Patent Description:
Operators of various types of mobile robots have a need to rapidly and reliably grasp objects with a manipulator, e.g., a manipulator employed on an unmanned ground robot. Some conventional mobile robots include an offset camera, which is offset from a manipulator end-effector, to provide a video feed to an operator control unit. It can be difficult at times for the operator to center the manipulator end-effector on an object prior to grasping when only an offset camera is available for situational awareness.

<CIT> describes an arm drive mechanism with a pair of rotating bodies, an endless circular body stretched between the rotating bodies, a screw shaft rotated by a drive motor, and a slider screwed with the screw shaft and tightly attached to part of the endless circular body. One rotating body is set to have a smaller diameter than that of the other rotating body.

<CIT> describes a coreless motor with a rotor having a magnet whose circumferential face is magnetized to multiple poles; a stator for rotatably supporting said rotor with a bearing interposed between said stator and said rotor; a coreless coil which is opposed to said circumferential face of said magnet with a space interposed between said coil and said circumferential face and which has a plurality of effective conductors that contribute to torque generation and a plurality of connection conductors that connect the adjacent effective conductors; and a support member having a coil supporting portion that supports said coreless coil, The coil supporting portion supports circumferential faces of said connection conductors to position said coreless coil in the radial direction.

The present invention provides an unmanned ground vehicle and a method for operating an unmanned ground vehicle with the features of the independent claims. Further advantageous embodiments are subject-matter of the dependent claims.

An unmanned ground vehicle includes a main body, a drive system supported by the main body, and a manipulator arm pivotally coupled to the main body. The drive system comprising right and left driven track assemblies mounted on right and left sides of the main body. The manipulator arm includes a gripper, a wrist motor configured for rotating the gripper, and an inline camera in a palm of the gripper. The inline camera is mechanically configured to remain stationary with respect to the manipulator arm while the wrist motor rotates the gripper.

<FIG> illustrates an example mobile robotic vehicle <NUM> that may be used as an unmanned ground vehicle capable of conducting operations in various environments such as urban terrain, tunnels, sewers, and caves. Moreover, the robot <NUM> may aid in the performance of urban Intelligence, Surveillance, and Reconnaissance (ISR) missions, chemical/Toxic Industrial Chemicals (TIC), Toxic Industrial Materials (TIM), and reconnaissance. Although the robot <NUM> shown includes a track driven drive system having flippers, other mobility platforms, configurations and morphologies are possible as well, such as wheel driven platforms, crawling or walking platforms, and so on.

The robot <NUM> can be designed to move about in a variety of environments, including an urban environment of buildings (including staircases), streets, underground tunnels, building ruble, and in vegetation, such as through grass and around trees. The robot <NUM> may have a variety of features which provide robust operation in these environments, including impact resistance, tolerance of debris entrainment, and invertible operability.

The robot <NUM> includes a main body <NUM> (or chassis) having a drive system <NUM> supported by the main body <NUM>. The main body <NUM> has right and left sides 110a, 110b as well as a leading end 110c, a trailing end 110d and a center of gravity CGM. In the example shown, the main body <NUM> includes right and left rigid side plates 112a, 112b disposed parallel to each other. At least one transverse support <NUM> rigidly couples the right side place 112a to the left side plate 112b. The rigid components are designed for strength and low weight and can be made from a material such as <NUM>-T6 aluminum. Alternative versions of the robot <NUM> can use other materials, such as other lightweight metals, polymers, or composite materials. The robot <NUM> may be electrically powered (e.g. by a bank of standard military BB-<NUM> replaceable and rechargeable lithium-ion batteries).

In some implementations, the drive system <NUM> includes right and left driven track assemblies 120a, 120b (also referred to as the main tracks <NUM>) mounted on the corresponding right and left sides 110a, 110b of the main body <NUM> and having right and left driven tracks 122a, 122b respectively. Each driven track 122a, 122b is trained about a corresponding front wheel, which rotates about a drive axis <NUM>. Although the robot <NUM> is depicted as having skid steer driven tracks, other drive systems are possible as well, such as differentially driven wheels, articulated legs, and the like.

The robot <NUM> includes at least one extendable flipper <NUM> mounted on the main body <NUM>. In some examples, the robot <NUM> is configured to releasably receive one or more flippers <NUM> onto the main body <NUM> (e.g., onto and concentric with one of the front drive wheels at the leading end <NUM> c of the main body <NUM>). As shown in <FIG>, the robot <NUM> includes right and left flippers 130a, 130b, which are shown in an extended configuration extending beyond the front or leading end 110c of the main body <NUM>.

