Deformation and configuration sensing using a magnetoinductive of electroinductive waveguide

Abstract

A computer implemented method includes receiving data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements, and determining, based on the received data, information indicative of a configuration of the waveguide.

Description

DEFORMATION AND CONFIGURATION SENSING USING A MAGNETOINDUCTIVE OF ELECTROINDUCTIVE WAVEGUIDEBACKGROUND

[0001] There are many applications in which sensing a configuration of an object is desirable or necessary. For example, configuration sensing may be used in robotics, human-machine interfaces, strain sensing, etc.

[0002] In controlling a limb of a robot, for example, determining the actual configuration of the limb can provide improved control. In some cases, the degree of actuation of each of the limb's actuators may be used to infer the configuration of the limb.

[0003] A configuration of an object may be sensed using a combination of magnets and hall sensors. Magnets and corresponding Hall sensors may be attached to various parts of the object, and the Hall sensors may be used to determine the relative positions of the magnets and Hall sensors.BRIEF SUMMARY

[0004] In an aspect, a computer implemented method comprises: receiving data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements; and determining, based on the received data, information indicative of a configuration of the waveguide.

[0005] According to an embodiment, at least one of: the determining includes obtaining, from the received data, time-domain data indicative of reflected magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the time-domain data; and the determining includes obtaining, from the received data, frequency-domain data indicative of a input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the frequency-domain data.

[0006] In an embodiment, determining the deformation based on the frequency-domain data includes determining frequencies corresponding with peaks or troughs in the input scattering parameter spectrum.

[0007] Determining the deformation may include determining one or more frequency shifts, relative to a input scattering parameter spectrum of a reference configuration, of the peaks or troughs in the input scattering parameter spectrum.

[0008] In an embodiment, the method further comprises at least one of: detecting an object proximate to the waveguide, based on the received data; detecting damage to the waveguide, based on the received data; filtering the received data, prior to determining the information indicative of the deformation, to remove features of the data associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide; omitting, from data used in the determining, a frequency range associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide; and selecting, for use in the determining, data indicative ofpropagation of magnetoinductive or electroinductive waves in the waveguide that corresponds to a time window during which at least one of data or power transfer with components external to the waveguide is suspended.

[0009] In an embodiment, first and second resonator elements of the plurality of resonator elements are respectively associated with first and second portions of a robot, wherein the first and second portions are movable with respect to each other such that relative movement of the first and second portions causes deformation of the waveguide.

[0010] In an embodiment, first and second portions are included in a part of the robot that is: a soft robotics component of the robot, an articulated soft robotics component of the robot, a continuum soft robotics component of the robot, a rigid robotics component of the robot, a robotic limb driven by hydraulic or pneumatic actuators, or a compliant mechanism.

[0011] An aspect provides computer readable instructions that, when performed by a processing device, cause the processing device to carry out a computer implemented method as described herein.

[0012] As aspect provides a computer readable storage medium storing instructions that, when performed by a processing device, cause the processing device to carry out a computer implemented method described herein.

[0013] An aspect provides a processing device arranged to determine a configuration of a deformable object, the device comprising: memory circuitry to store instructions; and

[0014] processing circuitry to perform the instructions, wherein the instructions are to cause the processing circuitry to: receive data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements, the plurality of resonator elements including at least first and second resonator elements, the first and second resonator elements are arranged to change their relative pose when the configuration of the deformable object is changed, wherein the relative pose describes at least one of (i) relative positions of the first and second resonator elements, and (ii) relative orientations of the first and second resonator elements; and determine, based on the received data, information indicative of the configuration of the deformable object.

[0015] An aspect provides a robotic component comprising: a first portion; a second portion, the second portion moveable relative to the first portion; and a pose sensor, the pose sensor comprising: a magnetoinductive or electroinductive waveguide comprising a plurality of magnetoinductively or electroinductively coupled resonant elements, the resonant elements including a first resonant element and a second resonant element, the first resonant element arranged to move with the first portion and the second resonant element arranged to move with the second portion.

[0016] In an embodiment, the robotic component further comprises an input component and a receiver component, the input component to supply at least one of power and data to the waveguide, and the receiver component to receive the at least one of power and data via the waveguide.

[0017] In an embodiment, the robotic component is selected from: a complaint mechanism, a soft robotic limb, a articulated soft robotic limb, a continuum soft robotic limb, a rigid robotic limb, or a robotic limb driven by hydraulic or pneumatic actuators.

[0018] In an embodiment, the robotic component further comprises processing circuitry arranged to receive data describing propagation of magnetoinductive or electroinductive waves in the waveguide and to determine a pose of the robotic component based on the received data.

[0019] In an aspect, a method of producing a configuration sensor for a robot, the method comprises: providing, a first resonant element that is arranged to move with a first portion of the robot, the first resonant element being a resonant element of a magnetoinductive or electroinductive waveguide of resonant elements; and providing a second resonant element that is arranged to move with a second portion of the robot, the second resonant element being a resonant element of the waveguide of resonant elements, wherein magnetoinductive or electroinductive coupling between the first and second resonant elements is dependent on a relative pose of the first and second elements.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0020] Examples of the invention are further described hereinafter with reference to the accompanying drawings.

[0021] FIG. 1 A illustrates an example of a magnetoinductive waveguide.

[0022] FIG. 1 B illustrates an example of an electroinductive resonator.

[0023] FIG. 1 C illustrates an example of an electroinductive waveguide.

[0024] FIG. 2A illustrates an example of a deformable object that includes a waveguide.

[0025] FIG. 2B illustrates another view of the deformable object of FIG. 2A.

[0026] FIG. 2C illustrates another view of the deformable object of FIG. 2A and FIG. 2B.

[0027] FIG. 2D illustrates a waveguide having electroinductive resonators.

[0028] FIG. 3 illustrates a method according to some examples.

[0029] FIG. 4 illustrates an example plot of frequency domain data that may be obtained from the waveguide of FIG. 2A to FIG. 2C.

[0030] FIG. 5 illustrates a plot illustrating the effect of bending the waveguide on the input scattering parameter spectrum.

[0031] FIG. 6A illustrates a simulation of frequency dependence of impedance with bend angle in the arrangement of FIG. 2A to FIG. 2C.

[0032] FIG. 6B illustrates another arrangement for the waveguide.

[0033] FIG. 6C illustrates another arrangement for the waveguide.

[0034] FIG. 6D illustrates another view of the waveguide of FIG. 6B or FIG. 6C.

[0035] FIG. 6E illustrates a simulation of frequency dependence of impedance with bend angle the waveguide of FIG. 6B, FIG. 6C, or FIG. 6D.

[0036] FIG. 7A illustrates an alternative resonator.

[0037] FIG. 7B illustrates an alternative resonator.

[0038] FIG. 8 illustrates another example of a waveguide.

[0039] FIG. 9A illustrates another example of a waveguide.

[0040] FIG. 9B illustrates another example of a waveguide.

[0041] FIG. 9C illustrates another example of a waveguide.

[0042] FIG. 10A illustrates an example of a waveguide with a nearby object.

[0043] FIG. 10B shows the resonant frequencies of the waveguide of FIG. 10A.

[0044] FIG. 1 1 illustrates a device according to some examples.

[0045] FIG. 12 illustrates a method according to some examples.

[0046] FIG. 13A illustrates an input scattering parameter spectrum, in this case input admittance, for a chain resonators with perturbations at different positions along the chain.

[0047] FIG. 13B illustrates the perturbations of the chain of resonators of FIG. 13A.

[0048] FIG. 14 shows contours of mutual inductance between two resonators placed parallel to one another but with their relative positions varied.

[0049] FIG. 15A illustrates a waveguide having a two-dimensional arrangement of resonators.

[0050] FIG. 15B shows an example of an admittance spectrum of the waveguide shown in FIG. 15B.

[0051] FIG. 16 illustrates an example of a scale-like or shingle-like arrangement of resonators.

[0052] FIG. 17 illustrates overlap of a first resonator and a second resonator.

[0053] FIG. 18 illustrates an example of a scale-like arrangement of resonators attached to an elastic substrate.

[0054] FIG. 19A illustrates an example of a waveguide having resonators on an inelastic substrate.

[0055] FIG. 19B illustrates an example of a waveguide having resonators on an elastic substrate.DETAILED DESCRIPTION

[0056] Deriving a configuration of an object from degrees of actuation of actuators can be unreliable. For example, if movement of the object is obstructed the actual movement may be less than would be inferred from the actuator. Further, in the case of a compliant mechanism, such as a soft robot, deriving the configuration of the mechanism from the actuators can be challenging, and may be particularly inaccurate when movement of the mechanism is obstructed.

[0057] Using magnets to detect the configuration of an object can lead to difficulties when magnetic or ferrous materials are present in the environment of the object. For example, a magnetic sensing arrangement may be inappropriate for a robot intended for use in ferrous pipes, since the magnet may be attracted to the walls of a pipe that the robot is traversing.

[0058] Furthermore, some methods of configuration sensing may involve multiple sensors, each providing a respective signal output. Each signal output must be transported to a suitable receiver (such as a processor programmed to determine the configuration). Accordingly, multiple wires or wireless communication circuits may be needed, which can increase cost and complexity, and may reduce reliability.

[0059] Examples described herein may address one or more of these limitations.

[0060] A magnetoinductive waveguide consists of an array of magnetically coupled resonators that is capable of supporting a propagating electromagnetic wave whose principle components are currents circulating in each resonator and their shared magnetic flux. Such waves have become known as magnetoinductive waves. No physical contact is needed between the resonators in order to support the magnetoinductive wave. A magnetoinductive waveguide is an arrangement in which a magnetoinductive wave can propagate (e .g. Shamonina, E., et al. "Magnetoinductive waveguide. " Electronics letters 38.8 (2002): 371 -373). A magnetoinductive waveguide includes an array of resonant elements, which may also be referred to as resonators, resonator elements, or meta-atoms. Each resonator may include a resistance, an inductance, and a capacitance in order to form a resonant circuit. FIG. 1 A shows an example of a magnetoinductive waveguide 100 that includes resonators 102, shown as 102a, 102b, 102c, 102d, 102e in FIG. 1A. In the example of FIG. 1A, each resonator 102 is formed of a conductive trace in the shape of a broken loop. The capacitive gap 104, which forms the break in the loop provides capacitance, the shape of the loop provides inductance, and the material of the trace provides resistance. The structure of the resonators 102 is not particularly limited. For example, the shape may be square, as shown in FIG. 1A, circular, etc. Further, the resonator 102 may include a spiral, or may be non-planar, e.g., by having elements on top and bottom surfaces of a substrate, or by having elements on different layers of a stacked substrate, with different surfaces or layers being connected with vias, for example. The resonators 102 may include resistive, capacitive or inductive components. The resonators 102 may be provided independently of a substrate. For example, the resonators 102 may be self-supporting, instead of being provided on a substrate.

