Patent Publication Number: US-2023158665-A1

Title: Modular robotic structure

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/758,169, filed on Apr. 22, 2020, which is a 371 of PCT/CA2018/051338 filed Oct. 23, 2018, which claims priority on Provisional U.S. Application No. 62/575,602 filed on Oct. 23, 2017, the content of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present application relates to modular articulated mechanisms, and more particularly, to modular robotic structures or robot articulated limbs. 
     BACKGROUND OF THE ART 
     It is generally known to have robot systems which are modular, reconfigurable and expandable to thus improve the flexibility and versatility thereof. For example, a manipulator arm of the robot system may be formed of a number of independent rotary modules releasably connected to each other. The manipulator arm may be disassembled and reassembled in order to obtain different arm configurations. A motor having a drive shaft may drive one module relative to another for pivoting the modules relative to each other. 
     Automation is becoming increasingly desirable in robotic design. However, existing robotic architectures have some drawbacks and limitations in terms of implementation, versatility, structural strength, flexibility, compactness and adaptability just to name a few. For example, the torque may require a large motor. Furthermore, the manipulator arm may occupy a large volume when the modules are folded and the motors installed. Accordingly, there is room for improvement. 
     SUMMARY 
     In one aspect, there is provided a motorized module for a modular robotic structure comprising a housing; a first wheel mounted to the housing and having a first axis of rotation; a second wheel mounted to the housing and having a second axis of rotation; an elongated structure mounted to the first and second wheels and configured to rotate the first and second wheels; a driver mounted to the housing between the first and second wheels, the driver having a rotatable pin extending along a first longitudinal axis, the rotatable pin rotating about the first longitudinal axis; a leadscrew mounted to the housing between the first and second wheels, the leadscrew extending along a second longitudinal axis, the leadscrew rotating about the second longitudinal axis; a transmission drivingly connecting the driver to the leadscrew; and a connector coupled to the leadscrew and configured to move longitudinally along the second longitudinal axis in response to a rotation of the leadscrew, the connector being attached to the elongated structure. 
     In another aspect, there is provided a manipulator arm for a modular robotic structure comprising a base module having a first shaft and a second shaft extending therefrom, the first and second shafts extending in opposite directions; a first module coupled to the base module and configured to rotate relative to the base module, the first module including a first pair of interconnected wheels and a second pair of interconnected wheels, the first pair of interconnected wheels having a first wheel drivingly engaged with the first shaft and a second wheel, the second pair of interconnected wheels having a third wheel idly engaged with the second shaft and a fourth wheel; and a second module coupled to the first module and configure to rotate relative to the first module, the second module being drivingly engaged with the fourth wheel. 
     In another aspect, there is provided a manipulator arm for a modular robotic structure comprising a first module having a first compartment defined therein between two spaced-apart longitudinal first arm elements, the first arm elements defining a boundary of the first module; a second module coupled to the first module and configured to rotate relative to the first module, the second module configured to be inserted in the first compartment. 
     In another aspect, there is provided a motorized module for a modular robotic structure comprising a housing; at least one wheel mounted to the housing; an elongated structure mounted to the at least one wheel configured to rotate the at least one wheel; and a driver drivingly connected to the elongated structure and configured to move longitudinally along a first path. 
     In another aspect, there is provided a system to allow a motorized module to be connected to a non-motorized module in order to form an articulated link. This link could be assembled in order to form a mobile robot or an articulated modular limb. 
     In another aspect, there is provided a system to allow converting existed modular articulated limb to become motorized limb by simply connecting a new motorized module in one or both sides of the limb. This operation could be realized by providing an appropriate shaft in order to turn a second module relative to a first module. 
     In accordance with a further aspect, a motorized module may comprise an actuator, a control system; sensor and communication system integrated therein. The module may further have a battery or another source of power in order to move the second module relative to the first module. 
     The present disclosure allows, among others, designing a mobile robot for Explosive Ordnance Disposal (EOD), mining and for construction. 
     Also the present disclosure allows designing an articulated arm used for EOD mining and construction. 
     In accordance with another aspect, there is provided a new lightweight frame design having a novel modular architecture that can be adaptable to many applications and shape. 
     In accordance with another aspect, there is provided a modular articulation in order to attach many robots together in a serial mode. 
     In accordance with another aspect, this robot could be a tele-operating or autonomous robot using integrated batteries or the like. 
