Unmanned Aerial Vehicles (UAVs) are transforming various fields, from surveillance to agriculture, necessitating advanced control systems for effective operation. This study explores three prominent control strategies for UAV trajectory tracking: Proportional-Integral-Derivative (PID) control, Sliding Mode Control (SMC), and Backstepping Control. Each method is enhanced through Gray Wolf Optimization (GWO), a nature-inspired algorithm designed to determine the optimal control gains, thereby maximizing performance in real-world scenarios. The paper begins by providing a thorough overview of each control technique, elucidating their underlying principles and typical applications in UAV systems. We employ GWO to fine-tune the parameters of each controller, enabling a systematic approach to optimization that takes advantage of the algorithm's ability to converge towards global optima. This optimization is critical, as the success of UAV operations heavily relies on precise trajectory tracking, which is inherently influenced by the selected control strategy. To evaluate the effectiveness of each approach, we conduct a series of simulations that track the UAV’s performance across various trajectories. Key performance indicators such as speed, precision, and robustness are meticulously analyzed. The results illustrate significant variances in how each controller performs under different operational conditions, with a detailed discussion of their respective advantages and limitations. For instance, while the PID controller is noted for its simplicity and ease of implementation, it may struggle with robustness in dynamic environments. In contrast, the Sliding Mode Controller exhibits superior resilience to disturbances, yet may require more complex tuning. The Backstepping Control method, on the other hand, demonstrates exceptional precision, particularly in complex maneuvers, but can be computationally intensive. This comparative analysis provides crucial insights for researchers and practitioners in the UAV domain, highlighting the importance of selecting the appropriate control strategy based on mission requirements. By integrating GWO into the optimization process, we pave the way for more efficient and reliable UAV control systems, ultimately contributing to the advancement of autonomous aerial operations. The findings underscore the potential for future work to explore hybrid control approaches that leverage the strengths of each method, further enhancing UAV capabilities in increasingly complex environments.

This study presents a detailed analysis of a pyroelectric detector based on a lithium niobate (LiNbO₃) crystal for optimizing its performance under different geometrical configurations and electrical load conditions. The effect of varying the pyroelectric disk radius and thickness, as well as the electrical load resistance, on voltage, current, power, and temperature profiles, was thoroughly investigated. Results indicate that larger disk radii (up to 5 mm) enhance voltage and current sensitivity, thereby maximizing power output. However, larger radii also lead to slower temperature decay, highlighting the need for efficient thermal management to prevent structural overheating and maintain long-term functionality. Additionally, increasing the disk thickness from 0.01 mm to 0.04 mm results in substantial improvements in voltage, current, and power, with the most significant changes occurring between 0.01 mm and 0.02 mm. Conversely, thicker disks show better heat dissipation, helping mitigate temperature rise. The analysis of varied electrical load resistances reveals that lower resistances (1 kΩ) generate higher power and voltage outputs, while higher resistances reduce the system’s electrical response. These findings underscore the importance of optimizing both geometrical and electrical parameters to enhance the overall performance and thermal stability of pyroelectric detectors in practical applications. These findings provide valuable insights for optimizing pyroelectric sensor performance through geometric and electrical load adjustments. Future work includes the fabrication of the sensor using the optimized parameters, followed by experimental validation to assess its real-world performance.

Abstract - In modern industry, the integration of sensors with advanced artificial intelligence (AI) algorithms is essential for enhancing workflow efficiency and decision-making capabilities. This work introduces two innovative approaches that use these technologies to monitor and analyze liquid properties in real-time, shown in Figure 1. In the first approach (Figure 1 (a)), we designed a cuboid-shaped fluidic cell [1], fabricated from various materials using novel 3D printing techniques, featuring a vibrating membrane at its base with two external piezoelectric actuators attached. The second approach (Figure 1 (b)) employed micromachined plates driven by AlN piezoelectric films, fabricated using MEMS technology, meticulously designed to achieve quasi-free-free vibration in the (0,5) mode [2]. Both types of sensors used a two-port structure, one for actuation and the other for detection. The integration of these devices with AI techniques allowed us to use frequency responses in a range with multiple resonances, highly sensitive to fluid properties [3], while eliminating the need for complex electronics to process and acquire data.

Figure 1. (a) Top and cross-sectional views of the 3D-printed liquid cell with piezoelectric actuators. (b) Portable, low-cost viscometer-densimeter that included a MEMS microresonator, a microcontroller unit, and conditioning electronic circuits. The system incorporated a 3D-printed fluidic cell for injecting liquid into the sensor.

