Flow Characteristics of Gerotor Motors with Pin and Nonpin Designs

The geometric design of a gerotor motor has a significant impact on its function, performance, quality, reliability and cost. When designing a gerotor motor all these features must be considered. A gerotor motor can be classified into two types based on the geometric design; gerolor (pin design) and gerotor (nonpin design). In this article geometric parameters of the two design types are discussed briefly and the operation of the gerotor motor is described as well. A numerical analysis is carried out by using computational fluid dynamics (CFD) tool (PumpLinx) to analyze the fluid flow and predict the performance of both types of gerotor designs. Various characteristics of the two designs of the gerotor motor are investigated and compared which include the gerotor design, fluid flow rate, velocity, pressure and output torque. Comparison of the results found out that using pin design gerotor motor, the flow rate, flow velocity, pressure and torque will vary greatly. Nonpin design can significantly reduce variations in all the flow characteristics thereby enhancing the stability and reduction in the leakage risk.

Modeling and Experimental Research of One Kind of New Planar Vortex Actuator Based on Shape Memory Alloy

In order to alleviate the problems of complex structure and low reliability of traditional Shape Memory Alloy (SMA) rotary actuator, a planar vortex actuator (PVA) based on SMA material was proposed to directly output torque and angular displacement. Based on the calculation method of PVA and the constitutive model of the phase transition equation of SMA, the mechanical model is established, and the pre-tightening torque, temperature, output torque, and rotation angle are obtained. The relationship expression between the tests has verified the mechanical model. The results show that the relationship between the excitation temperature and the output torque, the coefficient of determination between the calculated value and the tested value, is 0.938, the minimum error is 0.46%, and the maximum error is 49.8%. In the relationship between angular displacement and torque, the coefficient of determination between the calculated value and the test value is 0.939, the maximum error is 58.5%, and the minimum error is 28.0%. The test results show that the calculated values of mechanical model and experimental data have similar representation form.

Adaptive sliding mode observer–based integral sliding mode model-free torque control for elastomer series elastic actuator–based manipulator

In this brief, an adaptive nonsingular terminal sliding mode observer–based adaptive integral terminal sliding mode model-free control is proposed for the trajectory tracking control of the output torque of elastomer series elastic actuator–based manipulator. Considering the tip load and its external disturbance, an elastomer series elastic actuator–based manipulator model is established. In order to realize the output torque tracking control of elastomer series elastic actuator–based manipulator, by using the characteristics of elastomer series elastic actuator, the output torque control is transformed into position control. Based on the idea of model-free control, an ultra-local model is applied to approximate the dynamic of the manipulator, and all the model information is considered as an unknown lumped disturbance. The adaptive nonsingular terminal sliding mode observer is designed to estimate the lumped disturbance, and the absolute value of the tracking error is introduced into the sliding surface to make the selection of parameters more flexible. Then, on the basis of adaptive nonsingular terminal sliding mode observer, the adaptive integral terminal sliding mode model-free control is proposed under model-free control framework. The design and analysis of both observer and controller do not rely on accurate model information. Finally, the performance of the proposed method is verified by simulation results.

Lightweight Design and Dynamics Analysis of ZYL-15000D Directional Drill Reducer

Since the output torque of the rotary reducer of the ZYL-15000D-kilometer directional drill is proportional to the gear train transmission ratio, the output torque is large enough when the input speed and output speed meet the design goal. This paper selects the method of reducing the transmission ratio to optimize the size parameters of the reducer. MATLAB genetic algorithm is used in the optimization design, and the minimum volume of the rotary part reducer is taken as the objective of optimization design, while the design variables and constraints are determined. The optimal value of design variables was obtained through optimization, and the parameter values of each gear were determined accordingly. Through analysis, the total volume of the optimized gear reducer was reduced by 49.6%. Then, the 3D model of the optimized gear was created, and the analysis of the transient dynamics of the optimized gear was carried out with ANSYS Workbench software. According to the analysis results, the optimized gear met the strength requirements and provided a reference for the subsequent optimization design of other types of gear reducers.

