Reaction Torque Research Articles

Effects of Rotary Tine Tool Velocity on Soil Reaction Forces, Power, and Energy Intensity

Highlights Draft force and torque on a vertical rotary tine tool were studied for various longitudinal velocities and speed ratios. Draft force increased with longitudinal velocity but decreased with speed ratio, and soil reaction torque increased with both longitudinal velocity and speed ratio. Total power required by the tool increased with speed ratio, and energy intensity increased with speed ratio and longitudinal velocity, with substantial changes observed at higher velocities. Abstract. Studying soil-tool interaction can provide valuable information on the actuation force and energy requirements of a weeding tool operating in soil. Soil-tine interaction was investigated for a vertical rotary tine tool that was intended to be used as a weeding tool for an automated mechanical intra-row weeder. The main objective of the research was to investigate the effects of linear and rotational velocities on soil reaction forces and power associated with actuation of the rotary tine tool in soil. A series of soil bin experiments were conducted in loam soil. Soil horizontal (draft) force and torque on the tool were measured at three longitudinal/travel velocities of 0.09 m s-1, 0.29 m s-1, and 0.5 m s-1 that were used to move the tool linearly across the soil bin length. The speed ratio, defined as the ratio of the longitudinal velocity to the peripheral velocity of the rotary tines, determined the rotational speeds required for the study. The draft force and torque were evaluated at four speed ratio levels (0, 1, 1.5, and 2). An Analysis of Variance (ANOVA) performed for statistical analysis using p < 0.05 showed that both longitudinal velocity and speed ratio had significant main and interaction effects on the draft force and torque. In most cases, the draft force decreased while torque increased with increasing speed ratios for the different longitudinal velocities used in the study. Power and energy intensity were also calculated using draft force and torque measurements for different experimental settings. For increases in speed ratios, the power requirements for tool draft force decreased, whereas the power requirements for rotating the tool increased for each longitudinal velocity. At the highest test travel speed of 0.5 m s-1, the power decreased from 66 W to 28 W for draft and increased from 0 W to 76 W for rotation of the tool at increasing speed ratios. The maximum total power calculated for the tool was 110 W at 0.5 m s-1 and a speed ratio of 2. The study shows the changes in power and energy requirements of a vertical rotary tine tool for different operating parameters for weed control. This information could be valuable for optimizing the physical weeding process. Keywords: Energy intensity, Power, Rotary tool, Soil-tine interaction, Weed control.

Position-and-Torque-Sensorless Admittance Control with State Estimation Considering dq-axis Cross-Coupling Factors

This paper presents a position estimation compensation method considering dq-axis cross-coupling factors of Interior Permanent Magnet Synchronous Motors (IPMSMs) inductance for position-and-torque-sensorless admittance control. The cross-coupling factors are from dq-axis mutual inductance and deteriorate control and position estimation performance in control methods without the model. Since dq-axis cross-coupling factors of inductance vary with the rotor position and the current, measurement and estimation of the values are difficult. The proposed method estimates the cross-coupling factors and position estimation errors using dq-axis current variation from the injected voltage. In addition, the proposed method compensates the estimated position based on a voltage equation, including the dq-axis cross-coupling factors, by adding the estimated error. As a result, the vibration of current, velocity, and estimated reaction torque were reduced, and the performance of a position-and-torque-sensorless admittance control system was improved. The experimental results show the proposed method's validity and response by the sensorless admittance control.

Zero Reaction Torque Trajectory Tracking of an Aerial Manipulator through Extended Generalized Jacobian

Aerial manipulators are used in industrial and service robotics tasks such as assembly, inspection, and maintenance. One of the main challenges in aerial manipulation is related to the motion of the UAV base caused by manipulator disturbance torques and forces, which jeopardize the precision of the robot manipulator. In this paper, we propose two novel inverse kinematic control methods used to track a trajectory with an aerial manipulator while also considering resultant UAV base motions. The first method is adapted from the generalized Jacobian formulation used in space robotics and includes the change in system momentum resulting from gravity and UAV control forces in the inverse kinematic control equation. This approach is simulated for a 2 and 3 degree-of-freedom aerial manipulator tracking trajectories with the end-effector. Although the end-effector position error is approximately zero throughout the simulated task, we see significant undesired UAV base motions of several centimeters in magnitude. To ameliorate this by exploiting the kinematic redundancy, we modify the generalized Jacobian by adding an additional task constraint which minimizes the reaction torques from the manipulator, to form the extended generalized Jacobian. While the second approach results in improved precision and reduced base motion by an order of magnitude as compared to the generalized Jacobian, a drawback is the reduction in the available workspace as the solution seeks to minimize the manipulator center of gravity translation. We also demonstrate and compare both approaches in a load picking task. All the algorithms are completed computationally faster than real time in the MATLAB simulations, illustrating their potential for application in real-world experiments.

