Patent Publication Number: US-2017361470-A1

Title: Robotic system for confined space operations

Description:
PRIORITY CLAIM 
     This application claims priority from European Patent Application No. 16175502.0 filed on Jun. 21, 2016, the disclosure of which is incorporated by reference. 
     BACKGROUND 
     Field of Endeavor 
     The present disclosure relates generally to robotics and, more particularly, to a robotic device or system including robotic arms for an environment, including but not limited to, confined and complex geometries, e.g. given by pipework or turbine flow-paths in a power plant, for applications, such as, inspection, manipulation, and in-situ repair. 
     Brief Description of the Related Art 
     Robotic devices have been successfully utilized in many different applications, such as machining, assembly, inspection, repair and more. In spite of all of that, it has always been challenging to bring such devices into complex and confined geometries or environments. Conventional robotic devices may have the capability of accommodating various useful operations in non-confined geometries or environments but there is an on-going need for improved tools that may easily adapt to applications in confined and complex spaces. 
     In the context of industrial applications, robotic systems are a quite popular choice for inspection, repair or other manipulation tasks. For example, U.S. Pat. No. 8,374,722 B2 discloses a robotic arm to inspect rotary machines such as a gas turbine engines. The arm has a plurality of groups of links having articulations therebetween for movement in a first plane, the groups having articulations with respect to each other for movement in a second plane. At the distal end of the arm a spatial tip section is installed comprised of a series of elements articulated for movement about both planes so as to be able to move in a snake-like manner. The actuated arm can move around objects such as airfoils in the engine, and also move up or down to remain close to the rotary surface of the machine. However, the device requires a complex actuation, sensing and control system to achieve the targeted manipulation tasks. This limits payload capabilities for an end-tool, achievable robustness as well as the minimal achievable dimensions for operations in confined space. In addition, highly trained operators are required for safe operation of the manipulation arm. 
     In another WO Patent Application Number WO 0216995, a robotic arm comprising a plurality of longitudinal segments, each of which is connected by a plurality links, is described. The end of each segment is “guided” by wires or thin sheets so that by varying the length of the wires, the arm can be actuated and bent. By adjusting the tension in the control wires for each segment, the arm can move and adopt various spatial shapes and configurations. This may be done for example by winding each control wire on or off a spindle using a motor. The motors are controlled for example by a computer control system. Similar to the system described in U.S. Pat. No. 8,374,722 B2, a complex actuation, sensing and control system is necessary to achieve the desired operations in confined spaces. 
     While there are a number of other related prior arts directed towards the continuous improvement of robotic inspection and repair systems, there is a great need for new platforms which perform more and more complex operations within continuously smaller and more complex confined spaces (e.g. more and more complex and curved flow paths in gas turbines). This requirement goes hand in hand with ever increasing requirements for payload capacity, operation speed, simplicity and robustness. 
     SUMMARY 
     This summary will present a simplified overview of the present disclosure in order to provide a basic understanding. It is not intended to either identify key or critical elements of the disclosure or to delineate the scope of the present invention. Rather, the sole purpose of this summary is to present general aspects and concepts of the disclosure as well as its advantages as a prelude to the more detailed description that is provided hereafter. 
     A general object of the present disclosure is to provide the means to transport an end-tool along complex and confined geometries or environments for applications such inspection, maintenance, repair and other related operations. The general object of the invention is to provide a system which can bring increased payloads into complex, confined structures in a faster, simpler and more robust manner. 
