Flex-rigid sensor array structure for robotic systems

A flex-rigid sensor apparatus for providing sensor data from sensors disposed on an end-effector/gripper to the control circuit of an arm-type robotic system. The apparatus includes piezo-type pressure sensors sandwiched between lower and upper PCB stack-up structures respectively fabricated using rigid PCB (e.g., FR-4) and flexible PCB (e.g., polyimide) manufacturing processes. Additional (e.g., temperature and proximity) sensors are mounted on the upper/flexible stack-up structure. A spacer structure is disposed between the two stack-up structures and includes an insulating material layer defining openings that accommodate the pressure sensors. Copper film layers are configured to provide Faraday cages around each pressure sensor. The pressure sensors, additional sensors and Faraday cages are connected to sensor data processing and control circuitry (e.g., analog-to-digital converter circuits) by way of signal traces formed in the lower and upper stack-up structures and in the spacer structure. An encapsulation layer is formed on the upper PCB stack-up structure.

FIELD OF THE INVENTION

This invention relates generally to robotic systems and more particularly to end-effector sensors for arm-type robot mechanisms.

BACKGROUND OF THE INVENTION

Most modern robotic systems integrate mechanical, electrical/electronic and computer science technologies to provide autonomously controlled mechanisms capable of performing a variety of programmed operations (tasks). For example, articulated robots are a class of industrial robotic systems in which a control circuit converts user-provided software-based instructions into motor control signals that control a robot arm mechanism and attached end effector (e.g., a hand or gripper) to perform repetitive tasks, such as moving target objects from one location to another location. To perform such programmed operations, the software-based instructions provided to most articulated robots must specify three-dimensional (3D) coordinates of the starting location at which the target objects are located for pick-up, a designated 3D travel path through which the target objects may be moved without interference, and 3D coordinates defining the terminal location (e.g., a receptacle or support surface) at which the target objects are to be placed. When suitable software-based instructions are provided, the control circuit generates a corresponding series of motor control signals that cause the robot arm mechanism to move the end effector to the initial/starting location coordinates, then cause the end effector to close on (grasp) the target object, then cause the robot arm mechanism to lift/move the target object to the terminal location coordinates along the designated travel path, and then cause the end effector to open/release the target object.

Most conventional robotic systems utilize no sensing architecture, and those that do utilize single-modality sensing architectures. Conventional robotic systems that utilize no sensing architecture rely entirely on pre-programmed commands, and typically fail to adjust for minor positional variations to unanticipated environmental variations. In contrast, single-modality sensing architectures provide feedback information to a host robotic system's control circuit, thereby allowing the control circuit to modify user-provided program instructions in order to accommodate minor positional variations (i.e., relative to program-based coordinates). That is, although the above-described programmed operation approach may be solely used in highly ordered environments, most practical operating environments include random positional variances and other unanticipated events that can cause erroneous operations and possibly dangerous situations. For example, the inadvertent displacement of a target object away from its designated starting location coordinates may prevent successfully grasping by the end effector, and in some cases may result in damage to the target object and/or end effector/gripper (e.g., due to off-center contact between the end effector and the target object during the grasping operation). To avoid such incidents, modern robotic systems often employ single-modal sensing architectures (e.g., one or more force sensors disposed on the end effector) and/or camera systems that are configured to provide feedback information that allows the system's control circuit to recognize and adjust the programmed operation to accommodate minor variations. For example, a single-modal sensor disposed on an end effector may provide feedback information indicating the displacement of a target object away from the designated starting location coordinates (e.g., by way of unexpected contact with the target object during a grasping operation)—this feedback information may be utilized by the control circuit to adjust the robot arm mechanism such that the end effector is repositioned in a way that allows successful grasping of the displaced target object.

The lack of a rich end effector sensory feedback is one of the main limitations of modern robotic systems. That is, although single-modality sensing architectures may be used to prevent some industrial accidents, conventional single-modality sensors are currently unable to provide enough feedback information to allow a robotic system to perform complex assembly processes. For example, although single-modality pressure sensor arrangements may provide sufficient data to verify that a predetermined gripping force is being applied by an end effector onto a target object, such pressure sensors lack the rich sensor feedback needed to recognize when the target object is slipping from the end effector's grasp, and therefore are unable to avoid the resulting accident damage to the target object. In addition, when performing assembly tasks such as mounting a canister-type object over a cylindrical object, single-modality pressure sensor arrangements provide insufficient data regarding excessive contact between the cannister and cylindrical objects when the canister and cylindrical objects are misaligned. Note that while camera-type feedback systems may be useful to identify and adjust for such occurrences in some cases, critical portions of the camera's field of view are often occluded by the end effector, which limits the functionality of camera-type feedback systems. The image processing and inference times associated with camera-based techniques can also be too long to enable reflex-like adjustments to avoid inflicting damage. In contrast to single-modality sensors, the human hand consists of an unparalleled multimodal sensory system (i.e., mechanoreceptors sensing both pressure and vibration, and thermoreceptors sensing temperature), which largely contributes to its unprecedented dexterous manipulation. Specifically, the human multimodal sensing architecture provides fine-grained cues about contact forces, textures, local shape around contact points, and deformability, all of which are critical for evaluating an ongoing grasping operation, and to trigger force correction measures in case of instability.

What is needed is a sensing apparatus for robotic systems that overcomes the deficiencies of conventional single-modality sensor arrangements. In particular, what is needed is a low-cost sensing architecture that provides robotic end effectors with multi-modal tactile perception capabilities that facilitate enhanced human-like target object recognition and associated object manipulation control.

SUMMARY OF THE INVENTION

The present invention is directed to a flex-rigid sensor apparatus that is configured for use on an end effector (e.g., a gripper) of a robotic system, and utilizes a variety of sensors to collect tactile sensor data from surface features of a target object, thereby providing the robotic system's control circuit with multi-modal tactile perception capabilities that facilitate enhanced human-like target object recognition and associated object manipulation control. According to an aspect of the invention, the tactile sensor data is collected by multiple sensors mounted on a novel two-part rigid/flex PCB base structure including a (first) lower rigid printed circuit board (PCB) stack-up structure and an upper (second) flexible PCB stack-up structure. The lower/rigid PCB stack-up structure includes multiple layers of a rigid insulating material (e.g., FR-4) having patterned signal paths (e.g., copper traces and vias) formed thereon using an established rigid PCB manufacturing process, and the upper/flex PCB stack-up structure includes multiple layers of a flexible insulating material (e.g., polyimide) having patterned signal paths patterned thereon using an established flexible PCB manufacturing process. When the upper stack-up structure is mounted onto the lower stack-up structure during assembly, electrical connections are provided between contacts formed on the opposing interfacing surfaces facilitate the transmission of signals between input/output (I/O) pads formed on the lower/rigid PCB stack-up structure and contact structures (e.g., electrodes and/or pads) formed on the upper/flex PCB stack-up structure by way of associated signal paths formed on the two PCB stack-up structures. An advantage provided by the flex-on-rigid stack-up sensing architecture is the ability to facilitate the collection of sensor data from sensors disposed in at least two layers/planes by way of disposing first sensors in a first layer on an upper surface of the lower/rigid stack-up structure (i.e., between the two PCB stack-up structures), and disposing second sensors in a second layer on an upper surface of the upper/flex PCB stack-up structure). Moreover, because established low-cost PCB fabrication processes may be utilized to generate both the lower/rigid PCB stack-up structure and the upper/flex PCB stack-up structure, the flex-rigid sensor apparatus may be produced at a low cost and with a high production yield.

