Ultrasonic Array Sensor for Range and Bearing

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1 Ultrasonic Array Sensor for Range and Bearing To design, build and test an ultrasonic obstacle localisation system with at least three receivers and one transmitter. The system should report range and bearing to reflectors. embedded systems. Key units: ECE3073 and optionally ECE4075 or ECE4063. Most currently available ultrasonic ranging systems do not report the angle to the target. This project will use low cost piezoelectric transmitters and broadband microphones in a receiver array to uniquely estimate the angle of the incoming wavefront as well as the range. By carefully designing the receiver array using non uniform spacing [1], a unique estimate can be made of the angle of arrival even when faced with common cycle hopping errors. The receiver spacing will be small enough to enable phase difference to uniquely define arrival angle of isolated echoes. The project will involve hardware interfacing to an FPGA board simple amplification and ADCs. An ADC development board will be interfaced to the FPGA that will perform the arrival time estimation and array processing. A simple experimental verification of the project could involve tracking a pendulum swinging across the field view of the sonar sensor. Extensions possible include extracting three dimensional, hardware processing acceleration and application to tracking problems with a Kalman Filter. Transducers can be obtained from Jaycar or more sophisticated sources such as [1] Steckel, J.; Boen, A.; Peremans, H., "Broadband 3-D Sonar System Using a Sparse Array for Indoor Navigation," Robotics, IEEE Transactions on, vol.29, no.1, pp.161,171, Feb. 2013

2 Air Hockey Sensing and Control Number of Students: 2 Prerequisites: High competency required in digital design and software development in C for embedded systems. Key units: ECE2072 and ECE3073. Mathematical ability for estimation and control algorithms. and The ECSE Department has developed a high speed computer controlled air hockey table as a demonstration project for real time embedded systems. The air hockey table can be seen in the electronics workshop on the Eastern end of the first floor of building 35 near the stairwell. The aim is to score goals at each end by striking a puck that moves on an air cushion with paddles. Linear actuators control the position of the paddles each end and the paddles are swung by servo motors under computer control. The position of the puck is to be determined by an overhead camera. This project aims to improve on previous implementations of puck position estimation, timing and intelligent game playing. Most of the mechanical and electrical design of the table sensors and actuators is complete. Part of the project is to test and refine the hardware interfaces on DE-2 FPGA boards. The project will also involve the development of digital logic for interfacing the sensors and actuators. Embedded system software design is also required to form the intelligent control. Specifically the goals in 2015 are to achieve: trapezoidal motion control of the linear actuators that can be varied on the fly. millisecond timing accuracy of the arrival of the puck at the paddle. accurate strike control of the paddle to achieve good directional accuracy of the puck trajectory. development of a reliable goal scoring sensor. implementation of high level game playing strategies that maximise goal scoring against other automated systems and humans.

3 Sound Localisation and Tracking for Robotics ALLOCATED To investigate, design, build and test hardware and software to locate an audible sound source in an office environment using a rotating microphone array. The project can also extend to tracking sound sources using a mobile robot. embedded systems. Key units: ECE3073 and optionally ECE4075 or ECE4063. Many robotic applications would benefit from sound localisation. Applications include directing the attention of the robot to a user and filtering other sounds, user commands such as come here, locating an injured or trapped person, finding the source of a loud noise such as a smashed window, explosion or a falling object or person. This project will involve the processing of sound from an array of microphones mounted on a rotating servo motor. Signal processing can be performed using an FPGA or software. As an extension, the sensor array can be used for tracking applications using a mobile robot platform.

4 Laser Following Robotic Control To investigate, design, build and test hardware and software to enable two robots to coordinate their positions via a laser beam. One robot will direct the path direction of another of a large distance using a laser. The slave robot travels along the laser beam in a straight line. embedded systems. Some understanding of lasers and optics would be useful. Key units: ECE3073 and optionally ECE4075 or ECE4063. There are many cooperative multi robot applications such as map building, exploration and security surveillance. One common difficulty is the accurate coordination of two or more robots over a large distance (eg 50 metres) since robot sensors and vision only function well for ranges less than 10 metres typically. A laser beam can be sensed over large distances due to the limited divergence of the beam. Constraining the two poses of robots over a large distance via the laser beam can be extremely valuable for localisation and mapping applications that need to operate over large areas. The project will involve designing a system that can produce a reliable laser projection that is detectable a fixed distance from the floor on another robot and allow for natural variations in flatness of the floor of a building. Once detected, the laser needs to be tracked by a moving robot in a straight line path using a motion control system that incorporates the position error of the robot relative to the laser. Sensor design and signal processing can be performed using electronics, an FPGA board and/or software.

5 Real Time Fiducial Marker Recognition and Tracking ALLOCATED To investigate, design, build and test hardware and software to enable a robot to find its pose using real time recognition and tracking of fiducial markers placed at known positions in the environment. The markers are black and white geometric shapes that are easily recognised in an image and are to be designed and created as part of the project embedded systems. Key units: ECE3073 and optionally ECE4075 or ECE4063. and Outcomes A fiducial marker can be custom designed to suit the ease of unique recognition and localisation, even in a cluttered visual scene. With a calibrated camera and the pixel coordinates of a set of fudicial markers, a robot can localise itself reliably. The advantage of such an approach is that the system can be produced with low cost and involve passive sensing that is the beacons in the environment require no power and can be cheaply printed on paper. The project involves the following outcomes: the design of robust geometric shapes that can be processed in an image at frame rate. identification and extraction of the image coordinates of the markers in real time using software and/or FPGA hardware. The distance to the markers can vary considerably so a multi-scale image processing approach needs to be taken. calibration of the camera. localisation of the robot from the known marker positions and measured image coordinates of these markers calibration of the marker positions in 3D given known robot positions, camera calibration and image coordinates of the markers.

6 Negotiated Embedded System and Robotics Projects Student who can suggest interesting, practical and challenging embedded system design with interesting sensors or robotics projects will be considered for supervision. per project. By negotiation students need to work up a one page proposal that lists the background, equipment/resource/software requirements, objectives, constraints and measurable outcomes for the project. FPGA development boards (DE1 and DE2 boards), power supplies, arbitrary wave generators, soldering irons and 4 channel CROs are available in the projects lab to support these innovative projects. Consult electronics websites such as sparkfun for different wireless communication devices, extereoceptive sensors (eg ultrasonic, infrared rangers, laser, whisker touch, Kinect, electronic compass etc) and deadreckoning sensors (eg wheeled and visual odometry, IMU). Other useful equipment is available such as the Pendulum Lab equipment that includes DC motor/gearbox with optical shaft encoder and a pendulum crossing a beam sensor.