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Carlos J. Montalvo
Department of Mechanical Engineering, University of South Alabama, 150 Student Services Drive, Mobile, AL 36688, USA

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Journal article
Published: 20 June 2020 in Atmosphere
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The accuracy and precision of iMET-XQ (InterMET Inc., Grand Rapids, MI, USA) temperature measurements in ten different locations on an off-the shelf rotary-wing unmanned aerial vehicle (rw-UAV) were assessed, as a function of atmospheric conditions. The rw-UAV hovered near an instrumented South Alabama Mesonet tower. The mean ± standard deviation of all the temperature differences between the tower and the ten iMET-XQ sensors for all experiments are −0.23 °C ±0.24 °C. Both the UAV and the environment influence the accuracy and precision of the iMET-XQ temperature measurements. Heat generated by the electronic components within the UAV body has a significant influence on the iMET-XQ temperature measurements, regardless of solar radiation conditions, and is highly dependent on wind direction. Electronic components within the UAV body heat up and can cause sensors downwind from the UAV body to record temperatures that are too warm, even if the sensors are aspirated by propeller wash. iMET-XQ sensors placed on rotor arms not near UAV body heat sources, and properly aspirated by propeller wash, perform well. Measurements from iMET-XQ sensors suspended below the UAV are also accurate. When using an off-the-shelf UAV for atmospheric temperature sensing, the electronic components inside the body of the UAV must be properly located. It is recommended that multiple sensors are placed on the UAV. Sensor redundancy will mitigate data loss in case of malfunction during flight and the identification of poorly performing sensors.

ACS Style

Sytske K. Kimball; Carlos J. Montalvo; Madhuri S. Mulekar. Assessing iMET-XQ Performance and Optimal Placement on a Small Off-the-Shelf, Rotary-Wing UAV, as a Function of Atmospheric Conditions. Atmosphere 2020, 11, 660 .

AMA Style

Sytske K. Kimball, Carlos J. Montalvo, Madhuri S. Mulekar. Assessing iMET-XQ Performance and Optimal Placement on a Small Off-the-Shelf, Rotary-Wing UAV, as a Function of Atmospheric Conditions. Atmosphere. 2020; 11 (6):660.

Chicago/Turabian Style

Sytske K. Kimball; Carlos J. Montalvo; Madhuri S. Mulekar. 2020. "Assessing iMET-XQ Performance and Optimal Placement on a Small Off-the-Shelf, Rotary-Wing UAV, as a Function of Atmospheric Conditions." Atmosphere 11, no. 6: 660.

Journal article
Published: 30 March 2020 in Atmosphere
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Temperature measurements of InterMET Inc. aluminum-coated iMET-XQ sensors were tested in an outdoor setting under a variety of solar radiation and wind speed conditions. Twelve unshielded sensors were mounted side-by-side on the tower of a South Alabama Mesonet weather station next to a reference sensor on the tower. The iMET-XQ temperatures were most precise and accurate in solar radiation values that were close to zero, regardless of wind speed. Under overcast conditions, wind speeds of 2 m s−1 were sufficient to obtain precise and accurate temperature measurements. During the day-time, aspiration of wind speeds higher than or equal to 3 m s−1 is sufficient. An iMET-XQ was placed in a radiation shield next to the tower reference sensor to test the need for a radiation shield. A second iMET-XQ was placed unshielded on the tower. The iMET-XQ sensors with aluminum coating do not need to be shielded, but they do need to be aspirated. It is recommended that, when taking temperature measurements using unmanned aerial vehicles (UAV) with iMET-XQ sensors, the UAV either fly at 3 m s−1, be embedded in winds of those speeds, or to use the propeller wash of the UAV to aspirate the sensors.

ACS Style

Sytske K. Kimball; Carlos J. Montalvo; Madhuri S. Mulekar. Evaluating Temperature Measurements of the iMET-XQ, in the Field, under Varying Atmospheric Conditions. Atmosphere 2020, 11, 335 .

AMA Style

Sytske K. Kimball, Carlos J. Montalvo, Madhuri S. Mulekar. Evaluating Temperature Measurements of the iMET-XQ, in the Field, under Varying Atmospheric Conditions. Atmosphere. 2020; 11 (4):335.

Chicago/Turabian Style

Sytske K. Kimball; Carlos J. Montalvo; Madhuri S. Mulekar. 2020. "Evaluating Temperature Measurements of the iMET-XQ, in the Field, under Varying Atmospheric Conditions." Atmosphere 11, no. 4: 335.

Short communication
Published: 08 April 2019 in Acta Astronautica
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The Electric Sail is investigated here with a focus on tether deployment. The Electric Sail is envisioned to deploy multiple greater than 1 km tethers connected to a central confluence point. The barbell Electric Sail which contains two satellites and two tethers connected to a central confluence point is investigated here. The deployment process is complex and has a high likelihood of creating unnecessary vibrations. In order to deploy the satellites, kinetic energy must be introduced into the system to separate the satellites. This kinetic energy must be removed without creating significant axial vibrations or the remainder of the mission will be compromised. Creating axial vibrations will impart a significant amount of fatigue on the system or could cause the entire system to collapse on itself. A braking mechanism is envisioned to be used to remove the kinetic energy via friction. The force vs time curve of the brake is the focus of this paper by investigating different braking control laws for the barbell Electric Sail. It is shown through simulation that using a Gaussian distribution for the braking force results in the lowest residual energy in the system. This is shown by using a previously derived multibody nonlinear simulation tool coupled to a visco elastic tether bead model.

