Abstract: Techniques for performing multi-sensor calibration on a vehicle are described. A method includes obtaining, from each of at least two sensors located on a vehicle, sensor data item of a road comprising a lane marker, extracting, from each sensor data item, a location information of the lane marker, and calculating extrinsic parameters of the at least two sensors based on determining a difference between the location information of the lane marker from each sensor data item and a previously stored location information of the lane marker.

Abstract: The present teaching relates to method, system, medium, and implementations for sensor calibration. An ego vehicle determines whether a sensor deployed thereon to facilitate autonomous driving needs to be calibrated and sends, if it is determined that the sensor needs to be calibrated, a request for assistance in collaborative calibration of the sensor to a center. The request includes at least a first position of the ego vehicle on the route and a first configuration of the sensor with respect to the ego vehicle. When the ego vehicle receives a calibration assistant package, which includes information associated with a collaborative means present along the route and to be used to assist the ego vehicle to calibrate the sensor, it identifies, based on the information, the collaborative means along the route when the ego vehicle is in a vicinity of the collaborative means in order to capture a target present on the collaborative means to enable calibration of the sensor.

Abstract: Some embodiments include a radiographic inspection system, comprising: a drive mechanism configured to move along a structure; a detector attached to the drive mechanism; a radiation source attached to the drive mechanism and positionable relative to the detector such that a width of the structure casts a radiation shadow on an active area of the detector; and control logic coupled to the detector and configured to: receive an image from the detector; generate side wall loss information based on the image; and generate bottom wall loss information based on the image.

Abstract: A monocular image often does not contain enough information to determine, with certainty, the depth of an object in a scene reflected in the image. Combining image data and LIDAR data may enable determining a depth estimate of the object relative to the camera. Specifically, LIDAR points corresponding to a region of interest (“ROI”) in the image that corresponds to the object may be combined with the image data. These LIDAR points may be scored according to a monocular image model and/or a factor based on a distance between projections of the LIDAR points into the ROI and a center of the region of interest may improve the accuracy of the depth estimate. Using these scores as weights in a weighted median of the LIDAR points may improve the accuracy of the depth estimate, for example, by discerning between a detected object and an occluding object and/or background.

Abstract: The present teaching relates to method, system, medium, and implementations for sensor calibration. A request is received from an ego vehicle in motion on a route for assistance in collaborative calibration of a sensor deployed on the ego vehicle. The request specifies a position of the ego vehicle and a configuration of the sensor with respect to the ego vehicle. A collaborative means along the route is identified based on the ego vehicle's position, the configuration of the sensor, the route, and the position associated with the collaborative means. A calibration assistance package is generated in response to the request and sent to the ego vehicle. The calibration assistance package includes information about the collaborative means that can be used to identify the collaborative means while in motion along the route for calibrating the sensor while the ego vehicle is in the vicinity of the collaborative means.

Abstract: A stereo camera adjustment system disposes an adjustment plate that displays an adjustment chart for adjusting deviation of image information caused by position misalignment of the stereo camera at a predetermined position relative to a vehicle mounted with a stereo camera, capture an image of the adjustment chart, and process the captured image of the adjustment chart to correct the deviation of the image information. The stereo camera adjustment system includes a plate movement device that adjusts a disposed state of the adjustment plate relative to the vehicle, a detector that detects an attitude of the vehicle stopped at a defined position, and a controller that controls, based on the detected attitude of the vehicle, the plate movement device to adjust the disposed state of the adjustment plate such that the adjustment plate is at the predetermined position relative to the vehicle.

Abstract: A method for checking a calibration of N environmental sensors, wherein the N environmental sensors acquire an environment and each provide sensor data, N subfusions are formed from the acquired sensor data, each of the N subfusions leaves sensor data of one singular one of the N environmental sensors unconsidered upon the fusing, fusion results of the N subfusions are compared to one another, an incorrect calibration of the N environmental sensors is established based on a comparison result, and a check result is provided. Also disclosed are an associated device and a transportation vehicle.

