Underwater operation and sampling has been replaced by ROV (Remotely Operated Vehicle) and underwater manipulator gradually, which can avoid divers to face the dangers due to the environmental pressure and low temperature. When ROV to carry out the mission, the operator sees the undersea environment and the target with the information feedback from the sensors. Recently, we developed a general purpose controller for controlling underwater robotic systems. We plan to install the manipulator on the ROV with the same general purpose controller. One of the concerns in desgining is: the ROV generally mantains neutral buoyant in seawater. When adding or removing any components, the arrangement of balast weight needs to done again to keep the balance of the system. Moreover, the center of gravity will be changed such that dynamics of the ROV will be different when collaborating with the underwater manipulator. To resolve these problems, we review the design and hope to reduce the size and weight of each component.The new design also introduces the use of a junction box. The junction box keeps all the circuits, power converters and motor control card. It allows the reconfiguration of power and commands pathway much easier. To reduces of the size of the housings, the gear transmission set is moved out of the housing. According to the positioning accuray requirement of each axis, a DC servomotor or a DC motor is installed. Underwater manipulators do not require agile motion. Therefore we use a gear-worm set as the transmission between links to increase torque. The motion control is implemented with a Jacobian to calculate the increment joint angles for joint coordinate control. Human-interface was developed with Borland C++ Builder and OpenGL to let the operator to simulate and control of the manipulator with an input of a 3D joystick.

This thesis represents a comprehensive examination of the phonotactic behaviour (i.e. attraction to sound) of the female Gryllus bimaculatus under laboratory conditions. Chapter 2 is the first study to analyze the effect of substrate texture on walking performance in crickets. Substrate texture is found to play an essential role in the phonotactic responses of G. bimaculatus. Smooth substrate texture has a detrimental effect due to slipping, whereas a rough texture results in optimal walking performance due to the friction with the walking legs. Chapter 3 represents the first detailed lifetime study analysing phonotaxis in crickets. My results demonstrate that the optimal age to test phonotaxis in G. bimaculatus females is from day 7 to 24 after the final moult. I also found that selectiveness was persistent with age. These findings contradict the female choosiness hypothesis. This study is also the first to describe the effect of senescence on phonotaxis in insects, as responsiveness decreases with age. Chapter 4 compares the phonotactic behaviour of female crickets from different laboratory-bred colonies. From six tested cricket lab colonies, I found three groups statistically different from each other. Females raised under laboratory conditions at the University of Cambridge and Anglia Ruskin University were most reponsive at a frequency of 4.5 kHz, whereas females bred in Tokushima University in Japan were tuned towards a higher frequency of 5 kHz. These results suggest a degree of artificial allopatric speciation. Comparisons with crickets bred under low-quality conditions in a local pet shop demonstrate a loss of responsiveness, indicating that breeding conditions have a direct effect on phonotactic responsivity. Chapter 5 is the first study to report the presence of phonotaxis in males of G. bimaculatus. Previously it was unknown if G. bimaculatus males were able to perform phonotaxis, given that they were only recognised as endurance signal producers. In the present study, only 20% of the studied males (N=70) performed a weak phonotactic response. This finding has potential ecological implications in terms of male cricket territory establishment, and male-male interactions in the wild, which are discussed. Chapter 6 explores the song pattern recognition of the female G. bimaculatus by changing the duration of either the first, second or third pulse of the chirps. A long first pulse decreased the phonotactic response whereas phonotaxis remained strong when the third pulse was long. Chirps with three pulses of increasing duration of 5, 20 and 50 ms elicited phonotaxis, but the chirps were not attractive when played in reverse order. The data are in agreement with a mechanism in which processing of a sound pulse has an effect on the processing of the subsequent pulse, as outlined in the flow of activity in a delay-line and coincidence-detector circuit.