Stator flux barriers to improving interior permanent magnet motor characteristics

There are many methods to improve the characteristics of permanent magnet motors. One of them is by making flux barriers on the stator or rotor, or both. This paper discusses the adding stator flux barriers on the rectangular-shaped stator of the interior permanent magnet motor. The purpose is to increase the maximum rotation of the machine. The shape of the flux barrier is circular considering the ease of the manufacturing process, with the proposed diameter is one slot pitch. Several diameters of larger and smaller sizes will also be simulated for comparison. Other parameters, which are cogging torque and stator core loss, are also investigated. Design and simulation are carried out analytically and numerically using 2D finite element analysis. The simulation results indicate that the proposed flux barrier diameter can provide the maximum rotation with only a tiny decrease in output torque. In this regard, it can be concluded that the stator flux barriers affect the speed than output torque. Additional advantages are also obtained from the decrease in cogging torque and core loss at the base speed compared to a stator without flux barriers.

Dynamic Simulation Analysis and Experiment of Large-caliber Self-propelled Pipeline Crawler Based on ADAMS

The force states of driving wheels are different when the self-propelled pipeline crawler moves in the pipeline, so it is difficult to carry out accurate theoretical analysis and calculation on the force and output torque values of each driving wheel in horizontal, climbing and turning conditions of the crawler. Due to the complex mechanical properties of pipeline sealing and the limitation of visualization, it takes a long period and high cost to develop the robot in pipeline by experimental means. With the gradual application of virtual simulation means, the complicated dynamic analysis and solution process in the past has become relatively easy. In this paper, Solid works is used to establish a simplified model of the crawler, and ADAMS is used to analyze and simulate the dynamics of the crawler. The force of the multi-wheel driven pipeline crawler is given under the condition of horizontal, climbing 35° and turning, which provides the necessary analysis method and theoretical basis for the design optimization and improvement. Finally, the horizontal, climbing and bending motion performance of the crawler is verified by comprehensive pipeline experiment.

Slip-Clutch Torque Estimation via Real-Time Adaptive Lookup Table

Transfer case clutch is crucial in determining traction torque distribution between front and rear tires for four-wheel-drive (4WD) vehicles. Estimating time-varying clutch surface friction coefficient is critical for traction torque control since it is proportional to the clutch output torque. As a result, this paper proposes a real-time adaptive lookup table strategy to provide the time-varying clutch surface friction coefficient. Specifically, the clutch-parameter-dependent (such as clutch output torque and clutch touchpoint distance) friction coefficient is first estimated with available low-cost vehicle sensors (such as wheel speed and vehicle acceleration); and then a clutch-parameter-independent approach is developed for clutch friction coefficient through a one-dimensional lookup table. The table nodes are adaptively updated based on a fast recursive least-squares (RLS) algorithm. Furthermore, the effectiveness of adaptive lookup table is demonstrated by comparing the estimated clutch torque from adaptive lookup table with that estimated from vehicle dynamics, which achieves 14.8 Nm absolute mean squared error (AMSE) and 2.66% relative mean squared error (RMSE).

Cogging Torque Reduction in PMSM in Wide Temperature Range by Response Surface Methodology

In this paper, a wide temperature range permanent magnet synchronous motor (PMSM) is designed, which can be used as the servo mechanism of an electric actuator in a missile. Considering the operating characteristics of the actuator with large environmental temperature change and large temperature rise, the magnetic material characteristics at different temperatures are analyzed, and the influence of eccentric magnetic poles on the cogging torque is deduced. In order to reduce cogging torque in a wide temperature range, the poles of the motor are optimized based on the response surface method. By utilizing temperature rise calculations, the scheme that may exceed the maximum working temperature of the material is eliminated. Then, the response surfaces of the cogging torque with pole arc coefficient, thickness and asymmetry at different temperatures are established, and the optimal value ranges of the three parameters are determined. The minimum upper limits of cogging torque and meeting the specified output torque at different temperatures are used as the judging criteria, and the optimal schemes for different working environments are determined. Finally, a prototype is developed, and the output torque is more than 10 N·m, and the cogging torque is less than 0.2 N·m in a wide temperature range.