Abstract: A polyhedral sensor target includes multiple surfaces. A housing, such as a vehicle, may include a camera and a distance measurement sensor, such as a light detection and ranging (LIDAR) sensor. The housing may move between different positions during calibration, for instance by being rotated atop a turntable. The camera and distance measurement sensor may both capture data during calibration, from which visual and distance measurement representations of the polyhedral sensor target are identified. The camera and distance measurement sensor are calibrated based on their respective representations, for example by mapping vertices within the representations to the same location.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for determining that prediction outputs generated by a prediction system are sensitive to variations in the values of one or more of a set of target sensor calibration parameters. In one aspect, a sensitivity analysis system is configured to perform operations comprising updating the values of one or more target sensor calibration parameters of each sensor data tuple of a plurality sensor data tuples, comprising, for each sensor data tuple: providing the sensor data tuple with the current values of the target sensor calibration parameters to the prediction subsystem to generate a current prediction output; determining a gradient of a function of the current prediction output with respect to the target sensor calibration parameters; and updating the current values of the target sensor calibration parameters of the sensor data tuple using the gradient.

Abstract: A method is provided for filtering ultrasound image clutter. In the first stage of the method a data matrix is captured, wherein the data matrix contains information relating to the image, and singular value decomposition (SVD) is performed on the data matrix or a matrix derived from the data matrix. A spatial singular vector is then obtained from the SVD of the data matrix and a mean spatial frequency is estimated from them. A filtered data matrix is constructed based on the estimated mean spatial frequency and the SVD of the data matrix and a filtered image is constructed based on the filtered data matrix.

Abstract: A sheet storage device includes a reel around which a tape is wound, a drum onto which a sheet is wound together with the tape, an input and output opening through which the sheet is passed, and a frame that forms at least a portion of a transport path on which the sheet is transported from the input and output opening to the drum, the frame has a first and a second frame part, the first and second frame parts move relative to each other to switch between a state in which the transport path is formed and a state in which at least a portion of the transport path is open, the first frame part supports the reel, and forms a tape path extending from the reel to the drum, the first frame part moves together with the reel and the tape path relative to the second frame part.

Abstract: Provided is a robot, including: a chassis; a set of wheels coupled to the chassis; at least one motor; at least one motor controller; a range finding system; a plurality of sensors; a processor; and a medium storing instructions that when executed by the processor effectuates operations including: measuring, with the range finding system, distances to surfaces opposite the range finding system as the robot moves relative to the surfaces; monitoring, with the processor, the distance measurements taken by the range finding system; discarding, with the processor, outlier distance measurements that reflect an interruption in otherwise steadily fitting distance measurements taken as the robot moves towards and away from surrounding obstacles; and determining, with the processor, a position of an obstacle by identifying a position of the range finding system immediately before and after encountering the obstacle, signified by the interruption detected in the distance measurements.

Abstract: Disclosed are systems and methods that may be used for determining areas free of objects around a vehicle. The systems and methods include receiving first sensor data from a first sensor having a first field of view and a first range. The systems and methods also include receiving second sensor data from a second sensor having a second field of view and a second range. The systems and methods also include determining, by a processor, a first-sensor occlusion in the first field of view. The systems and methods further include determining, by the processor, an occlusion free-region of the first field of view based on data from the second sensor. Additionally, the systems and methods include operating, by the processor, the vehicle in an autonomous mode based on determining the occlusion free-region.

Abstract: Piezoelectric sensor controllers may facilitate detection and identification of various potential fault states with parameter measurements. In an illustrative embodiment of a piezoelectric-based sensor having response-parameter-based fault diagnosis, the sensor includes a piezoelectric transducer and a controller. The controller drives the piezoelectric transducer to generate bursts of acoustic energy and, based on a response of the piezoelectric transducer to said driving, identifies a corresponding transducer state from a set of potential states including multiple transducer fault states.

Abstract: The present disclosure relates to methods and systems for measuring a component. First measurements for a plurality of features of the component are obtained from a first measurement instrument. Second measurements for at least one of the plurality of features of the component are obtained from a second measurement instrument, the second measurement instrument having a higher measurement resolution than the first measurement instrument. A scaling factor for the at least one of the plurality of features, which relates the first measurements to the second measurements, is determined. Scaled measurements for the plurality of features of the component are generated by applying the scaling factor to the first measurements. The scaled measurements are output as measurements of the component.

