AEROS is a 3U CubeSat pathfinder toward a future ocean-observing constellation, which will operat... more AEROS is a 3U CubeSat pathfinder toward a future ocean-observing constellation, which will operate in a 500 km Sun-Synchronous orbit, targeting the Portuguese Atlantic region. AEROS features a miniaturized, high-resolution Hyperspectral Imager (HSI), a 5MP RGB camera, and a Software Defined Radio (SDR) to interface with Argos, a globally distributed system of remote platforms that collect and relay oceanographic and meteorological data. These sensors will facilitate the advancement of Portuguese scientific and technological knowledge, and international space industry partnerships, with data processed and aggregated for end-users in a new web-based Data Analysis Center (DAC). The HSI has 150 spectrally contiguous bands covering visible to near-infrared (470 nm-900 nm) with 10 nm bandwidth (full width at half maximum). The HSI collects ocean color data to support studies of oceanographic characteristics (e.g. primary productivity, mesoscale ocean fronts, and eddies) known to influence the spatio-temporal distribution and movement behavior of marine organisms. To inform performance estimates for the HSI, radiometric analyses were conducted to characterize band sensitivity given varying atmospheric and target conditions. Simulated HSI images were generated to assess suitability for scientific purposes through interpolation of spectral information from Sentinel-2 imagery combined with the AEROS's sensor spectral responses (real calibrated data) and missionspecific parameters. Usage of an SDR expands AEROS's operational and communication range and allows for remote reconfiguration. The SDR receives, demodulates, and retransmits short duration messages (401.650 MHz + 30kHz), from Argos sources including tagged marine organisms, vessels, autonomous vehicles, subsurface floats, and buoys. This allows AEROS to retransmit messages from Argos platforms to ground and processing stations that compute platform locations using Doppler effect measurements. The future DAC will collect, store, process, and analyze acquired data, taking advantage of its ability to disseminate data across the stakeholders and the scientific network. Correlation of animal-borne Argos platform locations and oceanographic data will advance fisheries management, ecosystem-based management, monitoring of marine protected areas, and bio-oceanographic research in the face of a rapidly changing environment. For example, correlation of oceanographic data collected by the HSI, geolocated with supplementary images from the RGB camera and fish locations, will provide researchers with near real-time estimates of essential oceanographic variables within areas selected by species of interest (e.g., sharks, rays, and tuna). This is essential for determining how keystone species, or those vulnerable to overexploitation, interact with their environment. Other relevant applications include monitoring sediment transport, erosion, pollution, and human activities.
The AEROS ocean observation mission and its CubeSat pathfinder Rute Santos (1),(4) , Orfeu Bertol... more The AEROS ocean observation mission and its CubeSat pathfinder Rute Santos (1),(4) , Orfeu Bertolami (2) , E. Castanho (3) , P. Silva (3) , Alexander Costa (4) , André G. C. Guerra (4) , Miguel Arantes (4) , Miguel Martin (4) , Paulo Figueiredo (4) , Catarina M. Cecilio (5) , Inês Castelão (5) , L. Filipe Azevedo (6) , João Faria (6) , H. Silva (7) , Jorge Fontes (8) , Sophie Prendergast (8) , Marcos Tieppo (9) , Eduardo Pereira (9) , Tiago Miranda (9) , Tiago Hormigo (10) , Kerri Cahoy (11) , Christian Haughwout (11) , Miles Lifson (11) , Cadence Payne (11)
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2013
Spin.Works has developed a complete micro-UAV system with the purpose of supporting forest manage... more Spin.Works has developed a complete micro-UAV system with the purpose of supporting forest management activities. The aircraft is based on a winged-body design spanning 1.8m with a maximum take-off weight of 2kg, and can carry out missions lasting up to 2h at a cruise speed of about 60km/h. The corresponding ground station ensures the mission planning functions, real-time flight monitoring and visualization, and serves also as a real-time and post-flight data exploitation platform. A particular emphasis is placed on image processing techniques applied to two operational concepts: a fire detection service and a forest mapping service. The real-time operations related to fire detection consist on object tracking and geo-referencing functions, which can be operated by a user directly over the video stream, enabling the quick estimation of the 3D location (latitude, longitude, altitude) of suspected fires. The post-flight processing consists of extracting valuable knowledge from the payload data, in particular tree coverage maps, orthophoto mosaics and Digital Surface Models (DSMs), which can be used for further forest characterization such as wood and cork volume estimation. The system is currently entering initial operations, with expanded operations expected during Q3 2013.