[0061] Magnetoinductive waveguides can be used to carry data, power or both. However, the coupling between resonators is affected by the relative orientation of the resonators. As such, deformation of the array (e.g., due to bending of a substrate) can reduce the effectiveness of the waveguide. For example, in some examples a bandwidth of the waveguide may be reduced when the resonators of the array are not maintained in the same plane. For this reason, magnetoinductive waveguides may be designed to avoid or prevent such deformation of the substrate, or to mitigate the effect of bending, e.g., by using small, closely placed resonators that are less sensitive to deformation-induced bandwidth reduction.

[0062] In examples described herein, the normally undesirable effects associated with deformation of a magnetoinductive waveguide may be used to measure, or characterize, the deformation. In examples, a signal indicative of the deformation along the extent of the waveguide may be carried by the waveguide itself, and so information relating to the deformation at various points along the waveguide can be carried to an output of the waveguide withoutadditional signal wiring. Similarly, power may be provided to the waveguide at a single input (e.g., at, or close to, one end of the waveguide), so wiring may be reduced compared with an arrangement having multiple powered sensors. Further, the waveguide may provide information regarding deformations along its length without the need for additional sensors (e.g., individual sensors for each joint of a robotic limb).

[0063] Electroinductive waveguides are described in M. Beruete, F. Falcone, M. J. Freire, R. Marques, J. D. Baena; Electroinductive waves in chains of complementary metamaterial elements. Appl. Phys. Lett. 20 February 2006; 88 (8): 083503. https: / / doi.org / 10.1063Z1 .2176850. Electroinductive waveguides have many similarities to magnetoinductive waveguides. In contrast to the magnetic coupling found in magnetoinductive waveguides, electroinductive waveguides are characterised by electric coupling between resonators that form the waveguide.

[0064] FIG. 1 B shows an example of an electroinductive resonator 102 that includes a conductive portion 106 and a non-conductive portion 108. The conductive portion 106 may be a conductive plate or film, such as metallic plate or film. The non-conductive portion 108 may be a hole, void, or slot in the conductive portion 106.

[0065] FIG. 1 C shows an example of an electroinductive waveguide 100 that includes resonators 102a, 102b, 102c, 102d, 102e.

[0066] The examples and embodiments described herein that include magnetoinductive waveguides could instead use electroinductive waveguides.

[0067] FIG. 2A to FIG. 2C show an example of a deformable object 200 that includes a waveguide 100 mounted on a support structure 204, according to an example. The waveguide 100 is formed of a series of elements 202 connected by connectors 210. The waveguide element 202 includes a resonator 102 mounted on substrate 206. The waveguide element 202 is mounted on a support structure 204 that is moveably linked to another structure, e.g., to another support structure 204, via at least one connector 210. In the example of FIG. 2A the resonator 102 is a metallic trace formed on a substrate 206. The waveguide element 202 is attached to the support structure 204, such that the substrate 206 moves with the support structure 204 (e.g., by being rigidly attached to the support structure 204).

[0068] FIG. 2B shows a series of waveguide elements 202 forming a waveguide 100, viewed from above (with respect to the waveguide element 202 of FIG. 2A). Arrow 208 shows, in FIG. 2B, the direction corresponding with the view of FIG. 2A. The waveguide elements 202 may move relative to each other by rotating about respective connectors 210, as shown in FIG. 2C.

[0069] The structure of the waveguide elements 202 is not particularly limited. For example support structures 204 and connectors 210 may be replaced with any structure. Where the waveguide 100 is to measure deformation of a deformable object 200, the resonators 102 may be associated with the deformable object 200 such that each resonator 102 moves with a respective portion of the deformable object 200. In some examples, a spacing between neighbouring resonators 102 is such that a magnetoinductive wave can be propagated along the waveguide 100 throughout the expected range of deformation of the deformable object 200.

[0070] FIG. 2A to FIG. 2C illustrate a loop of each resonator 102 oriented perpendicular to the extent of the waveguide 100. In contrast, the resonators 102 of FIG. 1 A lie in the plane of the waveguide 100. Coupling between resonators 102 tends to be greater in the perpendicular arrangement of FIG. 2A to FIG. 2C, which generally leads to greater sensitivity to deformations. However, the parallel arrangement of FIG. 1 A may be appropriate for some examples of a waveguide for deformation detection. For example, an arrangement of FIG. 1 A may be easier or less expensive to produce, or may have a form factor that is more appropriate for some applications.

[0071] In some examples, the waveguide 100 may include three or more resonators 102.

[0072] Signals may be input to the waveguide 100 by a conductive connection to one of the resonators 102, or by an input resonator that is magnetoinductively coupled with one or more resonators 102 of the waveguide 100. Similarly, signals may be read from (or output by) the waveguide 100 via a conductive connection to one of the resonators 102, or by an output resonator that is magnetoinductively coupled with one or more of the resonators 102. Input and output may be performed by the same components. For example, a conductive input / output connection may be provided. Similarly, an input / output resonator may be magnetoinductively coupled with one or more of the resonators 102.

[0073] In some examples, a single input may be provided. In some examples a single output may be provided. In some examples, a single communication connection may provide both input and output.

[0074] An input signal input at an arbitrary location along the waveguide 100 may be propagated throughout the waveguide 100, and similarly, reflected signals, or other signals carried from any location along the waveguide 100 may be output at an arbitrary location along the waveguide 100. Accordingly, there is considerable design freedom in selecting locations along the waveguide 100 for an input, output, or both. Moreover, additional wiring or signal carrying components running along the waveguide 100 may be unnecessary. For example, an input and output may be situated at a proximal end of a deformable object 200, with the waveguide 100 extending between the proximal end and a distal end. Processing circuitry for receiving and processing a signal from the waveguide 100 may be provided at the proximal end of the deformable object 200. In this arrangement, additional wiring is not needed to carry signals to or from the resonator 102 at the distal end of the deformable object 200 (or other locations along the deformable object 200). Further, in this arrangement, all of the resonators 102 may receive an input signal from a single input, and signals carrying information about each resonator 102 may be obtained from a single output.

[0075] In some examples, the standing wave modes of the waveguide 100 may be determined by measuring signals reflected in the waveguide 100. For example, the impedance of the waveguide 100 at different frequencies may be measured. A signal input to the waveguide 100 may sweep through frequencies in a range of frequencies to obtain a spectrum of the impedance with varying frequency. An output signal obtained from waveguide 100 may be measured using a vector network analyser, for example.

[0076] In some examples, first and second resonators 102 of the plurality of resonators 102 are respectively associated with first and second portions of a robot, where the first and second portions are movable with respect to each other, such that relative movement of the first and second portions causes deformation of the magnetoinductive waveguide 100. For example, the first and second portions may be included in a part of a robot that is a soft robotics component of the robot, an articulated soft robotics component of the robot, a continuum soft robotics component of the robot, a rigid robotics component of the robot, a robotic limb driven by hydraulic or pneumatic actuators, or a compliant mechanism.

[0077] FIG. 2D illustrates a waveguide 100 having electroinductive resonators that are oriented perpendicular to the extent of the waveguide 100, similar to the magnetoinductive waveguide 100 of FIG. 2A, FIG. 2B, and FIG. 2C. The support structure 204 is not shown in FIG. 2D, and in some examples, the conductive portion 106 may form the support structure 204.

[0078] The waveguide 100 of FIG. 2D includes a stack of conductive plates with slots cut in them. The coupling between the plates is via electric fields, rather than magnetic fields, but otherwise the propagation effects and the behaviour of the electroinductive waveguide 100 of FIG. 2D is the same as the magnetoinductive waveguide 100 of FIG. 2A, FIG. 2B, and FIG. 2C.

[0079] FIG. 2D provides three views of the electroinductive waveguide 100. In (b) the waveguide 100 is straight (not bent). In (a) the waveguide 100 is bent in one direction, and in (c) it is bent in the opposite direction. The bent structures in (a) and (c) will experience different coupling from the straight structure. As the slots are offset from the axis of the bend, a bend in one direction will increase the coupling between the resonators 102, while the bend in the other direction will reduce the coupling between the resonators 102.

[0080] FIG. 3 illustrates a method 300 according to some examples. The method 300 may be implemented by a computer. In operation 302 data is received that is indicative of propagation of magnetoinductive waves in a magnetoinductive waveguide (or electroinductive waves in an electroinductive waveguide). The magnetoinductive waveguide includes a plurality of resonators 102 that are coupled so as to support magnetoinductive waves. In some examples, the waveguide 100 may include two or more resonators 102, and may include three or more resonators 102. The resonators 102 may be magnetoinductively coupled with each other.

[0081] In operation 304 information is determined, based on the received data, the information indicative of a configuration of the magnetoinductive waveguide 100. The configuration may correspond with a shape of the waveguide 100, or a relative orientation and / or position of a plurality of the resonators 102. The configuration may correspond with of a deformation, e.g., a deformation with respect to, or deviation from, a reference configuration.

[0082] In some examples time domain data, frequency domain data or both may be obtained from the received data. The time domain data, frequency domain data or both may be used in determining 304 the information indicative of a configuration of the magnetoinductive waveguide 100.

