Hand Controller Systems For Advanced Dexterous Manipulation Computer Science Essay

Haptic feedback engineering has been progressively used in countries of industrial mechanization, teleoperations and serious gambling. Supplementing the conventional ocular and audio information with a force and haptic sense of a distant or practical environment has been shown to increase a user ‘s sense of submergence in a practical simulation and to better control of a distant device in telerobotic operations. However, to day of the month, there is neither a standardized general intent solution nor an low-cost, intuitive manus accountant system that can supply tactile feedback and control of more than three degrees-of-freedom ( DOF ) , although legion paradigms have been developed in support of the infinite and atomic industries. The present paper proposes a manus accountant leting intuitive use of multiple degrees-of-freedom and supplying force and haptic feedback to the operator. By uniting two Commercial-Off-The-Shelf ( COTS ) game accountants it is intended to be an low-cost, easy to utilize, and practical option to the expensive, task-specific, tactile devices presently available. The manus accountant is intended to supply equal control for a scope of deft use undertakings, such as commanding the robotic arm of a bomb disposal automaton, or commanding a Remotely Operated Vehicle ( ROV ) . It is proposed that the tactile feedback characteristics of the design will enable users to negociate, and gather information about, a distant environment under degraded ocular conditions. The undermentioned paper inside informations the advancement made in planing and constructing the manus accountant and practical environment to visualize the undertaking. Evaluation of the manus accountant was performed by leting users to research a practical environment and analyzing their feedback. Future work and development is discussed including possible paths to working and commercializing the consequences of this undertaking.

Purposes and Aims

The purposes of the undertaking were to work COTS devices to plan and construct a manus accountant system capable of commanding a practical object in 5 DOF, whilst exposing force and haptic information to the user. Haptic feedback was used to let users explore a practical environment through interactions between the controlled object and its practical milieus.

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The manus accountant designed had to be low-cost, intuitive to utilize and hold the possible to be applied to a scope of applications. For the intents of rating a practical environment was created. However, it was intended that the system could be used in ‘real universe ‘ state of affairss to command a device researching a distant environment. In these state of affairss the tactile feedback, generated by the manus accountant, must supply equal centripetal information to be good to the user ; bettering public presentation in undertakings where ocular cues possibly of hapless quality.

Introduction

Haptic feedback, or haptics, normally refers to the procedure by which the force and haptic information of a distant environment, existent or practical, is displayed to a user via a human-machine interface ( Burdea and Coiffet, 2003 ) . Information about a distant environment is gathered via detectors on a distant device and used to trip motors in the operator control unit or manus accountant. The forces and quivers imposed on the user are intended to reflect the force and haptic information of the distant device ‘s milieus ( Siciliano and Khatib, 2008 ) . Force information can include an object ‘s weight, hardness and inactiveness, whilst tactile information may dwell of surface information such as object smoothness ( Burdea, 1999 ) .

Generating tactile informations alongside conventional visual-audio shows has been shown to assist users command objects or tools in a practical environment ( Srinivasan and Basdogan, 1997 ) and to better the use of remotely operated telerobots in existent universe state of affairss ( Howe, 1994 ) . Maclean ( 2000 ) suggests that because of these qualities, utilizing tactile feedback is frequently required to give the best design solution, hence its inclusion in many applications. These include surgical applications and bomb disposal automatons, exoskeletons for defense mechanism and remotely operated vehicles including subsea, infinite and atomic waste managing undertakings ( Stone, 200 ) . Other applications range from the amusement industry for usage in computing machine games, to do them more realistic and immersive, to instruction, computer-aided design and industry ( Siciliano and Khatib, 2008 ) .

Using automatons for surgical operations allows smaller, agile equipment to be used. This consequences in smaller scratchs being made, therefore less encompassing tissue is damaged and the recovery clip for patients is reduced. Haptic feedback is important for many telerobotic surgery applications, such as minimally invasive surgery. Surgeons frequently have to feel variety meats and tissue during operations to derive centripetal information which could non be provided through any other agencies. Surgical automatons are able to garner force and haptic information through out an operation and a tactile feedback manus accountant displays this information to a sawbones ( Rovers, 2002 ) . Bello et Al ( 2010 ) discourse how of import tactile feedback is to medical simulations utilizing practical environments. They conclude that a “ good usage of haptics ” in preparation simulations is necessary to better public presentation of operations that require a reaction to tactile prompts. It is of import, nevertheless, that the tactile feedback accurately theoretical accounts the expected force response, and the tactile device is able to expose these forces to an appropriate declaration. In order for a user to distinguish between haptic information of an environment the tactile refresh rate must be at least 1 KHz compared to a graphical update rate of 30Hz ( Vafai and Payandeh, 2009 ) .This means for high fidelity force feedback the motors of a tactile device must be capable of updating 1000 times a 2nd.