     In one aspect of the present disclosure, a robotic system for operations, such as measurement and manipulation tasks in confined spaces and environments is provided. The robotic system disclosed herein may include a main drive unit, a non-actuated extendable arm unit, an axial drive, an arm guidance member and a head articulation unit. The main drive unit may include a mounting structure and an arm storage unit coupled to the mounting structure. Further, the non-actuated extendable arm unit may be coupled to the arm storage unit to be moved axially in a predefined direction in the lateral plane from the arm storage unit. The non-actuated extendable arm unit may include an elongated structure, flexible and thin in the lateral to plane, and rigid and wide in a vertical plane. This extendable arm unit is non-actuated but constructed in a ways to exhibit spring like characteristics in its longitudinal direction. Consequently, it is the shape of the confined space environment which defines the shape of the extendable arm unit. Furthermore, the axial drive unit may be coupled to the arm storage unit to enable axial extension and retraction of the non-actuated extendable arm unit from the arm storage unit. The arm guidance member may be coupled to the arm storage unit to guide the non-actuated extendable arm unit in a predefined direction in the lateral plane during extension and retraction. Moreover, the head articulation unit may be coupled to a free end of the non-actuated extendable arm unit to actuate and move the non-actuated extendable arm unit in varying directions within confined spaces and environments in a “follow-the-leader” manner. 
     In one embodiment, the mounting structure may include a plurality of plates and poles arranged in relation to each other to form first and second levels within the main drive unit to accommodate the arm storage unit extending across the first and second levels. Further, the axial drive unit, as per this embodiment, is disposed in the second level of the mounting structure to enable the non-actuated extendable arm unit to axially extend and contract from the arm storage unit along the direction defined by the arm guidance member. The axial drive unit includes an axial drive motor; and an axial drive tower pinion and spring arrangement driven by the axial drive motor to axially extend and retract the extendable arm. It also includes an arm attachment coupled to the axial drive tower pinion and spring arrangement to axially guide the non-actuated extendable arm unit. Furthermore, the arm guidance member of this embodiment is coupled to the plates along the first level to guide the non-actuated extendable arm unit in a predefined direction in the lateral plane during axial extension and retraction of the non-actuated extendable arm unit from the arm storage unit with respect to the mounting structure. Moreover, the non-actuated extendable arm unit of this embodiment may include an elongated structure and a plurality of wire guides. The elongated structure includes a pair of flat flexible sheet elements disposed spaced-apart from each other in the vertical plane. Further, the plurality of wire guides positioned within the spaced pair of flat flexible sheet elements are also spaced in the vertical plane. This construction forms the non-actuated extendable arm unit which is flexible and thin in the lateral plane, and rigid and wide in a vertical plane. In addition, the structure as such exhibits spring-like characteristics along its longitudinal axis. Consequently, this embodiment of the extendable arm unit can be pushed into a predefined shape of an external infrastructure from the arm storage unit by naturally adapting its own shape in the lateral plane, while maintaining an axially directed force. As such, the main purpose of the extendable arm is transmitting the push force from the axial drive to the head articulation while adapting its shape to the given confined space. 
     The head articulation unit may include a flexible body extending between opposite ends, the flexible body having an interface end coupled to a free end of the extendable arm unit and a plurality of wires guides to couple the head articulation unit with a motor positioned/located within the main drive unit. 
     In another embodiment, the mounting structure may include a plurality of plates arranged in relation to each other to form first and second levels within the main drive unit to accommodate the arm storage unit in the first levels and casing arrangement covering the first and second levels. Further, the arm guidance member, as per this embodiment, may be coupled to the plates along the first level to guide the non-actuated extendable arm unit in a predefined direction in the lateral plane while axially extending or retracting non-actuated extendable arm unit from the arm storage unit. Furthermore, the axial drive unit may be coupled to plates outside of the mounting structure and extend in the mounting structure along the first level to enable the non-actuated extendable arm unit to axially extend and retract from the arm storage unit along the direction defined by the arm guidance member. 