     In accordance with one possible applications, the robotic modular architecture could be configured for used with drones. The drone has a body including a light weight sandwich panel having a top and a bottom layer carrying solar cells. A pneumatic ring or other buoyant structures could be integrated to the drone structure in order to allow the drone to float on water. Also, a bumper, e.g. the pneumatic ring, could be provided on the drone structure to protect it against collision accident and to use it for emergency landing. A mechanism of compressed air can be provided to further inflate the ring and be used when necessary such as in landing or emergency situations. 
     According to a further aspect, the drone comprises a plurality of modular propulsion cylinders (for instance 3 to 12 propulsion cylinders per drone according to one implementation), each modular propulsion cylinder having its own controller and a propeller on at least one side. Such propulsion cylinder could be inserted into the body of a drone (plug and play) electrical connectors. Each propulsion cylinder can have a controller and a battery. The number of activated propulsion cylinder is determined by an algorithm in order to distribute the force and the optimization of the power need for a given task. 
     According to a still further aspect, a modular articulated robotic limb is mounted to a drone in order to manipulate object or to allows for in-flight capturing of a second drone. The limb may be provided in the form of an arm of a drone to pick an object and place the object in a basket carried by the drone. 
     In a further aspect, the drone is formed by a light weight sandwich panel. Formed by a central body and 2 disk on each side. The central bodies construct from fiber carbon and plastic that could be manufactured with a 3D printer. This body has a plurality of cylinders (e.g. a dozen) and a compartments for battery, control system, navigation, camera and sensor. Electrical connectors are provided for each cylinder. The disk is attached by the screws and covered by a solar panel 
     It is also contemplated to connect an extra engine on the top of the drone using a bracket, thereby allowing the drone to be used as a hydro-craft. 
     The ability to control the number and the sequence of the engine provides an advantage on the “fly capacity” in order to rotate the drone in three degrees of freedom (i.e. X, Y, Z). 
     It is also contemplated to provide different shape for the pneumatic ring in order to provide for a planer drone using a pneumatic wing having an aerodynamic shape. 
     In another aspect, a manual (none powered) articulated arm module is allowed to be converted into a motorized arm module by the addition of an independent module. This independent module uses a linear motor connected via a belt or chain in order to allow the manual rotation to be transformed to automated rotation. A manual articulated arm can thus be readily converted into an automated arm by mounting a motorized module on one side of a link of the articulated arm. The motorized module uses a linear mechanism attached to a timing belt. The linear mechanism uses leadscrew or ACME screw that provides motion precision to the rotation module with fewer backlashes. Also it allows the rotation to be rigid or flexible depending on the leadscrew. The ACME screw allows automatically lock the system against when the actuator or motor is shut down. This is specially advantageous if the module turn in X orientation like an elephant trump. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG.  1 A  illustrates a motorized module including a rotary motor driving a leadscrew in order to rotate pulleys using a timing belt or chain; 
         FIG.  1 B  illustrates an assembly of the motorized module shown in  FIG.  1 A , showing the motorized module covered with a cover; 
         FIGS.  1 C- 1 D  illustrate a mechanism of rotation including the pulleys and a hollow shaft cooperating with the pulley and bearings; 
         FIG.  1 E  illustrates a cross-sectional view of the assembly of the motorized module of  FIG.  1 B ; 
         FIGS.  1 F- 1 G  illustrate different views of the motorized module of  FIG.  1 B ; 
         FIG.  2    illustrates a base module connected on each side to a fixed shaft, all shafts are hollow shafts in order to pass wires or an extra pin through, also illustrates a hole in order to fix a camera therein; 
         FIG.  3 A  illustrates a manipulator arm including a first module connected to a portion of a second module; 
         FIG.  3 B  illustrates a cutaway portion of the first module of  FIG.  3 A ; 
         FIGS.  3 C- 3 D  illustrate the second module of  FIG.  3 A , the second module having an H-shape module; 
         FIG.  4    illustrates a manipulator arm that can be used as a robot or a part of the robot, the manipulator arm includes three module; 