[0083] FIG. 4 shows an example plot 400 of frequency domain data that may be obtained from the waveguide 100 of FIG. 2A to FIG. 2C. FIG. 4 shows, on the vertical axis, the negative ofimpedance at an input to the magnetoinductive waveguide 100, with frequency on the horizontal axis. The impedance drops at five frequencies, corresponding with standing wave modes of the waveguide 100, and these frequencies correspond with the peaks 402a-402e in FIG. 4 (as the negative of the impedance is plotted). The frequencies of these peaks change in dependence on the relative positions and orientations of the resonators 102. Herein the term “pose” may be used to describe the position and orientation of an element.

[0084] FIG. 5 is a plot 500 illustrating the effect of bending the waveguide 100 on the input scattering parameter spectrum. FIG. 5 is a waterfall plot, with a series of plots arranged vertically. The impedance of each plot is shown on the vertical axis and the frequency is shown on the horizontal axis. The peaks of FIG. 4 appear as valleys in FIG. 5, as the impedance, rather than the negative impedance, is plotted. Each of the plots arranged along the vertical axis corresponds with a different time instance during a process of bending the waveguide 100 of FIG. 3 upwards (reducing the distance between the resonators 102) and then downwards (increasing the distance between the resonators 102). As such, the vertical position of the plot is indicative of the bend angle of the waveguide 100. As can be seen, the peaks 402a-402e move closer together as the distances between the resonators 102 are decreased, and move apart as the distances between the resonators 102 are increased.

[0085] As the waveguide 100 is bent the relative poses between the resonators 102 changes, leading to changes in the coupling between the resonators 102. The change in coupling leads to changes in the frequencies of the standing wave modes (i.e ., the resonant frequencies, or resonances).

[0086] The frequency shifts are not symmetrical with the bend angle of the waveguide 100; the top to bottom symmetry in FIG. 5 is a result of bending the waveguide 100 up and down, such that it returning to its original configuration. The resonators 102 are not arranged symmetrically about the bend axis, and so deviations from the straight arrangement of the waveguide 100 in equal and opposite directions results in different resonant frequencies. As can be seen, the frequency shifts may be associated with a particular bend angle, such that a bend angle may be obtained from the frequency data. Similarly, the resonators 102 in the waveguide 100 illustrated in FIG. 2D are not symmetrical about the bend axis, such that the bends in (a) and (c) would result in different resonant frequencies in the waveguide 100.

[0087] The overall bend of the waveguide 100 is characterised by a bandwidth of the waveguide 100. The bandwidth corresponds with the distance between the outermost peaks 402a and 402e (i.e., the highest and lowest frequency peaks). More generally, the bandwidth may give an indication of the overall, or average, bend. In addition, other frequency shifts of the various peaks may provide more detailed information on the relative poses of the resonators 102. In some examples, peak heights may be used distinguish which element or elements are associated with a particular frequency shift.

[0088] Aggregate properties of the waveguide 100 change with configuration of the waveguide 100. Details of the propagation are varied by individual local changes between each pair of neighbouring resonators 102 (and possibly more distant resonators 102, such as next nearest neighbours, etc.). Where the local changes are uniform (e.g., the same bend angle is presentbetween each pair of neighbouring resonators 102) the resonant frequencies may spread out evenly as the coupling changes are the same for each element. Differing local deformations of the waveguide 100 lead to defects in the waveguide 100 and result in uneven spreading of the resonant frequencies.

[0089] The frequency shifts, or other frequency data, may be analysed by comparing with calibrated data, or according to an empirical scheme, such as a best fit to frequency shifts associated with known configurations. Alternatively, the frequency data may be analysed by comparing or fitting to a model or simulation of the system. In other examples, machine learning could be used to analyse frequency shifts. For example, a neural network may be trained to determine a configuration of the waveguide 100 based on the frequency data. In some examples, a combination of deterministic calculations and neural algorithms may be used. The neural algorithms may be simple, low order neural algorithms, for example. Accordingly, in examples, low power microprocessors may be sufficient to analyse the signals obtained from the waveguide 100 to obtain the configuration of the waveguide 100. According to some examples, uses input admittances may be analised according to the principle of superposition.

[0090] Accordingly, determining 304 the deformation based on frequency-domain data may include determining frequencies corresponding with resonant frequencies, represented by peaks or troughs in the input scattering parameter spectrum.

[0091] If more resonators 102 are included in the waveguide 100, the number of resonant modes, and so the number of peaks, will increase. The frequencies of the outermost peaks are not dependent on the number of resonators 102, and so the bandwidth of the waveguide 100 is not dependent on the number of resonators 102.

[0092] FIG. 6A shows a simulated frequency dependence of impedance with bend angle in the arrangement of FIG. 2B, with resonant frequencies 402a to 402e shown. Here the bend angle is the angle between successive joints. As can be seen, the spacing of the peaks increases as the bend angle increases from 0° in one direction and the spacing of the peaks decreases as the bend angle increases from 0° in the opposite direction (shown as a negative angle).

[0093] FIG. 6B to FIG. 6D show an alternative arrangement for the waveguide 100, where the resonators 102 are positioned symmetrically with respect a bending axis. In FIG. 6A, the resonator 102 is positioned such that its centre lies on a line that is perpendicular to both the bend axis and the bending direction (assuming the waveguide 100 is bent to the left or right in FIG. 6A, with the bend axis perpendicular to the plane of the figure). Accordingly, a change in the relative pose of the resonators 102 due to a bend to the left will be equal and opposite to a bend of the same magnitude to the right. That is, the positions and orientations of the resonators 102 resulting from a bend to the right will be a mirror image of the bend to the left.

[0094] FIG. 6C shows another symmetrical arrangement of resonators 102, with the resonators 102 centred on the bend axis. Accordingly the relative poses of the resonators 102 would be equal and opposite for any equal and opposite pair of bends.

[0095] FIG. 6D shows a view the the arrangements of FIG. 6B and FIG. 6C from above, with the resonators 102 lying along the bend axis in this view.

[0096] FIG. 6E shows a simulated frequency dependence of impedance with bend angle in a symmetrical arrangement, such as in FIG. 6B, FIG. 6C, or FIG. 6D. As can be seen, bends of the same magnitude in opposite directions result in the same frequency shifts in the peaks 402a to 402e.

[0097] The asymmetric arrangement is able to distinguish the direction of the bend. The lowest bandwidth of the symmetrical arrangement, indicated by the smallest horizontal distance between the outermost peaks in FIG. 6E (which is at 0°) is larger than the lowest bandwidth in the asymmetric arrangement, which corresponds with the smallest horizontal distance between the outermost peaks in FIG. 6A (which is at -80°). With other factors being equal, an arrangement with resonators 102 arranged asymmetrically about a bend axis will typically experience grater changes in pose relative to other resonators 102 of the waveguides 100, when compared with resonators 102 arranged symmetrically about the bend axis. Accordingly, resonators 102 arranged asymmetrically about the bend axis may be more sensitive to bending about the bend axis.

[0098] In examples, the resonators 102 are rigid. The deformation of the waveguide 100 is determined on the basis of changes in relative pose (e.g., relative spacing and / or orientation) between the resonators 102 that cause a change in coupling between the resonators 102. The deformation of the waveguide 100 is not determined on the basis of changes in the structure or configuration of the individual resonators 102 themselves. For example, the determination is not based on, or does not rely on, stretching or compressing resonators 102 in order to change the coupling between the resonators 102 to determine the configuration of the waveguide 100.

[0099] Implementations are not limited to a waveguide 100 with a single, or well defined bend axis, and other, more complicated deformations of the waveguide 100 may be detected.

[0100] The shapes of the resonators 102 are not particularly limited. The examples in FIG. 1A and FIG. 2A to FIG. 2C show square resonators 102, but the resonators 102 could be circular, triangular, or any other shape, including irregular shapes and concave shapes. For example, crescent moon-shaped resonators 102 may be suitable for positioning at (e.g., on or in) a wall of a deformable object 200, such as the deformable object 200 shown in cross-section in FIG. 7A. This arrangement may reduce obstruction or interference with other objects that are to be provided within deformable object 200.

[0101] The resonators 102 in FIG. 1 A and FIG. 2A to FIG. 2C are illustrated as each having a single loop, but in some examples, each resonator 102 may include multiple loops, e.g., arranged in a spiral, as shown in FIG. 7B. This may permit a reduction in the area of the resonator 102 while maintaining the same or similar coupling, for example.

[0102] The resonators 102 may be 3D shapes or structures. For example, the resonators 102 may include conductively connected loops or partial loops on different faces of a substrate, or on different layers of a layered substrate (e.g., connected by metal vias through the substrate or substrate layers). This may permit a reduction in the area of the resonator 102 while maintaining the same or similar coupling, for example.

[0103] Time domain data may be obtained by providing an input pulse having multiple frequencies to the waveguide 100. The pulse will propagate along the waveguide 100 and the propagated or reflected signal may be measured. A reflected signal may be measured at the same point as the input, or at a different point. The measured signal will have an envelope, with different frequencies arriving at different times, indicative of dispersion within the waveguide 100. The time domain data may include information relating to a location along the waveguide 100, since the time of flight of the signal is indicative of a point along the waveguide 100 from which it was reflected. For example, a feature of the signal may be determined to be associated with particular resonator 102, based on the time between inputting the signal and receiving the reflected signal at the output, where the time indicates the distance travelled by the signal from the input to the particular resonator 102, and from that resonator 102 to the output.

[0104] In some cases, time domain data may be easier to obtain or analyse than frequency domain data. For example, time domain signalling may be easier to implement in electronics, and may use fewer computational resources to analyse. As with frequency domain data, time domain data may be analysed using various methods, such as calibration, comparison with empirical data, comparison or fitting to a model or simulation of the system, or methods based on machine learning.

[0105] Time domain data and frequency domain data may both be used to interrogate the standing wave modes of the waveguide 100, and may provide complimentary information.

[0106] In some examples, time domain data may be measured directly and a Fourier transform used to obtain frequency domain data. In some examples, frequency domain data may be measured directly and a Fourier transform used to obtain time domain data. In some examples, both frequency and time domain data may be measured directly.

[0107] Where time domain data is measured directly, an input signal to the waveguide 100 may include a pulse having a plurality of frequencies. The time of flight of the respective frequencies of the reflected pulse and / or the envelope of the reflected pulse may be analysed to obtain information on the configuration of the waveguide 100.