Analysis and Roll Prevention Control for Distributed Drive Electric Vehicles

This work presents an approach to improve the roll stability of distributed drive electric vehicles (DDEV). The effect of the reaction torque from the in-wheel motor exerts additional roll moment, which is different from traditional vehicles. The additional roll moment can be achieved by active control of the wheel torque adjustment, which achieves a control effect similar to the active suspension. The anti-roll control strategy of decoupling control of roll motion and yaw motion are proposed. The direct yaw moment is calculated by the linear quadratic regulator (LQR) algorithm while the additional rolling moment is calculated by the sliding mode variable structure. For maneuvering rollover caused by excessive lateral acceleration, an anti-rollover control strategy is designed based on differential braking. A fuzzy control theory is used to decide the yaw moment to be compensated. The distribution method of the braking torque applied to the outer wheel alone, and the lateral load transfer rate is the main evaluation index for simulation verification of typical working conditions. The simulation results show that the proposed control strategy for DDEV is effective.

Dynamics analysis of knee joint during sit-stand movement

Sit-stand movement is one of the most common movement behaviors of the human body. The knee joint is the main bearing joint of this movement. Thus, the dynamic analysis of knee joint during this movement has deeply positive influences. According to the principle of moment balance, the dynamics of the knee joint during the movement were analyzed. Furthermore, combined with the data obtained from optical motion capture and six-dimensional ground reaction force test, the curve of knee joint torque was calculated. To verify the accuracy of the analysis of dynamic, the human body model was established, the polynomial equations of angle and angular velocity were fitted according to the experimental data, and the knee joint simulation of the movement was carried out. The result revealed that in terms of range and trend, the theoretical data and simulation data were consistent. The relationship between knee joint torque and ground reaction force was revealed based on the variation law of knee joint torque. During the sit-stand movement, the knee joint torque and the ground reaction force were directly proportional to each other, and the ratio was 5 to 6. In the standing process, the acceleration first increased and then decreased and finally increased in reverse, and the maximum knee torque occurred at an angle of about 140°. In the sitting process, the torque was maximized in the initial stage. The results of the dynamics analysis of knee joint during sit-stand movement are beneficial to the optimal design and force feedback control of seated rehabilitation aids, and can provide theoretical guidance for knee rehabilitation training.

Design, analysis and implementation of control moment gyroscope (CMG) mechanism to self-balance a moped bike

This paper presents the design and implementation of the control moment gyroscope (CMG) mechanism on the Okinawa IPRAISE Scooter, an electric moped, to self-balance it with or without a rider. The scooter can be balanced in static as well as in moving condition so that it won’t fall over. Higher torque amplification and momentum storage capacity makes CMG superior over other mechanisms like reaction wheel, mass balancing, controlling the movement of front steering, etc. CMG mechanism consists of a pair of spinning discs, i.e., flywheels which are driven continuously by DC motors about vertical z-axis. An encoder deployed to sense the tilt angle about longitudinal y-axis provides feedback to the PID controller. The controller, in turn, produces restoring torque by gimbal action with the help of a pair of stepper motors mounted on horizontal x-axis to maintain the scooter in vertical position. Thus, using gyroscopic effect of two spinning flywheels, CMG mechanism generates reactive torque which assist the user to balance the bike in several riding modes. Stack up calculations were performed to make a tradeoff between moment of inertia and mass of flywheels to arrive at the dimensions of the flywheel. Subsequently, 3D model of the mechanism is developed with the help of CREO. The mechanism is analyzed and simulated in ANSYS. Mock-up samples were procured. It is then mounted on the scooter and tested. One optimum location is finalized based on the center of gravity. Finally, the bike is found to balance itself resulting in a compact and robust mechanism giving safe and comfortable ride. This, however, comes at an additional ten percent power consumption, twenty-five percent increase in weight and nine percent increase in cost. Further improvement can be done by reducing this parameters by using lighter materials and small size motors.