         FIG.  5    illustrates a section of a module; 
         FIG.  6    illustrates an manipulator arm in accordance with another embodiment, a manual modular manipulator arm is transformed into a motorized arm using a motorized module on each side; 
         FIG.  7 A  illustrates a mobile robot formed from two motorized modules attached to a base; 
         FIG.  7 B  illustrates a motorized module in accordance with another embodiment, this module use a cam systems associated to a linear motorized movement, this cam system allows the rotation of 180 degrees of the shaft; 
         FIGS.  7 C- 7 D  illustrate the manipulator arm in a folded position ( FIG.  7 C ) and in an extended position ( FIG.  7 D ); 
         FIGS.  8 A- 8 F  illustrate a mobile robot using manipulator arm or arms; 
         FIG.  9    illustrates the mobile robot configured for use in Explosive Ordnance Disposal (EOD) applications, formed by two motorized modules and one C shape module pivoting ±90 degrees with a disrupter on top; 
         FIGS.  10 A- 10 C  illustrates a modular manipulator arm having a manually moving module ( FIG.  10 A ) and a modular manipulator arm transformed into a motorized arm by attaching motorized modules ( FIG.  100   ); 
         FIGS.  11 A- 11 K  illustrate a manipulator arm mounted on a drone; 
         FIG.  12 A  illustrates a cross-sectional view of a motor using a ferrofluid brake; and 
         FIG.  12 B  illustrates a turbine surrounded by the ferrofluid. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1 A  illustrates a motorized module  50  for a modular robotic structure. For example, the motorized module  50  may be used to rotate rotary modules of a robot. The motorized module  50  may include a housing  66  for housing a driver  52  (e.g. a rotary motor) drivingly coupled to a linear screw mechanism, or a leadscrew  54 , to convert rotational motion from the driver  52  into a linear motion. As used herein, the term “coupled” is used in its broadest sense to refer to elements which are connected, attached, and/or engaged, either directly or integrally or indirectly via other elements, and either permanently, temporarily, or removably. 
     As used herein, the term “drivingly” (e.g., “drivingly engaged” or “drivingly coupled”) describes a communicative relationship between components, for example where an output force from either a first component or a second component is directly or indirectly communicated to the other of the first component or the second component. For example, the term “drivingly engaged” is intended to include any engagement allowing two components to rotate together, at the same speed or at different speeds, and in the same direction or in different directions, including, but not limited to, direct connections, direct meshed engagement, engagement through meshing with one or more intermediate meshed element(s) (gear, pinion, etc.) and engagement through intermediate elements, e.g. idler gear. 
     The driver  52  may be any one of an electric, a pneumatic, and a hydraulic motor. The driver  52  may also be mechanically manipulated by a user. The driver  52  may have a rotatable pin  63  that extends along a first longitudinal axis, whereas the rotatable pin  63  may rotate about the first longitudinal axis. The leadscrew  54  extends along a second longitudinal axis, whereas the leadscrew  54  may rotate about the second longitudinal axis. The first and second longitudinal axes may be coplanar, that is, the axes extend in the same plane. In some embodiments, the coplanar and/or parallel axes may provide a compact design. For example, the compact design may refer to a design that has a width close to a width of the wheels. The first and second longitudinal axes may be parallel. The leadscrew  54  may include ACME threads. A transmission may be provided between the driver  52  and the leadscrew  54  to drivingly connect the driver  52  to the leadscrew  54 . In other words, the transmission may transfer the rotation of the driver  52  to rotate the leadscrew  54 . The transmission may include a set of gears. 
     In the embodiment shown in  FIG.  1 A , the leadscrew  54  is attached to an elongated structure  56 , such as a timing belt, a belt, a cam and follower, and the like, via a connector  58 . Thus, the structure  56  may be flexible such as a belt or a chain, or rigid such as a cam. As such, the connector  58  is attached to the structure  56 . The connector  58  is intended to refer to any suitable attachment to attach the leadscrew  54  and the structure  56  together. For example, the connector  58  may be coupled to the leadscrew  54  and configured to move longitudinally along the second longitudinal axis in response to a rotation of the leadscrew  54 . Thus, turning the leadscrew  54  may consequently translate or move the structure  56  via the connector  58 . 