[0108] The input and output signals used for determining the configuration of the waveguide 100 may be referred to as configuration sensing signals. The waveguide 100 may act as a data channel, and carry signals in addition to the configuration sensing signals. For example, the waveguide 100 may carry data for communication between components that are communicatively coupled to the waveguide 100. Additionally, or alternatively, the waveguide 100 may carry power to one or more components, for example to power active electronics of those components.

[0109] FIG. 8 shows an example of a waveguide 100 having a plurality of resonators 102. A first resonator 102a is coupled with a first component 802, and a second resonator 102e is coupled with a second component 804. The first resonator 102a and second resonator 102e are shown located at ends of the waveguide 100, but could be any of the resonators 102 of waveguide 100. Similarly, the first component 802 and second component 804 are shown located at the ends of the waveguide 100, but could be located anywhere along the waveguide 100. The first component 802 and second component 804 are examples of components that are external to the waveguide100. In some examples, the first component 802 and second component 804 may be positioned relatively close to the first resonator 102a and second resonator 102b, respectively.

[0110] The first component 802 is shown connected to the first resonator 102a by a first wire connection 806 and the second component 804 is shown connected to the second resonator 102 by a second wire connection 808. In other examples, magnetoinductive coupling could be used in place of one or both of the first wire connection 806 and second wire connection 808.

[0111] The first component 802 may be, for example, a power supply, and the second component 804 may be a component that is powered by the power supply, via waveguide 100. For example, if the deformable object 200 is a robotic limb, the second component 804 may be a light or a sensor, such as a video camera that receives power via the waveguide 100.

[0112] The second component 804 may receive data, such as control signals, from first component 802 via waveguide 100, and may provide data to the first component 802 via the waveguide 100. For example, where the first component 802 is a controller and second component 804 is a light or a sensor, such as a video camera, a control signal from first component 802 may instruct the second component 804 to turn on or off. For example, to switch the light on or off, or start or stop video recording. In addition, sensor data may be provided from the sensor to the first component 802 via the waveguide 100.

[0113] In some examples, both power and data may be carried between the first component 802 and the second component 804 via the waveguide 100. In some examples, power and data may be input separately at the same or different positions along the waveguide 100 by one or more first components 802.

[0114] As described above, the bandwidth of the waveguide 100 depends on the coupling between the resonators 102 and may decrease with changes in the configuration of the waveguide 100. In some examples, a bandwidth of a waveguide 100 that has resonators 102 arranged symmetrically around a bend axis (e.g., such that the bend axis passes though the loops of the resonators 102) may be less affected by bending of the waveguide 100. Similarly, coupling between resonators 102 located close to a bend axis may be less affected by deformations of the waveguide 100 than the coupling between resonators 102 located away from the bend axis. Accordingly, where the waveguide 100 is to carry signals in addition to the configuration sensing signals, improved performance with regard to those signals may be provided when the resonators 102 of the waveguide 100 are arranged close to, arranged symmetrically about, or arranged around the bend axis.

[0115] In some examples, a deformable object 200 may be provided with multiple waveguides 100. One or more of the waveguides 100 may be used for determining a configuration of the deformable object 200. In addition, one or more of the waveguides 100 may be used for carrying data, power, or both. Some waveguides 100 may perform more than one of carrying configuration sensing signals, carrying data and carrying power.

[0116] Where a waveguide 100 is to be used to carry configuration sensing signals and power, the power may be provided in a predetermined (e.g., narrow) frequency range. When frequencies are swept to generate the configuration sensing signals, the frequency sweep may step over (i.e.,omit) the predetermined frequency range for carrying power. Alternatively, a filter (e.g., a notch filter) may be used to remove the predetermined frequency range from the signal to be analysed to obtain the configuration of the waveguide 100. In other examples, the power transfer may be temporarily suspended while measuring the configuration of the waveguide 100, and resumed following measurement of the configuration.

[0117] Accordingly, the received data may be filtered prior to determining information indicative of a deformation of the deformable object 200, to remove features of the data associated with at least one of power or data carried via the magnetoinductive waveguide 100, the power or data to be provided to or from a component external to the magnetoinductive waveguide 100.

[0118] In some examples, a frequency range associated with at least one of power or data carried via the magnetoinductive waveguide 100, is omitted from the data used to determine the configuration of the waveguide 100.

[0119] In some examples, the configuration of the waveguide 100 may be determined based on selected data indicative of propagation of magnetoinductive waves in the magnetoinductive waveguide 100, where the data is selected to correspond to a time window during which at least one of data or power transfer with components external to the magnetoinductive waveguide is suspended.

[0120] FIG. 9A shows an example of a waveguide 100 having each resonator 102 arranged symmetrically about a bend axis of the deformable object 200. The deformable object 200 may be a fibre, for example. This arrangement may be useful for sensing strain. Stretching or compression of the fibre along its axis (i.e. , a change in the length of the fibre) will cause the spacing between the resonators 102 to vary, changing the coupling between the resonators 102 and leading to changes in the waves reflected from the waveguide 100.

[0121] FIG. 9B shows an example of a waveguide 100 having each resonator 102 arranged asymmetrically about a bend axis (e.g., off-centre with respect to the bend axis) of the deformable object 200, or fibre. This arrangement may be useful for detecting bending of the fibre along a particular axis. When the fibre is aligned along the z-axis and the resonators 102 are displaced from the bend axis along the y-axis, the waveguide 100 may be particularly sensitive to bending in the yz-plane.

[0122] FIG. 9C shows an example of a waveguide 100 having two sets of resonators 902 and 904. The resonator of the first set of resonators 902 and each resonator of the second set of resonators 904 is arranged asymmetrically about a bend axis (e.g., off-centre with respect to the bend axis) of the deformable object 200, or fibre, similarly to the arrangement of FIG. 9B. The first resonators 902 and second resonators 904 are displaced from the bend axis of the fibre in different directions. For example, the displacement of the second resonators 904 may be perpendicular to the displacement of the first resonators 902.

[0123] This arrangement may be useful for detecting bending of the fibre along various axes. When the fibre is aligned along the z-axis, the first resonators 902 are displaced from the bend axis along the y-axis, and the second resonators 904 are displaced from the bend axis along the x- axis, a component of bending in the yz-plane may be detected using the first resonators 902, anda component of bending in the xz-plane may be detected using the second resonators 904. The actual bend may be obtained from the composite of the bends measured in the yz- and yx-planes.

[0124] The set of first resonators 902 may be arranged to have a different set of resonant frequencies that the set of second resonators 904. For example, the first set of resonators 902 may be tuned to a frequency band that does not overlap the frequency band of the second set of resonators 904. In this case, they could be separately interrogated using a single output (e.g., a single pickup) in different frequency regimes. The resonant standing wave frequencies for the first resonators 902 may be tuned (for example) to a (relatively) low frequency, whilst the second resonators 904 may be tuned to a (relatively) high frequency. Accordingly, a single frequency sweep would provide monitoring of resonances in both sets of resonators.

[0125] In examples, the waveguide 100 may be used to sense objects that are proximate to the waveguide 100.

[0126] FIG. 10A shows an example of a waveguide 100 with a nearby object 1002. In this example, the nearby object 1002 is metallic. FIG. 10B shows the resonant frequencies 1004a to 1004e of the waveguide 100 in the absence of the nearby object 1002, and the resonant frequencies 1006a to 1006e when the nearby object 1002 is present. The frequency is plotted on the horizontal axis and the bend angle of the waveguide 100 is plotted on the vertical axis. Here, the bend angle is indicative of the average angle between successive resonators 102 of the waveguide 100. While the object 1002 was present, the waveguide 100 was moved from a configuration (at -20 on the vertical axis) in which it was bent toward the nearby object 1002, via a straight configuration (at 0 degrees), to a configuration with the waveguide 100 bent opposite the original bend (i.e., bent upwards in FIG. 10A). This generated the lines labelled 1006a-1006e. The object 1002 was then removed and the waveguide 100 and then bent back towards the original configuration to generate the lines labelled 1004a-1004e.

[0127] The resonance corresponding with line 1006c in the presence of object 1002 shows a notable “kink” or deviation 1008 from the corresponding line1004c in the absence of object 1002, due to the presence of the nearby object 1002. This deviation 1008 occurs at a bend angle of around 7°, when the waveguide 100 was closest to the nearby object 1002. Such deviations from the resonances in the absence of nearby objects may be used to determine the presence of, and possibly some properties of, nearby objects.

[0128] It is to be noted that some of the differences between the respective resonances with and without the nearby object 1002 are due to hysteresis in the movement of the support structure 204. For example, line 1006a is shifted to lower frequencies than line 1004a between - 10° and -15°.

[0129] A conductor in the vicinity of the waveguide 100 may lead to an increase of one or more of the resonant frequencies. Ferrite materials may cause the one or more of the resonant frequencies to decrease. Material with dielectric loss, or weakly conducting material, may lead to a decrease in the Q-factor (quality factor) of a nearby resonator 102.

[0130] This may have application, for example, in robotics. The waveguide 100 may be used to determine a configuration of a robotic limb. Where the limb becomes stuck on an object, ormeets resistance from an object in its environment, an expected configuration based on instructions to the actuators of the limb may differ from an actual configuration, as sensed by the waveguide 100. The ability to sense the object and possibly obtain information on its properties may provide useful information for a controller or operator to understand the cause of the deviation from the expected and actual configurations. Similarly, proximity sensing may assist with navigation, such as allowing a robot for operating within a pipe to sense the walls of the pipe.

[0131] In some examples, the configuration of the waveguide 100 may be determined from the resonant frequencies, for example by obtaining a best fit between the measured resonant frequencies and known calibration resonant frequencies associated with known configurations. Deviations from the measured resonant frequencies and the best-fit calibration resonant frequencies may then be analysed to obtain information on nearby objects 1002. The analysis may be based on a physical model or may use a suitably trained neural network, for example.

[0132] According to some examples, input admittances of the waveguide 100 may be analysed by applying the principle of superposition to obtain the configuration of the waveguide 100. To detect nearby objects, the admittance may then be monitored for deviations from the unperturbed case. Machine learning may be used to recognize signatures in the deviations, and using a trained neural network, determine the most probable configuration of the waveguide 100, and perturbations due to nearby objects.