According to an embodiment of the invention, the flex-rigid sensor apparatus includes an array of pressure sensors sandwiched between the lower/rigid and upper/flex PCB stack-up structures such that each pressure sensor is electrically connected between an associated lower (first) electrode disposed on the lower/rigid PCB stack-up structure and an associated upper (second) electrode disposed on the upper/flex stack-up structure. That is, opposing pairs of electrodes are respectively patterned on opposing (upper and lower) surfaces of the two PCB stack-up structures such that, during assembly, the pressure sensors are sandwiched between associated electrode pairs when the upper/flex PCB stack-up structure is mounted and operably connected (e.g., by way of reflow soldering) to the lower/rigid PCB stack-up structure. Additional connections are also provided between the signal paths of the two PCB stack-up structures (e.g., by way of metal vias provided on an optional spacer structure) to facilitate the transmission of signals to and from the upper pressure electrodes, and to also provide signal connections to additional sensors disposed on the upper surface of the upper/flex PCB stack-up structure. An additional advantage provided by this upper/lower electrode configuration is that it facilitates the use of low-cost, highly sensitive, high bandwidth and robust piezo-type (i.e., piezoelectric or piezoresistive) pressure sensors by orienting the poling direction of piezo-type sensor structures in a normal direction (i.e., perpendicular to the planes defined by the stack-up structures), whereby a voltage potential or resistance between the upper and lower electrodes is proportional to the amount of pressure force applied in the normal direction. In less-preferred embodiments, the pressure sensors may be implemented using strain gauge sensors, capacitive pressure sensors, or cavity-based pressure sensors. In addition, by sandwiching the pressure sensor array between rigid and flex stack-up structures, the rigid PCB material of the lower/rigid PCB stack-up structure provides a fixed (unyielding) base while the flexible PCB material of the upper/flex stack-up structure facilitates the collection of independent pressure sensor data from multiple spaced-apart pressure sensors (i.e., a point-type pressure force applied to a region of the upper/flex stack-up structure is transmitted substantially vertically to one or a small number of pressure sensors located below the region, and local deformation of the flexible PCB material substantially dampens the transference of pressure force to pressure sensors located away from the contacted region). With this arrangement, regions of the upper/flexible stack-up structure contacted by protruding surface features of the target object are pressed into underlying pressure sensors, thereby causing these underlying pressure sensors to generate relatively high contact pressure sensor data values, and regions of the upper/flexible stack-up structure that are not contacted by the target object remain relatively uncompressed, whereby the pressure sensors disposed under these uncompressed regions generate relatively low contact pressure sensor data values. Moreover, this arrangement facilitates forming the pressure sensor array with any number of pressure sensors arranged in a symmetric arrangement separated by a wide range of spacing distances between adjacent sensors without requiring changes to the arrangement of additional sensors (e.g., temperature sensors, proximity sensors and/or vibration sensors) disposed on the upper surface of the upper/flex PCB stack-up structure, thereby facilitating human-type pressure sensing capabilities by minimizing the distribution of the point-type pressure force to pressure sensors located away from the contacted region). That is, by providing a pressure sensor array including multiple closely-spaced pressure sensors, the flex-rigid sensor apparatus facilitates the generation of area-based pressure sensor data suitable for determining desired information regarding the target object (e.g., details regarding the target object's surface features and/or the target object's position and orientation relative to the robotic system's contact structure).

According to an embodiment of the invention, the flex-rigid sensor apparatus includes the lower/rigid and upper/flexible PCB stack-up structures, the two sensor layers rigidly disposed on upper surfaces of the two PCB stack-up structures, and sensor control and data processing circuitry operably coupled to input/output pads disposed on the lower surface of the lower/rigid PCB stack-up structure. In a preferred embodiment, the two sensor layers include a pressure sensor array disposed between the two PCB stack-up structures, and additional sensors (e.g., temperature sensors, proximity sensors and/or vibration sensors) disposed on top of the upper/flex PCB stack-up structure. The sensor control and data processing circuit(s) is/are configured to control sensor operations (e.g., pressure measurement operations of the pressure sensor array) by way of transmitting operating voltages or other control signals to selected input pads and reading resulting sensor data signals from associated output pads. In alternative practical embodiments, the sensor control and data processing circuitry is either connected directly to the input/output pads (e.g., by way of solder-based connecting structures), or coupled to the input/output pads by way of an intervening mezzanine connector. In either case the sensor control and data processing circuitry transmits control signals along control signal paths to one terminal of each sensor and receives corresponding sensor data signals passed along data signal paths from the other terminal of each pressure sensor. In an exemplary embodiment, the sensor control and data processing circuitry includes analog-to-digital circuitry configured to convert analog sensor data signals received from the various sensors into corresponding digital values, digital processing circuitry that generates tactile information in response to the corresponding digital values, and transceiver circuitry configured to transmit the tactile information to the host robotic system's control circuit.

According to another embodiment of the present invention, a simplified assembly and solder reflow method is implemented to produce the above-mentioned flex-rigid sensor apparatus are produced using that further reduces total fabrication costs. First, the lower/rigid stack-up structure is produced using conventional rigid electrically-insulating PCB fabrication techniques (i.e., such that the lower/rigid stack-up structure includes a laminated stack of rigid insulating material layers/substrates having a patterned conductive (e.g., copper) film formed thereon), and the upper/flexible stack-up structure is separately produced using conventional flexible (flex) PCB fabrication techniques (i.e., such that the upper/flexible stack-up structure includes one or more flexible insulating material layers/substrates having associated patterned conductive films/layers). In alternative embodiments the lower/rigid stack-up structure is fabricated using as a rigid insulating material either a glass-epoxy material (e.g., FR-4), ceramic (e.g., ceramic substrate or ceramics-filled PTFE), plastic (e.g., Bakelite) or insulated metal (e.g., an aluminum clad with thermally conductive dielectric), and the upper/flexible stack-up structure is fabricated using a flexible insulating material such as polyimide or polyethylene terephthalate (PET). To facilitate implementation of the vertically oriented piezoelectric-type pressure sensors, the conductive film formed on the uppermost surface of the lower/rigid stack-up structure is patterned to include an array of lower (first) pressure sensor electrodes, and the lowermost surface of the upper/flexible stack-up structure is patterned to include a corresponding array of upper (second) pressure sensor electrodes. With the stack-up structures formed in this manner, assembly of the pressure sensor array is performed by depositing solder paste portions on the lower and upper pressure sensor electrodes, then mounting the piezo-type pressure sensors on the lower/rigid stack-up structure (i.e., on the solder paste portion disposed over each lower pressure sensor electrodes) and mounting the upper/flexible stack-up structure over the lower/rigid stack-up structure (i.e., such that solder paste portion disposed on each upper pressure sensor electrode contacts the upper surface of an associated piezoelectric-type pressure sensor), and then performing a reflow soldering process to secure (electrically connect) the piezo-type pressure sensors to both the lower pressure sensor electrodes and the upper pressure sensor electrodes). The lower/rigid stack-up structure and the upper/flexible stack-up structure are also formed with patterned metal traces and via structures that collectively form signal paths extending between each pressure sensor electrode and a corresponding input/output (I/O) pad disposed on the lower/rigid stack-up structure's lowermost surface. In one embodiment, one or more sensor control and data processing circuits are simultaneously electrically connected to the I/O pads (e.g., during the reflow soldering process mentioned above), and an optional encapsulating layer is formed over the additional sensors after the solder reflow process is completed. This preferred configuration facilitates the inexpensive production of reliable and durable flex-rigid sensor apparatuses capable of performing the tactile exploration of a target object described above.