In teleoperation applications, such as Explosive Munition Disposal ( EOD ) operations ( Kron and Schmidt, 2004 ) , infinite operations, and the handling of risky stuffs ( Stone, 2000 ) , the user ‘s ability to feel objects and their milieus is extended to a distant location. In these applications, an appropriate usage of haptics can assist cut down the demand for a human operator to come in a unsafe environment by bettering control of a distant automaton or device ( Howe, 1994 ) .

Modern bomb disposal automatons, such as the Cutlass, have robotic operators capable of up to 9 DOF. These necessitate a manus accountant that is easy to utilize and capable of high degree-of-freedom input. The undertaking presented intends to turn to both these issues by bring forthing a device, capable of control in more than three degrees-of-freedom, which is intuitive to utilize and can be applied to a scope of undertakings.

In many of the applications described tactile feedback is of import because the undertakings are frequently carried out under debauched ocular conditions ( Nof, 1999 ) . This is really evident in the control of bomb disposal automatons where a deficiency of ocular information could, for illustration, be caused by hapless camera placement, low image quality, a hapless connexion between the user and the distant device, or undertakings being carried out in low light conditions ( Barnes and Counsell, 2003 ) . In these state of affairss the excess sensory informations provided by the force feedback allows operators to utilize a distant device to research an environment whilst maintaing a high grade of control. Hokayem and Spong ( 2006 ) besides suggest that due to limited real-time ocular information from cameras mounted on nomadic automatons, in a distant location, force information is needed to assist the operator understand the automaton ‘s environment but besides reduces the demand for high quality ocular feedback and shows.

Evidence from Tavakoli and Aziminejad et Al ( 2007 ) and Munglam and D’Amelio et Al ( 2006 ) suggests that when tactile information is displayed along side “ perfect ” ocular feedback, during a teleoperation undertaking, there is small difference in public presentation compared to the when ocular feedback is displayed entirely. However, when the user was presented with a debauched or erroneous ocular show the figure of mistakes incurred was greatly reduced with the debut of tactile feedback.

This research suggests that a manus accountant capable of exposing tactile feedback to an operator would be really good in existent universe teleoperation applications in which devices are operated in a distant environment. It has been shown that force and haptic feedback is of even greater importance in commanding these devices when the ocular shows available are of hapless quality.

Haptic feedback is an built-in portion of practical world interactions. Srinivasan and Basdogan ( 1997 ) suggest that the sense of touch is indispensable to gaining the full potency of practical environments, supplying “ a sense of submergence in the environment that is otherwise non possible ” . They conclude that greater submergence is likely achieved by utilizing simple tactile interfaces with ocular shows, instead than by utilizing improved ocular shows entirely. Insko et Al ( 2001 ) besides showed that utilizing simple inactive tactile objects to back up a ocular practical environment can better a user ‘s sense of presence in the practical universe.

Figure: Harris tactile arm and OCUFurther more, Mason and Walji ( 2001 ) investigated the effects of adding or taking ocular and tactile feedback from a undertaking on a user ‘s public presentation. Specifically, the undertakings involved “ reach-to-grasp ” motions towards practical objects. It was found that ocular cues of the traveling limb, or practical object being controlled, and accurate tactile information about practical objects are peculiarly of import to accomplish good public presentation in practical environment undertakings.

Synergistic 3D and serious-games based preparation has used tactile feedback to increase both the physical and psychological fidelity of simulations ( Stone, 2008 ) . These simulations range from medical preparation simulations to EOD operations and pieces developing. Stone ( 2008 ) outlines a series of human factors to see and guidelines to follow when developing a practical simulation and how these may impact the pick of operator interface or manus accountant used.

Figure: Omega 7 DOF deviceCurrent manus accountant solutions for implementing tactile feedback include bespoke or application specific accountants, high terminal tactile devices, such as those from Force Dimension, and Commercial-Off-The-Shelf ( COTS ) devices. Brooks & A ; Bejczy ( 1985 ) besides investigated a figure of paradigms that have been developed in support of the infinite and atomic industries. They suggest that presently there is no general intent solution manus accountant system, but instead present grounds in favor of peculiar designs for manus accountants over others. For case, a joystick manus accountant design facilitates a stronger appreciation by the user compared to many other manus accountant designs.

