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Haptic teleoperation of mobile manipulator systems using virtual fixtures.Wrock, Michael 01 November 2011 (has links)
In order to make the task of controlling Mobile-Manipulator Systems (MMS) simpler, a
novel command strategy that uses a single joystick is presented to replace the existing
paradigm of using multiple joysticks. To improve efficiency and accuracy, virtual fixtures
were implemented with the use of a haptic joystick. Instead of modeling the MMS as a
single unit with three redundant degrees-of-freedom (DOF), the operator controls either the
manipulator or the mobile base, with the command strategy choosing which one to move.
The novel command strategy uses three modes of operation to automatically switch control
between the manipulator and base. The three modes of operation are called near-target manipulation
mode, off-target manipulation mode, and transportation mode. The system enters
near-target manipulation mode only when close to a target of interest, and allows the operator
to control the manipulator using velocity control. When the operator attempts to move
the manipulator out of its workspace limits, the system temporarily enters transportation
mode. When the operator moves the manipulator in a direction towards the manipulator’s
workspace the system returns to near-target manipulation mode. In off-target manipulation
mode, when the operator moves the manipulator to its workspace limits, the system retracts
the arm near to the centre of its workspace to enter and remain in transportation mode.
While in transportation mode the operator controls the base using velocity control.
Two types of virtual fixtures are used, repulsive virtual fixtures and forbidden region virtual
fixtures. Repulsive virtual fixtures are present in the form of six virtual walls forming a
cube at the manipulator’s workspace limits. When the operator approaches a virtual wall,
a repulsive force is felt pushing the operator’s hand away from the workspace limits. The
forbidden region virtual fixtures prevent the operator from driving into obstacles by disregarding
motion commands that would result in a collision.
The command strategy was implemented on the Omnibot MMS and test results show that
it was successful in improving simplicity, accuracy, and efficiency when teleoperating a
MMS. / UOIT
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Design and Implementation of a Hard Real-Time Telerobotic Control System Using Sensor-Based Assist FunctionsVeras-Jorge, Eduardo J 21 November 2008 (has links)
This dissertation presents a novel concept of a hard real-time telerobotic control system using sensory-based assistive functions combining autonomous control mode, force and motion-based virtual fixtures, and scaled teleoperation. The system has been implemented as a PC-based multithreaded, real-time controller with a haptic user interface and a 6-DoF slave manipulator. A telerobotic system is a system that allows a human to control a manipulator remotely and the human control is combined with computer control. A telerobotic control system with sensor-based assistance capabilities enables the user to make high-level decisions, such as target object selection, and it enables the system to generate trajectories and virtual constraints to be used for autonomous motion or scaled teleoperation. The design and realization of a telerobotic system with the capabilities of sensing and manipulating objects with haptic feedback, either real or virtual, require utilization of sensor-based assist functions through an efficient real-time control scheme. This dissertation addresses the problem of integrating sensory information and the calculation of sensor-based assist functions (SAF's) in hard real-time using PC-based resources. The SAF's calculations are based on information from a laser range finder, with additional visual feedback from a camera, and haptic measurements for motion assistance and scaling during the approach to a target and while following a desired path. This research compares the performance of the autonomous control mode, force and motion-based virtual fixtures, and scaled teleoperation. The results show that a versatile PC-based real-time telerobotic platform adaptable to a wide range of users and tasks is achievable. A key aspect is the real-time operation and performance with multithreaded software architecture. This platform can be used for several applications in areas such as rehabilitation engineering and clinical research, surgery, defense, and assistive technology solutions.
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Haptic emulation of hard surfaces with applications to orthopaedic surgeryHungr, Nikolai Anthony 05 1900 (has links)
A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.
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Haptic emulation of hard surfaces with applications to orthopaedic surgeryHungr, Nikolai Anthony 05 1900 (has links)
A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.
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Haptic emulation of hard surfaces with applications to orthopaedic surgeryHungr, Nikolai Anthony 05 1900 (has links)
A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate
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