[0133] According to examples, information relating to nearby objects 1002 is carried by the waveguide 100. The waveguide 100 acts as both a sensor and a data channel to provide the sensor data to an output of the waveguide 100, such that additional sensors and wiring are not needed to obtain and carry the proximity sensing information about nearby object 1002.

[0134] The configuration sensing signals may also be used to detect damage to the waveguide 100. If a resonator 102 is damaged, such that its resonant frequency changes, the waveguide 100 will have one fewer resonance. The effective removal of one of the resonators 102 (e.g., by damage to the resonator 102) results in 100% wave reflections from the defect that is created by the removal.

[0135] In some examples, the damaged resonator 102 or resonators 102 may be identified based on amplitudes of the impedance peaks, or with time of flight data, for example.

[0136] The waveguide 100 may act as both a sensor and a data channel to provide the sensor data to an output of the waveguide 100. As such, additional wires and sensing components are not needed along the length of the waveguide 100. A single interface may be used for input and output. In particular, a separate output and associated wiring is not needed for each damage sensor.

[0137] Resonators 102 of the waveguide 100 may be individually attached to a deformable object 200 to be monitored. For example, each resonator 102 may be directly attached to a different part of a robotic limb. In other examples, the resonators 102 may be coupled together by one or more support structures 204, for example, forming a fibre similar to those shown in FIG. 9A to FIG. 9C. This may form a standalone configuration sensor that can be used to detect its own bend angle. In some examples, the fibre (or similar element) may be the deformable object 200.In some examples, the fibre may be attached to a deformable object 200 to measure deformation of the deformable object 200.

[0138] In some examples, the resonators 102 may be disposed on, or in, a flexible substrate.

[0139] Examples described herein may be applied to any system the configuration of which is to be monitored or measured. The waveguide 100 may be provided on or in a robot limb to determine the configuration of the limb. In particular, accurately determining the configuration of so-called soft robots or compliant mechanisms has been challenging, particularly if motion of a limb is obstructed. However, examples described herein may provide a convenient and reliable approach to detecting the configuration of such robots and mechanisms. Accordingly, examples described herein provide a convenient structure for providing proprioception.

[0140] In an example, the deformable object 200, e.g., as shown in FIG. 2A to FIG. 2C has first and second portions that are moveable relative to each other. The waveguide 100 is to operate as a pose sensor, and resonators 102 of the waveguide 100 are arranged to be magnetoinductively coupled. A first resonator 102 of the waveguide 100 is arranged to move with the first portion of the deformable object 200, and a second resonator 102 of the waveguide 100 is arranged to move with the second portion of the deformable object 200. The deformable object 200 may be a robotic component, such as a complaint mechanism, a soft robotic limb, an articulated soft robotic limb, a continuum soft robotic limb, a rigid robotic limb, or a robotic limb driven by hydraulic or pneumatic actuators.

[0141] The robotic component may include an input component and a receiver component, the input component to supply at least one of power and data to the magnetoinductive waveguide, and the receiver component to receive the at least one of power and data via the magnetoinductive waveguide.

[0142] The robotic component may include, or be coupled with, processing circuitry arranged to receive data describing propagation of magnetoinductive waves in the magnetoinductive waveguide and to determine a pose of the robotic component based on the received data.

[0143] Examples described herein may be applied to human-machine interfaces. For example, a human-machine interface may include a glove to be worn on the hand of a user. A waveguide 100 may be provided on one or more of the fingers of the glove to detect bending of the finger. In examples a waveguide 100 may be provided on each of the fingers of the glove.

[0144] Waveguides 100 for sensing a configuration of an object may be included, for example, in cables or fabric membranes. For example, waveguides 100 may be included in clothing or boat sails.

[0145] According to examples herein, for configuration determination the system exploits the variable coupling between resonators 102 that are moving relative to one another. For example, as a multi-jointed bending limb moves, one or more resonators 102 attached to each unit form a waveguide 100 whose reflection characteristics are varied by the changes to their coupling.

[0146] According to examples herein, the waveguide 100 provides a confined wave propagation environment in which the effective wavelength may be very short. This is because the waveguide 100 is composed of an array of coupled circuits (resonators 102 or meta-atoms) each of whichmay be tuned to the same frequency, or to a particular spatial frequency pattern. Launching waves into the waveguide 100 may result in a complex interference pattern with a large number of unique spatial configurations. Careful choice of injection locations and the overall symmetry of the waveguide 100 results in being able to identify changes to that propagation environment, e.g., based on detection of reflected waves.

[0147] Examples may provide a single wire connection, with signals injected to and received from the waveguide 100 at a single point, with the received signals indicating a configuration of the waveguide 100.

[0148] According to examples, configuration of the waveguide 100 may be determined without requiring a complex distribution of sensors. The waveguide 100 may be structurally simple and may be straightforward to apply to or install in a deformable object 200 to be monitored.

[0149] Herein, the term configuration may be used to refer to the spatial shape or deformation of an object.

[0150] Certain methods and systems as described herein may be implemented by one or more processors that process program code that is retrieved from a storage medium, such as non- transitory storage medium. FIG. 1 1 shows an example of a device 1 100 comprising a computer- readable storage medium 1 102 (e.g. memory device) coupled to at least one processor 1 104. The computer-readable medium 1 102 may be any medium or media that can contain, store, or maintain programs and data for use by or in connection with an instruction execution system. Computer-readable medium 1 102 can comprise any one of many physical media such as, for example, electronic, magnetic, optical, electromagnetic, or semiconductor media. More specific examples of suitable machine-readable media include, but are not limited to, a hard drive, a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory, or a portable disc.

[0151] In FIG. 1 1 , the computer-readable storage medium 1 102 comprises program code 1 106 to perform a method 300 corresponding to the embodiment shown in FIG. 3, that is: receiving data indicative of propagation of magnetoinductive waves in a magnetoinductive waveguide 100, the magnetoinductive waveguide 100 including a plurality of resonator elements; and determining, based on the received data, information indicative of a configuration of the magnetoinductive waveguide 100. The magnetoinductive waveguide 100 may be a waveguide 100, as described in any of the previous examples.

[0152] The device 1 100 may be included in a deformable object 200, or may be communicatively coupled with waveguide 100 in a deformable object 200.

[0153] It will be appreciated that various changes and modifications can be made to the embodiments of the present invention without departing from the scope of the present application.

[0154] FIG. 12 shows a method 1200 of producing a configuration sensor for a robot. The configuration sensor may be a waveguide 100 according to any of the previously described examples. The method includes providing 1202 a first resonant element that is arranged to move with a first portion of the robot, the first resonant element 102 being a resonant element of a magnetoinductive, or electroinductive, waveguide of resonant elements. The method 1200 alsoincludes providing a second resonant element 102 that is arranged to move with a second portion of the robot, the second resonant element being a resonant element of the waveguide of resonant elements. The magnetoinductive, or electroinductive, coupling between the first and second resonant elements is dependent on a relative pose of the first and second elements.

[0155] The first and second portions may be connected with each other via a moveable joint or a compliant structure, for example.

[0156] In some examples, the deformation may be determined based on the frequency-domain data includes determining the deformation based on at least one of: frequencies of peaks or troughs in the input scattering parameter spectrum, amplitudes of peaks or troughs in the input scattering parameter spectrum, or widths of peaks or troughs in the input scattering parameter spectrum.

[0157] FIG. 13A shows the input scattering parameter spectrum, in this case input admittance, for a chain of 5 resonators 102, or meta-atoms, with perturbations at different positions along the chain. Plot 1302a shows the unperturbed state, where the coupling (i.e., magnetoinductive coupling) between each pair of neighbouring resonators 102 is the same. This is the isotropic coupling case where all the resonators 102 are identical and form a regular chain with identical nearest neighbour distances. This corresponds with the arrangement 1304a shown schematically in FIG. 13B, where the resonators 102 are illustrated as unfilled circles and unperturbed couplings are illustrated as thin lines. The feed point for the magnetoinductive waves is shown as a grey arrow 1308.

[0158] The curves 1302b to 1302e show the input admittance for the same chain of resonators 102, with each having a perturbation in the coupling between one respective pair of resonators 102, for example, by changing a distance between that pair of resonators 102 while maintaining distances between other pairs of nearest neighbouring resonators 102 the same as in the unperturbed arrangement 1304a. In each of lines 1302b to 1302e the coupling between one pair of resonators 102 has been decreased with respect to the coupling of the unperturbed state corresponding with line 1302a, with the coupling between each other pair of resonators 102 the same as in the unperturbed state. FIG. 13B shows each of these states, with the perturbed coupling illustrated as a thick line.

[0159] Accordingly, in the M1 arrangement, corresponding with arrangement 1304b, the coupling 1310 between the pair of resonators 102 closest to the feed point 1308 is perturbed. That is, the coupling between the first and second resonators 102 is perturbed, where the resonators 102 are numbered in sequence along the chain, with the resonator 102 closest to the feed point 1308 being the first resonator 102. The coupling between other pairs of neighbouring resonators 102 is the same as in the unperturbed state 1304a.

[0160] In the M2 arrangement, shown as arrangement 1304c in FIG. 13B, the coupling 1312 between the second and third resonators 102 is perturbed. The M3 arrangement is shown as arrangement 1304d in FIG. 13B, the coupling 1314 between the third and fourth resonators 102 is perturbed. In the M4 arrangement, shown in arrangement 1304e in FIG. 13B, the coupling 1316 between the fourth and fifth resonators 102 is perturbed.

[0161] Curve 1302b corresponds with the M1 arrangement 1304b, Curve 1302c corresponds with the M2 arrangement 1304c, Curve 1302d corresponds with the M3 arrangement 1304d, Curve 1302e corresponds with the M4 arrangement 1304e.

[0162] Each of the curves 1302a to 1302e have been offset by 0.002 along the y-axis, to improve visibility of each of the curves. The baselines of these curves (i.e., the values away from the peaks) would overlap without this offset.

