Suspension Platform Research Articles

Youla Parameterized Adaptive Hybrid Control for Active Vibration Control Platform

Abstract To increase the vibration attenuation of the damped platforms, an adaptive hybrid vibration control algorithm based on Youla (Q) parameterization is proposed, where the vehicle suspension platform is considered as an application example. First, an inner controller is designed to keep the hybrid control system stable. Then, the controller is extended to the Youla parameterized controller set. Finally, the Q-parameters are adjusted online by using a recursive least squares (RLS) adaptive algorithm to eliminate vibration disturbances. Simulation results demonstrate that the hybrid algorithm is capable of effectively suppressing the vibration signals.

Magnetic circuit optimisation and actuator suspension experiment of the 6‐DOF magnetic suspension platform for mini/micro LED

AbstractTo improve the speed of mass transfer, a magnetic suspension platform (MSP) is used to transport the display chips. A novel 6‐DOF MSP is proposed in this paper. An improved Halbach array is used to supply the magnetic flux density. Two types of permanent magnets are utilised in the improved Halbach array. The smaller permanent magnet serves to consolidate the magnetic flux density, thereby enhancing the uniformity of the magnetic field. The finite element method is employed to analyse how variations in angle impact both the strength and uniformity of the magnetic flux density. The results show that the magnetisation direction of 45° is the most effective in terms of improving the uniformity and strength of the magnetic density. Finally, a 6‐DOF MSP prototype is manufactured. A magnetic density measurement experiment and a stable suspension experiment for the actuator are conducted. The results indicate an enhancement in the uniformity of the magnetic field within the air gap. Additionally, the maximum suspension positioning accuracy of the actuator is about 750 nm.

Data-driven [formula omitted] vibration control design and verification for an active suspension system with unknown pseudo-drift dynamics

This paper presents a data-based vibration control algorithm that can realize the vibration suppression of a laboratory suspension facility without knowing its drift dynamics. The vibration controller consists of two sub-controllers, a prestable controller that assists in generating higher quality operational data and a data-driven H∞ vibration controller that realizes vibration suppression. The proposed control algorithm only needs to know partial knowledge of the system dynamics without any information about the so-called pseudo-drift dynamics. We analyse and evaluate the control approach through simulation and experimentation based on a laboratory suspension platform. The comparison results shows that the data-based H∞ vibration control is quite promising. In addition, the influences of two critical parameters on the data-based controller are quantitatively studied, which can be used to optimize the control structure better and improve control performance.

A study on motion reduction for suspended platforms used in gravitational wave detectors

We report a reduction in motion for suspended seismic-isolation platforms in a gravitational wave detector prototype facility. We sense the distance between two seismic-isolation platforms with a suspension platform interferometer and the angular motion with two optical levers. Feedback control loops reduce the length changes between two platforms separated by 11.65,textrm{m} to 10,mathrm {pm,Hz}^{-1/2} at 100,textrm{mHz}, and the angular motion of each platform is reduced to 1,mathrm {nrad, Hz}^{-1/2} at 100,textrm{mHz}. As a result, the length fluctuations in a suspended optical resonator on top of the platforms is reduced by three orders of magnitude. This result is of direct relevance to gravitational wave detectors that use similar suspended optics and seismic isolation platforms.

Identification Model of Soil Physical State Using the Takagi–Sugeno Fuzzy Neural Network

Adjusting tillage parameters according to soil conditions can reduce energy consumption. In this study, the working parameters and soil physical parameters of plowing were determined using a designed electric suspension platform and soil instrument. The soil conditions were classified into three physical states, namely ‘hard’, ‘zero’, and ‘soft’ using a fuzzy C-means clustering algorithm, taking the soil moisture content and cone penetration resistance as the grading indexes. The Takagi–Sugeno (T–S) fuzzy neural network classifier was constructed using traction resistance, operating velocity, and plowing depth as inputs to indirectly identify the soil’s physical state. The results show that when 280 groups of test data were used to verify the model, 264 groups were correctly identified, indicating a soil physical state identification accuracy of 94.29%. The T–S fuzzy neural network prediction model can achieve the real-time and accurate physical state identification of paddy soil during plowing.