     The motorized module  50  includes may include one or more wheels  60 . For example, in the embodiment shown in  FIG.  1 A , the motorized module  50  includes a first wheel  60  mounted to the housing  66  and having a first axis of rotation  62 , and a second wheel  60  mounted to the housing  66  and having a second axis of rotation  62 . The first and second axes of rotation may be parallel. The wheels  60  may be mounted in a same plane (e.g. bottom plane of the housing  66 ). One or both of the wheels  60  may be a pulley. The wheels  60  may form a pair of interconnected wheels. In other words, the rotation of the wheels  60  may be linked. In the embodiment shown in  FIG.  1 A , the wheels  60  have the same size, e.g. diameter, and thus rotate at the same rate. The structure  56  may be mounted to the first and second wheels  60  and configured to rotate the wheels  60 . That is, in use, when the connector  58  is moved, the structure  58  rotate the wheels  60 . In the embodiment shown in  FIG.  1 A , the structure  56  is mounted around the two spaced apart wheels  60  that are also contained within the housing  66 . That is, the structure  56  is configured as an endless loop around the first and second wheels  60 . As such, the movement of the structure  56  may rotate the two wheels  60  at the same rate of rotation. The structure  56  may be attached to the wheels  60 . In other words, a first end of the structure  56  may be attached to one of the wheels  60  and a second end of the structure  56  may be attached to another one of the pulleys  60 . One or more of the wheels  60  may be a toothed wheel, and the structure  56  may include a chain configured to drive the toothed wheel. The motorized module  50  may include a brake configured to halt a movement of the structure  56 . In other words, the brake may arrest, or fix the rotation of the wheels  60 . 
     In the embodiment shown in  FIG.  1 A , the driver  52  is mounted between the wheels  60 , and the leadscrew  54  is mounted between the wheels. In alternate embodiments, the driver  52 , the leadscrew  54 , or both, may be mounted in other suitable locations relative to the housing  66  to rotate the wheels  60 . This configuration may provide a low profile and compact design of the motorized module  50 . 
       FIG.  1 B  illustrates a cover  64  mounted to the housing  66  of the motorized module  50 . The cover  64  may be attached to the housing  66  through screws  68 . Holes  70  may be defined in the cover  64  to receive the screws  68  to secure the cover  64  onto the housing  66 . 
       FIGS.  1 C- 1 D  illustrate other views of the motorized module  50 . As shown in  FIG.  10   , the driver  52  rotates a gear  72  which in turn rotates an adjacent second gear  74  attached to the leadscrew  54 . As such, the second gear  74  rotates the leadscrew  54  to move the connector  58  along, or parallel, to the second longitudinal axis of the leadscrew  54 . As the connector  58  moves, the structure  56  moves a corresponding distance. A pin  58 A may be connected to the connector  58  to extend through a slot defined in the housing  66 . The slot may define a range of movement of the connector  58 . The slot may extend in a direction parallel to the second longitudinal axis. A key  112 A may be defined in the wheel  60  to receive a corresponding key from a shaft. 
       FIG.  1 E  illustrates a cutaway of the motorized module  50 . 
       FIGS.  1 F- 1 G  illustrate the assembled motorized module  50 . As may appreciated in  FIGS.  1 F- 1 G , when assembled, the motorized module  50  is compact and can be used as a “plug and play” module. 
       FIG.  2    illustrates a base module  76 . A shaft  78  may be fixed on each of two opposed sides of the base module  76 . The shafts  78  may be hollow in order to pass wires or the like, or a pin therethrough. An aperture  80  may be defined in the base module  76 . The aperture  80  can be used to attach an instrument or a payload, such as a camera, on the base module  76 . One or motorized modules  50  may be coupled to the base module  76 . The wheel  60  may be mounted to the shaft  78 . 
       FIG.  3 A  illustrate a manipulator arm  81  for a modular robotic structure. The manipulator arm  81  may include the base module  76 , a first module  82  coupled to the base module  76  and configured to rotate relative to the base module  76 , and a second module  84  coupled to the first module  82  and configured to rotate relative to the first module  82 . The term “arm”, as used herein, is intended to encompass either a manipulator arm composed of a single arm element or an assembly comprising a multi-segment arm, where pairs of the segments may be interconnected by joints or the like. 
     The base module  76  has a first shaft portion  78 , or support shaft, and a second shaft portion  78 . The shaft portions  78  may refer to one shaft extending along a rotation axis. The shaft portions  78  may be two separate shaft extending from an end of the base module  76 . In the embodiment shown in  FIG.  3 A , the shafts  78  extend in opposite directions. The first module  82  may be connected to a portion of the second module  84 . 
     The first module may include a first pair of interconnected wheels and a second pair of interconnected wheels. The first pair of interconnected wheels has a first wheel  60 A fixedly connected with the first shaft  78  and a second wheel  88 A. The second pair of interconnected wheels has a third wheel  60 B rotatably mounted on the second shaft  78  and a fourth wheel  88 B. The second module  84  is drivingly engaged with the fourth wheel  88 B. For example, a shaft  79  may be fixedly attached to the second module  84  and the fourth wheel  88 B. As such, rotating the fourth wheel  88 B would rotate the second module  84 . The second module  84  may include a fifth wheel  96  drivingly engaged with the second wheel  88 A. 