Bespoke solutions, such as the Harris advanced tactile arm and Operator Control Unit ( OCU ) ( Figure 1[ 1 ]) , are built for a specific undertaking or application in head. Because of this they can non be applied to a scope of state of affairss. For illustration, the Harris OCU is configured for control of a peculiar robotic arm for remote deft use undertakings. Control of the automaton back uping the arm is performed with a separate manus accountant. Bespoke solutions are frequently expensive, and may necessitate a grade of preparation before basic undertakings can be performed.

High terminal tactile devices, such as those from Inition on the other manus, offer control and force feedback to a high dof, can be applied to a scope of applications, and are considered to be really accurate. However they are really expensive, runing from ?6,000 for the Omega device from Force Dimension ( Figure 2[ 2 ]) to ?70,000 for the Haption Virtouse3. Because of their monetary value these devices have non become widely used outside of research labs and research applications.

Figure: Phantom Omni deviceA really popular user interface for practical world interactions is the Phantom Omni from SensAble Technologies[ 3 ]( Figure 3 ) ( Burdea, 1999 ; Stone, 2000 ) . This off-the-rack desktop device provides six DOF input and three DOF tactile feedback. The stylus design makes it good suited for single-point interactions within a practical environment. In such interactions all forces are calculated to one point and communicated to the user through an interface usually with a stylus or pen design ( Okamura 2004 ) . The forces calculated and displayed to the user will merely be translational forces along the ten, Y and omega axes. No rotational, or torsion, forces can be displayed to the user through single-point interactions ( Otaduy and Lin, 2006 ; 2008 ) .

COTS tactile devices which are non as widely used include tactile baseball mitts, such as the Cyberforce System available from Inition, an illustration of a wearable tactile interface. Although these baseball mitts provide multiple points of interaction, leting more deft use of 3D objects, they are expensive, have complex user interfaces and be given to be rather heavy ( Burdea, 2000 ; Burdea and Coiffet, 2003 ) . Haptic baseball mitts must be calibrated and reconfigured for each user and can non expose the weight of a distant object ( existent or practical ) ; doing them inappropriate for many applications.

Figure: Representation of the 6 DOFForce feedback devices are common in the field of amusement, in peculiar picture and computing machine games, assisting to make a much more immersive feel for the user. These tactile devices tend to be rather simplistic, supplying few degrees-of-freedom and rough feedback in the signifier of quivers. However, their affordability and intuitive control makes them a acute country of research and development.

The Falcon game accountant ( Figure 4 ) , developed by Novint[ 4 ], has taken haptics for amusement intents a measure farther, bring forthing a game accountant with high declaration 3 DOF input and force and haptic feedback. Similar to the Phantom Omni, it is a single-point-interaction device ; nevertheless it is comparatively cheap and still provides simulation of objects, textures, kick effects etc in a 3D practical environment. For these grounds, the Falcon is being used as an initial accountant to be developed. Two Falcon manus accountants will be used to build an advanced manus accountant capable of input and end product in more than 3 DOF ; doing it more suited for undertakings necessitating deft use.

novint-falcon-limited-edition.jpg

Figure 4: Novint Falcon games accountant[ 5 ]

There are illustrations of the Novint Falcon being used outside of the gambling and practical world industries. Martin and Hillier ( 2009 ) , for case, asses the Falcon ‘s potency for usage as a robotic accountant. In their research, they characterise the Falcon device in footings of its geometric and inertial restraints, supplying utile information on the accountant ‘s scope of gesture or workspace and its declaration. The writers conclude that the Falcon is an appropriate device for robotic control. However its fittingness for purpose depends really much on the undertakings undertaken. Chotiprayanakul and Liu ( 2009 ) , and Linda and Manic ( 2009 ) besides both propose methods of utilizing the Novint Falcon to interface with distant telerobots. This research supports the thought that the manus accountant system proposed in this paper could potentially be used to command distant devices in existent universe applications.

Lange and Flynn et Al ( 2009 ) undertook usability appraisals of COTS picture games consoles and devices for rehabilitation intents. The devices investigated included the Playstation EyeToy and Nintendo Wii-mote interaction devices and the Novint Falcon. When participants were asked about their experiences it was reported that the Falcon provided the best feedback and was better suited for rehabilitation of motor accomplishments. However, participants found it hard to hold on and depict its workspace as restrictive, non leting operators to utilize their whole arm when commanding the device.

The manus accountant design proposed twosomes two Falcon accountants together to be controlled with a individual control stick manus accountant. This eliminates the ball clasp, doing hold oning the device easier and enabling longer usage of the manus accountant before user weariness becomes a job. The two Falcon devices are besides arranged in such a manner to maximize the workspace of the manus accountant system.