Novel Magnetic Suspension Platform with Three Types of Magnetic Bearings for Mass Transfer

For ultra-precision, large stroke, and high start/stop acceleration, a novel magnetic suspension platform with three types of magnetic bearings is proposed. The structure and working principle of the novel platform are introduced. The passive magnetic bearings are used to compensate for the weight of the actuator. The repulsive force of the passive magnetic bearing model is established and analyzed. The Lorentz force-type magnetic bearings are used to provide driving force and rotational torque in the XY-plane. The driving force model and rotational torque model are established. The electromagnetic suspension bearing is used to provide driving force in the Z-axis and rotational torque along the X-axis and Y-axis. A novel Halbach magnetic array is designed to improve the magnetic flux density in the air gap. The finite element method is used to validate the force model, torque model, and magnetic flux density in the air gap. The results show that the maximum force of the passive magnetic bearing is 79 N, and the rotational torque stiffness is 35 N/A in the XY-plane and 78 N/A along the Z-axis. The driving force stiffness is 91 N/A in the XY-plane and 45 N/A along Z-axis.

Design and Analysis of a 6-DOF Magnetic Suspension Platform with an Improved Permanent Magnetic Array.

For ultra-precision, large stroke, and high start/stop acceleration, a novel 6-DOF magnetic suspension platform with a novel structure of the permanent array is proposed. The structure and the working principle of the novel platform are introduced. An accurate model of the novel structure was established to calculate the magnetic density distribution for obtaining the parameters and performance of the magnetic suspension platform. The analytical model’s results were verified by the finite element method. The driving force model of the magnetic suspension platform was established based on the Lorentz force. Twelve laser displacement sensors were applied to perceive the posture and vibration acceleration of the platform. The hardware information and the measurement models were introduced and established based on the layout. Finally, the Lorentz force characteristics of the proposed platform were investigated and compared with the conventional magnetic platform by the finite element analysis. The results show that the average magnetic flux density is 0.54T, the horizontal current stiffness along the X-axis is 63.1N/A, the current stiffness along the Y-axis is 61.6N/A, and the average output torque is 7.2 N*cm of the novel platform, larger than those of the conventional ones.

Design and Analysis of a 2-DOF Electromagnetic Actuator with an Improved Halbach Array for the Magnetic Suspension Platform.

For large bearing capacity and low current consumption of the magnetic suspension platform, a 2-DOF electromagnetic actuator with a new structure of halbach array is proposed to improve driving force coefficients. The structure and the working principle are introduced. An accurate sub domain model of the new structure is established to accurately and rapidly calculate the magnetic field distribution for obtaining the parameters and performance of the electromagnetic actuators. The analytical model results are verified by the finite element method. The force/torque model of the magnetic suspension platform is established based on the proposed 2-DOF electromagnetic actuator. Three position-sensitive detectors and six accelerometers are applied to perceive in real time the posture and vibration acceleration of the platform, respectively. Their hardware information is introduced and measurement models are established based on the layout. Finally, the electromagnetic characteristics of the proposed actuator are investigated and compared with the conventional counterpart by finite element analysis. The results show that the average magnetic field, 0.432 T, horizontal and vertical force coefficient, 92.3 N/A and 30.95 N/A, and torque in x and z direction, 3.61 N·m and 8.49 N·m, of the proposed actuator are larger than those of the conventional one.

Characterization and implementation of a double-sided arm-toothed indirect-drive rotary electromagnetic energy-harvesting shock absorber in a full semi-trailer truck suspension platform

Heavy goods vehicles (HGVs), which usually travel on rough and dirt roads, have great potential for harvesting the dissipated energy during the damping routines. Thus, this study explores the benefits of energy-harvesting shock absorbers when integrated into HGVs due to their vibration's densities. The double-side arm-toothed indirect-drive rotary electromagnetic energy-harvester is consequently proposed. The contribution lies in that, (a) it could be the first time applying a double-side arm-toothed indirect-drive rotary electromagnetic energy-harvesting shock absorber in an articulated truck semi-trailer model; (b) complete characterization of the arm-toothed indirect-drive regenerative damper via parametrical conflict and sensitivity analyses; (c) quantitative assessment of the total harvestable power and voltage of the proposed 12 double-sided arm-toothed regenerative truck shock absorbers; and (d) Taguchi method simulation to perform a sensitivity ranking analysis of the truck influential parameters considering the harvested power, the truck ride quality and road holding criteria. The results indicate that the truck harvested an average power of 0.33, 1.33, 5.24, 21.3 W under road Classes of B, C, D, and E at 120 km/h. Regardless of the frequency range, the truck suspension can still maintain a comfortable driver ride index while simultaneously harvest power via the 12 integrated double-sided arm-toothed regenerative dampers.