     A first module assembly may include the base module  76  and two motorized modules  50 . The base module  76  may be connected between the two motorized modules  50  to form a C-shaped module of the first module assembly. As such, the first wheel  60 A correspond to a wheel  60  of the first motorized module  50 A and the third wheel  60 B corresponds to another wheel  60  of the second motorized module  50 B. 
     As mentioned before, the shaft  78  may be non-rotatably attached to the base module  76 . In use, the wheel  60 A of the first motorized module  50 A rotates, or turns, around the shaft  78 . A ring  86  may be mounted at an end of the shaft  78  to secure the wheel  60 A in place around the shaft  78 . At the other end of the motorized module  50 A, wheel  88 A may rotate a shaft  90 . Bushings or bearings  92  and  94  may be provided to the rotatable shaft  90 . Bearing  92  may be fixed on the motorized module  50 A. Bearing  92  may be fixed on the portion of the second module  84 . In operation, the wheel  88 A may rotate the shaft  90  to rotate the fifth wheel  96  of the second module  84 . The fifth wheel  96  may be fixed on the shaft  90  to rotate therewith. 
     The second motorized module  50 B, similarly to the first motorized module  50 A, may have the belt  56 B to rotate the third wheel  60 B around shaft  78  and to rotate fourth wheel  88 B around shaft  90 B. The shaft  90 B may rotate around bearing  98  mounted on the second motorized module  50 B. Unlike the connection between the first motorized module  50 A and the portion of the second module  84 , the shaft  90 B is non-rotatably attached to the portion of the second module  84 . Thus the shaft  90 B is fixed, or non-rotationally attached, to the second module  84  to allow the rotation of the second module  84  relative the second motorized module  50 B of the first module  82 . When the shaft  90 B rotates, the portion of the second module  84  rotates relative to the second motorized module  50 B. The shaft  90 B can be attached to a cover  100  or a wall of the second module  84 . In the embodiment shown in  FIG.  3 A , the two shafts  90  and  90 B are used to rotate the second module  84  relative to the first module  82 . 
     Each motorized module  50 A,  50 B, of the first module  82  may have an attachment  102  in order to include a battery  104  and/or a control unit. 
       FIG.  3 B  illustrates a cutaway of the first module  82  showing the base module  76  and the two motorized modules  50 A and  50 B. 
       FIGS.  3 C- 3 D  illustrate the second module  84 . The second module  84  may include a plate  106  and two motorized modules  108  connected on opposite sides of the plate  106 . The motorized module  108  may be similar to the motorized module  50  described above. In the particular embodiment shown in  FIGS.  3 C- 3 D , the second module  84  forms an H-shape of the second module  84 . In another particular embodiment, the second module  84  includes one or more non-motorized modules. The term “non-motorized” refer to a module that can transmit motion from one module to another, and does not necessarily have a powered motor. The shaft  90  is fixed, or non-rotatably attached, to the wheel  96  of the module  108 . The shaft  90  may include a key  112  to connect the wheel  88 A of the first motorized module  50 A and a ring  114  to secure the wheel  88 A in place around the shaft  90 . The second shaft  90 B is fixed, or non-rotatably attached, to the body  100  or wall of the second module  108 . 
       FIG.  4    illustrates a manipulator arm  116  that can be used as a robot or a part of the robot. The manipulator arm  116  includes the first module  82 , the second module  84  and a third module  118 . The manipulator arm  116  may include additional modules. 
     In the embodiment shown in  FIG.  4   , the third module  118  has an arm  120  that is shown in a folded position into a cavity of the third module  118 . The arm  120  can include a device, for example, an instrument, a robotic hand or a finger, a hammer and the like, as required by the robot. A motor  122  may be provided to rotate the device around the axis  126  and a motor  124  to rotate an object such as a hand or end effecter) attached to the arm. The device can rotate 360 degrees or more. The third module  118  can rotate at least 180 degrees around shafts  128 . For example, relative to a longitudinal axis of the second module  84 , the third module  118  can rotate at least between +90 degrees and −90 degrees. Shafts  128  are fixed on the third module  118 . For example, shaft  128  may be attached to wall  130  of the third module  118  via screws. The third module  118  may be connected to the second module  84  via the shafts  128 . The second module  84  may be connected to the first module  82  as described above. 