[0163] FIG. 13A also shows the effect of perturbing the coupling by increasing the coupling between one pair of neighbouring resonators 102, in curves 1306b to 1306e. Curve 1306a shows the unperturbed case. Curve 1306b corresponds with the M1 arrangement 1304b, curve 1306c corresponds with the M2 arrangement 1304c, curve 1306d corresponds with the M3 arrangement 1304d, curve 1306e corresponds with the M4 arrangement 1304e.

[0164] For clarity, the curves 1306a to 1306e have been offset by 0.3 along the y-axis, and each of curves 1306b to 1306e have been offset by 0.002 from the previous line, similarly to the curves 1302b to 1302e.

[0165] As can be seen, all curves exhibit 5 peaks but their frequency and amplitude patterns are unique to the configuration of couplings. Considering the curves 1302b and 1302e illustrating perturbations by reducing a coupling according to the M1 and M4 arrangements, 1304b and 1304e, both curves have resonances (peaks) at the same frequencies for the five resonances, but exhibit different patterns of peak values (peak amplitudes). In this example, the M4 arrangement 1304e has greater spectral weight at the outliers (first and fifth peaks) compared with the M1 arrangement 1304b. In contrast, comparing the M1 and M4 arrangements when coupling increases, (curves 1306b and 1306e), while both arrangements again have resonances that the same frequencies, the M1 arrangement 1304b has greater spectral weight at the outliers (first and fifth peaks) compared with the M4 arrangement 1304e. The M1 and M4 arrangements have a symmetrical arrangement of resonators 102, and differ in the location of the feed point 1308. The symmetry of the arrangement leads to the frequencies being the same for both arrangements. Accordingly, in some cases, distinct configurations of resonators 102 may have peaks at the same frequencies, but it may be possible to distinguish those arrangements by using additional information, such as peak heights / amplitudes, or peak widths.

[0166] In some examples, determining the deformation based on the frequency-domain data may include determining that the frequencies of peaks or troughs are consistent with both a first configuration and a second configuration (such as the M1 and M4 arrangements of FIG. 13B), and determining that the configuration of the waveguide is the first configuration and not the second configuration based on at least one of the amplitudes of peaks or troughs or the widths of peaks or troughs.

[0167] In some examples, determining information indicative of the configuration of the waveguide may include selecting, based on at least one of (i) the amplitudes of peaks or troughs, or (ii) the widths of peaks or troughs, between a plurality of configurations consistent with the frequencies of peaks or troughs.

[0168] In some examples, the configurations that the waveguide 100 can adopt may be subject to mechanical constraints. The may be due, for example, to limitations on the articulations that may be performed by the waveguide 100, or by a support structure 204 of the waveguide 100, or by a substrate of the waveguide, etc.

[0169] FIG. 14 shows contours of mutual inductance between two resonators 102 placed parallel to one another but with their relative positions varied in the z and x directions. The displacement between the centres of the resonators 102 in the x direction is indicated as x, and the displacement between the centres of the resonators 102 in the z direction is indicated as z.

[0170] The relative arrangement of the resonators 102 is illustrated in the inset to FIG. 14. The main figure of FIG. 14 shows contour lines of inductance with changing x and z. For example, all relative positions that correspond to points on the M=10nH contour line 1404 have the same coupling between the resonators 102.

[0171] As can be seen in FIG. 14, magnetoinductive couplings between adjacent resonators 102 are not unique, for example increasing the separation between two axially coupled resonators 102 (a displacement along the z-axis in the arrangement shown in the inset to FIG. 14) may reduce their coupling in the same way as sliding them across one another at constant altitude (i.e ., displacing the resonators 102 with respect to each other in a direction parallel with the resonators 102 while maintaining the same perpendicular displacement, corresponding with a displacement along the x-axis in the arrangement shown in the inset to FIG. 14). This leads to the contours shown in FIG. 14, where each point on a contour corresponds with a unique combination of displacements along the x-axis and the z-axis that results in the same coupling as every other point on the same contour.

[0172] Mechanical constraints on the movement of the meta-atoms may limit the possible range of values for x and z. For example, relative movement of the resonators 102 may be restricted to lie along the dotted line 1406. In this case, all of the coupling values along this line are unique. Accordingly, by applying knowledge of this mechanical constraint, the relative positions of the two resonators 102 can be constrained to x and y values on this line, such that the relative positions may be determined unambiguously from their mutual coupling.

[0173] Thus, some examples may include obtaining data indicative of mechanical constraints on the configuration of the waveguide, wherein determining information indicative of the configuration of the waveguide includes determining information indicative of the configuration based on the mechanical constraints.

[0174] Determining information indicative of the configuration of the waveguide may include selecting, based on the mechanical constraints, between a plurality of configurations consistent with the received data indicative of propagation of magnetoinductive or electroinductive waves.

[0175] In some examples, the exact mutual couplings of resonators 102 and their order define the input admittance, along with the individual resonator 102 parameters. External influences may also affect the input admittance. For example, the input admittance may be affected by resonators 102 of the waveguide 100 coming into proximity with a metal object.

[0176] FIG. 15A illustrates a waveguide 100 having a two-dimensional arrangement of resonators 102. The waveguide 100 may form a surface, having chains of resonators 102 extending in two directions, such that a first resonator 102 has a neighbouring resonator 102 along a first axis 1506 and another neighbouring resonator 102 along a second axis 1508, where the first 1506 and second 1508 axes are non-parallel. The axes may be perpendicular, for example, but in some examples may be arranged along axes that are neither parallel nor perpendicular. In this example, the first axis 1506 may be referred to as the x-axis, or the x- direction. Similarly, the second axis 1508 may be referred to as the y-axis, or the y-direction.

[0177] In some arrangements of uniform 2D surfaces, e.g., with all resonators 102 identical and having identical nearest neighbour coupling along both axes, a deformation with respect to the x- axis (e.g., bending about the x-axis) may result in the same input scattering parameter spectrum as an equivalent deformation with respect to the y-axis (e.g., bending about the y-axis). Accordingly, in such arrangements it may not be possible to distinguish between a deformation with respect to one axis and a corresponding deformation with respect to the other axis. This may be particularly the case where the waveguide 100 is fed from a point of high symmetry.

[0178] If the two dimensional waveguide 100 is fed from a lower symmetry location, the degeneracy may be broken to come extent, allowing deformations with respect to the two axes to be distinguished. However, in some arrangements it still might not be possible to obtain a complete pose of the waveguide 100.

[0179] The arrangement of FIG. 15A has a first coupling 1502 between nearest neighbour resonators 102 along a first direction 1506 (shown by dotted lines), and a second coupling 1504, different from the first coupling between nearest neighbour resonators 102 along a second direction 1508 (shown by shown by solid lines). This arrangement breaks the degeneracies between the two axes, allowing deformations with respect to the first direction / axis 1506 to be distinguished from corresponding deformations with respect to the second direction / axis 1508.

[0180] The difference in coupling between the first and second directions may be a difference in coupling strength, for example the coupling 1502 the in first direction 1506 may be weaker than the coupling in the second direction 1504, In some examples, the coupling 1502 along the first direction 1506 may have a different character from the coupling 1504 along the second direction 1508. For example, the coupling 1502 along the first direction 1506 may be magnetic and the coupling 1508 along the second direction 1504 may be electric. In another example the coupling 1502 along the first direction 1506 may be positive magnetic coupling, and the coupling 1504 along the second direction 1508 may be negative magnetic coupling.

[0181] The difference in coupling along the different directions will change the distribution of standing wave modes (e.g., peaks and troughs) with respect an arrangement having the same coupling in both directions by varying the dispersion character of the waves crossing the waveguide 100. In this case, a deformation with respect to the x-direction 1506 (e.g., bending in the x-direction) can be distinguished from a corresponding deformation with respect to the y- direction (e.g., bending in the y-direction), as they deformations have different effects on the response spectrum of the waveguide 100. 1

[0182] According to an example where coupling along the x-direction 1506 is weaker than the coupling along the y-direction 1508 (or equivalently, coupling along the y-direction is stronger than the coupling along the x-direction), with the coupling along both directions being positive coupling, then the standing wave admittance spectrum will consist of 5 groups, each with 5 peaks in it, for a total of 25 peaks. An example of this admittance spectrum is shown in FIG. 15B. The admittance spectrum for the flat, unperturbed arrangement is shown by line 1510.

[0183] Bending in the x-direction and reducing the coupling in this direction will cause the peaks within each group to bunch up, such that for each group of peaks, the frequency range of the group of peaks is reduced. This is shown by line 1512, which has been offset along the y-axis of the graph for clarity. As can be seen, within a particular group of peaks, the peaks forming that group are closer together than the peaks forming the corresponding group in the unperturbed line 1510. Similarly, if the displacement increases coupling in the x-direction then the peaks within a group would spread apart.

[0184] Bending in the y-direction controls the spacing between groups of peaks. For example, bending that reduces the coupling in the y-direction will cause the groups to close up, such that each group becomes closer to the other groups, and the frequency range between the lowest frequency peak and the highest frequency peak is reduced. This is shown by line 1514, which has been offset along the y-axis of the graph for clarity. As can be seen, the spacing between groups of peaks is less than the spacing between the groups in the unperturbed line 1510. Similarly, for a distortion that increases the coupling in the y-direction, the groups will spread away from one another.

[0185] Accordingly, bending along the first direction has a different signature from bending along the second direction, and so these may be distinguished.

[0186] In some examples, the arrangement of FIG. 15A may also be fed from a low-symmetry point.

[0187] In some examples, determining information indicative of the configuration of the waveguide includes determining the configuration with respect to a first axis and a second axis, wherein a mutual coupling between resonator elements adjacent to each other along the first axis is different from a mutual coupling between resonator elements adjacent to each other along the second axis. In some examples, each pair of resonator elements adjacent to each other along the first axis may have the same coupling as each other pair of resonator elements adjacent to each other along the first axis. Similarly, each pair of resonator elements adjacent to each other along the second axis may have the same coupling as each other pair of resonator elements adjacent to each other along the second axis.