A Robotic End-Effector for Screwing and Unscrewing Bolts From the Side

This letter presents a novel robotic end-effector for screwing and unscrewing bolts. In many industrial scenarios, it is required to manipulate bolts from the side using robots with end-effectors. Besides, the reaction torque during tightening needs to be balanced to the stability of the robot. To address these challenges, we design a robotic end-effector that can realize side screwing and torque counteraction. Specifically, through an open gear set and a width-adjustable screwing mouth, the end-effector can approach the bolt from the side in any direction and then screw and unscrew it. A gripper with force-magnification and self-locking drive is equipped to counteract the reaction torque during screwing and unscrewing. Considering the extensions for different application scenarios, a method to extend the end-effector by switching screwing mouths is given, and the extended end-effector is able to screw a variety of objects. After further analysis and optimization of the force and size, experiments are carried out. The results show that the end-effector can screw and unscrew the target bolt robustly and counteract the reaction torque. It is also applicable in different scenarios.

Design, Modeling, and Control Allocation of a Heavy-Lift Aerial Vehicle Consisting of Large Fixed Rotors and Small Tiltrotors

In this article, we propose an unconventional heavy-lift aerial vehicle (HLAV), present the design and its control allocation analysis, and prove the concept by the demonstration of the experimental test prototype in the outdoor environment. We aim for a mechanically robust and simple vehicle design that efficiently performs heavy lifting compared to other common aerial vehicles under certain width constraints, without using a complex swashplate mechanism. The HLAV performs the task of carrying the main load with two large propellers that are efficient, thanks to the greater disk area, and includes two small tilting propellers for controllability. This system has a “PPNN” (P: clockwise and N: counterclockwise) propeller arrangement to compensate for the reaction torques of equally sized propeller pairs placed on opposite sides. However, conventional quadcopters with the “PPNN” propeller arrangement lose their controllability upon hovering. Therefore, servo motors are integrated into the small propellers to ensure controllability. The nonlinear dynamic model of the HLAV is built by the Newton–Euler approach, and the system is linearized around the hover equilibrium point for controllability analysis. Model parameters are estimated using closed-loop system identification tools. High-level controllers are designed with the “loop shaping” method. To show feasibility, the proposed system is experimentally verified with a newly designed prototype, and sufficient trajectory tracking performance is achieved in a stable manner.

SHSA-based adaptive roll-safety 3D tracking control of a X-Rudder AUV with actuator dynamics

In this article, a novel adaptive robust trajectory tracking framework with roll control is created for a X-Rudder autonomous underwater vehicle (XAUV) subjects to system nonlinearities, unknown disturbances, and complex actuator dynamics. First, a roll control law is introduced to the kinematics control loop, and the hyperbolic-tangent Line-of-sight (HLOS) based guidance law is proposed, which considers the three-dimensional (3D) tracking errors, collaboratively governing heading, pitch, and roll. Second, a novel super-hyperbolic switching algorithm (SHSA) based sliding mode controller is deployed in the dynamics control loop to achieve trajectory tracking and roll control, which combines the advantages of the two hyperbolic functions, avoids the chattering problem while achieving rapid convergence, this enhancing the control accuracy and stability simultaneously. Besides, the robustness to unknown disturbances (including environmental disturbances and propeller reaction torque) is enhanced by nonlinear disturbance observers. To tackle the potential instabilities from compound actuator dynamics, an anti-windup compensator is resorted to compensate for the control truncation of propulsion system, and an optimal X-Rudder allocator is utilized to solve the rudder angle assignment problem with multiple constraints. Finally, comparative numerical simulations are carried out to verify the effectiveness of proposed controller.

