Linear servomotors (LSM) are widely used in industries. A LSM requires a mover positioning tool for precise control. A Vision-based digital image grating (DIG) measurement for LSM mover positioning ...is proposed in this study with advantages of simple system, low cost, and good robustness to environments. It estimates the LSM's rough position according to four mark-lines and obtains accurate LSM's positions by a fast least-square (FLS) image-matching algorithm. As a result, it can measure the LSM's position accurately in a wide range. The FLS proposed here represents the least-square cost function by the transformation parameters explicitly, and then calculates the parameters directly. Therefore, the image resampling process, which is inevitable for the existing least-square methods is not necessary. Simulations prove that the FLS is approximately 4.4 times faster than the classic inverse compositional Gauss-Newton (IC-GN) algorithm, and that the FLS is more accurate and robust than the IC-GN. Experiments show that the proposed DIG method can measure the LSM mover positions with an accuracy of 0.75 μ m mean absolute error.
This research article discusses the active pitching technique for the H-Type Darrieus turbine and its importance for the turbine's self-starting and enhanced power coefficient. The pitch of the ...turbine blades is changed at various points while the turbine is whirling using the servomotor pitching control system. The performance of the turbine is enhanced by the present blade pitching method. The current analytical analysis made use of the DMST (Double Multiple Stream Tube) model. Parametric study is done to create a turbine design suitable for pre-fabrication. Currently, a turbine with a servomotor is being employed in the research. The paper's conclusion is that the current pitching schedule can increase initial torque to initiate starting of the turbine and improve efficiency of turbine in terms of power coefficient up to 45% for operating tip speed ratio, 0 = 2.5 at wind velocity of 10 m/s.
•Industrial robot's servomotor bearing fault detection is presented.•Simple motion and welding motion of industrial robots is considered.•Currents signals of servomotor are converted to scalogram ...images for analysis.•Transfer learning expunged model training from scratch and streamlined operation.
In consequence of their superior performance and durability, industrial robots have enjoyed widespread adoption across a variety of industries. However, despite their sturdy build, they are susceptible to malfunction. The servomotor is a fundamental component of industrial robots, and to ensure smooth and uninterrupted functioning, it is essential to detect any defects it may develop. Although research has addressed methods for detecting bearing failure, diagnosis of a servomotor bearing failure in the industrial robot remains difficult and requires intensive research. In this paper, a novel method for detecting servomotor bearing defects in the industrial robot is provided by integrating knowledge transfer via transfer learning. Initially, current signals of the servomotor are transformed to scalogram images. This processed data is utilized to build the model for fault detection. Applying transfer learning eliminates model training from scratch and streamlined operations. The purported approach shows an average accuracy of more than 99 %.
Abstract
The engine is one of the key core components in aircraft, in order to enhance automation and efficiency in the process of installation and disassembly for current small engine, using ...automatic control technology, a set of automatic disassembly and assembly system for aircraft engines is developed to replace the traditional mechanical installation vehicle. Corresponding for small engine to study the automatic disassembly system, the system uses laser sensors to locate the engine disassembly and assembly. Servo motors are used to drive the walking mechanism, lifting mechanism, and fine-tuning mechanism to realize multi-degree-of-freedom adjustment during engine disassembly and assembly. And the digital video is used to monitor the gap collision. Finally, the paper realizes the automatic high-precision disassembly and assembly of small engines. Through verification, the efficiency of the disassembly and assembly system has increased by more than 70%, the work efficiency has been greatly improved.
We present a computation-driven approach to design optimization and motion synthesis for robotic creatures that locomote using arbitrary arrangements of legs and wheels. Through an intuitive ...interface, designers first create unique robots by combining different types of servomotors, 3D printable connectors, wheels and feet in a mix-and-match manner. With the resulting robot as input, a novel trajectory optimization formulation generates walking, rolling, gliding and skating motions. These motions emerge naturally based on the components used to design each individual robot. We exploit the particular structure of our formulation and make targeted simplifications to significantly accelerate the underlying numerical solver without compromising quality. This allows designers to interactively choreograph stable, physically-valid motions that are agile and compelling. We furthermore develop a suite of user-guided, semi-automatic, and fully-automatic optimization tools that enable motion-aware edits of the robot's physical structure. We demonstrate the efficacy of our design methodology by creating a diverse array of hybrid legged/wheeled mobile robots which we validate using physics simulation and through fabricated prototypes.
