Peter Ridley
Queensland University of Technology
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Publication
Featured researches published by Peter Ridley.
Mechanism and Machine Theory | 1992
E.H Bokelberg; K.H Hunt; Peter Ridley
Abstract This paper examines infinitesimal spatial motion, introducing the concept of a “differential screw” to characterize the difference between two successive instantaneous screw axes (ISAs) on an axode. The locus of spatial inflection points, a twisted cubic curve common to three ruled quadric surfaces, is here derived in a coordinate system attached to the fixed axode, using the relationships of the ISA to velocity and the differential screw, as well as the ISA, to acceleration. The notable geometry is then discussed, and the more familiar instances of spherical and planar motion are described as special cases. The novel approach adopted in this paper, even though it does not yield any new results, is essential in laying the groundwork for Part II [Mech. Mach. Theory27, 17–35 (1992)] that deals with accelerations and the spatial equivalent of the Bresse circle.
Mechanism and Machine Theory | 1992
Peter Ridley; E.H Bokelberg; K.H Hunt
Abstract As foreshadowed in Part I [Mech. Mach. Theory27, 1–15 (1992)] this paper further examines the acceleration of points of a rigid body in general spatial motion. Axodes (that define displacement of the body) and the derivative of a screw together provide the starting point. Whereas in Part I the emphasis is on inflections in point-paths, we now study yet another quadric surface, one that is analogous to the Bresse circle in planar motion. We relate this surface to a moving bodys acceleration centre and then to the ellipsoidal acceleration field generated by the motion. While some of the properties we describe are known, others we believe are new. In particular, the time-derivative of the active screw on the axode and its relation to a two-system of screws provides useful insight into an area that has hitherto not been adequately pursued.
Journal of Dynamic Systems Measurement and Control-transactions of The Asme | 2003
Peter Ridley; Peter Corke
This paper examines the kinematics and control of a Load Haul Dump Vehicle used in underground mining operations. The aim of the work is to develop an autonomous guidance strategy. A linear, state-space, mathematical model of the vehicle is derived purely from geometric consideration of the vehicle and its desired path. Autonomous regulation of the vehicle is shown to be theoretically feasible using state variable feedback of displacement, heading, and curvature error. A relationship between stability and vehicle speed is derived. This expression forms the basis of an adaptive tuning strategy, which optimizes the vehicles dynamic response.
international conference on robotics and automation | 2001
Peter Corke; Peter Ridley
This paper discusses the steering kinematics for a center-articulated mobile robot. Several models have been recently proposed in the literature and we use experimental data to compare and validate these models. The vehicle heading response to steering command is shown to include a dominant zero due a nonholonomic constraint, and this is verified by experiments conducted using a 30-t mobile vehicle at our laboratory. Simulation results are then used to show the significance of this zero and its effect on closed-loop heading angle control
Mechanism and Machine Theory | 2000
Peter Ridley; Peter Corke
Abstract This paper presents a method by which the pose and internal rigging forces may be calculated for a dragline bucket throughout its workspace. These calculations are experimentally verified by using data obtained from a one twentieth scale physical model. Predictions of the contours of constant bucket “carry” angle are presented for a full size bucket on a Marion 8050 dragline and compared with the results published by Knights and Shanks (P. Knights, D. Shanks, Bucket rigging influence on dragline productivity, The Australian Coal Journal 36 (1992)).
international conference on robotics and automation | 2004
Kane Usher; Matthew Dunbabin; Peter Ridley
In this paper, we outline the sensing system used for the visual pose control of our experimental car-like vehicle, the Autonomous Tractor. The sensing system consists of a magnetic compass, an omnidirectional camera and a low-resolution odometry system. In this work, information from these sensors is fused using complementary filters. Complementary filters provide a means of fusing information from sensors with different characteristics in order to produce a more reliable estimate of the desired variable. Here, the range and bearing of landmarks observed by the vision system are fused with odometry information and a vehicle model, providing a more reliable estimate of these states. We also present a method of combining a compass sensor with odometry and a vehicle model to improve the heading estimate.
Mechanism and Machine Theory | 1994
Peter Ridley
Abstract Solution of the inverse closure problem in robot kinematics has been unnecessarily complicated by those who have bypassed an appreciation of robot geometry in search for general methods of solution. This paper demonstrates that elementary graphical techniques can be applied to determine all of the possible robot configurations for a prescribed end effector location. In Part II, analytical solutions based on the geometric methods of Part I are presented. These solutions are derived using “straight down the line trigonometry” recommended by Hunt[1]. Ambiguities in identifying the multiple configurations, arising in [1], are resolved.
Faculty of Built Environment and Engineering | 2001
Peter Corke; Peter Ridley
Faculty of Built Environment and Engineering | 2001
Peter Corke; Peter Ridley; Kane Usher
Faculty of Built Environment and Engineering | 2003
Peter Ridley; Julien Fontan; Peter Corke
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Commonwealth Scientific and Industrial Research Organisation
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