The flippers <NUM>, 130a, 130b each have a distal end 130c, a pivot end 130d, and a flipper center of gravity CGF between the distal and pivot ends 130c, 130d. Each flipper <NUM>, 130a, 130b pivots about the drive axis <NUM> near the leading end 110c of the main body <NUM>. Moreover, each flipper <NUM>, 130a, 130b may have a driven flipper track <NUM>, 140a, 140b trained about flipper drive wheel 142a, 142b, which is driven about the drive axis <NUM> at the pivot end 130d of the flipper 130a, 130b.

In the example shown, flipper track supports <NUM> disposed on a flipper side plate <NUM> of the flipper <NUM> support the corresponding flipper track <NUM>. In some implementations, the flippers <NUM>, 130a, 130b can be rotated in unison in a continuous <NUM> degrees between a stowed position, in which the flippers <NUM> a, 130b are next to the right and left side plates 112a, 112b of the main body <NUM>, and at least one deployed position, in which the flippers 130a, 130b are pivoted at an angle with respect to the main tracks 122a, 122b. The center of gravity CGR of the robot <NUM> can be contained within an envelope of the <NUM> degree rotation of the flippers 130a, 130b.

In some implementations, the flipper side plates <NUM> of the respective right and left flippers 130a, 130b are rigidly coupled to one another through the articulator shaft to move together in unison. In other implementations, the flippers 130a, 130b pivot independently of each other. The combination of main tracks assemblies 120a, 120b and flippers <NUM>, 130a, 130b provide an extendable drive base length to negotiate gaps in a supporting surface. In some examples, the right main tack 122a and the right flipper track 140a are driven in unison and the left main tack 122b and the left flipper track 140b are driven in unison to provide a skid steer drive system.

The main body <NUM> may include one or more cameras <NUM> disposed near the leading end 110c of the main body <NUM> and may be positioned to have a field of view directed forward and/or upward. The camera(s) <NUM> may capture images and/or video of the robot environment for navigating the robot <NUM> and/or performing specialized tasks, such as maneuvering through tunnels, sewers, and caves, etc..

The robot <NUM> may include one or more robotic manipulator arms <NUM> (e.g., articulated arms) each having a pivot end 150p pivotally coupled to the main body <NUM> and a distal end 150d that may be configured to receive a head <NUM> or a gripper <NUM> or both. The arm <NUM> may be coupled to the main body <NUM> in a manner that allows the arm <NUM> to be stowed along the main body <NUM> in a compact configuration and pivot away from main body <NUM> to allow a wider range of CG-shifting, for example, to negotiate obstacles.

As shown in <FIG>, a head <NUM> and a gripper <NUM> are mounted on the distal end 150d of the arm <NUM>. The arm <NUM> has an arm center of gravity CGA and the head <NUM> has a center of gravity CGH. The head <NUM> may include a camera <NUM> (e.g., visible light and/or infrared camera), radar, LIDAR (Light Detection And Ranging, which can entail optical remote sensing that measures properties of scattered light to find range and/or other information of a distant target), LADAR (Laser Detection and Ranging), a communication device (radio frequency, wireless, etc.), and/or other components.

To achieve reliable and robust autonomous or semi-autonomous movement, the robot <NUM> may include a sensor system having several different types of sensors. The sensors can be used in conjunction with one another to create a perception of the robot's environment (i.e., a local sensory perception) sufficient to allow a control system for the robot <NUM> to determine actions to take in that environment. The sensor system <NUM> may include one or more types of sensors supported by the robot body <NUM>, which may include obstacle detection obstacle avoidance (ODOA) sensors, communication sensors, navigation sensors, and so on.

For example, these sensors may include proximity sensors, contact sensors, cameras (e.g., volumetric point cloud imaging, three-dimensional (3D) imaging or depth map sensors, visible light camera and/or infrared camera), sonar (e.g., ranging sonar and/or imaging sonar), radar, LIDAR (Light Detection And Ranging, which can entail optical remote sensing that measures properties of scattered light to find range and/or other information of a distant target), LADAR (Laser Detection and Ranging), laser scanner, ultrasound sensor, and so on.

In some implementations, the robot <NUM> includes a robot controller <NUM> in communication with the drive system <NUM>, the arm <NUM>, and any head(s) <NUM> or gripper(s) <NUM> mounted on the arm <NUM>. The robot controller <NUM> may issue drive commands to one or more motors driving the main tracks <NUM> and the flipper tracks <NUM>. Moreover, the robot controller <NUM> may issue rotational commands to a flipper motor <NUM> to rotate the flippers <NUM> about the drive axis <NUM>. The robot controller <NUM> may include one or more computer processors and associated memory systems.