In some embodiments the apparatus is formed with a skin-like encapsulating layer that is disposed on an uppermost surface of second PCB structure. In some embodiments the encapsulating layer consists essentially of a durable flexible material (e.g., silicone rubber) that provides suitable friction for grasping and holding target objects, and serves to protect the additional sensors and underlying pressure sensor array by way of acting as a thermal insulator and a shock absorber (i.e., by elastically deforming in response to contact forces applied by target objects during operation interactions). In a presently preferred embodiment, the encapsulating layer is implemented using a layer of silicone rubber having a thickness in the range of 0.5 mm to 10 mm and a material formulation characterized by having surface roughness from 0 to 300 microns RMS and a durometer of 30 A to 70 A. This specific silicone layer formulation and configuration facilitates utilizing the encapsulating layer as a speaker-like medium that transmits a high/low pressure wave front in response to slipping-type displacement of a target object when otherwise grasped by a robotic gripper. By forming the encapsulating layer using silicone having the specifications mentioned above, slipping displacement in a lateral direction relative to the encapsulating layer (i.e., parallel to pressure sensor array) causes the silicone layer's surface generate a high/low alternating pressure wave front that can be easily detected as vibration force components by the pressure sensors (or by other vibration sensors mounted on the apparatus). Accordingly, by configuring the apparatus to generate sensor data that indicates the start of a slipping process in response to detection of the vibration force components, the apparatus facilitates immediate corrective action by the host robotic system's control circuit (e.g., increasing the applied gripping force) to preventing further slipping and avoid damage to the target object.

According to another embodiment, the flexible-rigid sensor apparatus includes sensor control and data processing circuitry that is operably coupled (e.g., directly connected by way of solder-based connections or by way of a mezzanine connector or other circuit structure) to the input/output pads disposed on the lower surface of the lower/rigid PCB stack-up structure, and is configured to receive sensor data from the apparatus' sensors by way of associated signal paths. For example, pressure sensor data generated by a given pressure sensor is transmitted along an associated (first) signal path disposed in the lower/rigid PCB stack-up structure and through an associated input/output pads to an associated input terminal of the sensor control and data processing circuitry. Similarly, temperature or other sensor data is transmitted from a given additional sensor along an associated (second) path disposed in the upper/flex PCB stack-up structure, then along an associated additional sensor via disposed in the spacer structure, then along an associated (first) signal path disposed in the lower/rigid PCB stack-up structure to an associated input/output pads. Sensor control and data processing circuitry is thus operably coupled to receive multimodal (i.e., pressure and additional) sensor data from each sensor mounted on the apparatus by way of corresponding input/output pads. In one embodiment, sensor control and data processing circuitry includes an analog-to-digital converter (ADC) circuit that is operably configured to convert analog sensor data values received from the various sensors into corresponding digital sensor values, a sensor data processing circuit configured to generate tactile information in response to the digital pressure sensor values, and transceiver circuitry configured to transmit the tactile information to the robotic system's control circuit (i.e., by way of a USB or other serial data bus). In one embodiment, the sensor control and data processing circuitry is entirely directly connected by way of solder-based connections to the input/output pads disposed on the lower surface of the lower/rigid PCB stack-up structure. In an alternative embodiment, a first portion of the sensor control and data processing circuitry (e.g., including the ADC circuitry) is disposed on a first PCB structure that is directly connected to the lower/rigid PCB stack-up structure, and a second portion of the sensor control and data processing circuitry (e.g., including the sensor data processing circuit and transceiver circuitry) is disposed on a separate PCB structure that is operably coupled to the first portion by way of one or more mezzanine connectors (or other circuit structure) to receive digital sensor values in a serial data transmission from the ADC circuitry. This approach facilitates protecting the sensor data processing circuit and transceiver circuitry from damage that may be caused by pressure forces generated by contact between the apparatus and target objects, and facilitates a wide range of pressure sensor configurations (e.g., high resolution sensor arrays including a relatively large number of densely packed pressure sensors, or low resolution arrays including a relatively small number of pressure sensors) by facilitating the use of a single mezzanine connector capable of supporting all pressure sensor configurations. Various additional features are optionally implemented to further enhance the beneficial aspects of the invention. For example, two or more ADC circuits may be utilized to more efficiently accommodate different sensor types, and an optional sensor controller may be included to facilitate different sensing modes (e.g., static versus vibration measurements by the pressure sensor array). The tactile information generation process performed by the sensor data processing circuit may be enhanced by way of utilizing a programmable logic device (e.g., a field-programmable gate array (FPGA) a programmable-system-on-chip (PSOC) circuit, and efficient transmission of the tactile information may be accomplished using a Universal Serial Bus (USB) transceiver circuit.

According to a practical embodiment of the present invention, a robotic system implements two or more rigid/flex sensor apparatus on associated contact structures of opposing end effector (gripper) fingers. In one embodiment each rigid/flex sensor apparatus includes an associated sensor control and data processing circuitry, whereby each apparatus generates and transmits tactile information along one or more serial (e.g., USB) data buses that extend along the robot (arm) mechanism between the end effector and the control circuit. In other embodiments analog multimodal sensor data generated by the sensors of two or more rigid/flex sensor apparatus disposed on a single end effector/gripper may be converted into digital sensor data using ADC circuitry disposed on each apparatus, and then the digital sensor data may be collectively processed by a shared sensor data processing circuit, whereby the tactile information transmitted to the robot system's control circuit is generated in response to sensor data collected by multiple apparatuses. In one embodiment, the tactile information generated by one or both rigid/flex sensor apparatus is provided to a local gripper control circuit (actuator) mounted on the gripper to facilitate minimum-delay operations (e.g., increasing applied grasping force when object slipping is detected).

According to another embodiment of the present invention, a method for controlling a robotic system involves utilizing one or more rigid/flex sensor apparatus described above to generate tactile information in response to contact forces applied by a target object to corresponding contact structures of an end effector while grasping (or otherwise operably interacting with) the target object. The tactile information generated by the rigid/flex sensor apparatus is provided to the robotic system's control circuit, and optionally provided to a local gripper control circuit (actuator) mounted on the gripper to facilitate minimum-delay operations (e.g., increasing applied grasping force when object slipping is detected).

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention relates to a rigid/flex sensor apparatus (i.e., a target object sensing architecture) that greatly enhances the capabilities of robotic systems. The following description is presented to enable one of ordinary skill in the art to make and use the invention as provided in the context of a particular application and its requirements. As used herein, directional terms such as “upper”, “lower”, “lower”, “horizontal”, “vertical”, “front” and “back”, are intended to provide relative positions for purposes of description and are not intended to designate an absolute frame of reference. With reference to electrical connections between circuit elements, the terms “coupled” and “connected”, which are utilized herein, are defined as follows. The term “connected” is used to describe a direct connection between two circuit elements, for example, by way of a metal line formed in accordance with normal integrated circuit fabrication techniques. In contrast, the term “coupled” is used to describe either a direct connection or an indirect connection between two circuit elements. For example, two coupled elements may be directly connected by way of a metal line, or indirectly connected by way of an intervening circuit element (e.g., a capacitor, resistor, inductor, or by way of the source/drain terminals of a transistor). Various modifications to the preferred embodiment will be apparent to those with skill in the art, and the general principles defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the embodiments shown and described below, and the appended claims are accorded the widest scope consistent with the principles and novel features herein disclosed.

FIG. 1shows an exemplary robotic system200that is provided to illustrate the use of novel rigid/flex sensor apparatuses100-1and100-2according to a generalized embodiment of the present invention. Exemplary robot system200is an arm-type robotic system generally including a robot arm-type mechanism201and a control circuit (CC)203(e.g., a microprocessor). As explained in detail below, novel rigid/flex sensor apparatuses100-1and100-2are configured for use on respective finger structures255-1and255-2of a two-fingered gripper mechanism (end effector)250that is mounted on a distal end of arm-type mechanism201, where each novel rigid/flex sensor apparatus utilizes multi-modal sensors to collect sensor data corresponding to surface features of a target object90when robotic system200causes apparatuses100-1and100-2to operably interact with target object90(e.g., when arm-type mechanism203is actuated such that gripper250is moved into a position that allows finger structures255-1and255-2to securely grasp target object90during lifting, moving and placing operations in accordance with control signals generated by control circuit203). As also described below, the sensor data collected by the various sensors of each apparatus100-1and100-2is utilized to generate multimodal tactile information (e.g., by circuitry provided on the rigid/flex sensor apparatus or separate data processing circuitry) which is fed-back to control circuit203to provide robotic system200with multi-modal tactile perception capabilities that facilitate enhanced human-like target object recognition and associated object manipulation control.

