Motion Transmission Mechanism Research Articles

A low-cost underactuated compliant gripper with multifunctional jaws for precision manipulation

Precision manipulation tasks often require the use of compliant grippers to handle small and delicate objects accurately. This paper proposes a novel low-cost underactuated compliant gripper with integrated position and force sensors for precision manipulation. The gripper has a millimeter-scale grasping range and can adapt to objects of varying sizes and shapes. This is made possible by a flexure motion transmission mechanism that can undergo significant deformation, an underactuated seesaw flexure mechanism, and a pair of multifunctional jaws. Analytical models based on the pseudo-rigid-body approach are developed to analyze the kinematic, static, and dynamic characteristics of the gripper design. Finite element simulations are conducted to investigate the static and dynamic performance of the gripper. The gripper prototype is fabricated using 3D printing technology for a series of experimental tests. The results of these experiments demonstrate that the developed gripper has excellent motion tracking capabilities and high motion and force resolutions, enabling precise and accurate manipulation tasks. Furthermore, the gripper is capable of successfully grasping objects of different sizes and shapes through parallel and enveloping grasps.

Parameters of the straw separator elevator

The purpose of the research is to substantiate the parameters of the straw separator elevator. The scheme of the straw separator and its principle of operation are given. The proposed straw separator consists of elevators, a web, a shaker, a motion transmission mechanism, a sewing machine, a support and an electric motor. The results of experimental studies to determine the effect of the parameters of the straw separator on the friction composition of straw and its loss are presented. It is established that slope angles of the upper and lower blades of the elevators relative to the horizon are 360 and 560, respectively, the ratio of the slope angles of the elevators is 1.1, the ratio of the straw separator diameters is 0.74 and the number is 3, the sum of the lengths of the elevators is 2.75 m, and the frequency of the blade rotations is 400 m−1 should be.

Electromagnetic-triboelectric energy harvester based on vibration-to-rotation conversion for human motion energy exploitation

To overcome the frequent replacement and charging of chemical batteries, human motion has become a promising energy source for portable electronic devices and wireless monitoring equipment. Although various energy harvesters for the conversion of human energy into electrical energy have been investigated, the output performance of existing harvesters is too low and irregular to provide sustained power to electronic devices. This paper proposes a high-efficiency electromagnetic-triboelectric hybrid energy harvester (ET-HEH) based on vibration-to-rotation conversion. The proposed harvester comprises a rotational electromagnetic generator (REMG), motion transmission mechanism, and reciprocating vibration triboelectric nanogenerator (VTENG). Rotational and vibrational energy can be transmitted among these components and harvested synchronously to enhance the output. The experimental results reveal that the energy conversion efficiency of ET-HEH can reach more than 70 % under multiple vibration frequencies. The proposed harvester has higher output compared with traditional reciprocating vibration energy harvesters. The active power output of the harvester after rectification is stably maintained at approximately 300 mW during jogging, exceeds 800 mW during sprinting, and can continuously charge a smart band with a rated power of 400 mW. This study demonstrates a new mechanism for realizing vibration-to-rotation conversion and provides a practical approach toward the harvesting of human motion energy with high-efficiency.

Development of a New 2-DOF Wrist Mechanism Using Reverse Motion Transmission

In this letter, we introduced a novel 2-DOF robotic wrist with a hollow channel. The proposed wrist was developed by stacking two symmetric 5R spatial manipulators using a reverse motion transmission mechanism. As a result, the proposed wrist mechanism has not only a wide workspace, but also a huge hollow space compared to previous wrist models. The kinematic model is derived via the screw theory, and kinematic characteristics are analyzed in terms of two kinematic indices. The prototype hardware of compact size wrist was designed and implemented. Finally, the validity and feasibility of the wrist were confirmed through experiments.