     In the embodiment shown in  FIG.  4   , the first motorized module  50 A of the first module  82  is connected to a first motorized module  108 A of the second module  84 . As described above, the motor  52  of the first motorized module  50 A of the first module  82  rotates the wheel  96  of the first motorized module  108 A of the second module  84 . The rotation of the pulley  96  is transmitted to a wheel  132  of the first motorized module  108 A of the second module  84  via a belt of the second motorized module  108 A. The wheel  132  rotates shaft  128  which is fixed to the third module  118  and consequently rotates the third module  118 . 
     The second module  134  of the second module  84  is not motorized, i.e. does not include a motor. In this case, the shafts  90 B and  128  within the second module  134  are not interconnected. In this particular embodiment, the manipulator arm  116  may include one H-shape second module  84 . In other embodiments, the manipulator arm  116  can include multiple H-shape modules  84  interconnected between the first module  82  and the arm  120  to form a longer manipulator arm. The combination of shapes can be C—H—C, C—H—H, H—C—H, and the like. The C-shape module can be inside or outside the H-shape module. 
     The first module  82  may have a first compartment  82 A defined therein between two spaced-apart longitudinal first arm elements. The first arm elements may define a boundary of the first module  82 . The first arm elements may include the motorized modules  50 A,  50 B. The second module  84  may have a size and shape that is insertable in the first compartment  82 A. In other words, the second module  84  is configured to be inserted in the first compartment  82 A. The first module  82  may have a rectangular shape. The second module  84  may have a rectangular shape. The first compartment  82 A may define a first volume that is equal to or greater than a volume of the second module  84  to receive the second module  84  in the first compartment  82 A. 
     The second module  84  may have a second compartment  84 A defined therein between two spaced-apart longitudinal second arm elements. The second arm elements may define a boundary of the second module  84 . The second arm elements may include the motorized modules  50 A,  50 B. The third module  118  may have a size and shape that is insertable in the second compartment  84 A. In other words, the third module  118  is configured to be inserted in the second compartment  84 A. The third module  118  may have a rectangular shape. The second compartment  84 A may define a second volume that is equal to or greater than a volume of the third module  118  to receive the third module  118  in the second compartment  84 A. 
       FIG.  5    illustrates an embodiment of a connection between two module  82 ,  84 . In this embodiment, a shaft is inserted in a hollow shaft that retain module  82  to module  84  by a pin extending between the two shafts. 
       FIG.  6    illustrates an manipulator arm  136  in accordance with another embodiment. The first module  82  includes the base module  76  and two motorized modules  50 . It can also include only one motorized module  50  instead of the two motorized modules. The first module  82  can include one motorized module  50 . The base module  76  is connected to a rotary module  138  through the shaft  90 . The shaft  90  of the first module assembly  82  is fixed to the rotary module  138  with a pin  140 . Thus the shaft  90  rotates the rotary module  138  relative to the base module  76 . The rotary module  138  is attached to a base module  76 A of a second module  84 . Consequently, the rotation of the rotary module  138  of the first module  82  rotates the base module  76 A of the second module  84 . The second module  84  includes a rotary module  138 A connected to the base module through a shaft  90 A. The second module  84  includes one or more motorized modules  50  to rotate the shaft  90 A. The shafts  90 ,  90 A can rotate using a pulley system or a cam system. The rotary module  138 ,  138 A rotates ±90 degrees around the shaft  90 ,  90 A. In this particular embodiment, both of the motorized modules  50  are coupled to the shaft  90  to rotate the shaft  90  with coordination. The torque applied to the shaft  90  can thus be increased. In the shown embodiment in  FIG.  14   , the shaft  90  extends bore to bore. The rotary module  138 A of the second module  84  can be attached to subsequent module to form the manipulator arm  136  with a plurality of modules attached in series. 
       FIG.  7 A  illustrates a mobile robot  142  formed from two motorized modules  50  attached to a base module  76 . A rotary module  138  is attached to a rotatable shaft  90 . In this embodiment, the shaft  90  rotates ±90 degrees around a longitudinal axis of the shaft  90 . The base module  76  defines a box  144  to receive a removable battery and/or a control and communication system for the robot  142 . 