Referring to the upper right portion ofFIG. 1, robot mechanism201includes various mechanisms and structures that are operably configured in accordance with known techniques and controlled to manipulate a target object90by way of various actuators. In the exemplary embodiment robot mechanism201includes a shoulder/base mechanism210configured for fixed attachment to a work surface (not shown) by way of a fixed base211, an upper arm structure215extending from the shoulder/base mechanism210to an elbow mechanism220, a forearm structure225extending from the elbow mechanism220to a wrist mechanism230, a wrist structure235extending from the wrist mechanism230to hand/axial rotation mechanism240, and gripper (end effector)250operably connected to a terminal portion of the hand/axial rotation mechanism240. Gripper250is disposed at a distal end of robot arm mechanism201and includes two gripper fingers255-1and255-2configured to open (move away from each other) or close (move toward each other) in accordance with control signals generated by control circuit203. Robot mechanism201also includes multiple actuators, each actuator including a motor control circuit (MCC) configured to actuate one or more associated electric motors (not shown) in response to control signals received from control circuit203. For example, motor control circuit (MCC)204-1and associated first motor(s) form a first actuator disposed in shoulder-base mechanism210to facilitate selective rotation and pivoting of upper arm structure215relative to fixed base211, a second actuator including MMC204-2is disposed in elbow mechanism220to facilitate selective pivoting of forearm structure225relative to upper arm structure215, a third actuator including MMC204-3is disposed in wrist mechanism230to facilitate selective pivoting of wrist structure235relative to forearm structure225, a fourth actuator including MMC204-4is disposed in hand axial rotation mechanism240to facilitate selective pivoting of gripper250relative to wrist structure235, and a fifth actuator including MMC204-5disposed in end effector250that controls opening/closing of gripper fingers255-1and255-2relative to gripper250. As mentioned above, robot mechanism201is merely introduced to provide a simplified context for explaining the features and benefits of the present invention, and the specific configuration of robot mechanism201is not intended to limit the appended claims. For example, although end-effector250is depicted as a two-fingered gripper, gripper/end-effector250may also be implemented using a probe (i.e., having a single finger-like structure) implementing one flexible-rigid sensor apparatus, or a gripper mechanism having three or more fingers with a flexible-rigid sensor apparatus mounted on each finger.

Control circuit203is configured to generate sequences of primary control signals that are transmitted via signal lines (not shown) to the various motor control circuits204-1to204-5during each user-designated operation. That is, control circuit203generates the primary control signal sequence in accordance with user-provided instructions207, which are transmitted to control circuit203from a programming device80(e.g., a personal computer or workstation) and specify associated tasks to be performed by robot mechanism201. The primary control signal sequences thus control mechanical reconfigurations of arm-type mechanism201by actuating (turning on/off) the various actuators of arm-type mechanism201, whereby control circuit203causes gripper250to operably interact with target object90. For example, to perform an operable interaction involving controlling gripper250to grasp target object90, a control signal generator of control circuit203processes corresponding user-provided instructions207and generates/transmits first control signals to MCC204-5that cause the actuator disposed in end-effector250to increase a gap between gripper fingers255-1and255-2in accordance with an “open gripper” control instruction, then generates/transmits second control signals to MCCs204-1to204-4that cause upper the actuators disposed in arm structure215, forearm structure225, wrist structure235and axial rotation mechanism240to position end-effector250at designated X-Y-Z location coordinates such that gripper fingers255-1and255-2are disposed on opposite sides of target object90, and then generates/transmits third control signals to MCC204-5that causes end-effector250to decrease the gap between gripper fingers255-1and255-2and to apply a grasping force onto target object90(i.e., such that gripper fingers255-1and255-2apply opposing contact forces against opposite sides of target object90in response to the “close gripper” control instruction).

In addition to performing primary control signal sequences (i.e., operations performed in accordance with user-provided instructions207), control circuit203is also configured to generate secondary control signals that are inserted into (interrupt) the primary control signal sequence when feedback data107indicates an interrupt condition (e.g., a condition requiring an unscheduled termination of operations, or insertion of additional operations into the primary control signal sequence, or modification of one or more operations included in the primary control signal sequence). That is, control circuit203generates secondary control signals that cause robot mechanism201to execute pre-defined interrupt actions when feedback data107indicates the detection of corresponding predefined environmental conditions. That is, during operation of robotic system200to perform a specific task, control circuit203controls robot mechanism201by way of generating primary control signals as a default, and only interrupts the primary control signal sequence when an interrupt condition is indicated by feedback data107. In one embodiment of the present invention, robotic system200is configured such that feedback data107includes tactile information TI generated in accordance with the sensor data collected by rigid/flex sensor apparatuses100-1and100-2, and control circuit203is configured to generate secondary control signals in response to interrupt conditions indicated by tactile information TI. For example, when tactile information TI included in feedback data107indicates target object90is offset from the expected X-Y-Z location, control circuit203is configured to modify or replace a portion of the primary control signal sequence to adjust the position of gripper250such that it performs a grasping operation at an offset X-Y-Z location in accordance with associated secondary control signals (i.e., instead of performing the grasping operation at the original X-Y-Z location defined by the primary control signals). As described below, tactile information TI suitable for implementing such interrupt operations is produced in accordance with the sensor data generated by apparatuses100-1and100-2.

Referring to gripper250inFIG. 1, two rigid/flex sensor apparatuses100-1and100-2are respectively fixedly attached to opposing contact surfaces of gripper fingers255-1and255-2such that apparatuses100-1and100-2face target object90during operable interactions (i.e., such that apparatuses100-1and100-2are pinched between gripper fingers255-1and255-2, respectively, and corresponding surface portions of target object90when gripper250is actuated to grip target object90). Each apparatus100-1and100-2is configured to provide sensor data that is utilized to generate tactile information TI, which forms at least a part of feedback information/data107provided to control circuit203on data bus108during operable interactions (i.e., apparatus100-2includes all features and details of apparatus100-1described below). In alternative embodiments only one rigid/flex sensor apparatus may be used (i.e., either apparatus100-1or apparatus100-2), or more than two apparatuses may be used (e.g., in the case of a gripper including three or more fingers).

Referring to the dash-line bubble indicated at the lower portion ofFIG. 1, in an exemplary embodiment rigid/flex sensor apparatus100-1is configured for fixed connection to gripper finger255-1(e.g., by way of fixed attachment to a gripper finger support surface257), and generally includes a lower/rigid (first) printed circuit board (PCB) stack-up structure110, a lower sensor array/layer120, a spacer structure130, an upper/flex (second) PCB stack-up structure140, an upper sensor array/layer150, an optional encapsulating layer160, and optional sensor control and data processing circuitry170. The following detailed description is primarily directed to the various structures, layers and sensors of apparatus100-1, and that details regarding how rigid/flex sensor apparatus100-1may be configured for fixed connection to gripper finger255-1are omitted for brevity—in one embodiment the fixed connection may be implemented using techniques described in co-owned and co-filed U.S. patent application Ser. No. 16/832,690 entitled “TACTILE PERCEPTION APPARATUS FOR ROBOTIC SYSTEMS”, which is incorporated herein by reference in its entirety. Apparatus100-2includes the structures and configuration described below with reference to perception apparatus100-1.