The robot controller <NUM> may be implemented in hardware, software, firmware, or combinations of hardware, software and/or firmware. In some examples, the robot controller <NUM> may be implemented using a non-transitory computer readable medium storing computer executable instructions that when executed by one or more processors of a computer cause the computer to perform operations. Computer readable media may include non-transitory computer-readable media, such as disk memory devices, chip memory devices, programmable logic devices, random access memory (RAM), read only memory (ROM), optical read/write memory, cache memory, magnetic read/write memory, flash memory, and application specific integrated circuits. In addition, a computer readable medium that implements the robot controller <NUM> may be located on a single device or computing platform or may be distributed across multiple devices or computing platforms.

The proximity sensors may be converging infrared (IR) emitter-sensor elements, sonar sensors, ultrasonic sensors, and/or imaging sensors (e.g., 3D depth map image sensors) that provide a signal to a robot controller <NUM> when an object is within a given range of the robot <NUM>. The robot controller <NUM> (executing a control system) may execute behaviors that cause the robot <NUM> to take an action, such as changing its direction of travel, when an obstacle is detected.

In some examples, the sensor system includes an inertial measurement unit (IMU) in communication with the robot controller <NUM> to measure and monitor a moment of inertia of the robot <NUM> with respect to the overall center of gravity CGR of the robot <NUM>. The robot controller <NUM> may monitor any deviation in feedback from the IMU from a threshold signal corresponding to normal unencumbered operation. For example, if the robot begins to pitch away from an upright position, it may be "clothes lined" or otherwise impeded, or someone may have suddenly added a heavy payload. In these instances, it may be necessary to take urgent action (including, but not limited to, evasive maneuvers, recalibration, and/or issuing an audio/visual warning) in order to assure safe operation of the robot <NUM>.

When accelerating from a stop, the robot controller <NUM> may take into account a moment of inertia of the robot <NUM> from its overall center of gravity CGR to prevent robot tipping. The robot controller <NUM> may use a model of its pose, including its current moment of inertia. When payloads are supported, the robot controller <NUM> may measure a load impact on the overall center of gravity CGR and monitor movement of the robot moment of inertia. If this is not possible, the robot controller <NUM> may apply a test torque command to the drive system <NUM> and measure actual linear and angular acceleration of the robot using the IMU, in order to experimentally determine safe limits.

The robot controller <NUM> may include a communication system <NUM>, which includes, for example, a radio to communicate with the remote operator control unit (OCU) <NUM> to receive commands and issue status and/or navigation information. The OCU <NUM> may include a display <NUM> (e.g., LCD or touch screen), a keyboard <NUM>, and one or more auxiliary user inputs <NUM>, such a joystick or gaming unit. The OCU <NUM> may also include a computing processor and memory in communication. The processor is programmed for rendering graphics on the display <NUM>. The OCU <NUM> allows an operator or user to control the robot <NUM> from a distance.

In some examples, the user can select different levels of human control over the robot <NUM>, ranging from a teleoperation mode, in which the user directly controls the motors and actuators on the robot <NUM>, to autonomous operation, in which the user passes higher-level commands to the robot <NUM>. In partially autonomous operation, the robot <NUM> can perform tasks such as following a perimeter or wall, recovering from getting stuck in an opening or due to high centering on an obstruction, evading a moving object, or seeking light.

The robot controller <NUM> can be mounted in any appropriate location on the robot <NUM>. In some implementations, the robot controller <NUM> is mounted on the main body <NUM> in a location spanning between the drive tracks or wheels. Alternatively, the robot controller <NUM> can be located in another location to open more space for the arm <NUM>.

<FIG> illustrates the example robot <NUM> in a morphology with the manipulator <NUM> in an extended position. The robot <NUM> as illustrated includes an optional sensor suite <NUM>, e.g., an Intelligence, Surveillance, and Reconnaissance (ISR) sensor suite. The example manipulator <NUM> has a pivot end 150p pivotally coupled to the main body <NUM> and a distal end 150d that receives a gripper <NUM>. The manipulator <NUM> includes a first extension 150a extending away from the pivot end 150p and a second extension 150b extending away from the end of the first extension 150a. The second extension 150b is pivotally coupled to the first extension 150a, e.g., by way of a bridge housing a motor for pivoting the second extension 150b. Various other types of manipulators can be used.

<FIG> illustrate the gripper <NUM> with an inline camera <NUM>. <FIG> is a perspective view showing the inline camera <NUM> in a palm <NUM> of the gripper <NUM>. The gripper <NUM> includes a number of articulated gripper fingers 306a-b that surround the palm <NUM> of the gripper <NUM>. The gripper <NUM> includes a gripping motor configured to cause the articulated gripper fingers 306a-b to contract from an open position to a closed position to grip and object. For example, the gripper can include a gripper closure rack and a number of pulleys coupling the articulated gripper fingers 304a-b to the gripper motor.