Barrier Function-Based Adaptive Sliding Mode Control for Application to Vehicle Suspensions

A barrier function-based adaptive sliding mode control (SMC) strategy is proposed for the vehicle active suspension system in this article. The barrier function-based adaptive law is applied to design the sliding mode controller, which can ensure the finite-time convergence of the suspension system. Meanwhile, the proposed adaptive law can achieve greatly chattering reduction without requiring the prior information of the upper bound of system uncertainties. Furthermore, the time-delay estimation technique is applied to design the simple and efficient model-free controller. Therefore, the proposed controller has the strong robustness against the nonlinearities and uncertainties of the active suspension system, and it is very practical in actual scenarios. In addition, considering the transient and steady-state performance of the active suspension system, a prescribed performance function is adopted to constrain the vehicle displacement with its convergence rate, maximum overshoot, and steady-state value. Finally, compared with the conventional SMC and PD control, comparative experiments of a quarter-car active suspension platform are performed to verify the effectiveness of the proposed strategy.

Adaptive fuzzy backstepping control of underactuated multi-cable parallel suspension system with tension constraint

Multi-cable parallel suspension system (MCPSS) is designed to lift a heavy object with rapid development of deep resources exploitation. An adaptive fuzzy backstepping control strategy combining with nonlinear disturbance observer is studied to synthetically control the posture for the underactuated MCPSS with tension constraint in this article. Firstly, a theoretical modelling of the MCPSS with boundary constraints is derived by the extended Hamilton’s Principle. Secondly, the parameter uncertainties and time-varying disturbances are compensated by the fuzzy system and nonlinear disturbance observer, respectively. Thirdly, an adaptive fuzzy backstepping feedback controller based on the reference model is proposed to suppress vibration and control posture of the suspension platform. Finally, an Automatic Dynamic Analysis of Mechanical Systems (ADAMS) simulation and a numerical calculation are used to illustrate the theoretical model and the proposed control performance.

A Scalable Suspension Platform for Generating High-Density Cultures of Universal Red Blood Cells from Human Induced Pluripotent Stem Cells.

SummaryUniversal red blood cells (RBCs) differentiated from O-negative human induced pluripotent stem cells (hiPSCs) could find applications in transfusion medicine. Given that each transfusion unit of blood requires 2 trillion RBCs, efficient bioprocesses need to be developed for large-scale in vitro generation of RBCs.We have developed a scalable suspension agitation culture platform for differentiating hiPSC-microcarrier aggregates into functional RBCs and have demonstrated scalability of the process starting with 6 well plates and finally demonstrating in 500 mL spinner flasks. Differentiation of the best-performing hiPSCs generated 0.85 billion erythroblasts in 50 mL cultures with cell densities approaching 1.7 × 107 cells/mL. Functional (oxygen binding, hemoglobin characterization, membrane integrity, and fluctuations) and transcriptomics evaluations showed minimal differences between hiPSC-derived and adult-derived RBCs.The scalable agitation suspension culture differentiation process we describe here could find applications in future large-scale production of RBCs in controlled bioreactors.

A Novel 2-DOF Lorentz Force Actuator for the Modular Magnetic Suspension Platform.

The modular magnetic suspension platform depends on multi degree of freedom of Lorentz force actuators for large bearing capacity, high precision positioning and structure miniaturization. To achieve the integration of vertical driving force and horizontal driving force, a novel 2- (two degrees-of-freedom) DOF Lorentz force actuator is developed by designing the pose of the windings and permanent magnets (PMs). The structure and the working principle are introduced. The electromagnetic force mathematical model is established by the equivalent magnetic circuit method to analyze the coupling of magnetic flux. The distribution characteristics of magnetic flux density are analyzed by the finite-element method (FEM). It is found that the coupling of the magnetic flux and the large magnetic field gradient severely reduce the uniformity of the air-gap magnetic field. The electromagnetic force characteristic is investigated by FEM and measurement experiments. The difference between FEM and experiment results is within 10%. The reasons of driving force fluctuation are explained based on the distribution of air-gap magnetic field. The actuator performance are compared under the sliding mode control algorithm and PID control algorithm and the positioning accuracy is 20 μm and 15 μm respectively. Compared with the similar configuration, the motion range and force coefficient of the Lorentz force actuator in this paper are larger. It has a certain guiding significance on the structure design of the multi degree of freed Lorentz force actuator.