Matching tactile devices

Shah and Teuscher et Al. ( 2010 ) provide an illustration of how two Novint Falcons can be combined to construct a five-degree-of-freedom tactile device ( Figure 5 ) . In the constellation shown, secondary maps provided by the extra buttons on the Falcon ball clasp will be hard to implement and hold oning the stylus in such a manner will do user weariness ( Brooks and Bejczy, 1985 ) . However, the uniting two Falcon devices to bring forth a individual five-degree-of-freedom tactile feedback accountant is of peculiar involvement to this undertaking.

Figure 5: Combined Falcons commanding a stylus in 5 DOF ( Shah and Teuscher et Al ( 2010 )

Other illustrations of two tactile devices being combined include Krause and Neumann et Al ( 2005 ) and Iwata ( 1993 ) . In both these illustrations, two tactile devices capable of 3 DOF input and end product are coupled together, with a joint terminal effecter, to bring forth devices which can command a practical object in 6 DOF, and show force and torsion end product to the user.

Krause and Neumann ( 2005 ) depict the rotational forces, or torsion, caused by two forces moving on either side of a pen ( Figure 6 ) . The forces FA and FB are tantamount to the forces produced by each of the tactile devices moving on either terminal of a joint terminal effecter. Without adding extra hardware, matching the two devices together would bring forth a device capable of 5 DOF end product ; three translational forces and two rotational forces. The 3rd rotational force shown in Figure 6, stand foring the torsion along the long axis of the terminal effecter fall ining the two devices, would non be felt by a user. In order to rectify this, the writers added an extra motor and encoder within the terminal effecter which rotates about its long axis supplying “ the missing 3rd rotational grade of freedom ” .

moments.png

Figure 6: Rotational grades of freedom ( Krause and Neumann, 2005 )

The force diagrams shown in Figure 6 show that a torque force can be applied to an terminal effecter, and therefore felt by the operator, by using a force at either terminal antonym in way and normal to the way of rotary motion and normal to the way between where the force is applied and where the coveted torsion is felt.

Using this method, a coveted, known, torsion can be displayed to the user by ciphering and using the appropriate forces to each Falcon device either terminal of the joint manus accountant.

Haptic Rendering

In order to include tactile informations in practical simulations the construct of tactile rendition must be understood. This is the method of “ calculating and bring forthing forces in response to user interactions with practical objects ” ( Salisbury et al, 1995 ) . Unlike other modes, such as vision and sound, force information is exchanged in two waies ; both to and from the user. Conti and Barbagli ( 2004 ) depict a typical architecture for tactile rendition in a practical environment ( Figure 7 ) . It shows that tactile rendition can be implemented in three phases:

Collision sensing algorithms determine when there is contact between the practical representation of a device, the embodiment, and other objects in the practical environment.

Force response algorithms calculate the expected forces ensuing from these hits and return them as force and torsion vectors. These vectors are besides passed to the artworks simulation engine so the effects of these interactions can besides be rendered diagrammatically and the objects are seen to travel as expected.

Control algorithms display the deliberate force to the user via the tactile device ( Conti and Barbagali, 2004 ) .

Simulation engineSimulation Visual Rendering

Artworks engine

Force response

Collision sensing

Haptic Device

Control algorithms

Video

Haptic rendition

Figure 7: Haptic Rendering Architecture ( Conti and Barbagali, 2004 )

The force responses are partially determined by the form of the embodiment and the type of contact that it allows. For case, a single-point interaction, stand foring the really end point of a syringe or tool for illustration, can merely demo forces and places in 3 DOF. Torque forces will non be perceived by the user. This makes single-point interaction suitable for tactile devices which merely allow translational motion in the ten, Y and omega co-ordinate frame ( Figure 3 ) .

( EDIT MORE DETAIL ON SINGLE POINT INTERACTION )

However, if a tactile device allows for greater than 3 DOF input and end product it can be more accurately represented by a volumetric, or 3D, embodiment of any form in the practical environment. The force response algorithms must find both forces and torsions ensuing from interactions between the embodiment and objects in the practical environment in order to expose 6 DOF force feedback to the user ( Otaduy and Lin, 2006 ; 2008 ) .

( Edit information on Object-object interaction )

In the instance of the Phantom Omni, which allows 6 DOF input and 3 DOF force feedback, the practical device embodiment, must be a 3D object, in order to expose rotary motions of the device stylus, whilst the end product merely supports individual point interactions between the embodiment and other practical objects. This means apart from at a individual point ( usually the terminal tip ) of the embodiment, the embodiment will merely go through through other practical objects.

