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Stabilised Platforms

Hennie Mouton

James Hepworth

Control and Dynamics of a Two-Axis Stabilised Platform to Facilitate Astronomical Observations

james.hepworth@alumni.uct.ac.za

This project entailed the design and development of a first generation inertially stabilised telescope system, to be ultimately capable of the automatic tracking of celestial objects whilst mounted on moving hosts. This project encompasses the development of the initial mechanical, electrical, and control design of the two-axis gimballed structure.

The first generation system is a low-cost project aiming to achieve micro-radian tracking and stabilisation capabilities and to provide an indication of the feasibility of further project development. The system designed falls into the platform-stabilised class of inertially stabilised platforms, with the entire sensor payload (imaging sensor) being stabilised through use of a gimballed structure controlling the orientation of the sensor line-of-sight.

In this project, in order to reduce costs, the imaging sensor consists of a Raspberry Pi Camera mounted in a tube shaped platform designed to mimic the geometric and inertial properties of the Meade ETX-90 telescope intended to be used in further project development. High quality DC motors are used to actuate the pitch and yaw gimbals, a MEMS IMU provides feedback data of the relevant inertial rotation data whilst high resolution conductive plastic potentiometers provide gimbal angular position feedback. Tracking and Stabilisation control algorithms and low level hardware control are performed by an STM32F0 microcontroller whilst the target tracking system is performed by a Raspberry Pi Model 3B. Overall system control is achieved through the use of a LabVIEW supervisory control and data logging program developed for the system.

Future projects would entail the incorporation of the ETX-90 telescope, finite element modelling of the system’s structural dynamics, and the development of an adaptive control system informed by the results of the structural analysis.


Control Systems

John Ogundiran

Simulation and control of the underwater ROV -Seahog

OGNJOH002@myuct.ac.za

The focus of my masters is to improve on the simulation and control model of the underwater ROV (Seahog). Some of the advancements to be made are obtaining more accurate values for the hydrodynamic coefficients (virtual mass and damping effects) through a verified experimental method. The developed control system is also to be validated by installing the sensors (depth, IMU) on board the Seahog. A front camera and light tilt mechanism was designed to add one degree of motion so as to facilitate the camera's position control.


Underwater Robotics

 Phillip Schillinger

The Design and Development of a manipulation system for UCT’s ROV, the Seahog.

cp.schillinger@gmail.com

This dissertation focuses on the development and design of a detachable manipulator skid for the ROV Seahog.

The skid platform consists of an articulating arm fitted with a dual function gripper for the purpose of performing sampling operations for marine research purposes. Power to the system is provided by a pressure compensated hydraulic power pack and manipulation functions are controlled with a valve pack, fitted with bi-directional solenoid valves. A single connector forms the interface between the ROV and the skid and provides both power and control. Additional buoyancy is built into the skid to compensate for its additional weight.


Rescue Robotics

Thomas Mathew

Thomas Mathew

Design and Development of the Wheels and Chassis for the Scarab Low Cost Rescue Robot

thomas.mathew@myuct.ac.za

This project developed the mechanical housing for the Scarab as well as the wheels, motors and motor control circuitry. The wheels are designed to allow a drop from up to 3m. The housing is two wheeled with a fin that not only provides stability, but also allows for the unit to be thrown.


Grieg Knox

Grieg Knox

Design of the Communication, Power Management and Sensor Payload for an Inspection Class Robotic System

This project includes the development of a tether-less communication and power supply systems for the Scarab. This is achieved through the implementation of a Lithium-Ion battery management system. Additionally two interchangeable sensor payloads are being developed to provide the operator with the necessary feed back to identify a survivor.


Victor Fong

Wai "Victor" Fong

The Design and Development of a Mobile Operator Station for a Low-Cost Man-Packable Rescue Robotic System ​

fngwai001@myuct.ac.za

This project entails the design and implementation of an operator station for use of the Scarab robotic system. The station is in the form of a man-wearable carrier "backpack" that can be worn on the operator's back to transport the mobile platform. This includes a wireless interface to control and monitor the mobile platform using a hand-held controller. A charging module is also integrated for recharging of the platform whilst carried on the backpack and not in use.


​Underwater Robotics

Thomas Mathew

Maximillian Finbow

The Dynamic Modelling and Development of a Controller for a General Purpose Underwater Remotely Operated Vehicle

maxfinbow@gmail.com

This dissertation focuses on the dynamic modelling of the SEAHOG ROV at RARL. A fully verified thruster dynamic model was created, including a plant model of the thruster system and a propeller speed controller implemented through software fixed-point algorithms using a low cost micro-controller. For the SEAHOG ROV characteristics, computational techniques were used to obtain preliminary hydrodynamic, mass, inertia and buoyancy data. Proposed control hardware was modelled and an adaptive classical controller for heading and depth holding was designed through simulation methods  and simulated within the full SEAHOG system.

Max also undertook the successful commissioning of the SEAHOG ROV, including the completion of outstanding electrical, software and mechanical systems on the robot and preliminary wet tests of the complete system. He designed a multi-core architecture LabVIEW control interface to monitor and control the ROV's systems including open-loop control of thrusters, live feedback of video and sonar and other system data.  The mechanical design of the junction box was redesigned as was tether termination including troubleshooting and upgrades to the power-pod and electronics-pod.


Grieg Knox

Timothy Hope

The Characterisation of Magnetic Couplings and the Development of a Thruster and Tilt Unit for a General Class Remotely Operated Underwater Vehicle

tim.hope@live.com

The SEAHOG ROV at RARL utilises magnetic couplings in three different sub-systems; the thruster units, the camera's tilt unit and the gripper arm. This dissertation focuses on the mathematical analytical modelling of co-axial magnetic couplings to better predict torque and slip characteristics in the design phase. Additionally this dissertation details the overhauling of the SEAHOG's thruster units. Originally built in 2012 the thruster units have been modified to be capable of operating at full power continuously, interrupt based communications and provide over 70% more thrust.