Dynamic modelling of a multi-cable driven parallel platform with guiding devices

ABSTRACT In this paper, a mathematical model is presented to numerically simulate the dynamical responses in a multi-cable suspension platform taking into account the slack cables and guiding devices. The state change of the cable (slack versus tensioned) is considered and is described mathematically by a complementary condition equation, and the interactions between the guiding wheels and the shaft wall are described by the Heaviside step function. The Lagrange’s equation with constraints is used to derive the dynamic equations of the system, and a non-smooth generalized-α algorithm for non-smooth phenomena of multibody dynamics is applied to numerically solve the equations. The simulation results have shown the dynamic responses of the platform and the cable tension characters when different cables are excited by different longitudinal excitations. Moreover, the results have illustrated how the cable tension differences may affect the pressure on the shaft wall applied by the guiding devices.

Optimization of the Gibco™ CTS™ LV-MAX™ Lentiviral Production System in Stirred Tank Bioreactors

Background & Aim The use of viral vectors for gene therapy applications is an emerging market that has gained considerable clinical traction in recent years. As the demand for gene therapy solutions has increased, the ability to produce viral vectors at manufacturing scale has become more critical. The Gibco™ CTS™ LV-MAX™ Lentiviral Production System is a cGMP-manufactured, xeno-free, 293F-based suspension platform that produces lentiviral vectors with high infectious titers (>1 x 108 TU/mL). The CTS LV-MAX system comprises GMP-banked 293F Virus Production Cells (VPCs), chemically defined growth and production medium, as well as a high-efficiency transfection reagent, titer boosting supplement and novel production enhancer. Since VPCs lack the large T antigen and have been adapted for high density growth in serum-free suspension culture, the LV-MAX system is inherently more scalable and cost-effective than traditional adherent-based virus production platforms. Here, we describe the scale up of the CTS LV-MAX system into stirred tank bioreactors and provide guidance for large scale production of lentiviral vectors under serum-free, suspension conditions. Methods, Results & Conclusion Design of experiment (DOE) and statistical analyses were used to identify the impact of various factors impacting lentiviral production in the CTS LV-MAX System including pH, stir speed, and timing of various reagent additions in both the ambr® 15 microbioreactor system and 3L Thermo Scientific™ HyPerforma™ stirred tank bioreactors. This multi-platform experimental approach allowed for the rapid development of a robust 2L working volume stirred tank bioreactor process capable of generating lentiviral vectors at levels equivalent to those of traditional small scale shake flasks. Future efforts to scale up production into larger bioreactors will further serve to meet the overwhelming production needs currently facing the gene therapy industry.

Robust [formula omitted] proportional-integral observer-based controller for uncertain LPV system

The main contribution of this paper is a robust integrated design of H∞ proportional - integral (PI) observer and state-feedback controller for uncertain linear parameter-varying (LPV) system. In this design, both fault estimation and robust feedback stabilization are developed. Moreover, since the state-feedback controller is derived from the PI observer, the loop transfer recovery (LTR) properties can be designed to maximize the closed-loop performance. Meanwhile, the PI observer and controller gains are simultaneously obtained from a linear matrix inequality (LMI), which is inferred from estimation errors, Young equality and majorization lemma implementation. Finally, its application to a vehicle suspension platform is presented to highlight the performances of the developed method.

Large scale serum free suspension lentiviral production for cell and gene therapy application

Background & Aim Lentiviral vectors have become the center of attention for its use as gene transfer vectors in gene therapy. Here, we have developed a new lentiviral production system for the clinical grade production of Lentiviral vectors on a large-scale serum-free suspension platform. This technology employs a newly developed propriety set of GMP reagents comprising of culture media, suspension cells, transfection reagent and boosting enhancers. With new culture media and media supplement, high density cell growth is optimized for maximum LVVs production. Methods, Results & Conclusion Customized lentivirus transfection reagents ensure highly efficient plasmids delivery. LVVs production is further elevated by the boosting enhancers. Taken together, our innovative system is able to deliver >2-3.0E+08 (TU/mL) functional titer with un-concentrated LVVs. We demonstrate that this system can be linearly adapted to bioreactors and wavebags system for large scale LVVs production without compromising the virus yield, which is ideal for industrial needs of gene therapy. Lentiviral vectors have become the center of attention for its use as gene transfer vectors in gene therapy. Here, we have developed a new lentiviral production system for the clinical grade production of Lentiviral vectors on a large-scale serum-free suspension platform. This technology employs a newly developed propriety set of GMP reagents comprising of culture media, suspension cells, transfection reagent and boosting enhancers. With new culture media and media supplement, high density cell growth is optimized for maximum LVVs production. Customized lentivirus transfection reagents ensure highly efficient plasmids delivery. LVVs production is further elevated by the boosting enhancers. Taken together, our innovative system is able to deliver >2-3.0E+08 (TU/mL) functional titer with un-concentrated LVVs. We demonstrate that this system can be linearly adapted to bioreactors and wavebags system for large scale LVVs production without compromising the virus yield, which is ideal for industrial needs of gene therapy.

