Kedarisetty Siddhardha

Bio: Kedarisetty Siddhardha is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Acceleration & Multirotor. The author has an hindex of 2, co-authored 7 publications receiving 10 citations.

Autonomous reduced-gravity enabling quadrotor test-bed: Design, modelling and flight test analysis

Abstract: This work establishes conventional quadrotors as viable platforms to produce non-zero reduced-gravity. Toward this, a 1-D vertical manoeuvre with time-varying acceleration is proposed, which when followed by the quadrotor, the on-board payload experiences desired reduced gravity level for a specified time period. Since the proposed manoeuvre involves high axial accelerations and velocities, the standard steady-state thrust model cannot be used. A CFD tool—RotCFD—is used to study the thrust variation of a quadrotor in axial flight, and develop a thrust model. The developed model is experimentally validated through series of axial flight tests. As a consequence of the time varying forces—propeller thrust as well as drag—acting on the quadrotor, a control structure with fixed gains is neither capable of stabilizing the attitude nor maintaining the desired accelerations. A novel method of gain compensation is proposed which stabilizes the quadrotor and ensures quick acceleration convergence to the commanded value. Flight tests results for various reduced gravity levels from 0.8g–0.3g for a time interval of 3 seconds are presented to demonstrate the repeatability and reliability of the proposed control and automation strategies. Experimental results show that g-quality of the order 10 − 3 g is achieved.

A Novel Bi-rotor Configuration and its Control

Abstract: A novel bi-rotor configuration that uses reaction wheels to control the system attitude (roll and yaw) is presented in this article. This configuration exploits the fact that moment of inertia about the axis connection the two rotors (roll axis) is significantly less compared to moment of inertia about the other two orthogonal axes (pitch and yaw axes). A detailed mathematical model of the proposed configuration is presented. PD controllers are used to control the attitude and position of the system. Particle swarm optimization is used to obtain the controller gains and also to infer the role of actuator dynamics on system performance. The simulation results for attitude, position command tracking and way-point trajectory tracking are shown to demonstrate the performance of the proposed configuration.

Quadrotor hoverboard

Abstract: Riding on a quadrotor in a standing position demands extreme piloting skills. However, niche tasks like certain inspection and rescue missions can be accomplished by doing so. In this paper, we propose a control scheme that uses the center of gravity (CoG) variation caused by the tilt of the pilot standing on a quadrotor to maneuver it in the horizontal plane. Keeping potential applications in mind, we design controllers for two modes of operation: a) Maneuver via leaning mode during which the quadrotor converts the forward CoG shift into a proportional forward speed, and the sideward CoG shift to a yaw rate, thus enabling a turn, and b) Remote control mode in which the quadrotor platform rejects all the disturbances including the pilot’s movements and maintains the desired speed and turn commands provided by the pilot using a hand-held remote control. We use a simplified model of a human standing on a quadrotor to test the proposed control laws using simulations. The simulation results show that it is possible to control the quadrotor motion using CoG shifts caused by a pilot with moderate skills.

Microgravity Enabling Multirotors

Abstract: This work establishes multirotor unmanned aerial vehicles (UAVs) as viable microgravity platforms. Towards this, a vertical microgravity enabling maneuver suitable for multirotors, control and automation strategies, and techniques to enhance the performance of multirotors as microgravity platforms are proposed. Successful microgravity enabling maneuvers are performed to show the proposed control and automation strategies’ effectiveness using two multirotor test vehicles. Further, this paper shows that all the existing multirotors can be microgravity platforms and provide a method to calculate the maximum microgravity duration a multirotor can provide. Finally, experiments are conducted onboard one of the multirotors executing a microgravity enabling maneuver to observe the effect of microgravity on liquid level in a capillary and liquid meniscus shape in a glass cuvette. These experiments and the microgravity enabling flight tests demonstrate that multirotors can be turned into microgravity platforms. To the best of the author’s knowledge, the two UAVs presented in this paper are the first multirotor UAVs to achieve microgravity and the first UAVs—fixed-wing or rotary—to conduct onboard experiments in microgravity.