     The axial drive unit as per this embodiment may include an axial drive motor, an axial drive gear and belt arrangement, and an arm attachment. The axial drive gear and belt arrangement may be driven by the axial drive motor. Further, the arm attachment may be coupled to the axial drive gear and belt arrangement to axially push or pull the non-actuated extendable arm unit. The arm attachment may be coupled to the non-actuated extendable arm unit. Further, the arm guidance member may be coupled along a side portion of the first level to guide the non-actuated extendable arm unit in a predefined direction in the lateral plane during axial extension and retraction of the non-actuated extendable arm unit from the arm storage unit with respect to the mounting structure. Furthermore, the non-actuated extendable arm unit may include a flexible sheet (such as e.g. spring steel) orientated in the vertical plane and a plurality of mechanical segments connected by mechanical joints, connected in series along the lateral side edges of the flexible sheet, effectively embedding the sheet within. The flexible sheet of the non-actuated extendable arm unit exhibits the necessary spring characteristics along the extendable arm&#39;s longitudinal axis to allow a payload to be pushed into the predefined shape of an external infrastructure while passively adapting the arm&#39;s shape in the lateral plane. In this context, the segmented joint structure encapsulating the sheet enables the required mechanical robustness and rigidity to support heavy payloads during insertion. 
     Finally, in this alternative embodiment, the head articulation unit may include a steering chain arrangement, having an interface end coupled to a free end of the extendable arm unit, a steering motor coupled to the steering chain arrangement, and a head roll joint coupled to the steering chain arrangement. In this embodiment, the head-roll joint enables an additional rotational degree of freedom aligned with the longitudinal axis of the extendable arm. It creates additional structural flexibility for this second more rigid embodiment of the non-actuated extendable arm unit which is inherent in the first, described embodiment. This rotational flexibility of the head articulation unit is expected to benefit applications where an end-tool needs to align with the orientation of different components in the confined space infrastructure. 
     The robotic system may further include a carrier platform to mount the main drive unit thereon to move the main drive unit along a predefined path. The carrier platform may include a carrier plate, a driving motor, and a guidance member. The carrier plate may be adapted to mount the main drive unit thereon. The driving motor may be coupled to the carrier plate to drive the carrier platform. The guidance member is coupled to the carrier plate to guide the main drive unit along the predefined path. 
     In one embodiment, the robotic system may further include an end tool attached to the head articulation unit. The end tool, in an example, may be an exchangeable inspection scanner. The exchangeable inspection scanner may include a spreading mechanism coupled to the head articulation unit, a back skid coupled to the spreading mechanism at one side, a probe holder having at least one probe, the probe holder coupled to the spreading mechanism on other side opposite to the back skid and a linear guidance coupled to the probe holder to guide the probe holder and probes. In another example, the end tool may be an exchangeable camera system. The camera system may be mounted to the head articulation unit for the purpose of visual inspection. An interface may be provided for the camera system to be coupled to the head articulation unit. 
     In one embodiment, the mounting structure may further includes a plurality of electronic components mounted on the mounting structure to enable operations including at least an electric power distribution, sensor data acquisition, motor control function, communication between a plurality of devices. 
     The term “non-actuated” used herein, such as “non-actuated extendable arm unit” means the extended arm unit is not self-actuated but requires a suitable means as described herein to be actuated. For a better understanding of the various aspects of the present disclosure, its operating advantages, and its uses, reference now should be made to the accompanying exemplary drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present disclosure will be better understood with reference to the following description of a non-exclusive device embodiment, in conjunction with the accompanying drawings in which: 
         FIGS. 1A, 1B and 1C  illustrate a robotic system, in accordance with one exemplary embodiment of the present disclosure; 
         FIGS. 2A, 2B and 2C  illustrate a robotic system, in accordance with another exemplary embodiment of the present disclosure; 
         FIGS. 3A and 3B  illustrate a main drive unit of the robotic system of  FIGS. 1A-1C , in accordance with first exemplary embodiment of the present disclosure; 
         FIGS. 4A and 4B  illustrate an extendable arm unit of the robotic system of  FIGS. 1A-1C , in accordance with first exemplary embodiment of the present disclosure; 
         FIG. 5A and 5B  illustrates an axial drive unit of the robotic system of  FIGS. 1A-1C , in accordance with first exemplary embodiment of the present disclosure; 
         FIG. 6A-6E  illustrate a head articulation unit of the robotic system of  FIGS. 1A-1C , in accordance with first exemplary embodiment of the present disclosure; 
         FIGS. 7A and 7B  illustrate a main drive unit of the robotic system of  FIGS. 2A-2C , in accordance with second exemplary embodiment of the present disclosure; 
         FIGS. 8A and 8B  illustrate an extendable arm unit of the robotic system of  FIGS. 2A-2C , in accordance with second exemplary embodiment of the present disclosure; 
         FIGS. 9A and 9B  illustrate an axial drive unit of the robotic system of  FIGS. 2A-2C , in accordance with second exemplary embodiment of the present disclosure; 
         FIGS. 10A and 10B  illustrate a head articulation unit of the robotic system of  FIGS. 2A-2C , in accordance with second exemplary embodiment of the present disclosure; 
         FIGS. 11A and 11B  illustrate end tool, in accordance with an exemplary embodiment of the present disclosure; 
         FIGS. 12A and 12B  illustrate a carrier platform, in accordance with an exemplary embodiment of the present disclosure; and 
         FIGS. 13A and 13B  illustrate an example environment where the robotic system may be utilized for purposes, such as inspection, manipulation or repair. 