The tactile renderer being used is H3DAPI ( h3d.org ) , an unfastened beginning Application Programming Interface ( API ) capable of managing both artworks and haptics. This already contains the algorithms necessary to expose 3 DOF force feedback to the user. However, it does non incorporate 6 DOF force effects, so would non expose torsion forces to the user, via the tactile device, without alteration. Specifically, a new force response algorithm ciphering torque responses was implemented in H3D.

Singapogu and Sander et Al ( 2008 ) depict a method of bring forthing 5 or 6 DOF force feedback utilizing 3 DOF rendering techniques. They present an algorithm which calculates the losing torsion information “ based on the forces on multiple points ” in the practical environment. The algorithm is tested utilizing a 5 DOF tactile device and is found to bring forth the expected control of a practical stylus and end product to the tactile device.

The algorithm presented by Singapogu and Sander et Al ( 2008 ) may be utile for this undertaking as when the two Falcons are coupled together the highest grade of freedom available will be 5 DOF.

( Rigid organic structure mechanics involved in bring forthing the feedback/kinematic control of a stiff organic structure )

( Collision sensing and force response algorithms for both 3 dof and 6 dof control/force feedback. THEN include the Singapogu and sander survey )

Simulation Fidelity

The fidelity of a practical simulation refers to how good it represents its tantamount existent universe environment ( Stone, 2008 ) . Both Stone ( 2008 ) and Bello ( 2010 ) suggest that high fidelity simulations, i.e. those that closely match the existent universe in both physical and psychological properties, are non ever required to accomplish the same degree of larning in preparation simulations. The degree of fidelity required is more dependent on the type of accomplishments being developed and the undertakings being used to develop them.

The simulation developed to visualize the undertaking will be of low physical fidelity whilst keeping high psychological fidelity ( Stone, 2008 ) . That is to state, a comparatively simple 3D practical environment will be made with a low sum of ocular item, but the tasks themselves will closely fit the existent universe equivalent ; proving a user ‘s perceptual motor accomplishments instead than their determination devising accomplishments. This type of interaction frequently uses specialist equipment intentionally designed for the undertaking, which can be really expensive and unsuitable for other operations.

Although H3D is non specifically designed for developing extremely detailed practical environments, the inclusion of tactile feedback and realistic control means a high grade of psychological fidelity will be maintained. Because of this, more focal point will be put into developing a complete and realistic force feedback end product to the user, and an intuitive human-machine interface than developing an highly realistic practical environment. The undertakings used to prove the manus accountant are therefore likely to be abstract undertaking elements proving the manus accountant ‘s deft control of an object.

Advancement

Hardware

The initial program of matching two Falcon manus accountants with a common control stick accountant ( figure 8 ) has been realised in hardware ( figures 9 and 10 ) . This was accomplished utilizing ball socket assemblies connected with Delrin plastic rods.

two falcons.jpg

Figure 8: Initial program to match the two Falcon accountants

Figure 9: Two Falcons coupled togetherThe original ball clasp fond regards of each Falcon were modified such that a ball socket could be fixed. This needed dismantling the ball clasps and boring holes such that the ball sockets fit tightly and could be secured in topographic point. A ball socket was attached to either terminal of the joystick manus accountant. The delrin rods were threaded at either terminal so that it could be firmly fastened to the ball sockets, with one terminal connected to a Falcon and the other connected to the control stick manus accountant. The Falcons use forces to either terminal of the joystick manus accountant and the user will experience the amount of the forces from the two Falcons. coupled_falcon.JPG

This constellation requires the Falcons to be at an angle of about 450 leting the control stick accountant to hang over the border of a surface. This ensures the control stick is free to travel in all waies and Falcons can be placed closer together, cut downing the entire size of the system and doing control easier.

The length of the each of the delrin rods is equal to the tallness of the control stick. This is so it can be rotated without being restricted by the placement of the Falcons. The system can be disassembled, doing easy motion and version of the device possible. Full system.JPG

Figure 10: Full manus accountant systemFigure 11 shows a close up position of the PCB inside the Falcon ball clasp. Additional wires have been soldered over the button connexions, replacing the buttons of the Falcon with those on the control stick manus accountant. Any secondary maps required of the manus accountant can now be performed easy utilizing the pollex and index of the commanding manus to deject the buttons or trigger of the control stick accountant.

