselves that describe human condition and its impact on technological process key indicators. As part of the study, the tasks of forming theoretical foundations, methodologies and applied implementations aimed at increasing attractiveness of collaborative solutions for industrial enterprises are set. The result is achieved by improving quality and degree of integration of human factors models into robotic process` digital twins. An idea is proposed that consists in building a socio-cyber-physical system based on cobot models and a human factor model in context of "subject-subject" interaction, which will allow delegating more management functions to the ICS and provide greater flexibility for intelligent process control and an increased degree of robustness to an unfavorable state manifestation person. A conceptual model of the human factor and a prototype model of interaction between robot and operator are proposed. The mathematical model will allow taking into account toperator current state when designing a response to a disturbance, maintaining the high-level quality of collaborative production process. Software architecture elements and procedure for organizing the modes of operation of the ICS are presented.

This paper proposes a novel force-sensor-less contact motion control for quick and smooth industrial robot motion. Industrial robots serve important functions in modern industrial society. However, their general application is limited because they employ only position based high-stiffness control methods. The proposed method achieves smooth contact motion for new applications of industrial robots, and it solves two of the problems of contact motion control. First, impulsive force is reduced through active braking motion control. Second, wasted motion is decreased by applying integral-proportional(I-P) force control after contact. Experimental results show the validity of the proposed method with a three-degree-of-freedom(DOF) robot. The proposed method achieves a 78.7% decrease in settling time and a 6% reduction in impulsive force. The proposed method has the potential to improve fast contact motion through a profile control application.