AIAA Guidance, Navigation and Control Conference and Exhibit, 2008
A nonlinear control approach is developed for both the attitude and trajectory control and of an ... more A nonlinear control approach is developed for both the attitude and trajectory control and of an Apollo-like capsule with low L/D entering the martian atmosphere, resulting in a very high probability (>99%) of a safe parachute deployment very close to a pre-defined location above Mars surface, enabling a precision l anding (<1km). The attitude control is based on the feedback linearization of the inner (a ttitude dynamics) and outer (attitude kinematics) attitude control loops, in which the de sired dynamics of the linearized loop are tuned such as to ensure both robustness to uncertai nties, moderate demands to the attitude control system and a high tracking performance. The trajectory control also includes nonlinear tracking laws for the drag acceleration a nd range. The trajectory control is based on the modulation of the bank angle, such as to poi nt the lift vector in the direction most suitable to increase or decrease the vehicle’s rate of descent as required. The guidance algorithm associated to the trajectory tracking law attempts to follow a drag acceleration profile, a range profile and a heading angle as the flight progresses, in an attempt to circumvent the known shortcomings of previous entry guidance approaches (namely in terms of range prediction) while avoiding any analy tical predictions, numerical integration of the equations of motion, in-flight trajectory up dates or trajectory optimization during the flight. Monte-Carlo simulations have been carried o ut in high-fidelity 4DOF and 6DOF simulations, introducing significant perturbations to the initial state, the vehicle’s aerodynamics, its’ mass properties and in atmospheric models. Results compare very favorably to existing approaches both in terms of r obustness to uncertainties and overall system performance, while the guidance and control system hereby presented requires a comparably small computational cost.
Keeping the spacecraft (S/C) healthy and productive is the responsibility and the main concern of... more Keeping the spacecraft (S/C) healthy and productive is the responsibility and the main concern of the S/C flight control team (FCT). Space weather includes effects and conditions that favour the aging of a S/C and its instruments, e.g. degradation of sensors and solar arrays by charged particles and single event upsets (SEU). It is worth to stress out that it
2020 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR)
Considering the growth of drone usage in various applications in safety, security, and rescue dom... more Considering the growth of drone usage in various applications in safety, security, and rescue domains, the need to obtain a collision-free flight is a central problem in autonomous drones. In addition, being the environments in these applications mostly unstructured, dynamic, and unpredictable, the capability of reacting in real-time to the environment is paramount. Using the visual information from a monocular camera, this paper proposes an obstacle avoidance technique based on Time-to-Collision (TTC) estimations. An optimal control problem is formulated and solved in real-time using a Model Predictive Control (MPC) approach, in cascade with an attitude controller, to determine the rotors' actuation signals. The MPC algorithm uses the target information from the vision method to lead the drone to a position that ensures a correct tracking in real-time and, simultaneously, use the TTC data to generate potential fields in the vehicle reference frame ensuring obstacle avoidance. The results in simulation show that the drone can accurately compute the TTC, track a target, and maintain a safe distance from obstacles. Moreover, the strategy reveal to be computationally non-demanding, indicating that the obstacle avoidance approach presented can be easily integrated in a real-time solution.
The operational conditions encountered in under-the-ice environments are extreme and demanding, t... more The operational conditions encountered in under-the-ice environments are extreme and demanding, thus preventing human-centred exploration. The study of these environments is dependent on the development of robust and flexible navigation strategies to guide autonomous vehicles in these barely known ecosystems. This work proposes an integration of different underwater navigational strategies with a view to addressing a Simultaneous Localization and Mapping scenario. The navigational algorithm combines Dead Reckoning and Scan Matching techniques, complemented with Single Beacon navigation. In addition, the latter strategy includes a new method to identify and reject erroneous range measurements, which only depends on the collected range information. The navigation system is rooted in Kalman filtering theory, and relies on bathymetric information from the underwater ice cap and proprioceptive measurements. Through the implementation of a vehicle’s simulator, the simulations highlight Si...