     
    
    
     Like reference numerals refer to like parts throughout the description of several views of the drawings. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     For a thorough understanding of the present disclosure, reference is to be made to the following detailed description, including the appended claims, in connection with the above-described drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only, in order to avoid obscuring the disclosure. Reference in this specification to “one embodiment,” “an embodiment,” “another embodiment,” “various embodiments,” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearance of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but may not be of other embodiment&#39;s requirement. 
     Although the following description contains many specifics for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to these details are within the scope of the present disclosure. Similarly, although many of the features of the present disclosure are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the present disclosure is set forth without any loss of generality to, and without imposing limitations upon, the present disclosure. Further, the relative terms used herein do not denote any order, elevation or importance, but rather are used to distinguish one element from another. Further, the terms “a,” “an,” and “plurality” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 
     Referring to  FIGS. 1A to 13B , various embodiments and components of a robotic system  100  are depicted in accordance with various exemplary embodiments of the present disclosure. The robotic system  10  may be utilized in various environments, for application including, but not limited to, inspection, manipulation and repair. 
       FIGS. 1A to 2C  broadly depict a robotic system  10  in accordance with various embodiments of the present disclosure. The robotic system  10  includes a main drive unit  100 ,  200 , a non-actuated extendable arm unit  110 ,  210 , an axial drive unit  120 ,  210  (shown in  FIGS. 5A and 9A-9B ), an arm guidance member  130 ,  230 , and a head articulation unit  140 ,  240 . The main drive unit  100 ,  200  may include a mounting structure  101 ,  201 , and an arm storage unit  102 ,  202  (shown in  FIGS. 3A and 7B ) coupled to the mounting structure  101 ,  201 . Further, the non-actuated extendable arm unit  110 ,  210  may be coupled to the arm storage unit  102 ,  202  to be moved axially in a predefined direction in a lateral plane from the arm storage unit  102 ,  202 . The non-actuated extendable arm unit  110 ,  210  may include an elongated structure  111 ,  211  flexible and thin in the lateral plane, and rigid and wide in a vertical plane. Furthermore, the axial drive unit  120 ,  220  may be coupled to the arm storage unit  102 ,  202  to enable axial extension and retraction of the non-actuated extendable arm unit  110 ,  220  from the arm storage unit  102 ,  202 . The arm guidance member  130 ,  230  may be coupled to the arm storage unit  102 ,  202  to guide the non-actuated extendable aim unit  110 ,  220  in a predefined direction in the lateral plane during extension and retraction. Moreover, the head articulation unit  140 ,  240  may be coupled to a free end  110   a,    210   a  of the non-actuated extendable arm unit  110 ,  220  to actuate and move the non-actuated extendable arm unit  110 ,  220  in varying directions in the confined spaces and environments. To actuate the head articulation unit  140 ,  240 , head articulation motors  141 ,  241  may be configured selectively on the mounting structure  101  or within the head articulation unit  240  itself. Moreover, end tools may be coupled to the head articulation unit  140 ,  240  and will be described with reference to  FIGS. 11A and 11B . 
