Actuator Coordination Research Articles

Performance Analysis of Object Placement Systems Based on Siemens S7-1200 its’ Evaluation of Effectiveness and Accuracy

The evolution of industrial automation systems has led to innovative solutions for efficient and precise object manipulation. This study introduces a groundbreaking "Object Placement System Based on Siemens S7-1200," designed to enhance object positioning tasks in manufacturing environments. The system's core control unit is the Siemens S7-1200 Programmable Logic Controller (PLC), seamlessly integrated with a network of sensors and actuators for coordinated operations. Operators can easily define target positions and parameters for object placement through a user-friendly human-machine interface. The PLC facilitates real-time data exchange with sensors, enabling accurate object detection and adjustments during placement. The system's implementation involves meticulous PLC programming, sensor integration, and interface design. Experimental results validate its capability to achieve precise and repeatable object placements. The Siemens S7-1200 is a versatile PLC supporting controlled positioning of electrically driven axes and technology objects, tailored for small automation systems requiring simple or advanced Human-Machine Interface (HMI and communication capabilities. The object placement system leverages the capabilities of the S7-1200 PLC for integrated sensor and actuator coordination, ensuring accuracy and repeatability. The study concludes that the innovative system utilizing the Siemens S7-1200 PLC underscores its potential for optimizing production processes and enhancing operational efficiency in industrial automation systems. The demonstrated ability to achieve precise and repeatable object placements highlights the viability of the Siemens S7-1200 platform for advancing object manipulation in industrial settings. The S7-1200 system manual provides specific information about the operation and programming of the PLC. Additionally, the system is supported by the TIA Portal programming software, which offers flexibility and ease of use.

Design of routing protocol for enhancing quality of service in wireless ad hoc and sensor netw ork: LEQA

<p>Wireless sensor networks (WSNs) are now adopting mobile sensors due to their increased popularity in research and industry. To enhance WSNs' performance, mobility can be utilized to gather data. But, if the collector's route is fixed and movement is not manageable, current quality of service (QoS) strategies and protocols are ineffective in achieving timely data delivery while maintaining energy efficiency. In the real world, WSN networks use both actuator - actuator and sensor - actuator coordination. To conserve energy in communicati on tasks with heavy traffic and high volume, sensors/actuators can be relocated to desired locations. This study introduces a routing protocol that optimizes delivery latency and energy conservation in WSNs. The proposed latency, energy, and quality of ser vice aware (LEQA) protocol uses a cooperative approach to track the sink and coordinate communication between sensors and actuators. Each sensor schedules its time division multiple access (TDMA) to improve QoS metrics such as low energy consumption, low l atency, or packet loss. It also addresses sensor - actuator coordination and proposes a data communication protocol for efficient and fast communication with actuator nodes. This reduces energy consumption and minimizes latency.</p>

Omnidirectional compliance on cross-linked actuator coordination enables simultaneous multi-functions of soft modular robots

Earthworms have entirely soft bodies mainly composed of circular and longitudinal muscle bundles but can handle the complexity of unstructured environments with exceptional multifunctionality. Soft robots are naturally appropriate for mimicking soft animal structures thanks to their inherent compliance. Here, we explore the new possibility of using this compliance to coordinate the actuation movements of single-type soft actuators for not only high adaptability but the simultaneous multifunctionality of soft robots. A cross-linked actuator coordination mechanism is proposed and explained with a novel conceptual design of a cross-linked network, characterization of modular coordinated kinematics, and a modular control strategy for multiple functions. We model and analyze the motion patterns for these functions, including grabbing, manipulation, and locomotion. This further enables the combination of simultaneous multi-functions with this very simple actuator network structure. In this way, a soft modular robot is developed with demonstrations of a novel continuous-transportation mode, for which multiple objects could be simultaneously transported in unstructured environments with either mobile manipulation or pick-and-place operation. A comprehensive workflow is presented to elaborate the cross-linked actuator coordination concept, analytical modeling, modular control strategy, experimental validation, and multi-functional applications. Our understanding of actuator coordination inspires new soft robotic designs for wider robotic applications.

Adaptive auction protocol for task assignment in wireless sensor and actuator networks

The development of wireless sensor and actuator network is leading to high complexity networks and subsequently, new challenges in task assignment for effective sensor–actuator coordination. This article proposes an adaptive auction protocol for task assignment in multi-hop wireless actuator networks, considering a scenario where all actuators are immobile and each of them can obtain the target information from sensors. Unlike existing methods that neglect the adaptive auction area required by dynamic networks, the proposed method uses an adaptive factor [Formula: see text] (reflects the adaptive auction area) that is deduced based on the relation between network characteristics and protocol performance. Simulation results show that the adaptive protocol can dynamically change the auction area during the network operation. In addition, comparison with existing methods, such as simple auction protocol, 1 hop simple auction aggregation protocol, and 1 hop simple auction aggregation protocol greedy extension, shows that the adaptive auction protocol can choose the optimal solution at a low communication cost with a high probability, irrespective of the changes in the network.

Computationally Efficient Nonlinear One- and Two-Track Models for Multitrailer Road Vehicles

This paper presents nonlinear mathematical models of one- and two-track multitrailer vehicles. We derive nonlinear equations of motion in the form of a system of implicit ordinary differential equations (ODEs) by using Lagrangian mechanics. The system of ODEs has the minimum number of states and equations that enables efficient computations yet maintains the most important nonlinear vehicle dynamic behavior and allows actuator coordination and energy consumption evaluation. As examples, we build different models of a 4-unit long combination vehicle, i.e., two-track 11-axle and single-track 6-axle nonlinear models as well as a linear single-track 6-axle model. We compare the performance of these models to experimental data of different driving maneuvers. The nonlinear single-track model demonstrates close dynamic behavior to the experiment, which makes it an efficient alternative to the two-track model. The vehicle equations can be generated automatically by using the code provided in this paper and subsequently used for conducting frequency analysis, evaluating energy consumption, deriving performance measures from simulations, and facilitating optimal control applications that involve combined steering, braking and propulsion control.