AEROS is a 3U CubeSat pathfinder toward a future ocean-observing constellation, which will operat... more AEROS is a 3U CubeSat pathfinder toward a future ocean-observing constellation, which will operate in a 500 km Sun-Synchronous orbit, targeting the Portuguese Atlantic region. AEROS features a miniaturized, high-resolution Hyperspectral Imager (HSI), a 5MP RGB camera, and a Software Defined Radio (SDR) to interface with Argos, a globally distributed system of remote platforms that collect and relay oceanographic and meteorological data. These sensors will facilitate the advancement of Portuguese scientific and technological knowledge, and international space industry partnerships, with data processed and aggregated for end-users in a new web-based Data Analysis Center (DAC). The HSI has 150 spectrally contiguous bands covering visible to near-infrared (470 nm-900 nm) with 10 nm bandwidth (full width at half maximum). The HSI collects ocean color data to support studies of oceanographic characteristics (e.g. primary productivity, mesoscale ocean fronts, and eddies) known to influence the spatio-temporal distribution and movement behavior of marine organisms. To inform performance estimates for the HSI, radiometric analyses were conducted to characterize band sensitivity given varying atmospheric and target conditions. Simulated HSI images were generated to assess suitability for scientific purposes through interpolation of spectral information from Sentinel-2 imagery combined with the AEROS's sensor spectral responses (real calibrated data) and missionspecific parameters. Usage of an SDR expands AEROS's operational and communication range and allows for remote reconfiguration. The SDR receives, demodulates, and retransmits short duration messages (401.650 MHz + 30kHz), from Argos sources including tagged marine organisms, vessels, autonomous vehicles, subsurface floats, and buoys. This allows AEROS to retransmit messages from Argos platforms to ground and processing stations that compute platform locations using Doppler effect measurements. The future DAC will collect, store, process, and analyze acquired data, taking advantage of its ability to disseminate data across the stakeholders and the scientific network. Correlation of animal-borne Argos platform locations and oceanographic data will advance fisheries management, ecosystem-based management, monitoring of marine protected areas, and bio-oceanographic research in the face of a rapidly changing environment. For example, correlation of oceanographic data collected by the HSI, geolocated with supplementary images from the RGB camera and fish locations, will provide researchers with near real-time estimates of essential oceanographic variables within areas selected by species of interest (e.g., sharks, rays, and tuna). This is essential for determining how keystone species, or those vulnerable to overexploitation, interact with their environment. Other relevant applications include monitoring sediment transport, erosion, pollution, and human activities.
The AEROS ocean observation mission and its CubeSat pathfinder Rute Santos (1),(4) , Orfeu Bertol... more The AEROS ocean observation mission and its CubeSat pathfinder Rute Santos (1),(4) , Orfeu Bertolami (2) , E. Castanho (3) , P. Silva (3) , Alexander Costa (4) , André G. C. Guerra (4) , Miguel Arantes (4) , Miguel Martin (4) , Paulo Figueiredo (4) , Catarina M. Cecilio (5) , Inês Castelão (5) , L. Filipe Azevedo (6) , João Faria (6) , H. Silva (7) , Jorge Fontes (8) , Sophie Prendergast (8) , Marcos Tieppo (9) , Eduardo Pereira (9) , Tiago Miranda (9) , Tiago Hormigo (10) , Kerri Cahoy (11) , Christian Haughwout (11) , Miles Lifson (11) , Cadence Payne (11)
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2013
Spin.Works has developed a complete micro-UAV system with the purpose of supporting forest manage... more Spin.Works has developed a complete micro-UAV system with the purpose of supporting forest management activities. The aircraft is based on a winged-body design spanning 1.8m with a maximum take-off weight of 2kg, and can carry out missions lasting up to 2h at a cruise speed of about 60km/h. The corresponding ground station ensures the mission planning functions, real-time flight monitoring and visualization, and serves also as a real-time and post-flight data exploitation platform. A particular emphasis is placed on image processing techniques applied to two operational concepts: a fire detection service and a forest mapping service. The real-time operations related to fire detection consist on object tracking and geo-referencing functions, which can be operated by a user directly over the video stream, enabling the quick estimation of the 3D location (latitude, longitude, altitude) of suspected fires. The post-flight processing consists of extracting valuable knowledge from the payload data, in particular tree coverage maps, orthophoto mosaics and Digital Surface Models (DSMs), which can be used for further forest characterization such as wood and cork volume estimation. The system is currently entering initial operations, with expanded operations expected during Q3 2013.