     Referring now to  FIGS. 3A to 6E , as per one embodiment of the present disclosure, the robotic system  10  will be described in detail. In  FIGS. 3A and 3B , the main drive unit  100 , having the mounting structure  101  and the arm storage unit  102  coupled to the mounting structure  101  is depicted. The mounting structure  101  may include a plurality of plates  103   a  and poles  103   b  arranged in relation to each other to form first and second levels  104   a,    104   b  within the main drive unit  103  to accommodate the arm storage unit  102  which extends across the first and second levels  103   a,    103   b.  As depicted in example  FIGS. 3A and 3B , three plates  103   a  are horizontally disposed one above other in spaced manner and supported by poles  103   b  which are disposed along the corners of the plates  103   a  to obtain a rigid mounting structure  101 . The first level  104   a  of the mounting structure  101  is obtained between the above two plates  103   a,  and the second level  104   b  of the mounting structure  101  is obtained between the below two plates  103   a,  middle plate  103   a  being common to both the first  104   a  and second  104   b  levels. Further, each plate  102   a  may include an opening  105  that is axially aligned with the openings of the other plates. The axially aligned openings  105  may be capable of rotatably accommodating the arm storage unit  102  extending in the first  104   a  and second  104   b  levels. In an example form, the arm storage unit  102  may be a rotatable drum aligned and extending along the first and second levels  104   a,    104   b  of the mounting structure  101 . 
     As depicted in  FIGS. 4A, 4B and 5A and 5B , and described in conjunction with  FIGS. 1A-1C and 3A-3B , the axial drive unit  120  and the non-actuated extendable arm unit  110  (hereinafter will be referred to as ‘arm unit  110 ’) as per this embodiment may be disposed in the first level  104   b  of the mounting structure  101  to enable the arm unit  110  to axially extend and contract from the arm storage unit  102  along the direction defined by the arm guidance member  130 . Further, the arm guidance member  130  (hereinafter referred to as ‘guidance member  130 ’) of this embodiment may be coupled to the plates  103   a  along the first level  104   a  to guide the arm unit  110  in the lateral plane during axial extension and retraction of the arm unit  110  from the arm storage unit  102  with respect to the mounting structure  101 . The axial drive unit  120 , guidance member  130  and the non-actuated arm unit  110  of the present embodiment will be described with reference to example  FIGS. 4A-4B and 5A-5B . 
     The axial drive unit  120  includes an axial drive motor  121 , an axial drive tower pinion and spring arrangement  122  (hereinafter will be referred to as ‘drive tower  122 ’) and an arm attachment  123 . The drive tower  122  is driven by the axial drive motor  121  to axially expand and contract the arm unit  110 . The arm attachment  123  is coupled to the drive tower  122  to axially guide the arm unit  110 . 
     The arm guidance member  130  may be coupled to the plates  103   a  of the first level  104   a  to guide the arm unit  110  in a predefined direction in the lateral plane during axial extension and retraction of the arm unit  110  from the arm storage unit  102  with respect to the mounting structure  101 . The arm guidance member  130  may include a set of rollers  131  configured on both of the plates  103   a  of the first level  104   a  through which the arm unit  110  may pass and be guided therebetween to enable axial expansion and contraction of the arm unit  110 . 
     Further, the arm unit  110  may include an elongated structure  112  having a pair of flat flexible sheet elements  112   a,    112   b  (hereinafter “sheet  112   a / 112   b ”) disposed spaced-apartly from each other in the vertical plane. The sheets  112   a / 112   b  may be made, for example, of fiber glass without departing the scope of being made of other material having flexibility and strength enough to meet the industrial requirement. Further, the arm unit  110  may include a plurality of wires guides  113  that may be disposed within the spaced pair of sheets  112   a / 112   b  in spaced manner to provide additional rigidity to the structure. These wire guides  113  are disposed within the spaced pair of sheets  112  in spaced manner along the longitudinal direction of the sheets  112 . The sheets  112  and wire guides  113  define the arm unit  110  that is flexible and thin in the lateral plane, and rigid and wide in a vertical plane, and which exhibits spring-like characteristics along its longitudinal axis. This enables the arm unit  110  to be pushed into a predefined shape of the external infrastructure, from the arm storage unit  102  by passively adapting its own shape in the lateral plane through its free end  110   a.    