This paper considers real-time energy-optimal trajectory generation for a servomotor system that performs a single-axis point-to-point positioning task for a fixed time interval. The servomotor ...system is subject to acceleration and speed constraints. The trajectory generation is formulated as a linear-constrained optimal control problem (LCOCP), and the Pontryagin's maximum principle is applied to derive necessary optimality conditions. Instead of solving multipoint boundary value problems directly, this paper proposes a novel real-time algorithm based on two realizations: solving the LCOCP is equivalent to determining an optimal time interval of the speed-constrained arc and solving a specific acceleration-constrained optimal control problem (ACOCP), and solving an ACOCP is equivalent to determining optimal switch times of acceleration-constrained arcs and solving a specific two-point boundary value problem (TBVP). The proposed algorithm constructs sequences of time intervals, ACOCPs, switch times, and TBVPs, such that all sequences converge to their counterparts of an optimal solution of the LCOCP. Numerical simulation verifies that the proposed algorithm is capable of generating energy-optimal trajectories in real time. Experiments validate that the use of energy-optimal trajectories as references in a servomotor system does not compromise tracking performance but leads to considerable less energy consumption.
In order to monitor the abnormal condition that the zero point of the encoder does not coincide with the actual mechanical zero position in the full-closed control loop of a rotating axis, a Siemens ...840D numerical control system based on abnormal condition inspection method is proposed. According to the gathered data by the measurement system of a rotating axis servo motor, the logical comparison program in PLC (Programmable Logic Controller) is developed to monitor the zero point of rotating axis by using Siemens 840D numerical control system and STEP7 software platform. The verification experiment results show that the proposed method can quickly identify the abnormal displacement of the zero point for a rotating axis and disable the servo motor in time, which can effectively avoid the poor quality problem caused by the abnormal condition in rotating axis.
Analysis of a tree ring is the primary method for determining the growth and age of a tree. In a microdestructive tree-ring measurement system, the tree under test is drilled with a microdrill at a ...constant rotating speed to detect the difference in density between the early and late wood, thereby realizing a microdestructive measurement of the tree-ring. The measurement system comprises a microdrill with a diameter of 3 mm, mechanical transmission, direct current (DC) servomotor, stepper motor, and control and detection circuit. The DC servomotor and stepper motor realize rotation and translation of the microdrill, respectively, through mechanical transmission. When the microdrill rotates and drills into the tree, the control and detection circuit samples and acquires the armature current of the DC servomotor, which is proportional to the resistance encountered by the drill bit and reflects the change in the density of the tree. The tree-ring number can be obtained by filtering the sampled original signals of the armature current using a finite impulse response (FIR) filtering algorithm. The annual rings of larch and fir tree discs were measured and tested using the designed system. It was observed that the average annual ring measurement accuracy of the larch discs reached 95.28%, while that of the fir discs was 84.16%. The diameter of the drill hole in the trunk was less than 3 mm after measuring the living wood, thereby achieving a microdestructive measurement of the tree-ring.
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•We give a dynamic pressure calibration device based on servomotor and pistonphone.•New membrane-sealing and multi-leaf-spring structures are adopted in the device.•A kinematics and ...dynamics-based model is built to finalize the driving system.•We verified the device capacity both in theoretical and experimental ways.
The demand for low-frequency low-pressure measurements promotes continuous improvement of the dynamic pressure calibration device. This paper proposes an improved calibration device based on the low-speed servomotor and the pistonphone technique. Specifically, a new membrane-sealing structure between the piston and chamber is developed to substitute the traditional slit-sealing structure, so that the severe pressure leakage loss and friction are avoided. Secondly, a multi-leaf-spring supporting structure is adopted in the servomotor and crank link driving system, which avoided the high cost of using vibrator excitation and in the meanwhile, alleviate the radial bounce of piston. To help finalize the driving system, a theoretical model based on the kinematic and dynamic analysis is built. Finally, a prototype is built to conduct basic performance tests and primary sensor calibrations. The proposed technical and theoretical solutions can be extended to wider frequency and pressure ranges, rather than the given prototype in this paper.
Centrifugal microfluidics has been widely applied in the sample-in–answer-out systems for the analyses of nucleic acids, proteins, and small molecules. However, the inherent characteristic of ...unidirectional fluid propulsion limits the flexibility of these fluidic chips. Providing an extra degree of freedom to allow the unconstrained and reversible pumping of liquid is an effective strategy to address this limitation. In this study, a wirelessly charged centrifugal microfluidic platform with two rotation axes has been constructed and the flow control strategy in such platform with two degrees of freedom was comprehensively studied for the first time. Inductively coupled coils are installed on the platform to achieve wireless power transfer to the spinning stage. A micro servo motor is mounted on both sides of the stage to alter the orientation of the device around a secondary rotation axis on demand during stage rotation. The basic liquid operations on this platform, including directional transport of liquid, valving, metering, and mixing, are comprehensively studied and realized. Finally, a chip for the simultaneous determination of hexavalent chromium Cr(VI) and methanal in water samples is designed and tested based on the strategy presented in this paper, demonstrating the potential use of this platform for on-site environmental monitoring, food safety testing, and other life science applications.
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