Lower/rigid PCB stack-up110is microfabricated on a rigid PCB platform using standard rigid PCB fabrication and assembly processes, and primarily functions both as a structural base and also as a multi-layered medium for routing densely packed signals which are subject to electrical interference. The traces, vias, and micro-vias composing the various layers of lower/rigid PCB stack-up110collect signals information from electrodes and contact pads formed on upper surface111U (which interface both with sensors121and signals coming from sensors151by way of upper/flex PCB stack-up140), and route them to one or more sensor control and data processing integrated circuit(s)170operably connected to input/output pads formed on lower surface111L for digitization and optional processing to generate tactile information TI that is then forwarded to robotic controller203by way of data bus108.

An exemplary lower/rigid PCB stack-up110is shown in the bubble section ofFIG. 1and inFIGS. 2A and 2B. Referring toFIG. 2A, lower/rigid PCB stack-up110includes six (first) substrates112-1to112-6arranged in a stacked configuration. Each substrate112-1to112-6comprises a layer of rigid insulating material (e.g., FR-4) having traces (e.g., patterned portions of a thin copper layer) formed on its upper and lower surfaces, and metal via structures (or micro-via structures) extending through the rigid insulating material layer to electrically connect associated traces formed on the opposing upper and lower substrate surfaces. For example, referring toFIG. 2A, uppermost substrate112-6is processed such that its upper surface includes multiple lower pressure (first) electrodes113, sensor contact pads116and additional sensor contact pads117, all of which being formed by corresponding metal (e.g., copper) islands disposed in a predetermined spaced-apart arrangement on uppermost surface111U. Each lower pressure electrode113, sensor contact pad116and additional sensor contact pad117is operably coupled to a corresponding signal path by way of metal via structures that extend downward through substrate112-6. For example, the bubble portion ofFIG. 2Ashows a partial cross-section indicating that sensor contact pad116-1is connected to an associated copper trace118-1by way of via structure119-1, which extends through an opening formed between the upper and lower surfaces of substrate112-6. Once substrates112-1to112-6are processed in this manner, substrates112-1to112-6are fixedly interconnected using an established rigid PCB fabrication process (e.g., by way of intervening adhesive layers A-1to A-5) to produce lower/rigid PCB stack-up110. As indicated inFIGS. 1 and 2B, the interconnection process is performed such that upper substrate surface of uppermost substrate112-6forms an upper surface111U of lower/rigid PCB stack-up110, lower surface of lowermost substrate112-1forms a lower surface111L of lower/rigid PCB stack-up110, and each lower pressure electrode113and additional sensor contact pad116disposed on upper surface111U is electrically connected to an associated input/output pad114formed on lower surface111L by way of an associated signal path115, with each signal path being formed by a contiguous (i.e., electrically-connected) series of electrically conductive structures (i.e., copper traces and metal via structures) that pass through substrates112-1to112-6. For example, as indicated inFIG. 2B, lower pressure electrode113is electrically connected to associated input/output pad114-1by way of associated signal path115-1, which is formed by the indicated set of contiguous traces and via structures that pass between upper surface111U and lower surface110through substrates112-1to112-6. Note that the signal paths depicted inFIG. 2Bare arbitrarily formed for illustrative purposes and are not intended to represent an actual PCB stack-up configuration. In alternative embodiments lower/rigid PCB stack-up110may be produced using any number of rigid insulating material layers (first substrates).

Sensor arrays/layers120and150collectively include multimodal (i.e., various types of) sensors that are placed on or over upper surface111U of lower/rigid PCB stack-up110in a manner that facilitates operable connection of each sensor to sensor control and data processing circuitry170. In an exemplary embodiment, sensor arrays/layers120and150are disposed in respective horizontal planes, with lower (first) sensor array/layer120comprising sensors121disposed on upper surface111U of the lower PCB stack-up110, and upper (second) sensor array/layer150including additional (second) sensors151disposed on/over upper/flex PCB stack-up140. That is, in the depicted exemplary embodiment, apparatus100includes sensors121disposed between lower/rigid PCB stack-up110and upper/flex PCB stack-up140, and upper sensor array150disposed on upper surface141U of the upper/flex PCB stack-up140. In an alternative embodiment (not shown), lower array/layer may include one or more non-pressure sensors (e.g., a vibration/texture sensor, a proximity sensor or a temperature sensor) may be included with the pressure sensor array120(i.e., sandwiched between stack-ups110and140). In another alternative embodiment (not shown), one or more additional layers of sensors may be implemented by way of adding one or more additional flexible PCB stack-up structures over upper/flex PCB stack-up140.

According to a presently preferred embodiment, all sensors121forming the lower sensor array/layer120are pressure sensors, whereby sensor array/layer120is referred to below as pressure sensor array120. Pressure sensors121are disposed in a symmetric (i.e., equally-spaced) two-dimensional arrangement, with each pressure sensor121being electrically connected (e.g., by way of solder-based connections) between an associated pressure electrode113disposed on lower/rigid PCB stack-up110and an associated upper pressure electrode144disposed on upper/flex PCB stack-up140. For example, pressure sensor121-1has a lower terminal portion connected to associated lower pressure electrode113-1and an upper terminal portion connected to associated upper pressure electrode144-1. xxx

In the preferred embodiment each pressure sensor121is implemented using a piezoelectric sensor device (e.g., a piezoelectric material die comprising lead zirconate titanate (PZT) or other piezoelectric material). In other embodiments, pressure sensors121may be arranged in one of an asymmetric or random pattern arrangement on lower/rigid PCB stack-up110, and each pressure sensor may be implemented using other piezo-type (e.g., a piezo-resistive) sensor device, or may be implemented using another pressure sensor type (e.g., strain gauge, capacitive pressure sensor or cavity-based pressure sensor). In yet other embodiments (not shown) the pressure sensors may be connected to electrodes formed on upper surface111U or lower surface141L (i.e., not sandwiched between two electrodes respectively disposed on the two stack-up structures as in the preferred embodiment), and lower sensor array/layer may include one or more non-pressure sensors.

Referring again to the bubble section ofFIG. 1and toFIGS. 3A, 3B and 3C, an optional spacer structure130is disposed between upper surface111U of lower/rigid PCB structure110and lower surface141L of upper/flex PCB structure140to accommodate pressure array120.FIGS. 3B and 3Care cross-sectional views respectively taken along lines3B-3B and3C-3C ofFIG. 3A. Spacer structure130is optionally produced using either known rigid PCB fabrication and includes a rigid or flexible insulating material layer132or produced using known flexible PCB fabrication processes and includes a flexible insulating material layer132. In either case, insulating material layer132that is processed to define multiple sensor openings134(i.e., openings that pass entirely through insulating material layer132from upper surface131U to lower surface131LA, and to include pressure sensor ground vias136and additional sensor vias137, which are formed using a conductive material such as copper. As shown inFIGS. 3B and 3C, each pressure sensor ground via136and additional sensor via137forms an associated conductive path that passes entirely through insulating material layer132. For example, as indicated inFIG. 3B, pressure sensor ground via136-1includes an upper portion136-1U exposed on upper surface132U, a lower portion136-1L exposed on lower surface132L, and a central portion136-1C that forms a conductive path between upper portion136-1U and lower portion136-1L. Similarly, as shown inFIG. 3C, each additional sensor via137-1includes an upper portion137-1U exposed on upper surface132U, a lower portion137-1L exposed on lower surface132L, and a central portion137-1C that forms a conductive path between upper portion137-1U and lower portion137-1L. As described below, when spacer structure130is mounted between PCB stack-up structures110and140, each pressure sensor121is received within an associated sensor opening134. With this configuration, spacer structure130provides two primary functions: first, spacer structure130acts as mechanical support for the placement of further layers above pressure sensor array130and to distribute pressure forces applied to upper/flex PCB stack-up140to prevent saturation and potential damage to pressure sensors121, and second, spacer structure130provides electrical connections (i.e., by way of vias136and137) between upper/flex PCB stack-up and input/output pads114.