Publisher Erratum to “Estimation of the External Forces on a Robot Hand with Fingertip Tactile Sensors”

In human-robot collaboration, physical hand-over-hand communication of the human operator’s intention is essential for realizing direct and intuitive cooperation. When an external force acts on a robot hand holding an object, the torque exerted on the finger motor becomes a combination of the grasping torque required to maintain the grasping pose and reaction torque to the external force. To analyze intended interaction, we need to recognize multiple contacts inside and outside the fingertips. In this study, an external force estimation method was developed that uses tactile sensors to measure both grasping and external forces acting on the fingertips of a robot hand. Because a tactile sensor cannot measure all the external force components, it is impossible to directly compute the magnitude and contact angle of an external force. The shear and frictional forces lost during tactile sensing are backwardly estimated according to the difference between the estimated and measured torques. The magnitude and contact angle are computed to estimate external force, which can be used to determine the intention of the user. Simulations based on real sensor responses and experiments were performed to validate the proposed estimation method.

Peculiarities of balancing in-line two and four-cylinder piston engines

The balancing of the kick reactive torque (KRM) in in-line two- and four-cylinder internal combustion engines is considered. It is shown that these internal combustion engines can be balanced by a special arrangement of the axes of the balancing shafts, which ensure the balance of the inertia forces of reciprocating moving masses. With the help of the developed programs, a comparative analysis of the possibilities of balancing the kick reactive torque with different layouts of the balancer shafts for the considered internal combustion engines was carried out. It is established that this balancing method is the most effective for two-cylinder internal combustion engines. The expediency of developing devices for regulating the position of the balance shafts axes is shown. Keywords: in-line two-cylinder and four-cylinder internal combustion engines, balance, balance shaft, kick moment. gusarov39@yandex.ru, apelinskiy_mami@mail.ru, prvm@rambler.ru

Three-Dimensional Printable Ball Joints with Variable Stiffness for Robotic Applications Based on Soft Pneumatic Elastomer Actuators.

This paper contributes to a new design of the three-dimensional printable robotic ball joints capable of creating the controllable stiffness linkage between two robot links through pneumatic actuation. The variable stiffness ball joint consists of a soft pneumatic elastomer actuator, a support platform, an inner ball and a socket. The ball joint structure, including the inner ball and the socket, is three-dimensionally printed using polyamide−12 (PA12) by selective laser sintering (SLS) technology as an integral mechanism without the requirement of assembly. The SLS technology can make the ball joint have the advantages of low weight, simple structure, easy to miniaturize and good MRI compatibility. The support platform is designed as a friction-based braking component to increase the stiffness of the ball joint while withstanding the external loads. The soft pneumatic elastomer actuator is responsible for providing the pushing force for the support platform, thereby modulating the frictional force between the inner ball, the socket and the support platform. The most remarkable feature of the proposed variable stiffness design is that the ball joint has ‘zero’ stiffness when no pressurized air is supplied. In the natural state, the inner ball can be freely rotated and twist inside the socket. The proposed ball joint can be quickly stiffened to lock the current position and orientation of the inner ball relative to the socket when the pressurized air is supplied to the soft pneumatic elastomer actuator. The relationship between the stiffness of the ball joint and the input air pressure is investigated in both rotating and twisting directions. The finite element analysis is conducted to optimize the design of the support platform. The stiffness tests are conducted, demonstrating that a significant stiffness enhancement, up to approximately 508.11 N·mm reaction torque in the rotational direction and 571.93 N·mm reaction torque in the twisting direction at the pressure of 400 kPa, can be obtained. Multiple ball joints can be easily assembled to form a variable stiffness structure, in which each ball joint has a relative position and an independent stiffness. Additionally, the degrees of freedom (DOF) of the ball joint can be readily restricted to build the single-DOF or two-DOFs variable stiffness joints for different robotic applications.

The pulse-elevator: A pump for granular materials

Granular materials include fuels, foods, feedstocks, and raw materials, and they are frequently created in drilling, exploration, and comminution. However, despite this ubiquity, they can be much more difficult to transport than other materials. Screw conveyors can be used, as can bailing, gas-blowing, and vibro-conveyors, but all have issues related to some combination of complexity, inclination, differential friction, and torque reaction. We propose an entirely new concept: a combination of the vibro-conveyor and the Tesla valve. This ‘pulse-elevator’ is a single piece of inert material, it can operate vertically, it does not depend upon frictional interactions, and it is effectively torqueless. This paper describes the mechanism in analytical, numerical, and experimental terms, and then illustrates two successful experimental use cases: powder uplift from a hopper, and the replacement of augering in a rock-drilling application. These cases are particularly relevant for the facilitation of ISRU and subsurface exploration in space.