AIAA Guidance, Navigation and Control Conference and Exhibit, 2008
A nonlinear control approach is developed for both the attitude and trajectory control and of an ... more A nonlinear control approach is developed for both the attitude and trajectory control and of an Apollo-like capsule with low L/D entering the martian atmosphere, resulting in a very high probability (>99%) of a safe parachute deployment very close to a pre-defined location above Mars surface, enabling a precision l anding (<1km). The attitude control is based on the feedback linearization of the inner (a ttitude dynamics) and outer (attitude kinematics) attitude control loops, in which the de sired dynamics of the linearized loop are tuned such as to ensure both robustness to uncertai nties, moderate demands to the attitude control system and a high tracking performance. The trajectory control also includes nonlinear tracking laws for the drag acceleration a nd range. The trajectory control is based on the modulation of the bank angle, such as to poi nt the lift vector in the direction most suitable to increase or decrease the vehicle’s rate of descent as required. The guidance algorithm associated to the trajectory tracking law attempts to follow a drag acceleration profile, a range profile and a heading angle as the flight progresses, in an attempt to circumvent the known shortcomings of previous entry guidance approaches (namely in terms of range prediction) while avoiding any analy tical predictions, numerical integration of the equations of motion, in-flight trajectory up dates or trajectory optimization during the flight. Monte-Carlo simulations have been carried o ut in high-fidelity 4DOF and 6DOF simulations, introducing significant perturbations to the initial state, the vehicle’s aerodynamics, its’ mass properties and in atmospheric models. Results compare very favorably to existing approaches both in terms of r obustness to uncertainties and overall system performance, while the guidance and control system hereby presented requires a comparably small computational cost.
Keeping the spacecraft (S/C) healthy and productive is the responsibility and the main concern of... more Keeping the spacecraft (S/C) healthy and productive is the responsibility and the main concern of the S/C flight control team (FCT). Space weather includes effects and conditions that favour the aging of a S/C and its instruments, e.g. degradation of sensors and solar arrays by charged particles and single event upsets (SEU). It is worth to stress out that it
2020 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR)
Considering the growth of drone usage in various applications in safety, security, and rescue dom... more Considering the growth of drone usage in various applications in safety, security, and rescue domains, the need to obtain a collision-free flight is a central problem in autonomous drones. In addition, being the environments in these applications mostly unstructured, dynamic, and unpredictable, the capability of reacting in real-time to the environment is paramount. Using the visual information from a monocular camera, this paper proposes an obstacle avoidance technique based on Time-to-Collision (TTC) estimations. An optimal control problem is formulated and solved in real-time using a Model Predictive Control (MPC) approach, in cascade with an attitude controller, to determine the rotors' actuation signals. The MPC algorithm uses the target information from the vision method to lead the drone to a position that ensures a correct tracking in real-time and, simultaneously, use the TTC data to generate potential fields in the vehicle reference frame ensuring obstacle avoidance. The results in simulation show that the drone can accurately compute the TTC, track a target, and maintain a safe distance from obstacles. Moreover, the strategy reveal to be computationally non-demanding, indicating that the obstacle avoidance approach presented can be easily integrated in a real-time solution.
The operational conditions encountered in under-the-ice environments are extreme and demanding, t... more The operational conditions encountered in under-the-ice environments are extreme and demanding, thus preventing human-centred exploration. The study of these environments is dependent on the development of robust and flexible navigation strategies to guide autonomous vehicles in these barely known ecosystems. This work proposes an integration of different underwater navigational strategies with a view to addressing a Simultaneous Localization and Mapping scenario. The navigational algorithm combines Dead Reckoning and Scan Matching techniques, complemented with Single Beacon navigation. In addition, the latter strategy includes a new method to identify and reject erroneous range measurements, which only depends on the collected range information. The navigation system is rooted in Kalman filtering theory, and relies on bathymetric information from the underwater ice cap and proprioceptive measurements. Through the implementation of a vehicle’s simulator, the simulations highlight Si...
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Papers by Tiago Hormigo