[0188] In some examples, determining information indicative of the configuration of the waveguide includes determining the configuration with respect to the first axis based on respective groups peaks or troughs in an input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the configuration with respect to the second axis based on the peaks or troughs in the respective groups of peaks and troughs. The configuration with respect to the first axis may be based on spacings between the groups peaksor troughs. The configuration with respect to the second axis may be based on spacings between peaks within the same group of peaks.

[0189] In some examples, determining the configuration with respect to the first axis is based on a distribution of the groups peaks or troughs, and determining the configuration with respect to the second axis is based on a distribution of the peaks or troughs within the respective groups of peaks and troughs.

[0190] FIG. 16 shows an example of a scale-like or shingle-like arrangement 1600 of resonators 102, e.g., resembling pangolin scales. In such a waveguide 100 a first resonant element and a second resonant element may be arranged relative to each other in a scale-like or shingle-like arrangement.

[0191] In the example of FIG. 16, the resonators 102 are provided on or in respective carriers 1604. The waveguide 100 may have a flat or reference configuration, where each resonator 102 is parallel with other resonators 102 of the waveguide 100. In this configuration, a substrate of the waveguide 100 (not shown) may be flat, and bases of respective resonators 102 may lie on a common line or plane. Configuration 1602a of FIG. 16 shows a relatively small deformation from a flat arrangement, with the deformation increasing in each successive configuration of 1602b, 1602c, and 1602d. In this example, the deformation corresponds with bending a substrate of the waveguide 100. In the example of FIG. 16 the bend is shown with the ends of the waveguide 100 bending downward, such that the resonators 102 move apart from each other, reducing the overlap between neighbouring resonators 102 and coupling between neighbouring resonators 102 decreases. However, in some examples the waveguide 100 may be arranged to additionally or alternatively bend in the opposite direction, such that the ends of the waveguide 100 in FIG. 16 would be bent upwards relative to the middle of the waveguide 100, such that neighbouring resonators 102 move closer to each other and the overlap between neighbouring resonators 102 would increase, leading to increased coupling between neighbouring resonators 102. According to such an arrangement an “upward” bend and a “downward” bend would have different effects on the coupling between neighbouring resonators 102, and so “upward” and “downward” bending may be distinguished from each other.

[0192] In some scale-like arrangements, such as that shown in FIG. 16, adjacent resonators 102 partially overlap, in at least some configurations (such as a flat configuration or a reference configuration), which may provide strong coupling between the resonators 102 that varies as the waveguide 100 flexes, as the flexing will cause the scales / resonators 102 to move or slide across one another modifying their mutual flux. Such a structure will generally have stronger coupling than an equivalent planar coupled structure (e.g., as shown in FIG. 1A to FIG. 1 C). The increased coupling of the scale-like arrangement results in greater resonant peak separations and a higher sensitivity to small deformations. In addition, the scale-like arrangement may occupy less height (e.g., perpendicularly from a substrate or support structure of the waveguide 100) when compared with an axially-coupled waveguide 100 (e.g., as illustrated in FIG. 2A to FIG. 2D, or FIG. 9A to FIG. 9C). In some examples, the resonator 102a may be laid almost flat when the waveguide 100 is in a flat / reference configuration, which may provide a significant reduction in height while maintaining strong mutual coupling between neighbouring resonators 102.

[0193] Some example waveguides 100 do not necessarily have a neutral or reference configuration. For example, a structure or substrate on which the waveguide 100 is mounted may mechanically prevent the waveguide 100 from obtaining a flat configuration. In some arrangements a non-flat neutral or reference configuration may be defined.

[0194] In some examples according to a scale-like arrangement, the first resonant element, or a carrier of the first resonant element, may be slidably in contact with the second resonant element, or a carrier of the second resonant element. In some examples, the carrier may be a substrate of the resonator 102, a casing of the resonator 102, a shell of the resonator 102, a support structure of the resonator 102, etc. In some examples, the carrier may be omitted.

[0195] The first and second resonant elements may overlap in a direction perpendicular to the first resonant element, a direction perpendicular to the second resonant element, and a direction perpendicular to a line between the respective centres of the first and second resonant elements. For example, FIG. 17 shows a first resonator 102a and a second resonator 102b mounted on a waveguide substrate 1712. The first resonator 102a and second resonator 102b overlap in a direction perpendicular to the first resonator 102a, since the line 1706, which is perpendicular to the first resonator 102a, intersects both the first resonator 102a and second resonator 102b. In this example, the first resonator 102a and second resonator 102b are parallel to each other, such that the line 1706 is also perpendicular to the second resonator 102b, such that the first resonator 102a and second resonator 102b also overlap in a direction perpendicular to the second resonator 102a. In addition, a line 1710 between the centres of the first resonator 102a and second resonator 102b has a perpendicular line 1708 that intersects both the first resonator 102a and second resonator 102b, such that the first resonator 102a and second resonator 102b overlap in a direction 1708 perpendicular to a line 1710 between the respective centres of the first 102a and second 102b resonators. The first resonator 102a and second resonator 102b may be nearest neighbours in the waveguide 100.

[0196] In some examples, the first and second resonator elements are arranged obliquely on a substrate, such that the first and second resonator elements overlap each other.

[0197] In some examples, the first resonant element may be arranged to obliquely overlap the second resonant element. In some examples, the first and second resonant elements may be parallel and offset from each other, or may be parallel and staggered with respect to each other.

[0198] FIG. 18 shows an example of a scale-like arrangement having resonators 102 attached to an elastic substrate 1804 by respective attachment elements 1808. The attachment elements 1808 are arranged to maintain a fixed angle 1810 relative to the substrate 1804, such that deformation on the substrate (e.g., by linear stretching) does not change the angle between the resonator 102 and the substrate 1804. The angle may be a predetermined angle. The angle between the substrate 1804 and each resonator 102 may be the same. In configuration 1812, which may correspond with the substrate 1804 being in an unstrained state, a separation between corresponding points of neighbouring resonators 102 is indicated as a. Configuration 1814 may correspond with the substrate 1804 being in a strained state, in which the elastic substrate 1804 is stretched such that the separation between corresponding points of neighbouring resonators 102 is b, with b > a, the angle 1810 between the substrate 1804 and theresonators 102 is the same as in configuration 1812, but the overlap between neighbouring resonators 102 changes, leading to a change in the mutual coupling of neighbouring resonators 102 that can be detected as a change in the propagation of magnetoinductive or electroinductive waves in the waveguide 100.

[0199] FIG. 19A shows an example of a waveguide 100 having resonators 102 on an inelastic substrate 1904 that can bend but not stretch. In this example, the spacing between resonators 102 at the point the resonators 102 meet the substrate 1904 (e.g., attachment elements 1908) is fixed. In this example, the attachments between the substrate 1904 and the respective resonators 102 are not hinged, such that the angle 1906 between the resonator 102 and substrate 1904 (e.g., between the resonator 102 and a tangent to the substrate 1904 at the point of attachment between the resonator 102 and substrate 1904) is fixed. In this case, the resonators 102 are lifted away from each other as the bend radius decreases, leading to a change in the coupling between neighbouring resonators 102.

[0200] FIG. 19B shows an example of a waveguide 100 having resonators 102 on an elastic substrate 1910 that can bend and stretch. In this example, the spacing between resonators 102 at the point the resonators 102 meet the substrate 1910 (e.g., attachment elements 1908) is not fixed.

[0201] In this example, the attachments between the substrate 1910 and the respective resonators 102 are hinged, such that a perpendicular distance between an attachment 1908 of a resonator 102 (or a point at which the resonator 102 meets the substrate 1910) and a neighbouring resonator 102 is maintained (e.g., has a fixed value). In some examples, contact between neighbouring resonators 102, or a carriers of neighbouring resonators 102, may be maintained during bending and / or stretching of the substrate 1910. That is, the resonators 102 lie against one another.

[0202] In this case, the stretching of the substrate 1910 during the bending results in the resonators 102 sliding over one another, leading to a more rapid change in the coupling between neighbouring resonators 102 than the change due to lifting of the resonators 102 in a corresponding waveguide 100 according to FIG. 19A.

[0203] The arrangements of FIG. 19A and FIG. 19B are examples only, and it is to be understood that various attachments, such as hinged attachments and non-hinged attachments, may be used in combination with elastic or non-elastic substrates, as well as substrates that may bend or substrates that are not bendable. Accordingly, the attachment between resonators 102 and substrate may be selected based on one or more of expected deformations or configurations of the waveguide 100, target coupling strengths between neighbouring resonators 102 (e.g., over expected configurations), or dimensions of the waveguide 100 (e.g., a perpendicular height of the waveguide 100 over a range of expected configurations).

[0204] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwiserequires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0205] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect or example are to be understood to be applicable to any other aspect or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Examples are not restricted to the details of any foregoing examples. The Examples may extend to any novel one, or any novel combination, of the features disclosed in this specification, or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0206] The following sets out examples of the present invention.

[0207] Example 1 . A computer implemented method comprising: receiving data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements; and determining, based on the received data, information indicative of a configuration of the waveguide.

[0208] Example 2. The computer implemented method of example 1 , wherein at least one of: the determining includes obtaining, from the received data, time-domain data indicative of reflected magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the time-domain data; and the determining includes obtaining, from the received data, frequency-domain data indicative of a input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the frequency-domain data.

[0209] Example 3. The computer implemented method of example 2, wherein determining the deformation based on the frequency-domain data includes determining frequencies corresponding with peaks or troughs in the input scattering parameter spectrum.

[0210] Example 4. The computer implemented method of example 3, wherein determining the deformation includes determining one or more frequency shifts, relative to a input scattering parameter spectrum of a reference configuration, of the peaks or troughs in the input scattering parameter spectrum.

[0211] Example 5. The computer implemented method of any one of examples 2 to 4, wherein determining the deformation based on the frequency-domain data includes determining the deformation based on at least one of: frequencies of peaks or troughs in the input scattering parameter spectrum, amplitudes of peaks or troughs in the input scattering parameter spectrum, or widths of peaks or troughs in the input scattering parameter spectrum.

[0212] Example 6. The computer implemented method of example 5, wherein determining the deformation based on the frequency-domain data includes determining that the frequencies of peaks or troughs are consistent with a first configuration or a second configuration, anddetermining that the configuration of the waveguide is the first configuration and not the second configuration based on at least one of the amplitudes of peaks or troughs or the widths of peaks or troughs.