       FIG.  7 B  illustrates a motorized module  150  in accordance with another embodiment. The motorized module  150  includes a cam  152  and follower  154  system instead of the pulley and belt system. The follower  154  is pivotally mounted on the cam  152 . The motorized module  150  includes a motor  52  and a linear screw  54  similarly to the ones described above. The follower  154  is connected to the attachment  58  of the linear screw  54 . As such, the linear screw  54  moves the follower  154  to turn the cam  152 . In a particular embodiment, the cam  152  rotates the shaft 180 degrees, i.e. ±90 degrees around the longitudinal axis of the shaft  90 . 
       FIGS.  7 C- 7 D  illustrate the manipulator arm  116  in a folded position ( FIG.  7 C ) and in an intermediate extended position ( FIG.  7 D ). The manipulator arm  116  can further extend from what is shown in  FIG.  7 D . In other words, the manipulator arm  116  may be extend in a straight position. 
       FIGS.  8 A- 8 D  illustrate a mobile robot  142  mounted on wheels  156  in various positions and/or configurations. Tracks  158  are partially shown in  FIGS.  8 A- 8 D . Optionally, the mobile robot  142  can include tracks  158 . In  FIG.  8 D , the mobile robot  142  includes two manipulator arms  116  mounted on chassis or a base module  76 . 
       FIGS.  8 E- 8 F  illustrate two manipulator arms  116  mounted one base module  76 . In the embodiment shown, the H-shape module  76  is combined with an internal C-shape module on each side. Each C-shape module is further combined with an internal H-shape module. In  FIG.  8 F , the manipulator arms  116  are combined into a walking robot. 
       FIG.  9    illustrates the mobile robot  142  configured for use in Explosive Ordnance Disposal (EOD) applications. The mobile robot  142  includes two motorized modules  50  mounted on a base module  76 . A C-shape module is connected to the motorized modules and is rotatable ±90 degrees around axis x. In this embodiment, a disrupter  160  is mounted on the C-shape module. 
       FIG.  10 A  illustrates a modular manipulator arm  162  having a manually moving module  164 , that is a non-motorized module. An example of such modular articulated arm is described in U.S. Pat. No. 6,323,615. A charge (not shown) can be attached to the module  164 . The module  164  rotate ±90 degrees around shaft  166 . The shaft  166  can be hollow or plain (solid). In an embodiment using a hollow shaft  166 , another shaft can be inserted inside the hollow shaft to allow a rotation. The manual structure can be transformed into a motorized structure by adding a module containing a motor which is connected to the manual structure through the hollow shaft of the manual structure to turn one module relative to the other. When the motor is removed, the structure can be used manually rotated. Thus, we can transform a manual structure into a motorized structure and vice versa. The motor can be a motorized module  50 . 
     The hollow shaft  166  is fixed on cap  168 . The module  164  has a fixed trust  170  and rotating bearing  172 . The cap  168  is fixed to module  174 . This combination allow the module  164  to turn freely relative to module  174  in such a way that gravity can compensate a portion of the force needed to do the movement independent of the weight of the charge attached to the module  164 . 
     Referring to  FIGS.  10 A- 10 C,  162 A  is the modular manipulator arm  162  transformed into a motorized arm ( FIG.  10 B ) by attaching the motorized modules  50 . This transformation can be done by retrofitting the modular articulated arm  162  with motorized modules  50 , as described above. In this embodiment, the shaft  166  includes a key  112  in order to attach the shaft  166  to the pulley  88  of the motorized module  50 . Consequently, the pulley  88  rotates the shaft  166  instead of manually rotating the module  164  relative to module  174 . A second motorized module  50  can be optionally used to increase the torque transmitted to the shaft  166 , for example, when the arm  162  is used as an elephant trunk. 
     The base module  76 , the first module  82 , the second module  84 , and/or the third module  118  may be connected via a communication system to communicated data or instructions commands between the modules  76 ,  82 ,  84 ,  118 . For example, the communication system may include wires, wireless antennas, and the like. 
     Referring to  FIGS.  11 A- 11 E , the manipulator arm  116  is shown mounted on a drone  176 . The manipulator arm  116  is similar to the manipulator arms described above. The manipulator arm  116  attached on the drone  176  can be controlled in order to manipulate objects and/or to capture a second drone in the flight, for example to ensure a security area or to take down unauthorized drones, i.e. like a “police” drone application. The manipulator arm  116  can also pick objects and placed them on a basket  194  ( FIG.  11 G ). The basket  194  can be placed on or in the drone  176 . 
