Navigation, Spacecraft and Payload Control
PI: Hari Hablani
Satellite-Based Navigation of Flight Vehicles
ISRO has invested significant resources in establishing and providing navigation signals to users from national satellites system NavIC (Navigation with Indian Constellation). Our research is concerned with developing algorithms to use these signals for precise navigation of land vehicles, aeroplanes, satellites, launch vehicles, and missiles.
Position Estimation Error with Nav IC Signals
Control of Satellites and Payloads and Minimization of Mutual Interference
Remote sensing, communication and navigation satellites have payloads with mirrors, radars and infrared sensors that scan the earth, ocean and space with satellite platforms as their base. But this motion causes the platforms to reorient, which interferes with the operation of the payloads. Additionally, due to environmental perturbing forces, the satellites deviate from their intended ideal position and velocity, which interferes with the spatial registration of images acquired with remote sensing. The objective of this research is to understand the mechanics of these interferences and minimize them.
Sun-Synchronous Spacecraft Remote Sensor Scanning the Earth
Space-Based Radar Scanning the the Ground
Steady state error in tracking a ground station
Steady state rate error in tracking a ground station
Spacecraft Controllers Errors in Tracking a Ground Station
Agile Maneuvers of Reconnaissance and Surveillance Spacecraft with Control Moment Gyros
As spacecraft become heavy with their imaging payloads, the high-torque control moment gyros (CMGs) become the actuators of choice so that the spacecraft can be reoriented rapidly to acquire and track successive objects or areas of interest on the ground. But CMGs have spinning wheels and their momentum is turned around to produce the desired spacecraft control torque. But this occasionally results in alignment of the CMGs momentums, and the CMGs then cannot produce the desired torque, a state known as a singularity. The objective of this research is to develop control algorithms for CMGs so that they steer away from singularity while acquiring and tracking the targets of interest. An additional objective is to demonstrate these controllers on a CMG testbed at ISRO Inertial Systems Unit.
Navigation of Precision Munition with Infrared and Millimeter-Wave Radar Sensors Homing in on Moving Ground Targets
The objective of this research is to develop navigation and guidance algorithms for dual-sensor air-to-surface precision munition to neutralize moving tanks in mountainous areas covered with snow and trees or in deserts in inclement weather. The infrared and millimetre-wave radar dual-sensor is particularly apt for targets with electronic countermeasures, suppressed radar signature, and small temperature difference with cluttered surroundings. Navigation algorithms and Kalman filters are developed to meet or exceed the specified performance metrics of a probability of detection, a probability of false alarm and circular error probable radius of miss distance.
Munition Homing in on the tank with Infrared Sensor and Millimeter wave radar
Dynamics and Guidance of Reentry Spacecraft
The objective of this research is to develop an understanding and a simulation of reentry dynamics under classic guidance laws, namely, the constant drag deceleration, and the constant descent rate to land at a specific site. Furthermore, the objectives are to overcome the limitations of these guidance laws by treating reentry as a two-point boundary value problem with initial conditions at the interface of the final orbit or approaching interplanetary trajectory and the reentry trajectory ending at the desired landing latitude and longitude on the land or ocean with a desired touchdown velocity.
Entry and Descent Navigation of Lunar Lander
The objective of this research is to develop a high-accuracy inertial navigation system aided with a radar altimeter for entry and descent on the Moon’s surface.