The gripper <NUM> also includes a wrist motor configured for rotating the gripper <NUM> about a gripper roll axis. The inline camera <NUM> can be centered within the palm <NUM> of the gripper <NUM>. For example, the inline camera <NUM> can be equidistant from the articulated gripper gingers 306a-b and centered on the gripper roll axis of the wrist motor. The gripper <NUM> can optionally include an offset gripper camera <NUM> on the manipulator arm <NUM> for providing an additional or alternative view of the gripper <NUM>. In some examples, the gripper <NUM> includes more than one offset gripper camera.

The inline camera <NUM> is mechanically configured to remain stationary with respect to the manipulator arm <NUM> while the wrist motor rotates the gripper <NUM>. For example, the gripper <NUM> can include a camera housing tube between the pulleys housing the inline camera <NUM>. The camera housing tube can be coupled to the manipulator arm <NUM> independently of a gripper coupling to the manipulator arm by the wrist motor. Electrical cables can then extend through the camera housing tube for carrying power and communication signals for the inline camera <NUM>.

It can be difficult at times for an operator to control the gripper <NUM> to contact an object prior to grasping when only an offset camera is available for situational awareness. Inline cameras that do not remain stationary when the wrist motor rotates the gripper can be disorienting. Since the example inline camera <NUM> is configured to remain stationary, the inline camera <NUM> may be useful to provide improved situational awareness during grasping and avoid operator disorientation that may be experience with non-stationary inline gripper cameras.

The inline camera <NUM> is mechanically configured to remain stationary. This can be useful in comparison to allowing an inline camera to rotate and creating a stationary image via video processing. For example, no electrical slip-rings are required to achieve continuous gripper rotation. Processing artifacts and lag due to video processing can be avoided. The image window need not be constrained be a round image window.

<FIG> is a top cross-sectional view of the gripper <NUM> showing an example gripper closure rack <NUM> and an example camera housing tube <NUM>. <FIG> is a top cross-sectional view of the gripper <NUM> showing an example closure rack <NUM>, an example housing <NUM> for the inline camera <NUM>, and an example wrist roll housing <NUM>. <FIG> also shows an inline camera housing clamp <NUM> and an inline camera cable exit <NUM>.

<FIG> is a cut-away from of the gripper <NUM>. The camera <NUM> is mounted within a stationary sleeve <NUM> that is anchored to the gripper chassis <NUM>. This camera <NUM> and sleeve <NUM> remain stationary with respect to the gripper chassis <NUM> regardless of the rotation of the gripper fingers. A rack <NUM>, which can rotate with the gripper palm <NUM>, transfers linear motion to the gripper finger pinions <NUM>, that drive each finger open/close. The rack <NUM> is driven linearly by a lead screw <NUM>, which is driven by an electric motor <NUM>. <FIG> is an exploded view of the parts of the gripper <NUM>.

<FIG> is a flow chart of an example method <NUM> for controlling the robot <NUM>. The method <NUM> can be performed by the robot controller <NUM>. The robot controller <NUM> provides a video feed from an inline camera in a palm of a gripper on a manipulator arm to a remote operator control unit (<NUM>). The robot controller <NUM> controls a wrist motor to cause the wrist motor to rotate the gripper about a gripper roll axis, such that the inline camera remains stationary with respect to the manipulator arm while the wrist motor rotates the gripper (<NUM>). The robot controller <NUM> controls a gripper motor to cause the gripper to contract from an open position to a closed position to grip an object (<NUM>).

<FIG> illustrates an example graphical user interface (GUI) <NUM> displayed on the OCU <NUM>, which is illustrated as a touchpad computer in this example. The GUI <NUM> includes a first window <NUM> displaying a first camera feed from the inline camera <NUM> of the gripper <NUM>. The GUI <NUM> includes a second window <NUM> displaying a second camera feed from the offset gripper camera <NUM>. The GUI <NUM> includes an area <NUM> for receiving operator input for controlling the gripper <NUM>. In operation, the operator can cause the wrist motor to rotate the gripper, and because the inline camera <NUM> is configured to remain stationary with respect to the manipulator arm <NUM> while the wrist motor rotates the gripper, the orientation of the first camera feed in the first window <NUM> will remain unchanged even though the articulated gripper fingers may be seen rotating.

Claim 1:
An unmanned ground vehicle comprising:
a main body (<NUM>);
a drive system (<NUM>) supported by the main body, the drive system comprising right and left driven track assemblies (120a, 120b) mounted on right and left sides of the main body; and
a manipulator arm (<NUM>) pivotally coupled to the main body, the manipulator arm comprising a gripper (<NUM>), a wrist motor configured for rotating the gripper, and an inline camera (<NUM>) in a palm (<NUM>) of the gripper, wherein the inline camera is mechanically configured to remain stationary with respect to the manipulator arm while the wrist motor rotates the gripper, characterised in that the in-line camera is mechanically configured to remain stationary with respect to the manipulator arm also while the gripper contracts from an open position to a closed position to grip an object.