Research on the Design Method of a Bionic Suspension Workpiece Based on the Wing Structure of an Albatross.

An air suspension platform uses air pressure to realize the suspension function during the suspension process, and it has the disadvantage of large air pressure and a small suspension force. In this study, an air suspension platform was built using bionic design to reduce the required air pressure and increase the suspension force. A suspension structure mapping model was established according to the physiological structure characteristics of albatross wings. A bionic model was established by using the theoretical calculation formula and structural size parameters of the structural design. A 3D printer was used to manufacture the physical prototype of the suspended workpiece. Based on this, a suspension test rig was built. Six sets of contrast experiments were designed. The experimental results of the suspension test bench were compared with the theoretical calculation results. The results show that the buoyancy of the suspended workpiece with a V-shaped surface at a 15-degree attack angle was optimal for the same air pressure as the other workpieces. The surface structure of the suspended workpiece was applied to the air static pressure guide rail. By comparing the experimental data, the air pressure of the original air suspension guide rail was reduced by 37%, and the validity of the theory and design method was verified.

Non-viral and viral delivery solutions for next generation cell therapy

Abstract The successes of chimeric antigen receptor (CAR) T cells in treating blood cancers have highlighted the cell therapy era. However, the difficulty of delivering molecules into immune cells has been an obstacle to more rapid advancement. Here we present an innovative large-scale Lentivirus (LV) production system as a solution to lower the cost and time of viral production. On the other hand, the next generation cell therapy will rely heavily on gene editing, especially in a safer non-viral integration manner. We have demonstrated that our novel non-viral all-in-one electroporation method provides high efficiency of gene knock-in in primary T cells. The new LV production system was developed for the clinical grade production of lentiviral vectors (LVVs) on a large-scale serum-free suspension platform. This technology employs a newly developed propriety set of GMP reagents comprising of culture media, suspension cells, transfection reagent and boosting enhancers. The system is able to deliver greater than 1 × 108 (TU/mL) functional titer with un-concentrated LVVs. For CRISPR/Cas9 gene editing in primary T cells, we were able to reach more than 90% knockout efficiency for most genes we tested, including T cell receptor (TCR), with Cas9 RNP electroporation using Neon Transfection System. More importantly, gene knock-in efficiency can be reached to greater than 30% with all-in-one electroporation, which delivers Cas9 RNP and donor DNA in one reaction using our newly developed electroporation buffer. Moreover, TCR knockout in addition to a knock-in at another locus can also be done in a single electroporation using our all-in-one method, which is ideal for developing next generation CAR and TCR-T cells.

Dynamic simulation of a multi-cable driven parallel suspension platform with slack cables

In this paper, a modelling method and an accurate numerical procedure are presented to simulate the dynamical responses of a multi-cable driven parallel suspension platform system. For such systems, the cables might become slack due to external excitations and due to the fact that cables can become tensionless when been pushed in longitudinal direction. In lateral and torsional directions, the constraint forces between the cables and platform can be positive as well as negative. This paper will deal with the non-smooth cable vibrations (in longitudinal, lateral and torsional directions) by taking into account the slackness of the cables. Firstly, the Lagrange equation with constraints is used to derive the equations of motion of the multi-cable suspension platform. Then, by expressing the equations of motion and constraint equations at velocity level, a non-smooth algorithm is used to numerically solve the equations. Finally, the numerical results are compared with an ADAMS simulation, and the two results agree well with each other. Moreover, the results in this paper significantly improve the numerical results used in the analysis of the dynamics for multi-cable systems which usually neglect the lateral properties of the cables.