Bending and torsional vibration attenuation of multi-panel deployable solar array using reaction wheel actuators

PurposeThis paper aims to present a multi-axis actuating approach to attenuate the bending and torsional vibration of the solar array through the reaction wheel (RW) actuators.Design/methodology/approachThe motion equation of the solar array with the RW actuators is derived in modal coordinates for controller design. The reaction torques, induced by the speed change of the RW actuators, are controlled for vibration attenuation through the constraints on the actuators’ rotating speed. The proposed control approach is firstly verified with numerical simulation on the finite element model of a full-scale solar array. Experimental study of a simplified elastic plate model is subsequently performed for feasibility and validity investigation.FindingsBoth the numerical and experimental studies demonstrated the success of adopting RW as the actuator. Results from numerical simulation reveal that the vibration response peak can be reduced by 80% with 2% of mass increase by using the RW actuators.Practical implicationsIt is demonstrated that the multi-axis actuating method using RW actuators has a great potential in vibration attenuation of the multi-panel deployable solar array.Originality/valueAn approach to reduce bending and torsional vibration of solar array based on RW actuators is investigated. Theoretical analysis, numerical simulation and experimental study are conducted to demonstrate the validity of the proposed vibration attenuation approach and its potential application in the spacecraft design.

Electromagnetic torque and reactive torque control of induction motor drives to improve vehicle variable flux operation and torque response

Electromagnetic torque and reactive torque control of induction motor drives to improve vehicle variable flux operation and torque response

A New Robust Method to Investigate Dynamic Instability of FTV for the Double Tripod Industrial Driveshafts in the Principal Parametric Resonance Region

The present work aims to design a robust method to detect and certify the deterministic chaos or ergodic process for the forced torsional vibrations (FTV) of a double tripod industrial driveshaft (DTID) in transition through the principal parametric resonance region (PPRR) which is considered by the researchers in the field as one of the most important resonance regions for the systems having parametric excitations. The DTID’s model for FTV considers the following effects: nonuniformities of inertial characteristics of the DTID’s elements, the harmonic torque excitation induced by the asynchronous electrical motor used for a heavy-duty grain mill, and the harmonic reaction torque generated by different granulation of the substance needed to be milled. Based on these aspects, a model of the FTV for the DTID was designed which was a modified, physically consistent model already used by the authors to investigate the FTV of automotive driveshafts (homokinetic transmission). For the DTID elements, the dynamic instability for nonstationary FTV in the PPRR using time–history analysis (THA) was analyzed—THA represents the phase portraits. Time–history analysis is a detection method for possible chaotic dynamic behavior for the nonstationary FTV (NFTV) in transition through PPRR. If this dynamic behavior was seen, a new robust method LEA–PM was created to certify and confirm the deterministic chaos for the NFTV of DTID. The new method, LEA–PM, is composed of the Lyapunov exponent’s approach (LEA) coupled with the Poincaré Map (PM) applied to the global system of differential equations that describe the FTV of DTID in the PPRR. This new robust method, which embeds LEA and PM, LEA–PM, establishes if the mechanical system has a deterministic chaotic dynamic behavior (strange attractor) or an ergodic dynamic process in this resonant region. LEA represents a new method that includes not only the maximal Lyapunov exponent method (MLEM) but also new mathematical criteria that is “the sum of all Lyapunov exponents has to be negative” which, coupled with MLEM, indicates the presence of deterministic chaos (strange attractors). THA–LEA–PM had been used for the NFTV of DTID computing the phase portraits, the Lyapunov exponents, and representing the Poincaré Maps of the NFTV for the DTID’s elements in transition through PPRR, founding deterministic chaos or ergodic dynamic behavior. Based on the obtained results, numerical simulations revealed the pitting manifestations of the DTID’s elements, typical for the geared systems transmission, mentioned recently in experimental data research for the homokinetic transmissions. Using the new robust method, THA–LEA–PM (time–history analysis coupled with LEA–PM) can be used in future research for chaotic dynamic analysis of DTID’s NFTV transition through superharmonic resonances, subharmonic resonances, combination resonances, and internal resonances. Time–history analysis as a detection method for chaos and LEA–PM as a certifying method for deterministic chaos can be integrated as a design tool for DTID’s FTV control of the homokinetic transmission.