Abstract: Piezoelectric sensor controllers may facilitate detection and identification of various potential fault states with novel parameter measurements. In an illustrative embodiment of a piezoelectric-based sensor having a shorted-reverberation based resonant frequency measurement, the sensor includes a piezoelectric transducer that provides residual reverberation after being driven. The sensor further includes a controller that provides a low impedance path for the piezoelectric transducer during the residual reverberation and that measures current through the low impedance path to determine a resonant frequency of the piezoelectric transducer.

Abstract: Systems, methods, and computer readable medium are provided for determining a wall loss measurement associated with corrosion and/or erosion present within an insulated pipe. A calibration image is acquired for the pipe wall at a first location and used in conjunction with an inspection image acquired for the pipe wall at a second location to determine an inspection thickness of the pope wall. An amount of wall loss measurement can be determined based on a difference of a calibration thickness for the pipe wall at the first location and the inspection thickness of the pipe wall at the second location. The wall loss measurement characterizing an amount of wall material lost due to corrosion and/or erosion present in the pipe wall at the second location. The wall loss measurement can be output for further processing and/or display.

Abstract: A vehicle control device that is capable of performing abnormality determination of a sensor by majority decision without increasing the number of sensors. A vehicle control device includes a camera and a radar configured to detect a predetermined detection target; and a communication device configured to communicate with outside. The vehicle control device determines whether there is an abnormality in the camera and the radar on the basis of: first acquisition means configured to acquire information on the predetermined detection target from each of the camera and the radar; second acquisition means configured to acquire information, on the predetermined detection target, detected by a road-to-vehicle communication device external to an own vehicle and received by the communication device; information from the camera and the radar acquired by the first acquisition means; and information from the road-to-vehicle communication device external to the own vehicle acquired by the second acquisition means.

Abstract: The current disclosure describes techniques for managing vertical alignment or overlay in semiconductor manufacturing using machine learning. Alignments of interconnection features in a fan-out WLP process are evaluated and managed through the disclosed techniques. Big data and neural networks system are used to correlate the overlay error source factors with overlay metrology categories. The overlay error source factors include tool related overlay source factors, wafer or die related overlay source factors and processing context related overlay error source factors.

Abstract: When a combination of a plurality of sensors is used for obstacle detection, the present invention is to detect the relative positions of the sensors, to correct inter-sensor parameters, and to provide accurate obstacle detection. This calibration system is provided with a first landmark detecting unit for detecting the position of a first landmark from three-dimensional shape information; a landmark associating unit for determining a correspondence relation, between the first landmark position detected by the first landmark detecting unit and an attachment position to the vehicle of the first landmark estimated by a vehicle landmark relative position estimating unit; and a vehicle sensor relative orientation estimating unit for estimating the relative position and orientation of the vehicle and a first measurement section based on the information from the vehicle landmark relative position estimating unit and a landmark associating unit.

Abstract: A mobile computing device used for measuring the height of an object, such as a human user, may be positioned on a reference surface, such as the ground plane. The reference surface is detected and a position guide is generated in an augmented reality (AR) plane on a display of the mobile computing device. The AR plane enables the object being measured to be positioned at a measurement position located at a predefined distance along the reference surface from the mobile computing device. The top and bottom of the object are detected in an image taken by the mobile computing device. The height of the object is measured based on the predefined distance and a distance between the top and bottom of the object in the image. The height of the object can also be measured with assistance from software development kits (SDKs) included in the mobile computing device.

Abstract: Provided are an object detection device, POS terminal device, object detection method, and program capable of carrying out appropriate processing according to whether an object is covered by a translucent container. A distance measurement unit measures the distances to each position on an opposing object. An irradiation unit irradiates light onto the object. A reflected light intensity measurement unit measures the intensities of the reflected light that has been irradiated by the irradiation unit and reflected from each position on the object. An object determination unit determines whether the object is covered by a translucent container based on the distances measured by the distance measurement unit and the reflected light intensities measured by the reflected light intensity measurement unit.

Abstract: The object is to enable easy acquisition of an element that is not design data. The technique is characterized in that when generating construction field management information used to manage a construction field, a construction field management device acquires measurement data that is three-dimensional shape data measured by a measurement device, and compares design data created by a designer with the acquired measurement data, thus extracting non-design data that is not the design data, from the measurement data. Also, as the non-design data, data of a scaffolding/tool and a component of the design data in a temporarily placed state are extracted, and the status of these is analyzed and displayed on a display unit.