Figure 11: Ball clasp PCBA finger trigger control stick was used because, in a comprehensive reappraisal of manus accountant engineering, Brooks and Bejczy ( 1985 ) found that it performs better than most hand-grips in a scope of classs, including controllability, human-handle interaction and human restrictions. In peculiar, the wrap around grasp one can use to a finger trigger control stick allows the application of greater force for longer periods. In contrast, a pinch appreciation similar to the standard ball clasp of the Falcon, merely facilitates a little force to be applied for a short clip before user weariness would go a consideration.buttons.JPG

Initial trials showed there is excessively much freedom of motion of the control stick accountant before the Falcons would bring forth any force feedback. That is, the control stick can be moved a noticeable distance in each way before being restricted by its connexions to the Falcons. This makes commanding a practical object hard as motions of the manus accountant in the existent universe are non replicated in the practical environment by motions of the tactile device embodiment. In order to rectify this, the motion of the control stick has to be restricted, such that force feedback is produced even when the control stick is subjected to little alterations in place. To curtail the motion, the initial movable ball sockets will be replaced with automatically fixed connexions which minimise any unneeded rotary motion.

Virtual Simulation

Figure 12: Blender underwater sceneA individual Falcon is capable of 3 DOF input, and 3 DOF end product. This means the practical representation of a Falcon can be moved in the ten, Y, and omega waies and forces ensuing from hits in the practical environment are felt by the user along these axes. It is believed, nevertheless, that by uniting the two Falcon accountants the three losing rotational forces displayed in figure 4 can be controlled by the user, and torque forces can besides be felt on the end product of the combined accountant. underwater_blend.png

Research from Krause and Neumann ( 2005 ) suggests that because a individual Falcon can non expose rotational forces, when the two devices are coupled in the constellation described, a user will non be able to comprehend the torsion produced along the long axis linking the two Falcons together, i.e. the rotary motion about the length of the control stick clasp. This is because the control stick accountant will be automatically fixed at the top and bottom. This allows for 5 DOF control of a practical object and 5 DOF force feedback end product.

To visualize 5 DOF control a three dimensional practical representation of the tactile device is required. Interactions between the 3D embodiment and 3D practical objects will ensue in multiple points of contact ( Singapogu et al, 2008 ) . Desired torque values can so be found by ciphering the forces moving on these multiple points and the rotational effects they cause.

Figure 13: Submerged scene rendered in H3DThe initial proposal was to develop an application with falcon control in the game engine Blender. Haptic informations would so be added to the theoretical accounts utilizing the tactile renderer H3D. However, it was non possible to command objects in Blender with a Falcon without altering the programme itself. Therefore liquidizer was used strictly as a patterning tool whilst the applications with falcon control and tactile information were developed in H3D.underwater.bmp

The practical undertaking to prove the manus accountant system will include control of a subsea Remotely Operated Vehicle. Thus a simple submerged scene was developed in Blender ( figure 12 ) and rendered in H3D ( figure 13 ) .

There is a noticeable difference between the Blender and H3D render of the same scene. This is likely due to differences in how some effects are implemented. For case, the topographic point light effects used in Blender do non look to be as effectual in H3D.

Figure 14: Application demoing two Falcon avatarsAlthough the H3D render appears more simplistic and rougher, for this undertaking merely low physical fidelity simulations are required. More significantly, the tactile informations implemented in the application should closely resemble what a user would anticipate to experience transporting out a similar undertaking in the existent universe. Sphere.bmp

At this phase of the undertaking simple scenes with tactile information have been developed. These have by and large consisted of simple objects and forms with different frictional surface belongingss. Interaction with these objects has been achieved with individual and multiple Falcons commanding simple embodiments capable of single-point interaction. This can be seen in Figure 14, which shows two stylus embodiments controlled by the two Falcons interacting with a practical object.As good as bring forthing different force feedback effects, events based on the place of the tactile device embodiment have been implemented. These include grabbing and altering the coloring material of objects on contact with the embodiment.

Models made in liquidizer have been exported to H3D and frictional surface belongingss added. These theoretical accounts have been controlled by a individual Falcon to recognize single-point interaction with objects. Figure 15 shows an ROV theoretical account controlled by a individual Falcon in 3 DOF which can react to forces imposed on it by a traveling regular hexahedron with a solid surface. rov_avatar.bmp

Figure 15: 3 DOF control of ROV modelCurrently, these interactions occur at the Centre of the ROV theoretical account as this is the default beginning of the embodiment. This can be changed by interpreting the point of tactile interaction until it is aligned with the coveted point of the theoretical account. In this case sooner the terminal of the operator arm.