Autonomous Mars-Gravity Enabling Quadrotor

Abstract: Study of various physical phenomena in reduced gravity environments is of importance to several branches of science. This paper describes the trajectory design and automation control strategy for a quadrotor to maintain an acceleration such that a payload on-board experiences Mars-gravity for a short time period. A 1-D vertical trajectory with time varying acceleration is proposed for this purpose. A detailed kinematic analysis is presented to arrive at an acceleration schedule for the quadrotor to follow this trajectory. The analysis will also enable a designer to choose an appropriate motor-propeller combination for a quadrotor to follow this trajectory, given the constraints on peak altitude of the executed trajectory and duration for which reduced gravity needs to be maintained. The efficacy of the proposed approach and automation strategy is demonstrated using a detailed 6-DoF model simulation. Since the proposed trajectory is highly unsteady, the widely used steady state thrust model for quadrotors will not suffice. Therefore, a better thrust model is developed using blade element theory where the model parameters are estimated using experiments conducted in a wind tunnel. Our kinematic analysis shows that an appropriately designed quadrotor is capable of replicating Mars gravity environment for duration of 4 seconds while executing a vertical trajectory with peak altitude less than 45 m, which is validated through simulation and a preliminary flight test.

Gemini: A Compact Yet Efficient Bi-Copter UAV for Indoor Applications

Abstract: Quad-copters are the premier platform for data collection tasks, yet their ability to collect data in indoor narrow spaces is severely compromised due to their huge size when carrying heavy sensors. In this letter, we study a bi-copter UAV configuration that has similar levels of versatility and improves the compactness or efficiency at the same time. Such an arrangement allows for the preservation of propeller size, meaning that we can effectively reduce the horizontal width of the UAV while still maintains the same payload capacity. Furthermore, pitch, roll and yaw control can also be achieved through mechanically simple means as well, increasing reliability and precision. We also found that the Gemini platform is the most power-efficient yet practical solution for indoor applications among all the twelve common UAV configurations. This letter will detail the entire process of creating the platform from picking the ideal propeller through aerodynamic analysis, system design, optimization, implementation, control, and real flight tests that demonstrate its ability to function seamlessly.

Configurations, flight mechanisms, and applications of unmanned aerial systems: A review

Abstract: Unmanned Aerial Systems (UASs) have a variety of applications in our daily life that have attracted the attention of many researchers around the world. There are a variety of innovations in the flight mechanisms that UASs are applying for flight. There is also a significant interest in the development of new types of drones that can fly autonomously in different locations, such as cities, marine, and space environments and perform various missions. This paper reviews the different configurations, flight mechanisms, and applications of UASs. First of all, UASs are divided into four main categories, including Horizontal Takeoff and Landing (HTOL), Vertical Takeoff and Landing (VTOL), Hybrid, and Bio-Based drones. Then each category is divided into some sub-categories in order to have a coherent review. The characteristics, advantages and drawbacks of each category are discussed elaborately. Moreover, a comprehensive study is carried out on the applications of UASs and their specifications.

CFD analysis of the aerodynamic effects on the stability of the flight of a quadcopter UAV in the proximity of walls and ground

Abstract: Quadcopters are attracting a growing interest in many applications such as cargo delivery or surfaces inspection. These applications are often subjected to flights in the proximity of walls or ground that generate external forces and torques on the vehicle due to aerodynamic effects, because of what strong safety guarantees are required. In this research a methodology based on dynamic meshes was developed and applied to computational simulations to reproduce the flight of the drone over an obstacle. Thus, the effect of the ground proximity on the drone performance was assessed, and also its combination with the flow around the body at different translational velocities. The results shown a decrease of the drag force, and an increase of the lift and forward pitch moment due to the presence of the ground. These effects are magnified by the translational velocity, which also deviates the flow generated by the propellers and delays the interaction with the obstacle. Both in the approaching and leaving to the obstacle, increases of up to 60% in the pitch moment are observed. This sudden variations must be properly counteracted to guarantee the stability and safety of the drone operation.

Trajectory tracking control for a quadrotor unmanned aerial vehicle based on dynamic surface active disturbance rejection control

Abstract: This paper proposes a dynamic surface active disturbance rejection control (ADRC) strategy to deal with trajectory tracking problems for a quadrotor unmanned aerial vehicle (UAV). Compared with bac...

Design and real-time implementation of a wireless autopilot using multivariable predictive generalized minimum variance control in the state-space

Abstract: The contribution of this work is the numerical simulation and the experimental assessment of a network distributed control system using an unmanned aerial vehicle and a remote master controller connected by a wireless network. A novel multi-input multi-output long-range predictive horizon minimum variance control approach is developed and implemented in altitude, heading, lateral and longitudinal velocities control problems under the influence of process noise, measurement noise and time-delay. The proposed autopilots exhibited damped and fast response speeds with optimal control and output variance minimization, outperforming a classic model predictive control approach in convincing experimental field tests in real-world environments and scenarios.