Abstract: Systems, devices, apparatuses, components, methods, and techniques for cadence determination and media content selection are provided. An example media-playback device comprises a media-output device that plays media content items, a cadence-acquiring device, and a cadence-based media content selection engine. The cadence-acquiring device includes an accelerometer and a cadence-determination engine configured to determine a cadence based on acceleration data captured by the accelerometer. The cadence-based media content selection engine is configured to identify a media content item based on the cadence determined by the cadence-determining engine and cause the media-output device to playback the identified media content item.

Abstract: A method for measuring the thickness on measurement objects, whereby at least one sensor measures against the object from the top and at least one other sensor measures against the object from the bottom and, at a known distance of the sensors to one another, the thickness of the object is calculated according to the formula D=Gap?(S1+S2), whereby D=the thickness of the measurement object, Gap=the distance between the sensors, S1=the distance of the top sensor to the upper side of the measurement object, and S2=the distance of the bottom sensor to the underside of the measurement object, is characterized by the compensation of a measurement error caused by tilting of the measurement object and/or by displacement of the sensors and/or by tilting of the sensors, whereby the displacement and/or the tilting is determined by calibration and the calculated thickness or the calculated thickness profile is corrected accordingly. The invention further concerns a device for applying the method.

Abstract: Aspects of the present invention relate to systems and methods for calibrating an autonomous navigation system. According to a first aspect of the present invention, calibration of the autonomous navigation system may be controlled by a calibration map.

Abstract: The present invention provides methods and systems related to determine a state of the UAV by updating a determined state of UAV with a relative proportional relationship. The UAV may be provided with a monocular camera, a proximity sensor and a processor. The processor may determine external state information of the UAV based on image data captured by the monocular camera, and calculate a relative proportional relationship to be applied to the determined external state information. The updated external state information of the UAV may be more precise or even equal to the actual state information of the UAV, thus enabling more accurate control and navigation for the autonomous flight.

Abstract: A mobile device comprises a communicator configured to communicate with another communication device; an acceleration sensor configured to detect an acceleration value; a direction sensor configured to detect a change of a direction of the mobile device; and at least one controller configured to determine number of steps of a user of the mobile device based on the acceleration value, and a direction of walking of the user based on the change of the direction of the mobile device to perform notification to the other communication device through the communicator when cumulative number of steps of the walking of the user in one of directions exceeds a first value.

Abstract: A calibration method includes forming an external optical path, forming an internal optical path, and conducting a phase comparison between the second part of signals of the internal and external optical paths sequentially received by a second receiving device and the first part of signals of the internal and external optical paths sequentially received by a first receiving device. Two-way phase signals are outputted with part of a base reference being eliminated. Phase comparison is conducted again between the two-way signals with part of the base reference being eliminated, and the final phase signal is outputted with the base reference being eliminated. The distance-measuring device includes a transmitting device, first reflective surface, first and second receiving devices, first and second filters, and a phase detector.

Abstract: A method of calibrating a measuring apparatus includes determining apparatus parameters that have an influence on a measurement spectrum generated by the measuring apparatus, generating the measurement spectrum by exposing a measurement target on a sample to light generated by the measuring apparatus, calculating an error of the apparatus parameters by comparing the measurement spectrum to an ideal spectrum corresponding to the apparatus parameters, and calibrating the measuring apparatus based on the calculated error of the apparatus parameters.

Abstract: A parking steering assistance system is provided that calculates and provides a parking guide line applied with a tire dynamic radius value. The system includes an obstacle recognition unit configured to recognize an obstacle adjacent to a vehicle after parking is completed. A distance calculating unit is configured to calculate distance information between the obstacle and the vehicle, and a parking controller is configured to control a tire dynamic radius correction which is applied when calculating a parking guide line by using the distance information between the obstacle and the vehicle.

Abstract: Systems, methods, and devices for an intrusion detection system are described herein. For example, one or more embodiments include transmitting a DSSS signal, receiving a reflected DSSS signal from a target, correlating the reflected DSSS signal and the transmitted DSSS signal, and determining a distance to the target based on the correlation between the reflected DSSS signal and the transmitted DSSS signal.

Abstract: An image processing apparatus includes an edge extracting section which extracts an edge in a range image and a removing section which removes a distance value of a pixel of an edge part extracted by the edge extracting section in the range image.