ACS Style

Carlos Montalvo; Harrison White. Braking control law for a barbell Electric Sail. Acta Astronautica 2019, 160, 1 -6.

AMA Style

Carlos Montalvo, Harrison White. Braking control law for a barbell Electric Sail. Acta Astronautica. 2019; 160 ():1-6.

Chicago/Turabian Style

Carlos Montalvo; Harrison White. 2019. "Braking control law for a barbell Electric Sail." Acta Astronautica 160, no. : 1-6.

Journal article
Published: 28 October 2018 in Aerospace
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This paper investigates the design and flight test of two fixed wing aircraft connected at the wing tips. Connecting multiple aircraft introduces flexible modes into a typically rigid body system. These flexible modes make manual control of the entire system extremely difficult if not impossible. An autopilot system that seeks to keep this aircraft system wings level and a constant pitch angle is investigated here. The autopilot system is shown to work in an example simulation for a two body aircraft connected at the wing tips. An experimental aircraft system is also designed, built and flown with reasonable success proving the implementation of said controller on a real system.

ACS Style

Collin Carithers; Carlos Montalvo. Experimental Control of Two Connected Fixed Wing Aircraft. Aerospace 2018, 5, 113 .

AMA Style

Collin Carithers, Carlos Montalvo. Experimental Control of Two Connected Fixed Wing Aircraft. Aerospace. 2018; 5 (4):113.

Chicago/Turabian Style

Collin Carithers; Carlos Montalvo. 2018. "Experimental Control of Two Connected Fixed Wing Aircraft." Aerospace 5, no. 4: 113.

Journal article
Published: 03 September 2018 in Advances in Space Research
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A CubeSAT is a small satellite on the order of 10 cm along each axis. A 1U satellite is a small cube with 10 cm sides. A 2U CubeSAT has the volume of two single 1U satellites. The size of the satellite is 10 × 10 × 20 cm. These satellites are used for a variety of missions and created by a variety of different organizations. When deployed from a rocket, a CubeSAT may obtain a large angular velocity which must be reduced before most science missions or communications can take place. Maximizing solar energy charging also involves better pointing accuracy. To control the attitude of these small satellites, thrusters, reaction wheels or magnetorquers are used. On a standard CubeSAT, 3 reaction wheels are used as well as 3 magnetorquers. In the initial phase of the CubeSAT mission, the magnetorquers are used to reduce the angular velocity of the satellite down to a manageable level. Once the norm of the angular velocity is low enough, the reaction wheels can spin up reducing the angular velocity to zero. This paper derives a simple control scheme that allows the performance of the de-tumbling maneuver to decline while reducing the number magnetorquers by 1. Thus, the de-tumbling maneuver is completed using 2 magnetorquers rather than 3. This reduces complexity of the satellite, saves weight and reduces energy consumed by the satellite which can be used for other power hungry devices.

ACS Style

Matthew Monkell; Carlos Montalvo; Edmund Spencer. Using only two magnetorquers to de-tumble a 2U CubeSAT. Advances in Space Research 2018, 62, 3086 -3094.

AMA Style

Matthew Monkell, Carlos Montalvo, Edmund Spencer. Using only two magnetorquers to de-tumble a 2U CubeSAT. Advances in Space Research. 2018; 62 (11):3086-3094.

Chicago/Turabian Style

Matthew Monkell; Carlos Montalvo; Edmund Spencer. 2018. "Using only two magnetorquers to de-tumble a 2U CubeSAT." Advances in Space Research 62, no. 11: 3086-3094.

Research article
Published: 01 August 2018 in SIMULATION
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Radial Basis Functions are a modern way of creating a regression model of a multivariate function when sampled data points are not uniformly distributed in a perfect grid. Radial Basis Functions are well suited to atmospheric characterization when unmanned aerial vehicles (UAVs) are used to sample the given space. Multiple UAVs reduce the time for the Radial Basis Functions to yield a suitable solution to the measured data while data from all aircraft are aggregated and sent to Radial Basis Functions to fit the data. The research presented here focuses on the requirements for a high correlation value between the sampled data and the actual data. It is found that the number of centers is a large driver of the goodness of fit in the Radial Basis Function routine, much like aliasing is an issue in sampling a sinusoidal function. These centers act like a sampling rate for the spatially varying wind field. If the centers are dense enough to fully capture the spatial frequency of the wind field, the Radial Basis Functions will produce a suitable fit. This also requires the number of data points to be larger than the number of centers. The ratio between the number of centers and number of sampled data points declines as the number of centers increases. The results presented here are revealed using a two-dimensional Fourier series analysis coupled to a spatially varying atmospheric wind model and a Radial Basis Function regression model.

