Showing papers by "Asokan Thondiyath published in 2018"

Theoretical and Experimental Investigations on the Effect of Overlap and Offset on the Design of a Novel Quadrotor Configuration, VOOPS

Abstract: The theoretical and experimental investigations of a novel configuration for a Vertical Take Off and Landing (VTOL) quadrotor system with a Vertically Offset Overlapped Propulsion System (VOOPS) is presented in this paper. The objective of the VOOPS concept is to improve the load carrying capability of the VTOL system without any increase in the footprint or reduction in endurance. This has been accomplished by overlapping the propeller blades with a vertical offset such that they don’t intersect. This way VOOPS can accommodate a larger propeller size without increase in footprint. The aerodynamics of the overlap and offset on the quadrotor performance has been analyzed using Blade Element and Momentum Theory (BEMT) and a methodology has been proposed to find their effects on thrust, drag, and power. The important design constraints for VOOPS are offset and overlap of the propellers, whose limits are evaluated using the blade-bending profile and the geometry of the propeller, respectively. The mathematical model and the design of a VOOPS quadrotor system is also presented. A quadrotor with VOOPS configuration has been designed and experimental studies have shown that the theoretical results obtained are in good agreement with the experiments. The practical implementation of VOOPS configuration and the consequences of the design changes are also presented.

Design and Analysis of a Novel Underwater Glider - RoBuoy

Abstract: Underwater gliders are special class of autonomous underwater vehicles (AUVs) proven to be power efficient with better range and endurance compared to the conventional underwater robots. Most of the existing underwater gliders use ‘change of mass’ based variable buoyancy (VB) method in which the overall system architecture and construction are complex. A novel underwater glider RoBuoy based on the ‘change of volume’ concept of variable buoyancy method is presented here. RoBuoy uses actuated metallic bellows to change the volume which makes the system simple and modular in construction without any compromise in the performance. It uses minimal number of parts compared to the existing gliders which reduces the overall complexity of the system. Also, most of the conventional gliders use the external fluid for its working which may result in corrosion or fouling of parts and requires frequent maintenance. In the proposed glider, all the vital parts required for its working, apart from the sensing payloads are enclosed inside the hull, thereby increasing the durability. In this paper, a detailed design of RoBuoy is discussed with its possible modes of operation. An integrated mathematical model considering the individual dynamics of the actuator, hull/fuselage, and the wings has been developed and the open loop performance of the glider is studied at different input conditions. An experimental prototype has been designed and fabricated based on optimized dimensions, with the required mechatronic system. Experiments have been conducted and the results prove the feasibility of the concept.

GraspMan - A Novel Robotic Platform with Grasping, Manipulation, and Multimodal Locomotion Capability

Abstract: In this paper, we present the design of a novel, hybrid multipurpose robotic platform equipped with a pair of graspers to synergize grasping, manipulation, and locomotion. The multipurpose grasper consists of two underactuated fingers with an active gripping surface, which passively conforms to an object while grasping. Each finger has a spring loaded synchronous belt drive which functions as the active gripping surface. The grasper is capable of handling a range of objects with irregular geometry and size. Two such underactuated graspers are connected through a serial kinematic chain and this provides the platform both manipulation and locomotion capability. Graspers act as “legs” or “wheels” of the robot during locomotion and can easily adapt to terrain variations. Fewer number of actuators, simple and scalable kinematic structure, and computationally efficient control are some of the main features of the design. Design details and kinematic analysis are presented. Experiments were conducted on a prototype robot to demonstrate multiple modes of operation.

Performance analysis of vertically offset overlapped propulsion system based quadrotor in an aerial mapping mission

Abstract: In this paper, the authors present the performance analysis of a Vertically Offset Overlapped Propulsion System (VOOPS)-based quadrotor in an aerial mapping mission. The dynamic model of the VOOPS ...

Design and Development of a Depth Controller for an Autonomous Underwater Vehicle with Variable Buoyancy Engine using Coefficient Diagram Method

Abstract: Although the 'Coefficient Diagram Method (CDM)' can generate a stable controller which is robust and give the desired performance, the optimality and cost function are not yet under consideration. Herein, we design and develop an optimal controller for the depth control of an 'Autonomous Underwater Vehicle (AUV)' by analyzing a 'Linear Quadratic Regulator (LQR)' based controller using the CDM. The coefficient diagrams of conventional LQR controller and CDM controller are analyzed and the parameters to design an optimal LQR controller are identified. This controller is implemented for the depth control of an AUV with a 'Variable Buoyancy Engine (VBE)' and is found to have better performance as compared to the LQR and CDM. The objective here is to reduce the control efforts needed for depth control. Finally, we report the detailed theoretical analysis and simulation results.