Abstract: A wearable device assembly has a housing supporting a controller, display and indicator system thereon. The controller has at least one sensor wherein activity of a user wearing the device is detected. The controller selectively illuminates the indicator system to indicate a level of activity of the user.

Abstract: A method, in a mobile device, of controlling region determination by the mobile device, includes: determining a present pressure at the mobile device; determining, based on the present pressure and a reference pressure, that the mobile device moved from a first region to a second region within a structure, the first region and the second region being different regions of the structure and vertically displaced from each other; and performing region determination in response to determining that the mobile device moved from the first region to the second region.

Abstract: A method comprises capturing image frames of an input area using a plurality of imaging devices, each having a field of view encompassing at least a portion of the input area; processing captured image frames to identify a plurality of targets therein; analyzing the identified plurality of targets to determine if the targets represent a plurality of projections of an input object; and if so, identifying a pattern of the projections thereby to identify the input object.

Abstract: In a method for calibrating a star probe of an image measuring machine, the star probe includes one or more probe heads. Probe configuration information for the star probe is configured when there is no probe configuration file of the star probe stored in a storage device of the image measuring machine, and one of the probe heads to be calibrated is selected from the star probe. The method calibrates a radius value of the selected probe head, and calibrates the deviation between the center point of the selected probe head and the focus of the camera lens. The method further generates a star probe model of the star probe according to the probe configuration information and the probe calibration information, and displays the star probe model of the star probe on a display device of the image measuring machine.

Abstract: A wearable device has a carrier having an aperture. A device has a USB connection and a protrusion wherein the protrusion is received in the aperture to connect the device to a wristband. The device is a USB type device having athletic functionality. The device may further be configured to receive calibration data such that a measured distance may be converted to a known distance based on athletic activity performed by a user.

Abstract: A method for measuring the height of a person is provided. A person is positioned in a room having a floor and a ceiling, and the method comprises the steps of: i) providing a measuring device; ii) calibrating the measuring device to determine a first distance from the floor to the ceiling; iii) placing the measuring device on the person's head; iv) measuring a second distance from the person's head to the ceiling; and v) subtracting the second distance from the first distance to calculate the person's height. An apparatus for performing the measurement is also included.

Abstract: A shape calculation apparatus obtains measurement data of a first shape of a first partial region on a surface to be measured, and obtains measurement data of a second shape of a second partial region partially overlapping the first partial region on the surface to be measured. The apparatus determines a first shape correction parameter and a second correction parameter so that the value of an evaluation function for evaluating shape data obtained by correcting the measurement data of the first and second shapes by the first shape correction parameter and the second correction parameter falls within a tolerance range. The apparatus generates shape data of an entire region including the first and second partial regions by respectively correcting the measurement data of the first and second shapes using the first shape correction parameter and the second correction parameter, and combining the corrected shape data.

Abstract: The invention is applicable to the field of phase type photoelectric distance measurement and provides a calibration method based on phase measurement of a double-wavelength laser tube and a distance measurement device of the double-wavelength laser tube. The method comprises the following steps of: 1, forming an external optical path; 2, forming an internal optical path; and 3, sequentially switching a first light-wave and a second light-wave of light-wave transmitting devices (1 and 2) during operation of the steps 1 and 2 to compare phases of the sequentially-received light-waves of the internal and external optical paths through a receiving device (7), and outputting a phase signal for eliminating a base reference.

Abstract: Methods are described for measuring series of nominally identical production workpieces on a dimensional measuring apparatus such as a coordinate measuring machine. One master workpiece of the series is calibrated, to provide correction values which are used to build an error map of the measuring apparatus. This map is used to correct measurements not only of subsequent nominally identical workpieces of the same series, but also of multiple different subsequent series of different workpieces. Each subsequent series also has a master workpiece which is calibrated and used to further build the error map. As this process is repeated over time, the error map becomes more and more densely populated. In due course, it becomes possible to dispense with the use of a calibrated master workpiece, because measurements can be corrected using error values which already exist in the error map.

Abstract: A method of generating a library of reference spectra includes storing an optical model for a layer stack having at a plurality of layers, receiving user input identifying a set of one or more refractive index functions and a set of one or more extinction coefficient functions a first layer from the plurality of layers, wherein the set of one or more refractive index functions includes a plurality of different refractive index functions or the set of one or more extinction coefficient functions includes a plurality of different extinction coefficient functions, and for each combination of a refractive index function from the set of refractive index functions and an extinction coefficient function from the set of extinction coefficient functions, calculating a reference spectrum using the optical model based on the refractive index function, the extinction coefficient function and a first thickness of the first layer.