     The drone  176  may be formed by a light weight sandwich panel. The panel may include a central body  178  and two outer disks  180 . The disks  180  are mounted on opposite sides of the central body  178 . In a particular embodiment, the central body  178  is constructed from carbon fiber and/or plastic materials. These materials may be manufactured with a 3D printer. Other materials may also be used. The body  178  includes propulsion cylinders  182  and compartments for battery, control systems, navigation, cameras and sensors. The propulsion cylinder  182  may refer to or include an “engine” or an “engine cylinder”. 
     Referring to  FIG.  11 F , each engine  182  has a respective controller  184 , battery  186  and propeller  188 . The propeller  188  can be placed on one side of the propulsion cylinder  182  or on both sides thereof. The engine  182  can be inserted into the body  178  of the drone  176  through a “plug and play” mechanism. The “plug and play” feature allows a modular configuration of the engines  182 . Thus, a user can configure the drone  176  with the appropriate number of engines  182 . For example, the drone  176  can be include 3 to 12 engines  182 . In the embodiment shown, the body  178  has twelve cylinders or engines  182 . If all the engines  182  are installed, i.e. the twelve engines, then the number of activated engines  182  can be determined by an algorithm in order to distribute the force (e.g. load) and optimize the power needed for the task. In a particular embodiment, the drone  176  can activate four of the twelve engines  182 . Additional engines may be activated when more power is needed. The ability to control the number and/or the sequence of the engines  182  can allow additional flying capacity of the drone  176  in order to rotate the drone  176  in three degrees of freedom XYZ ( 3 -DF) ( FIGS.  11 G- 22 H ). These degrees of freedom include at least roll, yaw and pitch motions. Electrical connectors  190  ( FIG.  11 F ) are also provided to connect the propulsion cylinders  182  with other components and compartments to provide, for example, electrical energy and/or control commands. In the embodiment shown, electrical connector  190  is engaged directly from the engine  182  to the central body  178 . 
     Referring to  FIG.  11 G , additional engines  192  are mounted on a surface of the disk  180  of the drone  176  through a bracket  196 . The engines  192  are configured for use in water. As such, the drone  176  may be used like a hydro craft by floating on the surface of the water while the engines  192  are submerged in the water. 
     Referring to  FIGS.  11 H- 11 J , a round pneumatic ring  198  is attached to the body  178  in order to allow the drone  176  to float on water and/or to protect the drone  176  in collisions. The pneumatic ring  198  may be filled with a gas that is lighter than air. In the embodiment shown in  FIG.  11 J , the pneumatic ring  198  has an aerodynamic wing shape  200  instead of the round shape in order to make the drone  176  a planer drone using a pneumatic wing  200 . The wing  200  can be folded into the body  178  and optionally inflated into the wind shape for aerodynamic benefits. The wing  200  can be filled with any suitable gas. One or both disks  180  can be attached by screws  202  and covered by a solar panel  204 . The final assembly provide a waterproof characteristic using a rubber joint  206  ( FIG.  11 K ). 
     Referring to  FIGS.  12 A- 12 B , a motor  250  is shown. The motor  250  has a ferrofluid braking system which includes a rotatable turbine  252  fixed to a shaft  254 . The turbine  252  and the shaft  254  rotate together. The turbine  252  is located in a cavity of a cylinder filled with a ferrofluid  256 . A solenoid  258  is mounted around the cavity to magnetically engage the ferrofluid  256  when the solenoid  258  is activated. The viscosity of the ferrofluid  256  can adjusted, for example from a liquid state to a solid state by applying a current in the solenoid  258 . The viscosity depend on the current supplied to the solenoid  258 . Thus, the friction between the turbine  252  and the ferrofluid  256  can be adjusted depending on the intensity of the current applied in the solenoid  258 . If the ferrofluid is changed to the solid state, the turbine may not be able to rotate. This can allow the motor  250  to control the shaft movement, e.g. braking of the shaft  254 , in an ON/OFF mode. In a particular embodiment, when the solenoid  258  is activated by the current, i.e. switched ON, the motor  250  brake the movement of the shaft  254 . When the solenoid  258  is deactivated, i.e. switched OFF, the shaft  254  rotate. 
     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, the pulleys and belt system can be replaced with a cam and follower system or ferrofluid system for translating the axial movement of the linear screw to rotational movement of the shaft. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.