A simplified upper/flex PCB stack-up140is shown in the bubble section ofFIG. 1and inFIGS. 4A and 4B. Referring toFIG. 4A, upper/flex PCB stack-up140includes three substrates142-1to142-3, with each substrate comprising a layer of flexible insulating material (e.g., polyimide) having associated copper traces formed on opposing surfaces and operably connected by metal via structures extending through the flexible insulating material. Substrates142-1to142-3are processed using known flexible PCB fabrication techniques such that the lower surface of lowermost substrate142-1includes multiple upper pressure (second) electrodes143, sensor contact pads146and additional sensor contact pads147that are formed as described above and disposed in an arrangement that substantially mirrors the lower pressure electrodes113, sensor contact pads116and additional sensor contact pads117formed on upper surface111U of lower/rigid PCB stack-up110(described above). The upper surface of uppermost substrate142-3, which forms upper layer101U of apparatus100, includes one or more additional sensor (third) electrodes143disposed in a predetermined arrangement, and each upper pressure electrode144and additional sensor electrode143is electrically connected to one or more associated additional sensor contact pads147by way of an associated signal path145in a manner similar to that described above with reference to signal paths115of lower/rigid PCB stack-up110(described above). For example, as indicated in the bubble portion ofFIG. 1and inFIG. 4B, additional sensor electrode143-1is electrically connected to associated additional sensor contact pad147-1by way of an associated signal path145-1. Once processing is completed, substrates142-1to142-3are fixedly interconnected using an established flexible PCB fabrication process (e.g., by way of intervening adhesive layers A-6and A-7) to complete the production of upper/flex PCB stack-up140. As indicated inFIGS. 1 and 4B, the interconnection process is performed such that the upper substrate surface of uppermost substrate142-3forms an upper surface141U of upper/flex PCB stack-up140and the lower surface of lowermost substrate142-1forms a lower surface141L of upper/flex PCB stack-up140.

In an alternative embodiment (not shown), an upper/flex PCB stack-up is formed using four or more flexible insulating material layers, with each layer composed of two flexible insulating material sheets having patterned copper on each (upper/lower) sheet surface. The bottom layer of the lowermost (first) sheet includes the upper pressure sensor electrodes that are soldered to the top contacts of the pressure sensors, and other contact pads that provide electrical connections to the various vias disposed on the underlying spacer structure. The top layer includes signal paths for routing signals to one or more intermediate sensors (e.g., a strain gauge), or may be used to serve as a multilayer flex-PCB ground layer or some combination of the two. The lower sheet of the upper layer is bonded to the lower layer via a lamination process or soldering process and serves as a shield electrode for capacitive proximity sensors or patterned to provide additional signal paths.

Referring again to the bubble section ofFIG. 1, upper sensor array/layer150is disposed on upper layer141U of upper/flex PCB stack-up140and includes one or more additional sensors151, where each additional sensor151is of a sensor type different from pressure sensors (e.g., each additional sensor151comprises one of a vibration sensor, a proximity sensor and a temperature sensor). Each additional sensor151is electrically connected to associated additional sensor electrodes143disposed on upper/flex PCB stack-up140, whereby control signals and data signals are transmitted between each additional sensor151and sensor control and data processing circuitry170by way of signal paths provided on PCB stack-up structures110and140. For example, additional sensor151-1is electrically connected to associated additional sensor electrode143-1, which is connected by way of (second) signal path145-1to additional sensor contact pad147-1, which in turn is electrically connected to sensor control and data processing circuitry170by way of an associated signal path115provided on lower/fixed PCB stack-up structure110in the manner described below with reference toFIG. 5C. In one embodiment additional sensor151-1comprises one of a vibration/texture sensor (e.g., either piezoelectric/piezoresistive or MEMS-based sensor configured to detect vibrations), a proximity sensor (e.g., a capacitive-coupling-type sensing element) or a temperature sensor (e.g., a resistive temperature detector (RTD), a thermoelectric sensor, or other variants) configured to generate temperature data in response to a local temperature applied to a corresponding portion of apparatus100. In other embodiments, at least one additional sensor151is a vibration/texture sensor, at least one additional sensor151is a proximity sensor, and at least one additional sensor151is a temperature sensor.

Referring to the upper portion of the bubble section ofFIG. 1, flexible-rigid sensor apparatus100-1also includes an optional encapsulating layer160consisting essentially of a durable flexible material (e.g., silicone rubber) that is disposed on an uppermost surface141U of upper/flex PCB stack-up140. In one embodiment, encapsulating layer160is formed in accordance with specific material parameters that allow it to perform the protection and grasping friction functions described in co-owned and co-filed U.S. patent application Ser. No. 16/832,690 entitled “TACTILE PERCEPTION APPARATUS FOR ROBOTIC SYSTEMS”, which is cited above.

Referring to the upper portion of the bubble section ofFIG. 1, flexible-rigid sensor apparatus100-1also includes a sensor control and data processing circuitry170that is operably coupled (e.g., directly connected by way of solder-based connections or by way of a mezzanine connector as described below) to input/output pads114, where sensor control and data processing circuitry170is configured to receive sensor data from sensors121and151by way of associated signal paths115and145. For example, pressure sensor data SD-P1, which is generated by pressure sensor121-1, is transmitted along an associated (first) signal path115-1disposed in the lower/rigid PCB stack-up structure110from associated lower pressure sensor electrode113-1to associated input/output pad114-1, and from input/output pad114-1to an associated input terminal of sensor control and data processing circuitry170. Similarly, temperature or other sensor data is transmitted from additional sensors151along an associated (second) signal paths145disposed in upper/flex PCB stack-up structure140, then along associated additional sensor vias137disposed in spacer structure130, then along associated (first) signal paths115disposed in lower/rigid PCB stack-up structure110to an associated input/output pad114, from which it is transferred to an associated input terminal of sensor control and data processing circuitry170.

FIGS. 5A to 5Ddepict a method for producing flexible-rigid sensor apparatus100-1according to a simplified exemplary embodiment.

FIG. 5Adepicts lower/rigid PCB stack-up structure110and upper/flexible PCB stack-up structure140during an early stage of the production method. At this point lower/rigid PCB stack-up structure110is produced using the rigid PCB fabrication process described above with reference toFIGS. 2A and 2B, and upper/flexible PCB stack-up structure140is produced using the flexible PCB fabrication process described above with reference toFIGS. 4A and 4B. Although not shown, spacer structure130(seeFIG. 5B) is also produced, for example, using the flexible PCB process utilized to provide upper/flexible PCB stack-up structure140.

FIG. 5Aalso depicts applying solder flux (paste) portions to the I/O and contact pads and electrodes disposed on the upper/lower surfaces of lower/rigid PCB stack-up structure110and upper/flexible PCB stack-up structure140. Specifically, first solder flux portions521are applied to each pressure sensor electrode and contact pad disposed on upper surface111U of lower/rigid PCB stack-up structure110, second solder flux portions522are applied to each pressure sensor electrode and contact pad disposed on lower surface141L of upper/flexible PCB stack-up structure140, third solder flux portions are applied to each additional sensor electrode146disposed on upper surface141U of upper/flexible PCB stack-up structure140, and optional fourth solder flux portions524are applied to each input/output pad114disposed on lower surface111L. For example, first solder flux portions521and522are applied such that a first solder flux portion521-1is applied to pressure sensor electrode113-1and a second solder flux portion522-1is applied to pressure sensor electrode144-1, and such that a first solder flux portion521-2is applied to additional sensor contact pad117-1and a second solder flux portion522-2is applied to contact pad147-1.