The spectra obtained with the sensors were subjected to various advanced data processing and machine learning techniques, performing an exhaustive search for the optimal combinations of hyperparameters that best fit the sensor data. Convolutional neural networks (CNNs) were found to be highly effective in working with frequency characteristics and estimating the viscosity and density of different types of liquids. In the second approach, these models were implemented on a microcontroller board, which also managed all electronics and communication with the sensor, resulting in a precise, compact, portable, and low-cost device.

Cell-based systems proved effective for monitoring the properties of aqueous solutions, achieving calibration errors below 2% and resolutions of 7.79 · 10^-3 mPa·s for viscosity, and 1.09 · 10^-3 g/mL for density. The microelectromechanical resonator-based instrument was capable to detect very small adulterations in olive oil with other vegetable oils, as low as 2%, with calibration and resolution errors of 0.47% and 0.14 mPa·s for viscosity, and 0.0331% and 9.25 · 10^-5 g/mL for density. The calibration and resolution accuracies obtained were comparable to or exceeded those in the state of the art, and were on par with other commercial laboratory instruments of greater complexity, cost, and stationary nature.

Our findings demonstrate the significant potential of integrating sensors with machine learning techniques to achieve accurate detection of physical properties in fluids and address complex and critical industrial challenges, such as olive oil fraud. These advancements pave the way for the development of next-generation sensors that are not only accurate and reliable but also scalable and adaptable to diverse applications, providing valuable tools for the new industry.

This article presents a comprehensive study on the control of linear speed and angular position in mobile robots using Proportional-Integral-Derivative (PID) controllers, with a focus on optimizing PID gains through metaheuristic optimization techniques. We begin by developing a detailed mathematical model of the robotic system, capturing its dynamics and response characteristics. Utilizing metaheuristic algorithms, such as Genetic Algorithms and Particle Swarm Optimization, we adaptively tune the PID parameters to enhance system performance in varying operational environments. The simulation results demonstrate significant improvements in trajectory tracking accuracy, reduced overshoot, and quicker settling times compared to conventional PID approaches. Additionally, the optimized PID controller showcases robust performance under different conditions, validating the effectiveness of our modeling and optimization strategy. This research not only highlights the potential of metaheuristic methods in fine-tuning PID controllers but also provides valuable insights into the simulation of mobile robotic systems, contributing to advancements in robotic control and navigation technologies.

In photovoltaic (PV) systems, efficient energy extraction is critical, especially under partial shading conditions where multiple local maxima can complicate the search for the true Maximum Power Point (MPP). This paper presents a robust approach to Maximum Power Point Tracking (MPPT) using the Particle Swarm Optimization (PSO) metaheuristic, tailored specifically for partial shading scenarios. The PSO method is advantageous due to its ability to handle the complex, non-linear nature of the power-voltage (P-V) and current-voltage (I-V) characteristics under varying irradiance levels. Unlike conventional MPPT techniques, which may converge to local maxima, the PSO-based method dynamically adjusts the duty cycle of the DC-DC converter, efficiently navigating the search space to locate the global MPP. The proposed method is evaluated through extensive simulations, where it consistently demonstrates superior performance in tracking the true MPP, regardless of the shading pattern. The paper provides a detailed analysis of the P-V and I-V curves under different shading conditions, showcasing how the PSO algorithm outperforms traditional methods in both convergence speed and accuracy. The results indicate a significant improvement in the power output of the PV system, highlighting the effectiveness of PSO in optimizing energy harvest. This study contributes to the growing field of renewable energy by offering a reliable and efficient solution for maximizing power generation in partially shaded PV systems.

1. Introduction

When heart function is impaired by 30%-50%, noticeable heart failure symptoms can occur. For end-stage heart failure patients, current ventricular assist devices can achieve a flow rate of 3-6 L/min, but invasive implantation methods pose significant risks of thrombosis and infection ^[1]. Research on non-blood-contact ventricular assist devices, both domestically and internationally, has mainly focused on pneumatic or hydraulic methods ^[2]. Although these methods can generate high pressures, they do not achieve non-blood-contact within the body. To improve existing ventricular assist devices, this study has preliminarily designed a wireless-powered pneumatic ventricular assist device. The device replaces percutaneous cable energy supply with magnetic resonance wireless energy technology, non-invasive is realized. It uses an internal gasbag to compress the ventricle, achieving non-blood-contact assistance. This approach offers a potential new technological pathway for the treatment of heart failure, but further research and validation are needed.