     In one embodiment, the wire guides  113  may contain longitudinally extending rods having distal ends with holes (not shown for clarity). As per this embodiment, the wire guides  113  may incorporate wires, such as Bowden cables (not shown for clarity) passing through the holes to actuate the head articulation unit  140  to steer the non-actuated arm unit  110  by actively adapting its own shape in the lateral plane through its free end  110   a.  For that purpose, as shown in  FIG. 6A , the head articulation unit  140  may include a flexible body  142  extending between opposite ends  143   a,    143   b.  The opposite ends  143   a,    143   b  respectively include upper and lower steering wires attachments  144   a,    144   b  for actuating the flexible body  142  in a desired manner by actuating the wires  144   a,    144   b  through the head articulation motors  141 . Further, the flexible body  142  includes an interface end  144   c  coupled to a free end of the arm unit  110  through which wires pass to be coupled to the end tool  300 . The steering wires attachments  144   a,    144   b  with the wires couple the head articulation unit  140  with the head articulation motors  141  (see  FIG. 4B ) disposed in the main drive unit  101  to transmit mechanical movement from the head articulation motors  141  installed on the mounting structure  101  along the second level  104   b  to the head articulation unit  140 . The head articulation unit  140  with the flexible body  142  and motor  141  may be capable of enabling steering or twisting movements (head-roll degree of freedom) of head articulation unit  140 , and ultimately to move the end tool  300  in desired direction. By moving the head articulation motors  141  installed on the mounting structure  101  in same direction the steering is achieved while by moving the motors  141  in opposite directions head twisting is achieved. In addition, the wire guides  113  may also include electrical transmission cables (not shown for clarity) that may provide electrical data or power signals to motors and/or sensors embedded in the head articulation unit  140  and/or end-tool. 
       FIGS. 6B-6E  illustrates various examples in which the unit  110  may be moved by the head articulation unit  140  that is driven by the at least one of the motor drive arrangements  141  configured in the mounting unit  101  to enable the end tool  300  towards the targeted area in the environment.  FIGS. 6B and 6C  respectively illustrate top and isometric views of the arm unit  140  and the end tool  300  when the head articulation unit  140  enables the arm unit  110  to move straight in forward to backward direction in the given confined environment.  FIGS. 6C and 6D  respectively illustrate top and isometric views of the arm unit  110  and the end tool  300  when the head articulation unit  300  enables the arm unit  110  to move left or right in the confined space environment. 
     Referring now to  FIGS. 7A to 10B , another embodiment of the robotic system  10  is described. The main drive unit  200  of this embodiment, similar to above, includes a mounting structure  201  and the arm storage unit  202  coupled to the mounting structure  201 . The mounting structure  201  includes a plurality of plates  203   a  arranged in relation to each other to form first and  204   a  second  204   b  levels within the main drive unit  200  to accommodate the arm storage unit  202  in the first level  204   a.  The mounting structure of this embodiment also includes casing arrangement  205  for covering the first and second levels  204   a,    204   b.  Further, the arm storage unit  202  coupled to the mounting structure  201  is positioned in the first level  204   a.  As seen in  FIG. 7B , the arm storage unit  202  may include spiral grooves  202   a  engraved in the upper and lower plates  203   a  to store the arm unit  210  therealong. 