FIG. 5Bdepicts mounting piezoelectric-type pressure sensors121and additional sensors151such that each sensor contacts an associated solder flux portion. For example, pressure sensor121-1is mounted between lower/rigid PCB stack-up structure110and upper/flexible PCB stack-up structure140such that its lower surface/terminal contacts associated first solder flux portion521-1, which is disposed on lower pressure sensor electrode113-1, and such its upper surface/terminal contacts associated second solder flux portion522-1, which is disposed on associated upper pressure sensor electrode144-1. Note that each pressure sensor121is also received inside an associated sensor opening (e.g., sensor121-1is received inside sensor opening134-1). Note also that spacer structure130is mounted such that via structures are similarly mounted between corresponding solder flux portions (e.g., additional sensor via137-1is disposed between solder portions521-2and522-2), and that each additional sensor151is also mounted onto one or more solder flux portion523.

FIG. 5Cdepicts apparatus100-1during the performance of a solder reflow process that is utilized to form electrically conductive connections between associated electrodes, contact pads, sensors and other circuitry of the assembly described above with reference toFIG. 5B. The solder reflow process is performed in accordance with known techniques (e.g., by applying a suitable amount of heat energy H, indicated by wavy lines, to the assembled stack) such that each solder flux portion melts and forms a corresponding electrically conductive structure. For example, the reflow process melts the corresponding solder flux portion disposed between a lower end terminal of pressure sensor121-1and its associated lower pressure sensor electrode113-1and between the upper end terminal of pressure sensor121-1and its associated upper pressure sensor electrode144-1, thereby forming a conductive connection531-1between a lower end of pressure sensor121-1associated lower pressure sensor electrode113-1, and forming a conductive connection531-2between an upper end of pressure sensor121-1associated upper pressure sensor electrode144-1. The reflow process also simultaneously melts all other solder flux portions, thereby forming a corresponding conductive connection533that secures additional sensor151-1to its associated additional sensor electrode143-1on upper surface141U of upper/flexible PCB stack-up structure140, and corresponding conductive connections that secure sensor control and data processing circuitry170to lower surface111L of lower/rigid PCB stack-up structure110(e.g., conductive connections534-1and534-2respectively secure input/output pads114-1and114-2to corresponding input terminals of sensor control and data processing circuitry170). Upon completion of the reflow process, electrical connections are established that facilitate the transmission of pressure and additional sensor data between sensor control and data processing circuitry170and all sensors disposed on apparatus100. For example, pressure sensor data SD-P generated by pressure sensor121-1is transmitted along an associated (first) signal path115-1disposed in lower/rigid PCB stack-up structure110and through an associated input/output pad114-1and conductive connection534-1to an associated input terminal of sensor control and data processing circuitry170. Similarly, additional (e.g., temperature, vibration, proximity or other) sensor data is transmitted from additional sensor151-1by way of conductive connection533and additional sensor electrode146-1to associated (second) signal path145-1, along signal path145-1through upper/flex PCB stack-up structure140to upper additional sensor contact pad147-1, then through spacer structure130by way of conductive connections531-2and532-2and additional sensor via137-1to lower additional sensor contact pad117-1, then along associated (first) signal path115-2disposed in the lower/rigid PCB stack-up structure110and through associated input/output pad114-2and conductive structure534-2to an associated input terminal of sensor control and data processing circuitry170. Sensor control and data processing circuitry170is thus operably coupled to receive multimodal (i.e., pressure and additional) sensor data from each pressure sensor and each additional sensor of apparatus100-1by way of corresponding input/output pads114. In a presently preferred embodiment, sensor control and data processing circuitry170is configured to generate tactile information in response to this pressure and additional sensor data, and to interrupt primary control signal sequences (e.g., to correct offset conditions) in the manner described in co-owned and co-filed U.S. patent application Ser. No. 16/832,690, which is cited above.

FIG. 5Ddepicts the deposition of optional encapsulating material560over upper surface141U and additional sensor151-1, thereby forming encapsulating layer160and completing the fabrication of rigid/flex sensor apparatus100-1. In a presently preferred embodiment, encapsulating layer160is implemented using a layer of silicone rubber having a thickness T1in the range of 0.5 mm to 10 mm and a material formulation characterized by having surface roughness from 0 to 300 microns RMS (root mean square) and a durometer of 30 A to 70 A. Additional features and benefits associated with encapsulating layer160, along with techniques for collecting and utilizing sensor data indicative of slipping-type displacement of a target object relative to encapsulating layer160, are described in co-owned and co-filed U.S. patent application Ser. No. 16/832,690, which is cited above.

FIGS. 6, 7A and 7Bdepict a flex/rigid apparatus100A according to a presently preferred embodiment in which one or more metal layers118A and148A are disposed on a lower/rigid PCB stack-up structure110A and an upper/flex PCB stack-up structure140A, respectively, and are utilized to form a Faraday cage that protects pressure sensors121A from environmental interference. Referring toFIG. 6, apparatus100A is similar to apparatus100(described above) in that it includes a spacer structure130A and a pressure sensor array120A disposed between lower/rigid PCB stack-up structure110A and upper/flex PCB stack-up structure140A. Other that the differences described below, lower/rigid PCB stack-up structure110A, pressure sensor array120A spacer structure130A and upper/flex PCB stack-up structure140A are configured and assembled as described above with reference to apparatus100, and therefore associated details are omitted here for brevity.

Apparatus100A differs from apparatus100in that at least a portion of insulating material layer132A of spacer structure130A is sandwiched between a first ground plane structure118A and a second ground plane structure148A that collectively form a Faraday cage around each pressure sensor121A disposed inside each sensor opening136A. Ground plane structures118A and148A are defined as contiguous layers of a conductive material (e.g., copper) that are respectively formed on lower/rigid PCB stack-up structure110A and upper/flex PCB stack-up structure140A and extend the entire length L and width W of sensor array120A. In the depicted exemplary embodiment, ground plane structure118A comprises a partial copper layer formed on upper surface111AU that is patterned to provide peripheral spaces around (i.e., electrical isolation for) lower pressure sensor electrodes113A, and is spaced from extra sensor electrodes117A, but otherwise forms a continuous sheet-like ground plane structure. Similarly, ground plane structure148A comprises a solid, unbroken copper layer formed on lower surface141AL that is spaced from extra sensor electrodes147A, but otherwise forms a continuous sheet-like ground plane structure. Note that respective portions of ground plane structure118A are utilized to form lower sensor contact pads116A, and that respective portions of ground plane structure148A are utilized to form both upper pressure sensor electrodes144A and upper sensor contact pads146A.

Apparatus100A also differs from apparatus100in that thin insulating layers119A and149A are respectively formed over ground plane layers118A and148A to ensure electrical isolation between adjacent sensors. Lower insulating layer119A includes square openings119A-1that facilitate connections between lower pressure sensor electrodes113A and lower portions of pressure sensors121A and includes round openings119A-2that facilitate connections between lower sensor contact pads116A and lower ends of corresponding via structures136A. Similarly, upper insulating layer149A includes square openings149A-1that facilitate connections between upper pressure sensor electrodes144A and upper portions of pressure sensors121A and includes round openings149A-2that facilitate connections between upper sensor contact pads146A and upper ends of corresponding via structures136A.

FIG. 7Ais a cross-sectional side view showing flexible-rigid sensor apparatus100A in an assembled state, andFIG. 7Bis an enlarged partial section view showing portion of apparatus100A that includes a pressure sensor121A-1in greater detail.FIG. 7Ashows apparatus100A after completion of an assembly process utilizing the various layers and structures shown inFIG. 6, where in one embodiment the assembly process is performed as described above with reference toFIGS. 5A to 5Dand includes the formation of an encapsulating layer160A over upper/flex PCB stack-up structure140A. As indicated inFIG. 7A, both ground plane layers118A and148A are electrically connected together by way of at least one additional sensor contact pad117A-1and via structure137A-1, which are coupled to a ground source, for example, by way of signal path115A-1and input/output contact pad114A-1.