Figure 16 shows two liquidizer theoretical accounts rendered in H3D with a simple underwater background. This was implemented by delegating images to each side of the application background, making a 360 degree consequence. underwater_background.bmprov_underwater.bmp

Figure 16: Submerged scene with background image

The bulk of the above illustrations were implemented utilizing X3D, an architecture to stand for 3D scenes and objects, because they require really small calculation. An X3D scene graph is made up of Fieldss which are informations storage constituents for stipulating the belongingss of objects, and nodes, that group fields together specifying scene objects.

Adding surface belongingss to objects created in H3D requires making a surface node with tactile belongingss and adding it to a form ‘s visual aspect. H3D specifies five surface nodes for adding tactile informations to an object. The simplest of these are SmoothSurface and FrictionalSurface. The belongingss of a node can be altered by altering the associated field value. For illustration, altering the value of the ‘stiffness ‘ field in the SmoothSurface node will change the hardness of the object, and the user will see an appropriate alteration in the force feedback.

Effectss caused by events happening in the practical environment are achieved by ‘routing ‘ between Fieldss in H3D. This means that if two Fieldss are routed together, a alteration in one field will direct an event to the other, leting it to alter consequently. For case, if a place or orientation field were to alter due to the user traveling a practical embodiment, the coloring material of a form may alter. Routing can be used to implement events such as those described above, or more complicated force effects as a consequence of hits between objects.

X3D is frequently used for making the scene geometry and construction for applications whilst Python books define application and user-interface behavior. Thus for more complicated applications and computation of force effects it is likely that Python and C++ books will be used. Examples of codification are included in the proficient appendix for mention.

Future Work

In order to expose 5 DOF force feedback in as natural a manner as possible it will be necessary to bring forth an effectual force and torsion at a individual point along the common control stick manus accountant. To accomplish this, the coveted forces and torsions ensuing from user interactions with practical objects must be computed in the tactile renderer, decomposed into right and left falcon forces and a individual force vector applied to each Falcon.

Figure 17: Diagram demoing the hierarchy of categories in H3D[ 6 ]

The force response algorithms in H3D can be implemented globally through a ‘HapticForceEffect ‘ category, or algorithm ( shown in black in Figure 17 ) . The force effects already computed by the tactile renderer are HapticForceField, a HapticForceEffect category that produces a changeless force and HapticSpring, a HapticForceEffect category that generates a spring force based on Hooke ‘s jurisprudence:

.

Where K=spring changeless, and x=difference between avatar place and that of the device ( position-device_position )[ 7 ].

The construction for implementing torsion is already in topographic point, as the HapticForceEffect base category for all force effects, shown in black, “ generates force and torsion based on the place and orientation of the haptics device ” 9. However, a new HapticForceEffect category, similar to HapticSpring, must be implemented to cipher the coveted torsion from the place and orientation of the tactile device. The C++ codification execution of HapticSpring is included in the proficient extension for mention.

Torque is calculated as the cross merchandise of a supplanting vector R and force vector F. . It is believed that by ciphering the forces moving on multiple points, a torsion can be resolved at a point between the multiple torsion vectors.

Achieving multiple contact points should be comparatively consecutive frontward as each Falcon is capable of individual point interaction. To make a 3D stylus or embodiment between the two points of the Falcons will necessitate specifying a new HAPIHapticsRenderer subclass[ 8 ].

Once 5 DOF control of simple objects, such as a simple stylus, is achieved more advanced applications will be developed. This will include 5 DOF control of more complex 3D objects and interactions with other objects in the practical environment. Ideally, the terminal undertaking will let control of a practical ROV, every bit good as control of a robotic arm attached to the vehicle.

More advanced tactile informations will be added to objects in the practical environment. This will be to increase the pragmatism of the force feedback and prove the scope of the device ‘s end product. This tactile information may include utilizing deformable surfaces, tactile beds, and a scope of textures.

Rigid organic structure natural philosophies may besides be implemented utilizing the H3D specific node ‘DynamicTransform ‘ . This will assist to make more realistic practical environments and undertakings.

Detailed clip program

Figure 18: Time tabular array for completion

Figure 18 shows a clip program for completion of the undertakings discussed antecedently. It is intended that the undertakings necessitating the most clip will be undertaken Oklahoman whilst others can be developed at the same time.

Testing and Evaluation

A practical simulation will be performed in which, participants will utilize the manus accountant to command a subsea vehicle to finish a peculiar undertaking. An terminal effecter or tool to interact with objects in the practical environment, and the user should experience the force and haptic response that they would anticipate to experience in a similar existent universe application.

Lange and Flynn et Al ( 2009 ) introduce the construct of usability appraisals as an effectual method to set up how easy a device or application is to utilize. From the consequences of a usability appraisal it is possible to place the countries that need betterment. Lange and Flynn decompose serviceability into the undermentioned classs:

Learnability: the user ‘s ability to set about basic undertakings the first clip they use the device.