The Reactive Torque of a PMBL Motor with Magnets in Closed Rotor Slots

A mathematical model of a PMBL motor with permanent magnets embedded in the rotor body is considered. The model is based on decomposing the active region into homogeneous cylindrical sections with de-energized magnetic sheets at their boundaries. The techniques applied in the method for separating the Fourier variables and magnetization of magnetically hard and magnetically soft media are used as model numerical analysis tools. It is shown, based on calculated and experimental data, that in a PMBL motor with magnets located in closed rotor slots, a discrete bevel of magnets per stator tooth pitch does not make it possible to eliminate the reactive torque. It can only be minimized to about 2% of the nominal torque. If there is no bevel, the reactive torque amplitude will be as large as one tenth of the nominal torque. It is found that with the externally placed magnets, the considered discrete bevel provides almost complete absence of the reactive torque. It has been concluded that for PMBL motors with closed rotor magnets, it is advisable to have a continuous bevel of the stator core slots per tooth pitch.

Envelope-Based Variable-Gain Control Strategy for Vibration Suppression of Solar Array Using Reaction Wheel Actuator

The orbital operation of spacecraft can excite the long-drawn and low-frequency vibration of the solar array, which is prone to affecting the task execution of the system. To address this issue, an envelope-based variable-gain control strategy is proposed to suppress vibration of the solar array using the reaction wheel (RW) actuator. The RW actuator is individually mounted on the solar array to provide reaction torque through the speed change of its rotor. The governing equation of motion of the solar array actuated by a RW actuator is deduced with the state space representation. The control relation between the measured bending moment and the rotational speed of the RW actuator with the constant-gain coefficient is firstly developed and demonstrated in numerical simulation. Changing the gain coefficient to be inversely proportional to the envelope function of vibration, a variable-gain control strategy is proposed to improve the damping effect of the RW actuator. Simulation results show that the vibration suppression performance of the RW actuator is improved compared to the constant-gain control. As the actual on-orbit natural frequency of the solar array is not always exactly known, the robustness of the control system is analyzed for the deviation between the estimated and the actual natural frequency values. The proposed variable-gain control is also experimentally verified using a simplified elastic plate model. Experimental results indicate that the vibration attenuation time is decreased to 29.1% and 50.22% compared to the uncontrolled and the constant-gain controlled states, respectively.

Analysis of the Longitudinal-Bending-Torsional Coupled Vibration Mechanism of the Drilling of a Roof Bolter for Mine Support System

The condition of the drilling of a roof bolter for mine support system is complex, and the existing analytical approaches for the vibration of the drilling for oil wells cannot be fully applicable to it. In order to reveal the vibration mechanism of bolt drilling, some models for longitudinal, bending, and torsional coupled vibration were established based on the energy method and finite element method. A global matrix was assembled in the order of units. Taking the drilling condition as the boundary conditions, a reduced-order model was constructed. The simulations for drilling mudstone show that the order of mode shape is positively correlated with the corresponding natural frequency, and the low-order mode shape plays a decisive role in the vibration characteristics of a drill string. The order of causing drill string displacement from large to small is as follows: longitudinal vibration, torsional vibration, and bending vibration. Compared with the bit, the displacements of longitudinal and torsional vibration of the tail of the drill string are decreased by 93.2% and 84.7%, respectively. The perturbed force and reaction torque are the main reasons for inducing the coupled vibration of it. This research provides a theoretical basis for analysing the vibration characteristics of the drilling of roof bolters for mine support systems and developing their absorbers.

New direct power synergetic-SMC technique based PWM for DFIG integrated to a variable speed dual-rotor wind power

In this work, a new direct power synergetic-sliding mode (DPSSM) technique based pulse width modulation (PWM) strategy for doubly-fed induction generator (DFIG) integrated to variable speed dual-rotor wind power (DRWP) systems is designed. The designed strategies produce voltage pulse width locations identical to those of a classical two-level inverter. In this novel control a synergetic-sliding mode (SSM) command and PWM technique to replace the hysteresis comparators and the switching table, for generating the reference voltage using PWM strategies for a classical inverter. Compared with traditional direct active and reactive powers control (DARPC), in this novel strategy, the switching frequency is maintained constant, and the undulations of the reactive power, current, torque, and active power are minimized remarkably. Simulation results verify the validity of the designed strategy.