FIG. 7Bshows a portion of apparatus100A including a pressure sensor121A-1after completion of the assembly process performed as described above with reference toFIGS. 5A to 5D. As indicated inFIGS. 7A and 7B, spacer structure130A is disposed between a lower/rigid PCB stack-up structure110A and an upper/flex PCB stack-up structure140A, and includes flexible insulating material layer132A that defines a sensor opening134A-1. For brevity, the portion of apparatus100A depicted inFIG. 7Bis limited to show only an upper portion of lower/rigid PCB stack-up structure110A including lower pressure sensor electrode113A-1, and to show a lower portion of upper/flex PCB stack-up structure140A including upper pressure sensor electrode144A-1. As described above with reference toFIG. 5C, pressure sensor121A-1is electrically connected to electrodes113A-1and144A-1by way of solder-based connection structures532A-1and532A-2, respectively. During operation, ground plane layers118A and148A are connected to a ground source, whereby portions of ground plane layers118A and148A are operably configured to form a Faraday cage around each pressure sensor121A. For example, portions118A-1and118A-2disposed adjacent to the lower end of pressure sensor121A-1and portions148A-1and148A-2disposed adjacent to the upper end of pressure sensor121A-1form a Faraday cage around pressure sensor121A-1disposed inside sensor opening134A-1defined through spacer structure130A. In a similar manner, respective portions of ground plane layers118A and148A form Faraday cages around each pressure sensor121A disposed inside each sensor opening134A defined through spacer structure130A. In this way, spacer structure130A enhances the sensitivity of pressure sensor data generated by each pressure sensor (e.g., pressure sensor121A-1), which further facilitates the use of PZT-type pressure sensor elements by protecting the very small signals generated by PZT dies from environmental interference.

FIGS. 8 to 10Bdepict a flexible-rigid sensor apparatus100B according to another exemplary embodiment. As indicated in the upper portion ofFIG. 8, apparatus100B is similar to the embodiments described above in that it includes a pressure sensor array120B and a spacer structure130B disposed between a lower/rigid PCB stack-up structure110B and an upper/flexible PCB stack-up structure140B, with an upper sensor array150B and an encapsulating layer160B formed on/over upper/flexible PCB stack-up structure140B, where each of these structures is formed in accordance with the embodiments described above.

As indicated in the lower portion ofFIG. 8, apparatus100B differs from earlier-described embodiments in that apparatus100B also includes a base structure180B and a pair of mezzanine connectors190B-1and190B-2, and further in that sensor control and data processing circuitry170B includes a first circuit portion170B-1disposed on an upper (first) PCB structure171B-1that is directly connected to the lower/rigid PCB stack-up structure110B, and a lower (second) circuit portion170B-2disposed on a separate (second) PCB structure171B-2that is operably coupled to first circuit portion170B-1by way of mezzanine connectors190B-1and190B-2.

Base structure180B comprises a machined or molded metal (e.g., aluminum or steel) structure including a support plate181B having two through-openings186B extending between a planar upper surface181B-U and an opposing planar lower surface181B-L, a mounting flange182B integrally connected to a rear edge181B-R of support plate181B and including mounting holes183B configured for rigid connection of base structure181B to a robotic gripper (not shown), for example, by way of bolts or other fasteners (not shown). An integral peripheral wall184B surrounds support plate181B and mounting flange182B and forms a protective housing that, in combination with encapsulation layer160B, surrounds and protects lower (pressure) sensor array120B and upper (additional) sensor array150B. An upper wall portion184E-U of peripheral wall184B extends perpendicular to and upward from (above) support plate181B-U, whereby upper support plate surface181E-U and an inside surface of upper wall portion184B-U form an upper pocket region181B-UP configured to receive and secure upper (first) PCB structure171B-1and the other PCB and other structures of apparatus100B that are depicted above base structure180B inFIG. 8. Similarly, a lower wall portion184B-L of peripheral wall184B extends perpendicular to and downward from (below) support plate181B-U, whereby lower support plate surface181B-L and an inside surface of lower wall portion184B-L form a lower pocket region181B-LP configured to receive and secure lower PCB structure171B-2.

FIGS. 9A and 9Bare top and bottom plan views, respectively, showing first circuit portion170B-1, andFIGS. 10A and 10Bare top and bottom plan views, respectively, showing second circuit portion170B-2. Referring toFIG. 9A, circuit portion170B-1includes an array172B including contact pads173B that are disposed on an upper surface171B-1U of upper PCB structure171B-1, where contact pads173B are arranged for solder-based connection to input/output pads (not shown) provided on a lower surface of lower/rigid PCB stack-up structure110B (shown inFIG. 8). Referring toFIG. 9B, upper PCB structure171B-1includes signal paths and corresponding contact pads disposed on lower surface171B-1L that facilitate the transfer of sensor data signals directly to analog-to-digital (ADC) circuits175B-1and175B-2. In one embodiment, ADC circuit175B-1receives pressure sensor data from pressure sensor array120B and transmits corresponding digital pressure sensor data signals PSD to a data processor176B (seeFIG. 10A) by way of mezzanine connector190B-1, and ADC circuit175B-2receives additional sensor data from upper sensor array150B and transmits corresponding digital additional sensor data signals ASD to data processor176B by way of mezzanine connector190B-2. Referring toFIG. 10A, data processor176B is disposed on an upper surface171B-2U of lower PCB structure171B-2and generates tactile information TI using one or more of a microprocessor, a programmable logic device (e.g., a field-programmable gate array (FPGA)), and a programmable-system-on-chip (PSOC) circuit. Tactile information TI is transmitted from data processor176B to a transceiver circuit177B, which retransmits tactile information TI as part of a feedback data signal107B transmitted on a data bus108B to system control circuit203. In one embodiment, transceiver circuit177B is implemented using a Universal Serial Bus (USB) circuit, and data bus108B is implemented using a USB bus.FIG. 10Bdepicts a lower surface171B-2L of lower PCB structure171B-2, which in one embodiment includes optional connections178B-1and178B-2and one or more support structures179B.

Referring again toFIG. 8, separating sensor control and data processing circuitry170B into upper and lower portions170B-1and170B-2that are separated by rigid support plate181B provides several benefits. First, rigid support plate181B serves to absorb pressure forces, whereby this arrangement facilitates protecting sensor data processing circuit176B and transceiver circuitry177B from damage that may be caused by pressure forces generated by contact between apparatus100B and target objects. Moreover, by configuring ADC circuits175B-1and175B-2to transmit digital sensor signals PSD and ASD using serial signal transmissions, this arrangement facilitates the use of a wide range of pressure sensor configurations (e.g., high resolution sensor arrays including a relatively large number of densely packed pressure sensors, or low resolution arrays including a relatively small number of pressure sensors) by facilitating the use of the same mezzanine connectors190B-1and190B-2to implement any of the sensor configurations.

Although the present invention has been described with respect to certain specific embodiments, it will be clear to those skilled in the art that the inventive features of the present invention are applicable to other embodiments as well, all of which are intended to fall within the scope of the present invention. For example, although the present invention is described with specific reference to articulated-type robotic systems that use two-finger end effectors, the rigid/flex sensor apparatus disclosed herein may also be beneficially utilized in advanced robotic systems that utilize three, four or five finger end effectors (e.g., human-like robotic hands), and may be integrated into a gripper-type end effector using any of the details provided in co-owned and co-filed U.S. patent application Ser. No. 16/832,800 entitled “ROBOTIC GRIPPER WITH INTEGRATED TACTILE SENSOR ARRAYS”, all of which being incorporated herein by reference in its entirety. Moreover, although the present invention is described with reference to single lower/flex PCB stack-up structure, two or more lower/flex PCB stack-up structures may be utilized to provide additional sensor layers without departing from the spirit of the invention.