Efficiency: how rapidly and aptly users can execute a undertaking after they have got to clasps with the design

Memorability: how proficient a user is after a period non utilizing the device.

Mistakes: quantitative step of the figure of mistakes made, how terrible the mistakes are and whether or non a user could retrieve from an mistake

Satisfaction: how gratifying the design is to utilize

These are merely an illustration of the classs which may be addressed in a usability appraisal. The appraisal can take the signifier of both participant questionnaires and observations, ensuing in both quantitative and qualitative informations.

An rating of the manus accountant presented will be made based on the consequences of a usability appraisal with mention to some of the above standards.

An probe into how good the proposed design compares to current solutions for advanced deft use is of import if a standardized general intent solution is to be achieved. The parametric quantities of the manus accountant will be compared to those of a similar bespoke solution for a tactile manus accountant capable of similar deft use. These parametric quantities will include the cost of the device, its truth, the figure of degrees-of-freedom ( DOF ) users can command and the scope of the force feedback end product. Qualities such as the accountant ‘s easiness of usage and possible to command a scope of undertakings will besides be compared.

( True critical analysis of the proposed system. Stipulate the advantages and restrictions. )

Costss to day of the month

Two Novint Falcon games accountants. $ 249.95 or ?158 each. ( www.home.novint.com )

Ball socket assembly, M5, PK2: ?3.63 ( farnell.com )

Ball socket assembly, M6, PK2: ?3.92 ( farnell.com )

Delrin Natural Rod 12mm Defense Intelligence Agency ten 1000mm: ?2.54 ( directplasticsonline.co.uk )

Logitech Attack 3 control stick: ?17.99 ( Amazon.co.uk )

Entire costs therefore far entire ?344.08. No farther costs are anticipated.

Safety

The possible jeopardies involved in set abouting this undertaking are:

Table: Hazard appraisal

Hazard

Precaution

Prolonged usage of Novint Falcon accountants – taking to tire and potentially Insistent Strain Injury

Take regular interruptions harmonizing to maker specifications – 10-15 minute interruption every hr of usage.

Electrical shocks/damage

When modifying the Falcon accountants, guarantee power supply is away. Besides guarantee power supply is right harmonizing to maker specifications. Do non utilize during lightning storms

Foreign transformers non rated for the 240V from the brinies – rated for 100-120V

Sourced a new power supply to power the falcons. Adjustable electromotive force and current had to be controlled to give 30V and max 1A to each falcon as specified by maker.

Drumhead

Research discussed in this paper gives a wide apprehension of what tactile feedback is and the advantages of implementing force feedback in a scope of applications. It has been shown that the add-on of force feedback, aboard visual-audio shows, in teleoperation and practical world undertakings can better user public presentation, addition acquisition and heighten a user ‘s submergence in a practical environment.

However, of more importance are the current manus accountant solutions for implementing tactile feedback. There were found to be several disadvantages of the current solutions including monetary value, a accountant ‘s inability to be adapted to a scope of undertakings and in the instance of exoskeleton devices, the usage of engineering unproven for existent universe usage.

Design of the proposed manus accountant system was undertaken with these disadvantages in head. The purpose was to bring forth a comparatively inexpensive manus accountant, which is easy to utilize and can be applied to a broad scope of undertakings or applications. COTS devices were exploited because they are comparatively inexpensive compared to high terminal tactile devices and are intentionally easy to utilize in order to appeal to a broad audience and in many instances it is assumed that the device will be used for a broad scope of undertakings. A drawback of COTS devices nevertheless is the low figure of degrees-of-freedom on the input and end product.

The paper describes the advancement made so far in uniting two COTS devices, the Novint Falcon, to bring forth a individual manus accountant system capable of more than 3 DOF input and force feedback end product.

An apprehension of the tactile renderer used to visualize the undertaking has been shown through the development of several simple applications. More advanced techniques, such as implementing force effects and force response algorithms, have been researched extensively leting for immediate advancement to be made on the following phase of development: implementing 5 DOF control and force feedback.

The cardinal undertakings involved in bring forthing the force and torsion values required for 5 DOF feedback have been identified and back uping research has shown several possible ways for finishing these undertakings.

The undertaking will be evaluated through usability appraisals including user questionnaires and observations. From the consequences of these appraisals it will be possible to find, among other things, how easy the system is to utilize and how good it can execute deft use undertakings.

( Appendix 1: Paths to development and commerce )