Abstract: An apparatus for evaluating layers, including interlayer gaps, in a multi-layer structure; the multi-layer structure presenting a plurality of edges generally aligned athwart an axis; the apparatus includes: (a) a sensing unit configured for sensing at least one parameter; (b) a positioning unit coupled with the sensing unit; the positioning unit being configured to effect moving the sensing unit generally along the axis; and (c) a control unit coupled with at least one of the positioning unit and the sensing unit. The control unit provides an electrical signal to the sensing unit. The control unit monitors changes in the at least one parameter as the sensing unit moves past the plurality of edges. The control unit employs the changes in the at least one parameter to effect the evaluating.

Abstract: The method includes: calculating an increment of a sliding distance of a dresser by multiplying a relative speed between the dresser and a polishing member by a contact time between them; correcting the increment of the sliding distance by multiplying the calculated increment of the sliding distance by at least one correction coefficient; calculating the sliding distance by repeatedly adding the corrected increment of the sliding distance to the sliding distance according to elapse of time; and producing the sliding-distance distribution of the dresser from the obtained sliding distance and a position of a sliding-distance calculation point. The at least one correction coefficient includes an unevenness correction coefficient provided for the sliding-distance calculation point.

Abstract: A measuring apparatus for optically measuring a distance to a target object is described. The measuring apparatus has a transmitting device for emitting periodically modulated optical measuring radiation towards the target object, a receiving device for detecting optical measuring radiation which returns from the target object, and an evaluation device for receiving and evaluating detection signals from the receiving device. The measuring apparatus also has a calibration device for calibrating the measuring apparatus, wherein the calibration device is designed to calibrate the measuring apparatus on the basis of detection of uncorrelated radiation which does not correlate with the modulated measuring radiation emitted by the transmitting device. In this case, the uncorrelated radiation may be in the form of background radiation. Alternatively, uncorrelated measuring radiation can be emitted by the transmitting device and can be detected by the receiving device.

Abstract: Determining dipper geometry. A method of determining dipper geometry includes obtaining a first set of data associated with an industrial machine for a first orientation of the industrial machine, and obtaining a second set of data associated with the industrial machine for a second orientation of the industrial machine. The first set of data includes at least one of a first length associated with a hoist rope and a first angle associated with the hoist rope, and the second set of data includes at least one of a second length associated with the hoist rope and a second angle associated with the hoist rope. The value of the physical characteristic of the dipper is then determined based on the first set of data and the second set of data.

Abstract: Disclosed is a sensor that can accurately detect displacement and prevents the phenomenon of a contact section between a shaft member and a sliding element receiver being shifted. The sensor comprising: a case having a through hole; a resistance substrate fixed at an inside of said case; a shaft member having a first end portion which is one end of the shaft member placed within said case and a second end portion which is other end of the shaft member exposed to an outside of said case from said through hole, said shaft member being placed at said through hole in a movable manner in an axial direction; and a sliding element receiver having a bearing end contacting with said second end portion of said shaft member, and attached with a brush sliding together with said resistance substrate, said sliding element receiver being capable of moving relatively against said resistance substrate with said shaft member. A hemispherical end face is formed at said first end portion.

Abstract: The present invention provides a method of calculating a surface shape of a target surface, including the steps of defining, as a measurement target region, each of a plurality of regions on the target surface in which adjacent regions overlap each other, and obtaining data that give the heights at the plurality of positions in each of the plurality of regions, and removing, for each of the plurality of regions, an average data from the data that are obtained in the step of obtaining the data and give the heights at the plurality of positions in each of the plurality of regions, thereby generating correction data for each of the plurality of regions.

Abstract: Step detection and step length estimation techniques include detecting salient points in sensor data of one or more sensors. A step frequency is estimated based on a time interval between the detected salient points. A step length of the step may then be computed based on a nonlinear combination of the estimated step frequency and a function of the sensor data, and/or a step model. Alternatively, the step length of the step may be computed based on a combination of a nonlinear function of the estimated step frequency and a (linear or nonlinear) function of the sensor data, and/or a step model.