     Furthermore, the axial drive unit  220 , as seen  FIGS. 9A-9B  as described in conjunction to  FIGS. 7A-8C , may be coupled to plates  203   a  outside of the mounting structure  201  and extend in the mounting structure  201  along the second level  204   b  to enable the arm unit  210  to axially extend and contract from the arm storage unit  202  along the direction defined by the arm guidance member  230 . The axial drive unit  220  as per this embodiment may include an axial drive motor  221 , an axial drive gear and belt arrangement  222  coupled with a gear box  222   a,  and an arm attachment  223 . The axial drive gear and belt arrangement  222  is driven by the axial drive motor  221  with the help of gear box  222   a.  The arm attachment  223  may be coupled to the arm unit  210  to drive the arm unit  210 . 
     Further, the arm guidance member  230  may be coupled to the plates  203   a  along the first level  204   a  to guide the arm unit  210  in a predefined direction in the lateral plane during axial extension and retraction of the arm unit  210  from the arm storage unit  202  with respect to the mounting structure  201 . In one example arrangement, as shown in  FIG. 9A , the arm guidance member  230  may be coupled along a side portion  230   c  of the first level  204   a  to guide the arm unit  210 . As per this arrangement, the arm guidance member  230  includes a set of two plates  231  arranged vertically and in spaced manner from each other. Through the spaced plates  231 , the arm unit  210  is advanced to expand or contract from and on the arm storage unit  202  and supported by a set of arm guidance member  230 . 
     Furthermore, the arm unit  210  (seen in  FIGS. 8A-8B ) of this embodiment may include a sheet structure  211  embedded a plurality of mechanical segments  212 . The sheet  211  may be made, for example, of spring steel without departing the scope of being made of other material having flexibility and strength enough to meet the industrial requirement. The flexible sheet  211  extends in the lateral plane and the various mechanical segments  212  coupled by mechanical joints  212   a  are mounted laterally along the sheet  211  to obtain the arm unit  210 . As in the first described embodiment, the arm unit  210  also flexible and thin in the lateral plane, and rigid and wide in a vertical plane, exhibits spring-like characteristics along its longitudinal axis to be pushed from the arm storage unit  202  into a predefined shape of an external infrastructure, by passively adapting its own shape in the lateral plane. 
     The head articulation unit  240 , as seen  FIGS. 10A-10C  and as described in conjunction with  FIGS. 7A-9C , may be configured to the arm unit  210 . The head articulation unit  240  may include a steering chain arrangement  241 , a steering motor  242  and a head roll joint  243 . The head articulation unit  240  includes an interface end  241   a  coupled to a free end of the arm unit  210 . The steering motor  242  is installed in the head articulation unit  240 . Further, the steering motor  242  is coupled to the steering chain arrangement  241  to actuate the steering chain  241 . The steering chain arrangement  241  may extend from the steering motor  242  of the head articulation unit  240  to the tip of the head articulation unit  240 . 
     Referring now to  FIGS. 11A and 11B , the robotic system  10  may further include various kinds of end tools  300  depending as per the requirement and nature of the job to be carried out by the robotic system  10 . In the context of this disclosure, the robotic system  10  may be utilized for the purpose of inspection and will be described accordingly, without departing from the scope of being utilized for other applications. For the purpose of inspection, the end tool  300  may be an exchangeable inspection scanner  300 . The exchangeable inspection scanner  300  may be configured to the head articulation unit  140 ,  240  to scan a specific surface area in a given confined space environment using methods such as ultrasound or eddy current inspection. In an example embodiment, as shown in  FIG. 11A , the exchangeable inspection scanner  300  may include a spreading mechanism  310 , a back skid  311 , a probe holder  312 , and a linear guidance  314 . The spreading mechanism  310  may be coupled to the head articulation unit  140 ,  240 . The back skid  311  may be coupled to the spreading mechanism  310  at one side and the probe holder  312  may be coupled to the spreading mechanism  310  on other side opposite to the back skid  311 . The probe holder  312  is capable of holding at least one measurement probe  312   a,  for example for non-destructive testing. Further, the linear guidance  314  may be coupled to the probe holder  312  to guide the probe holder  312  and probes  312   a  linearly along the linear guidance  314 . The spreading mechanism  310  enables the probe holder  312  and probes  312   a  to extend transversely in to the structure for inspection as for example between the opposing airfoils of gas turbine blades. 