ACS Style

Brandon Troub; Rockwell Garrido; Carlos Montalvo; Jd Richardson. Characterization of a two-dimensional static wind field using Radial Basis Functions. SIMULATION 2018, 95, 561 -567.

AMA Style

Brandon Troub, Rockwell Garrido, Carlos Montalvo, Jd Richardson. Characterization of a two-dimensional static wind field using Radial Basis Functions. SIMULATION. 2018; 95 (6):561-567.

Chicago/Turabian Style

Brandon Troub; Rockwell Garrido; Carlos Montalvo; Jd Richardson. 2018. "Characterization of a two-dimensional static wind field using Radial Basis Functions." SIMULATION 95, no. 6: 561-567.

Journal article
Published: 01 July 2018 in Acta Astronautica
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This paper seeks to investigate the space flight dynamics of a rotating barbell Electric Sail (E-Sail). This E-Sail contains two 6U CubeSats connected to 8 km tethers joined at a central hub. The central hub is designed to be an insulator so that each tether can have differing voltages. An electron gun positively charges each tether which interacts with the solar wind to produce acceleration. If the voltage on each tether is different, the trajectory of the system can be altered. Flapping modes and tension spikes are found during many of these maneuvers and care must be taken to mitigate the magnitude of these oscillations. Using sinusoidal voltage inputs, it is possible to control the trajectory of this two-body E-Sail and propel the system to Near-Earth-Objects or even deep space.

ACS Style

Carlos Montalvo; Bruce Wiegmann. Electric sail space flight dynamics and controls. Acta Astronautica 2018, 148, 268 -275.

AMA Style

Carlos Montalvo, Bruce Wiegmann. Electric sail space flight dynamics and controls. Acta Astronautica. 2018; 148 ():268-275.

Chicago/Turabian Style

Carlos Montalvo; Bruce Wiegmann. 2018. "Electric sail space flight dynamics and controls." Acta Astronautica 148, no. : 268-275.

Research article
Published: 05 February 2018 in Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
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A comparison between two types of sensors and two types of simulation software are investigated here for a student built rocket. Many students use an open source software package called OpenRocket which uses empirical aerodynamics based on the shape of the rocket. This software is compared to the standard set of rigid body dynamic equations using coefficients for the aerodynamics based on windtunnel and computational fluid dynamics tests. During experimentation two sensors are used and price and resolution is compared. The first sensor is a turn-key sensor called the TeleMega which has many features such as telemetry and on board data logging. In an effort to reduce costs, the Arduino Mega platform has been augmented with a custom made shield capable of measuring Global Positioning System (GPS), angular velocity, and attitude information with on board data logging as well. Although this sensor has limited functionality, the cost is substantially reduced. It is shown that all sensors and simulation software have their strengths and weaknesses with appropriate usage for each.

ACS Style

William Brown; Michael Wiesneth; Thomas Faust; Nghia Huynh; Carlos Montalvo; Kent Lino; Andrew Tindell. Measured and simulated analysis of a model rocket. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 2018, 233, 1397 -1411.

AMA Style

William Brown, Michael Wiesneth, Thomas Faust, Nghia Huynh, Carlos Montalvo, Kent Lino, Andrew Tindell. Measured and simulated analysis of a model rocket. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 2018; 233 (4):1397-1411.

Chicago/Turabian Style

William Brown; Michael Wiesneth; Thomas Faust; Nghia Huynh; Carlos Montalvo; Kent Lino; Andrew Tindell. 2018. "Measured and simulated analysis of a model rocket." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 4: 1397-1411.

Research article
Published: 07 June 2017 in International Journal of Micro Air Vehicles
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This paper analyzes the performance of a micro-airship fleet (0.5 m diameter) to navigate indoors with waypoint control while tolerating collision between airships and the environment. Very little focus has been placed on studying airships in groups or how well they can rebound back into formation after a collision. With a micro-airship fleet, it is possible to remove the major problem of collision avoidance in multi-unmanned aerial vehicle missions, which can result in damage or even mission failure when other types of aircraft are used. These vehicles could be a viable option for missions where speed and precise control are not an important design constraint, such as indoor reconnaissance or long-term surveillance. A three degree of freedom simulation is created in which five airships are commanded to waypoints throughout a hall way. The control logic used involves independent proportional–derivative control without any communication between airships. Collisions occur during missions; thus, a contact model is included in the simulation to model these effects. Airship parameters were estimated using an actual airship to assure the simulation is accurate. The results show that the airships are able to navigate to their destinations even after several collisions.

ACS Style

Brandon Troub; Brandi DePineuil; Carlos Montalvo. Simulation analysis of a collision-tolerant micro-airship fleet. International Journal of Micro Air Vehicles 2017, 9, 297 -305.

AMA Style

Brandon Troub, Brandi DePineuil, Carlos Montalvo. Simulation analysis of a collision-tolerant micro-airship fleet. International Journal of Micro Air Vehicles. 2017; 9 (4):297-305.

Chicago/Turabian Style

Brandon Troub; Brandi DePineuil; Carlos Montalvo. 2017. "Simulation analysis of a collision-tolerant micro-airship fleet." International Journal of Micro Air Vehicles 9, no. 4: 297-305.