2. Methods

The pneumatic ventricular assist actuator mainly consists of an external power source, a wireless energy supply unit, a control system, and the actuator. The wireless energy supply unit provides energy to the internal control circuitry and compression actuator, thereby achieving non-invasive and minimizing the risk of secondary infection. The assist actuator is composed of a microcontroller, an air pump, an air storage gasbag, and a compression gasbag. The microcontroller manages the intake and exhaust pumps to control the expansion and contraction of the gasbag, thereby compressing the heart and achieving non-blood-contact assistance.

3. Results

A hollow silicone heart with a Young's modulus similar to that of the human heart was used as the test object to evaluate the assistive compression capability of the actuator at different compression frequencies. The results showed that the actuator could achieve an assistive compression pressure of 2 kPa at human heart rates (60-120 beats/min), meeting 74% of the required assistive pressure for the human heart. After extended testing, the assistive effect showed only a 3.33% reduction, indicating that the actuator can operate effectively for long periods.

4. Conclusion

The pneumatic ventricular assist actuator proposed in this study achieves non-invasive and non-blood-contact assistance, avoiding the thrombus and infection issues associated with traditional heart pumps. Preliminary experimental results indicate that the device can provide long-term, effective ventricular assistance in simulated human environments. However, the device is still in the early stages of exploration and requires further research and validation. It holds potential to become a viable technological pathway for the treatment of heart failure in the future.

References

[1] Weymann A, Foroughi J, Vardanyan R, et al. Artificial muscles and soft robotic devices for treatment of end‐stage heart failure[J]. Advanced Materials, 2023, 35(19): 2207390.

[2] Ranieri S B, Pascaner A F, Camus J M, et al. Towards the Development of a Multipurpose Console to Drive Pneumatic Assist Devices in Severe Heart Failure Refractory to Medical Treatment[C]//2019 Global Medical Engineering Physics Exchanges/Pan American Health Care Exchanges (GMEPE/PAHCE). IEEE, 2019: 1-4.

In recent years, there has been significant progress in the fabrication of exploration and inspection robots and actuators designed for confined spaces that are inaccessible to humans [1][2]. However, the fabrication process of existing robots and actuators designed for narrow environments is complex. Film actuators offer an effective strategy to address this problem. The structure of film actuators is relatively simple, and they are characterized by a lightweight and thin profile. The use of film actuators in exploration and inspection robots allows for the transportation of a large number of robots simultaneously. Accordingly, we proposed a new robotics concept using film actuators and structures called “Filmotics” [3].

Textured actuator using polyimide film was fabricated in our laboratory. Polyimide film exhibits high environmental resistance and mechanical properties. The actuator is fabricated by simultaneously welding two types of polyimide film and transferring a pattern on the surface. An aluminum foil is deposited on one side of the actuator, and a pattern for electric heating is formed by laser processing. The actuator is heated by applying electrical power to the electrodes and unfolds. The actuator returns to its initial curved state by natural cooling.

In this research, ultra-thin endoscope was fabricated to detect the inside of a narrow environment. The film endoscope is shown in Fig. 1. A small camera is mounted on top of the textured actuator. The endoscope can move through the field of view with one DOF by applying electrical power to the textured actuator. The curvature radius and the generated force of the textured actuator were evaluated when the electric power was applied. Additionally, the camera took pictures of the surrounding conditions while the actuator drove. The dimensions of the fabricated film endoscope are 28 mm × 45 mm, with a maximum protrusion of 4.1 mm and a mass of 85.4 mg. The actuator is constructed from film, it is imperative that the camera does not impede the operation of the actuator drive. The camera was selected based on its diminutive dimensions, minimal weight, and limited number of electrodes for wiring. The dimensions of the camera are 1.1 mm × 1.1 mm × 2.2 mm, and its mass is 4.6 mg. The camera is damaged by high temperatures. Thus, the temperature of the textured actuator surface was monitored for a five-minute interval. The results showed that the elevated temperature generated during actuator operation was not transferred to the camera mounted on the actuator tip. The radius of curvature of the endoscope was 19 mm by applying an electrical power of 1.5 W and a temperature of 216 ℃. The generated force was 20 mN under the same conditions. It is therefore expected to be useful in confined environments.