The use of simple teeth surfaces in non-conjugate gears

Nowadays, the dominant place in the practical use of rotational motion transmission mechanisms has conjugate, and, in particular, teeth gear. Reproduction of high-order surfaces used in conjugated gears requires the use of sophisticated and expensive equipment. An alternative to such gears are approximate gears. The paper analyzes the possibility of using gears with non-conjugate engagement when using the simplest surfaces - a plane, a cylinder and their various combinations, as the working surfaces of the teeth. It is shown that with the simplest outlines of the teeth it is possible to get the high-quality transmission. The results of mathematical modeling of approximate gears are presented. A comparison of the studied gears with the involute one in terms of the cyclic error of the tooth frequency is given. The resulting values of the position error and the gear ratio are minimal and, in particular, for multi-row gears can be negligible. The insensitivity of approximate gears to the errors in wheel manufacturing and gear assembly is shown. Several gear configurations and various motion transmission configurations are provided. Prospects for the use of gears with the simplest outlines of the teeth are associated with the lack of need for complex gear-processing equipment and the possibility of manufacturing and repair in the field conditions. In addition, such transmissions are indispensable for experimental installations because of the possibility of rapid changes in parameters that do not require significant time for design and manufacture.

Study on the use of alternative transmission mechanisms applied to additive manufacturing machines

Fused Filament Fabrication (FFF) is one of the widest Additive Manufacturing technologies used for the manufacturing of prototypes with complex geometry and different materials. However, nowadays commercial FFF machines have limitations in terms of process reliability and product quality. To overcome these limitations and increase the geometrical accuracy it is necessary to study the motion transmission mechanisms of the extruder head.In this sense, in this study, a development of an alternative transmission of linear movement in the Fused Filament Fabrication machines is proposed. Once the mechanism has been developed, this one is testing in order to quantify its accuracy. After the initial development, a virtual design will be generated, followed by a functional prototype. Manufacturing accuracy is usually 1 mm for domestic machines (±0.5) and better for industrial machines. The obtained results of the proposed transmission mechanism improve the accuracy up to 82 % and 0.27 was reached in the repeatability, that is a parameter not provided by the manufacturers.

Compact Modular Cycloidal Motor With Embedded Shape Memory Alloy Wires

In this study, we develop a rotary motor using embedded shape memory alloy (SMA) wires, with the aim of realizing a novel compact and modular motor that can generate high-torque bidirectional continuous rotation. Thus, we focus on designing the motion transmission mechanism and torque amplifier of the motor. The designed motion transmission mechanism that functions to convert the contraction/expansion of the SMA wires to rotational motion enables the motor to generate continuous rotation with relatively short-length SMA wires. Additionally, a double-disc cycloidal speed reducer designed as the torque amplifier allows the motor to reliably generate high torque with a compact structure due to its simple configuration, size variability, and torque amplification functionality. One of the advantages of the motor is that an actuating module could be additionally incorporated into the motor to achieve higher torque. In this case, the overall size and weight of the motor are marginally increased although the output torque capacity almost doubles. Hence, the energy density of the motor significantly increases. The study describes the main concept, operating principle, design, and experimental results of the output torque capacity, positioning characteristics, and frequency response of the proposed motor.

Development of new electrostatic micro cam system driven by elastic wings

In this paper, we improve and develop a micro cam system, in which reciprocating linear movement of two electrostatic linear comb-drive actuators (ELCA) is transformed into the unilateral rotation of a cam rim through six elastic wings of motion-transmission mechanisms. The system was fabricated by using SOI-MEMS technology and only one photo mask. Our experimental results show that the new micro cam system runs stably while the driving frequency ranging from 1 to 30 Hz with the driving voltage Vpp = 100 V. In addition, the average angular velocities of the cam rim matched with the theoretical results better than the velocities measured in the previous micro cam system.

2E3-3 上肢から下肢への運動伝達に基づく無動力歩行アシスト装具の開発

2E3-3 上肢から下肢への運動伝達に基づく無動力歩行アシスト装具の開発

Interprotomer motion-transmission mechanism for the hexameric AAA ATPase p97

Multimeric AAA ATPases represent a structurally homologous yet functionally diverse family of proteins. The essential and highly abundant hexameric AAA ATPase p97 is perhaps the best studied AAA protein, playing an essential role in various important cellular activities. During ATP-hydrolysis process, p97 undergoes dramatic conformational changes, and these changes are initiated in the C-terminal ATPase domain and transmitted across the entire length of the molecule to the N-terminal effector domain. However, the detailed mechanism of the motion transmission remains unclear. Here, we report an interprotomer motion-transmission mechanism to explain this process: The nucleotide-dependent motion transmission between the two ATPase domains of one protomer is mediated by its neighboring protomer. This finding reveals a strict requirement for interprotomer coordination of p97 during the motion-transmission process and may shed light on studies of other AAA ATPases.