     In one embodiment, the end tool  300  may be an exchangeable camera system  316  mounted to the head articulation unit  140 ,  240  for the purpose of visual inspection, such exchangeable camera system  316  may include an interface  316   a  for the camera to be coupled to the head articulation unit  140 ,  240 . 
     In one embodiment, the mounting structure  101 ,  202  may further includes a plurality of electronic components (not shown) mounted on the mounting structure  101 ,  202  to enable operations including at least an electric power distribution, sensor data acquisition, motor control function, communication between a plurality of devices. The electronic components may be disposed in the mounting structure  101 ,  202  in the second level  104   b,    204   b.  In one embodiment, various wiring arrangements (not shown) are configured to respective units to electrically transmit data signals and electric power along the respective unit. 
     As shown in  FIGS. 12A and 12B , the robotic system  10  may further include a carrier platform  400  to mount the main drive unit  100 ,  200  thereon to move the main drive unit  100 ,  200  along a predefined path. The carrier platform  400  may include a carrier plate  410 , a driving motor  420 , and a guidance member  430 . The carrier plate  410  may be adapted to mount the main drive unit  100 ,  200  thereon. The driving motor  420  may be coupled to the carrier plate  400  to drive the carrier platform  410 . The guidance member  430  is coupled to the carrier plate  410  to guide the main drive unit  100 ,  200  along the predefined path. The carrier platform  400  may be driven in a direction, such as linear direction, circular direction or omnidirectional as per the need, depending upon an environment in which the robotic system  10  may be used. For example, if the carrier platform  400  is moved in a circular direction along the circumference of an object, the main drive unit  100 ,  200  installed on the carrier platform  400  moves a with the a platform  400  along the given circular path. 
       FIGS. 13A and 13B  depict an environment  1000  where the robotic system  10  of the present disclosure may be utilized for the purpose of inspection. The environment  1000  may be turbine blades  1001  along the rotor and stator of a gas turbine where the robotic system  10  may be used for inspection purposes. However, without departing from the scope of the present disclosure, there may be other environments where the robotic system  10  may be utilized as per the requirement. 
     While the disclosure has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. 
     REFERENCE NUMERAL LIST 
     
         
           10  Robotic system 
           100 ,  200  Main drive unit 
           101 ,  201  Mounting structure 
           102 ,  202  Arm storage unit 
           103   a,    203   a  Plates 
           103   b  Poles 
           104   a,    204   a  First level 
           104   b,    204   b  Second level 
           105  Opening 
           205  Casing arrangement 
           110 ,  210  Non-actuated extendable arm unit 
           110   a,    210   a  Free end 
           111 ,  211  Flexible sheet arrangement 
           112  Elongated structure 
           112   a,    112   b  Pair of flat flexible sheet elements 
           113  Wires guides 
           211  Flexible elongated sheet 
           212  Mechanical joints 
           120 ,  220  Axial drive unit 
           121  Axial drive motor 
           122  Axial drive tower pinion and spring arrangement 
           123  Arm attachment 
           221  Axial drive motor 
           222  Axial drive gear and belt arrangement 
           222   a  Gear box 
           223  Arm attachment 
           130 ,  230  Arm guidance member 
           131  Rollers 
           230   c  Side portion 
           231  Set of two plates 
           140 ,  240  Head articulation unit 
           141  Head articulation motors 
           142  Flexible body 
           143   a,    143   b  Opposite ends 
           144   a,    144   b  Upper and lower steering wires attachments 
           144   c  Interface end 
           241  Steering chain arrangement 
           242  Steering motor 
           243  Head roll joint 
           241   a  Interface end 
           300  End tool, exchangeable scanner 
           310  Spreading mechanism 
           311  Back skid 
           312  Probe holder 
           312   a  Probes 
           314  Linear guidance 
           316  Exchangeable camera system 
           316   a  Interface 
           400  Carrier platform 
           410  Carrier plate 
           420  Driving motor 
           430  Guidance member 
           1000  Environment 
           1001  Turbine blades