The endoscope is thin and suitable for confined environments. The direction of bending can be changed by changing the texture pattern. In the future, a multi-degree-of-freedom endoscope will be developed by adding multiple textures.

1. Suzumori, K.; Kondo, F.; Tanaka, H. Miniature Walking Robots. The Robotics Society of Japan. 1993, 385-390.
2. Braccini,M ; Gardinazzi,Y ; Roli,A ; Villani,M. Sensory–Motor Loop Adaptation in Boolean Network Robots. Robust Motion Recognition Based on Sensor Technology. 2024, 24, 3393.
3. Yamaguchi, D.; Hanaki, T.; Ishino, Y.; Hara, M.; Takasaki, M.; Mizuno, T. Concept and Prototype of Soft Actuator for Liquid Nitrogen Temperature Environments. Journal of Robotics and Mechatronics. 2020, 32, 1019-1026.

Background and purpose

Soft actuators are characterized by high safety and shape adaptability due to their high softness. However, their low rigidity makes them unsuitable for tasks requiring high load capacity, such as grasping and manipulating heavy objects. Therefore, actuators with stiffness-adjustable materials are being developed [1][2]. They can change their own stiffness and improve their load capacity while maintaining the shape adaptability that is a strong point of soft actuators. The purpose of this study is to fabricate a stiffness-adjustable soft actuator using a normal FDM 3D printer.

Structure

The actuator to be developed consists of a conductive material, a flexible material, and SMP (Shape Memory Polymer). The actuator function is achieved by a flexible material with a bellows structure on one side, which is curved by air pressure. The conductive material is used to heat the SMP which becomes less rigid upon heating. The stiffness of the actuator is variable, allowing the actuator to be driven in a low-stiffness state and then made stiff to maintain the curvature.

Experiments

The actuator consists of a conductive material in the shape of a U, SMP in the shape of a plate, and a flexible material in the shape of a bellows actuator.　By applying electric power of 90 W to the conductive material, the thermal characteristics were investigated by using thermal sensor experimentally. Figure 1 illustrates the temperature profile of the actuator, while Figure 2 depicts the actuator's appearance in its curved posture. After 60 seconds, it became 65.1 °C from 18.6 °C which is the room temperature. It is enough high to be rubbery state of the SMP, and under this condition, pneumatic pressure was applied up to 400 kPa, resulting in a curvature of 18.3 m^-1 at maximum. Additionally, the driving characteristics were investigated in a high stiffness state without applying power. The result was 1.32 m^-1 at 400 kPa, confirming that different curving quantity can be achieved at different stiffness levels. Furthermore, the stiffness was varied after curving, and the tip force was measured. When the load cell was pushed down the actuator’s tip to be the curvature of 10.6 m^-1 from the maximum curvature while maintaining the rubbery state by application of electric power, the reaction force was 125.2mN. Conversely, when the actuator became rigid state by stopping the application of electric power and cooling naturally to the room temperature, the tip force was 140.5mN.

The developed actuator can be curved at low stiffness condition and its stiffness can be higher with maintaining the deformation state. Therefore, the actuator is expected to be applied to robot hands capable of grasping heavy objects.

Acknowledgments

This study was partly supported by JSPS KAKENHI Grant Number JP23K03644 and JKA through its promotion funds from KEIRIN RACE

References

[1] Takashima, K.; Rossiter, J.; Mukai, T.; McKibben Artificial Muscle Using Shape-memory Polymer. Sensors and Actuators A, 2010, Vol. 164, pp. 116-124.

[2] Zhang, Y.; Zhang, N.; Hingorani, H.; Ding, N.; Wang, D.; Yuan, C.; Zhang, B.; Gu, G.; Ge, Q.; Fast-Response, Stiffness-Tunable Soft Actuator by Hybrid Multimaterial 3D Printing. Advanced Functional Materials, 2019, Vol.29,1806698.