Chain gear design using artificial neural networks

AbstractIn this study, the analytical calculation and analysis for the data corresponding to these gears have been made to obtain alternative test and training data sets to be used at the artificial neural networks(ANNs) with the constraints and requirements for the design of chain gears of power and motion transmission mechanisms are determined. In the input layer, the constraints and requirement values(input power, number of revolution of the pinion, number of revolution of the gear and center distance) of chain gears are used while at the output layer chain code(i.e., the chain gear type and chain sequence number), specifying the functional and physical properties, is used. Then the network is tested with the test data. The analytical calculation results and ANN predictions are compared by using statistical error analyzing methods such as absolute fraction of variance(R2), root mean square error(RMSE), and mean error percentage(MEP) for the training and test data. The chain code has been determined by the ANN with an acceptable accuracy. It is concluded that ANNs can be used as an alternative method in chain gear design. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 38–44, 2012

A New Actuation System With Simulated Electrocardiogram Signal for MR Elastography

Elasticity is an important physical attribute of biological tissue. Elasticity of normal tissue can differ significantly with pathological tissue in its stiffness. It is important to develop a clinical viable method to determine and visualize the elasticity of histological tissue. Magnetic resonance (MR) elastography is a promising noninvasive method to quantitatively measure the viscoelastic properties of biological tissue. We developed a new quasi-static actuation system with the spatial modulation of magnetization (SPAMM) imaging pulse sequence. The MR compatible actuation system consists of an ultrasonic motor, a force sensor, motion-transmission mechanism, ECG signal generation, and controller. The high torque ultrasonic motor, USR60-E3 by Shinsei Corporation, Japan, can function well in the magnetic environment. The simulated ECG signal is generated using function generator, and outputted to both MR scanner and controller respectively. SPAMM imaging sequence is utilized to acquire tagging images of the deformed tissue. The actuation is synchronized with the SPAMM sequence via simulated ECG signal. Indentation force is measured by MR compatible force sensor for the subsequent stiffness inversion procedure. Imaging experiments were conducted using this actuation system and a GE SIGNA 1.5T MR scanner. Clear tag-deformed images of agar gel phantom have been acquired. The results demonstrated the feasibility of utilizing SPAMM sequence and the proposed actuation system for tissue characterization. In comparison with dynamic method of MR elastography, this quasi-static method is relatively simple to implement since no motion sensitive gradient or gradient synchronization is required. A limitation of indentation method is the difficulty to obtain significant deformation of tumor inside the liver organ. Since radio frequency (RF) needle is inserted into liver organ during tumor ablation, the proposed system with needle-based actuation making use of this inevitable insertion will be able to intra-operatively image the liver tumor during ablation. The RF needle can directly vibrate the pathological tissue within the liver organ.

Control of electromechanical systems in sliding conditions

An algorithm of controlling the angular velocity of a two-weight system with an elastic motion transmission mechanism is synthesized. The system’s dynamics is investigated theoretically; the domain of the existence of stable conditions is estimated; and it is shown that the system’s image point slides along the phase trajectory of the reference model, which serves to assign the dynamic characteristics of the designed system. The results of the mathematical simulation of control processes are presented.

Increasing the Mechanical Work Output of an Active Material Using a Nonlinear Motion Transmission Mechanism

A nonlinear motion transmission mechanism for improving the mechanical work output of an active material drive element is presented. This improvement is achieved by addressing the typical mismatch between the characteristics of a driven load, such as a constant force or spring load, and the active material’s force-displacement behavior; this behavior is described, at a constant drive level, by a linear decrease in the possible force with increasing displacement. The motion transmission mechanism consists of a simple linkage that couples the active material to the load. As the active material does work on the load, the linkage changes the mechanical advantage or leverage of the active material with respect to the load, thereby tailoring the load to best exploit the active material’s force-displacement behavior. A kinematic model is used to predict the maximum quasi-static mechanical work output that can be obtained. Optimization of the model geometry results in a transmission with a theoretical work enhancement of 37% for a constant load, and a theoretical work enhancement that approaches 100% for a spring load. The possibility of work enhancement is verified in an experiment that demonstrates a work output improvement of 27% for the constant load case.

運動伝達機構における非線形ばね特性解析 非線形ばね試験ユニットによる影響評価

運動伝達機構における非線形ばね特性解析 非線形ばね試験ユニットによる影響評価