Robust Precision Manipulation With Simple Process Models Using Visual Servoing Techniques With Disturbance Rejection

This paper presents a high-performance vision-based precision manipulation technique that does not rely on an object, contact, or gripper model, which are challenging and often times impractical to acquire. Instead, we utilize a simple process model that roughly maps object velocities to actuator velocities, and we maintain system efficiency and robustness via advanced vision-based control techniques with disturbance rejection mechanisms. For obtaining simple models, we derive a set of actuator coordination rules for achieving common task space motions. The performance degradation due to modeling inaccuracies is then minimized via the model predictive control framework and a correction matrix method. Our experimental results show that the proposed strategy results in high-performance precision manipulation with minimal modeling effort. Note to Practitioners —Compliant, soft robotic grippers make it easier to grasp objects with various shapes and sizes; these grippers adapt to the shape of the object, which provides robustness to positioning errors and often removes the necessity to precisely plan the contact locations. These advantages make compliant grippers ideal to use in industrial settings as well as in service robotics, where the variety of object shapes and sizes are immense. On the other hand, for the tasks that require precise object manipulation (e.g., for a peg-in-hole problem), these hands are more challenging to control than their rigid counterparts: it is harder to obtain their precise models, and they often do not have enough proprioceptive sensors to calculate the full pose of the system. In this paper, we propose solutions to utilize vision feedback for positioning an object using compliant hands. These solutions do not rely on precise models of the gripper or the full knowledge of the gripper state. We adopt various control techniques to provide precise positioning in steady state as well as to maintain efficiency in the transient.

Estimation of the instantaneous centre of rotation with nonholonomic omnidirectional mobile robots

In order to move safely and accurately, mobile platforms using steerable wheels require adequate coordination of their actuators. One possibility to achieve actuator coordination is to control the motion of the chassis’ instantaneous centre of rotation (ICR) and motion around it. Considering the chassis as a rigid body, the ICR is located at the intersection of each wheel’s zero motion axis. In practice however, these axes may not concur, in particular when compliant actuators are used for wheel steering. They then no more define precisely an ICR and only an estimation of its position can be computed. Moreover, most parametrizations of the ICR position bring in singularities with no physical meaning, which hinder estimation. This paper introduces the H representation, a new parametrization of the motion state space free of any non-structural singularities, and presents an algorithm which estimates the ICR within the joint space. The proposed approach is compared in terms of reliability, efficiency, accuracy and robustness with three methods working within the operational space. Results suggest that the proposed estimation approach provides the best compromise for these performance indicators.

Two-Degree-of-Freedom Control of a Two-Link Manipulator in the Rotating Coordinate System

As applications and tasks of robotic manipulators become more diverse and complicated, the desired motions of the robots also become more sophisticated and complicated. In spite of this diversity of tasks, the coordinate system to describe the tasks has not been changed much; the conventional Cartesian coordinate system is still the most widely used coordinate system. It is found in this paper that the rotating coordinate system significantly simplifies the kinematics of a two-link robotic manipulator with the biarticular actuation coordination, which is inspired from human muscles that can generate torques at adjoining two joints simultaneously. Taking the advantage of this simple kinematic relationship by the rotating coordinate system and the biarticular actuator coordination, the dynamics of the two-link manipulator is analyzed, and a disturbance observer (DOB) is designed based on the derived dynamics to nominalize the actual dynamics and to reject undesired disturbances. The proposed DOB-based control algorithm can achieve better control performance in the rotating coordinate system, and comparative experiments verify the effectiveness of the proposed coordinate system and control methods.

Coordination in wireless sensor–actuator networks: A survey

Wireless Sensor–Actuator Networks (WSANs) have a myriad of applications, ranging from pacifying bulls to controlling light intensity in homes automatically. An important aspect of WSANs is coordination. Unlike conventional Wireless Sensor Networks (WSNs), sensor and actuator nodes must work hand-in-hand to collect and forward data, and act on any sensed data collaboratively, promptly and reliably. To this end, this paper reviews current state-of-the-art techniques that address this fundamental problem. More specifically, we review techniques in the following areas: (i) sensor–actuator coordination, (ii) routing protocols, (iii) transport protocols, and (iv) actuator-to-actuator coordination protocols. We provide an extensive qualitative comparison of their key features, advantages and disadvantages. Finally, we present unresolved problems and future research directions.

Digital Control of Interferometric Metrology Lines

A recent paper presented principles and digital control of Fabry-Perot interferometers, showing some ongoing and potential applications in the field of precision engineering. Among these, metrology lines were mentioned, the aim being to reveal sub-nanometric displacements in view of dimensional stabilization/monitoring of demanding space telescopes. The core is a confocal optical cavity, in vacuum, whose light path is sensitive to supporting structure length variations. The latter are tracked and revealed by a frequency actuator which acting on the incident light keeps the interferometer signal (the tracking error) centered to zero although the optical path varies. Concept and digital control of metrology lines are outlined and some experimental results from an on-ground breadboard are discussed. Due to on-ground and test contingencies, a displacement actuator (piezo-electric ceramics) was also active on the cavity, which required actuator coordination. Digital control was designed around a stylized model of plant and disturbance, called the Embedded Model, to be included in the control unit. Control algorithms and code are derived from the model; control gains either derive from the model or from closed-loop eigenvalues. No performance optimization is sought, but requirements are met and stability/performance is guaranteed in the presence of neglected dynamics and actuator/sensor constraints.