The presentation will report on the Advanced Multilayer Adaptive Thin Shell (AMATS)
project aimed at developing actively controlled deployable primary reflectors with collecting
area significantly larger than the size of the satellite. The project, supported by the ESA
GSTP program, involves MateriaNova (Mons, Belgium) and Universite Libre de Bruxelles
(ULB). By utilizing a flexible polymer substrate material with an integrated piezoelectric
polymer control layer, the reflector can be folded into a small space while using active control
to compensate for thermal, viscoelastic and manufacturing errors. The targeted applications
are in the Long Wave Infrared (LWIR, λ = 10μm) which is gaining interest for Earth
observation, astronomical applications, and up- and downlink laser satellite communication
(because data transmission under adverse weather conditions is possible in LWIR). These
applications would benefit enormously from the increase of the reflector size while the surface
figure accuracy for LWIR seems to be achievable with active control.
The project builds on a previous demonstration of the control of a spherical thin polymer
shell using a piezoelectric polymer (PVDF-TrFE) activated by an array of independent
electrodes on the back side of the reflector. In the AMATS project, the design has been
improved by the addition of a thermal balancing layer, and the geometry is being adapted
to a petal-design suitable for folding into a 3U CubeSat.
The presentation will report on:
1. Progress in manufacturing of the petal polymer reflector.
2. The thermal response of the reflector.
3. The recent developments of a metrology system adapted to the in-lab measurements
of the surface figure of a petal spherical reflector with large aberrations, an extension
of the Software Configurable Optical Testing System (SCOTS) initially developed in
the University of Arizona.
4. The numerical simulation of the folding-deployment phases, the estimation of viscoelas-
tic aberration and their control.

1. Introduction

Solar panels are essential components of satellites that harvest solar energy as a source of power to support their operation. Due to their thin shapes and relatively complex and intricate structure, solar panels need to be folded in such a way as to enable a safe and simple launching procedure without causing any damage or harm to the panels. Then, they unfold when the satellite reaches in space.

This research concerns the application of a thermoplastic polymer by incorporating it into the elastic hinge as an actuator to facilitate the unfolding process of the panels with minimal impact. The field of smart or responsive materials has been growing rapidly day by day in recent decades. Researchers can now fabricate structures that can respond to external mediums or stimuli, like temperature, pressure, electric current, heat, humidity, and light, in many interesting ways [1]. These fabricated structures using smart materials can act as sensors and actuators, are self-repairable, or change shape on demand.

2. Materials and methods

The polymeric composite investigated in this research includes the thermoplastic polymer (thermoplastic polyurethane, TPU) as a matrix and carbon fibers as reinforcement to facilitate joule heating. The heating-responsive shape memory effect in this thermoplastic polymeric composite was used to perform the deployment of the hinge in a controlled manner. To demonstrate the deployment of the solar panels in a space satellite and the unfolding of a hinge, an experimental setup was created, as shown in Figure 1. The polymeric composite was attached to the metallic measurement tape, and an electric current was used to stimulate its recovery to its initial shape.

The mechanical properties of TPU, elastic cloth, and composite were characterized using the uniaxial tensile test on a Shimadzu 10 kN UTM with a constant strain rate of 10^-3 s^-1. The Differential Scanning Calorimetry (DSC Model Q200) technique was used to study the melting of TPU and the glass transition temperature.

Link of Figure 1

Figure 1: Experimental setup to demonstrate the controlled deployment of polymeric composite hinges.

3. Results and discussion

The mechanical properties of the polymeric composite obtained by the tensile test lie in between those of TPU and elastic cloth. The DSC graph (heat flow vs. temperature) of TPU 265A reveals the following thermal properties:

• The TPU 265A begins to melt at nearly 50 °C.
• The melting peak temperature (T_m) is 57.32 °C.
• The crystallization begins at a temperature of approximately 23 °C.
• The crystallization peak temperature (T_P) is 18.88 °C.

The measuring tape was bent at 180° into two equal lengths and then released to its natural position without applying any force. The bent tape acts as a hinge. After performing the rotation of the hinge 10 times, the average number of rotations the ball bearing made from its starting position to its final position was recorded. The results showed that the rotation without the application of polymeric composite at the hinge was significantly higher (630° rotation) than that with the application of polymeric composite at the hinge with the electric power supply, which was 1-2° rotation.

4. Conclusions

Through this research, experimental research was performed to investigate the optimal operating conditions and demonstrate the feasibility of achieving minimal impact during unfolding. The application of the TPU to a recyclable deployment hinge is possible. It can be heated and cooled multiple times without degrading its properties. The temperature required to become soft and viscous is not too high (around 50 °C). Moreover, it is light in weight, easy to manipulate, and less costly than the other materials.

References

[1] Wang, C.; Pek, J.X.; Chen, H.M.; Huang, W.M. On-Demand Tailoring between Brittle and Ductile of Poly (methyl methacrylate) (PMMA) via High Temperature Stretching. Polymers 2022, 14, 985.