[0213] Example 7. The computer implemented method of example 5 or example 6, wherein determining information indicative of the configuration of the waveguide includes selecting, based on at least one of the amplitudes of peaks or troughs or the widths of peaks or troughs, between a plurality of configurations consistent with the frequencies of peaks or troughs.

[0214] Example 8. The computer implemented method of any one of examples 1 to 7, further including obtaining data indicative of mechanical constraints on the configuration of the waveguide, wherein determining information indicative of the configuration of the waveguide includes determining information indicative of the configuration based on the mechanical constraints.

[0215] Example 9. The computer implemented method of example 8, wherein determining information indicative of the configuration of the waveguide includes selecting, based on the mechanical constraints, between a plurality of configurations consistent with the received data indicative of propagation of magnetoinductive or electroinductive waves.

[0216] Example 10. The computer implemented method of any one of examples 1 to 9, wherein determining information indicative of the configuration of the waveguide includes determining the configuration with respect to a first axis and a second axis, wherein a mutual coupling between resonator elements adjacent to each other along the first axis is different from a mutual coupling between resonator elements adjacent to each other along the second axis.

[0217] Example 11 . The computer implemented method of example 10, wherein determining information indicative of the configuration of the waveguide includes determining the configuration with respect to the first axis based on respective groups peaks or troughs in an input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the configuration with respect to the second axis based on the peaks or troughs in the respective groups of peaks and troughs.

[0218] Example 12. The computer implemented method of example 1 1 , wherein determining the configuration with respect to the first axis is based on a distribution of the groups peaks or troughs, and determining the configuration with respect to the second axis is based on a distribution of the peaks or troughs within the respective groups of peaks and troughs.

[0219] Example 13. The computer implemented method of any one of examples 1 to 12, wherein the method further comprises at least one of: detecting an object proximate to the waveguide, based on the received data; detecting damage to the waveguide, based on the received data; filtering the received data, prior to determining the information indicative of the deformation, to remove features of the data associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide; omitting, from data used in the determining, a frequency range associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide; and selecting, for use in the determining, data indicative of propagation of magnetoinductive orelectroinductive waves in the waveguide that corresponds to a time window during which at least one of data or power transfer with components external to the waveguide is suspended.

[0220] Example 14. The computer implemented method of any one of examples 1 to 13, wherein first and second resonator elements of the plurality of resonator elements are respectively associated with first and second portions of a robot, wherein the first and second portions are movable with respect to each other such that relative movement of the first and second portions causes deformation of the waveguide.

[0221] Example 15. The computer implemented method of example 14, wherein first and second portions are included in a part of the robot that is: a soft robotics component of the robot, an articulated soft robotics component of the robot, a continuum soft robotics component of the robot, a rigid robotics component of the robot, a robotic limb driven by hydraulic or pneumatic actuators, or a compliant mechanism.

[0222] Example 16. Computer readable instructions that, when performed by a processing device, cause the processing device to carry out the computer implemented method of any one of examples 1 to 15.

[0223] Example 17. A computer readable storage medium storing instructions that, when performed by a processing device, cause the processing device to carry out the computer implemented method of any one of examples 1 to 15.

[0224] Example 18. A processing device arranged to determine a configuration of a deformable object, the device comprising: memory circuitry to store instructions; and processing circuitry to perform the instructions, wherein the instructions are to cause the processing circuitry to: receive data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements, the plurality of resonator elements including at least first and second resonator elements, the first and second resonator elements are arranged to change their relative pose when the configuration of the deformable object is changed, wherein the relative pose describes at least one of (i) relative positions of the first and second resonator elements, and (ii) relative orientations of the first and second resonator elements; and determine, based on the received data, information indicative of the configuration of the deformable object.

[0225] Example 19. A robotic component comprising: a first portion; a second portion, the second portion moveable relative to the first portion; and a pose sensor, the pose sensor comprising: a magnetoinductive or electroinductive waveguide comprising a plurality of magnetoinductively or electroinductively coupled resonant elements, the resonant elements including a first resonant element and a second resonant element, the first resonant element arranged to move with the first portion and the second resonant element arranged to move with the second portion.

[0226] Example 20. The robotic component of example 19, further comprising an input component and a receiver component, the input component to supply at least one of power and data to the waveguide, and the receiver component to receive the at least one of power and data via the waveguide.

[0227] Example 21 . The robotic component of example 19 or example 20, wherein the robotic component is selected from: a complaint mechanism, a soft robotic limb, a articulated soft robotic limb, a continuum soft robotic limb, a rigid robotic limb, or a robotic limb driven by hydraulic or pneumatic actuators.

[0228] Example 22. The robotic component of any one of examples 19 to 21 , further comprising processing circuitry arranged to receive data describing propagation of magnetoinductive or electroinductive waves in the waveguide and to determine a pose of the robotic component based on the received data.

[0229] Example 23. The robotic component of any one of examples 19 to 22, wherein at least one of: the first resonant element, or a carrier of the first resonant element is slidably in contact with the second resonant element, or a carrier of the second resonant element; the first and second resonant elements are arranged relative to each other in a scale-like or shingle-like arrangement; the first and second resonant elements overlap in a direction perpendicular to the first resonant element, a direction perpendicular to the second resonant element, and a direction perpendicular to a line between the respective centres of the first and second resonant elements; the first resonant element obliquely overlaps the second resonant element; the first and second resonant elements are parallel and offset, or parallel and staggered.

[0230] Example 24. The robotic component of any one of examples 19 to 22, wherein the first and second resonator elements are arranged obliquely on a substrate, such that the first and second resonator elements overlap each other.

[0231] Example 25. A method of producing a configuration sensor for a robot, the method comprising: providing, a first resonant element that is arranged to move with a first portion of the robot, the first resonant element being a resonant element of a magnetoinductive or electroinductive waveguide of resonant elements; and providing a second resonant element that is arranged to move with a second portion of the robot, the second resonant element being a resonant element of the waveguide of resonant elements, wherein magnetoinductive or electroinductive coupling between the first and second resonant elements is dependent on a relative pose of the first and second elements.

Claims

CLAIMSWhat is claimed is:1 . A computer implemented method comprising: receiving data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements; and determining, based on the received data, information indicative of a configuration of the waveguide.

2. The computer implemented method of claim 1 , wherein at least one of: the determining includes obtaining, from the received data, time-domain data indicative of reflected magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the time-domain data; and the determining includes obtaining, from the received data, frequency-domain data indicative of a input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the deformation based, at least in part, on the frequency-domain data.

3. The computer implemented method of claim 2, wherein determining the deformation based on the frequency-domain data includes determining frequencies corresponding with peaks or troughs in the input scattering parameter spectrum.

4. The computer implemented method of claim 3, wherein determining the deformation includes determining one or more frequency shifts, relative to a input scattering parameter spectrum of a reference configuration, of the peaks or troughs in the input scattering parameter spectrum.

5. The computer implemented method of any one of claims 2 to 4, wherein determining the deformation based on the frequency-domain data includes determining the deformation based on at least one of: frequencies of peaks or troughs in the input scattering parameter spectrum, amplitudes of peaks or troughs in the input scattering parameter spectrum, or widths of peaks or troughs in the input scattering parameter spectrum.

6. The computer implemented method of claim 5, wherein determining the deformation based on the frequency-domain data includes determining that the frequencies of peaks or troughs are consistent with a first configuration or a second configuration, and determining that the configuration of the waveguide is the first configuration and not the second configuration based on at least one of the amplitudes of peaks or troughs or the widths of peaks or troughs.

7. The computer implemented method of claim 5 or claim 6, wherein determining information indicative of the configuration of the waveguide includes selecting, based on at least one of the amplitudes of peaks or troughs or the widths of peaks or troughs, between a plurality of configurations consistent with the frequencies of peaks or troughs.

8. The computer implemented method of any one of claims 1 to 7, further including obtaining data indicative of mechanical constraints on the configuration of the waveguide, wherein determining information indicative of the configuration of the waveguide includes determining information indicative of the configuration based on the mechanical constraints.

9. The computer implemented method of claim 8, wherein determining information indicative of the configuration of the waveguide includes selecting, based on the mechanical constraints, between a plurality of configurations consistent with the received data indicative of propagation of magnetoinductive or electroinductive waves.

10. The computer implemented method of any one of claims 1 to 9, wherein determining information indicative of the configuration of the waveguide includes determining the configuration with respect to a first axis and a second axis, wherein a mutual coupling between resonator elements adjacent to each other along the first axis is different from a mutual coupling between resonator elements adjacent to each other along the second axis.11 . The computer implemented method of claim 10, wherein determining information indicative of the configuration of the waveguide includes determining the configuration with respect to the first axis based on respective groups peaks or troughs in an input scattering parameter spectrum of the magnetoinductive or electroinductive waves, and determining the configuration with respect to the second axis based on the peaks or troughs in the respective groups of peaks and troughs.

12. The computer implemented method of claim 1 1 , wherein determining the configuration with respect to the first axis is based on a distribution of the groups peaks or troughs, and determining the configuration with respect to the second axis is based on a distribution of the peaks or troughs within the respective groups of peaks and troughs.

13. The computer implemented method of any one of claims 1 to 12, wherein the method further comprises at least one of: detecting an object proximate to the waveguide, based on the received data; detecting damage to the waveguide, based on the received data; filtering the received data, prior to determining the information indicative of the deformation, to remove features of the data associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide;omitting, from data used in the determining, a frequency range associated with at least one of power or data carried via the waveguide to be provided to or from a component external to the waveguide; and selecting, for use in the determining, data indicative of propagation of magnetoinductive or electroinductive waves in the waveguide that corresponds to a time window during which at least one of data or power transfer with components external to the waveguide is suspended.

14. The computer implemented method of any one of claims 1 to 13, wherein first and second resonator elements of the plurality of resonator elements are respectively associated with first and second portions of a robot, wherein the first and second portions are movable with respect to each other such that relative movement of the first and second portions causes deformation of the waveguide.

15. The computer implemented method of claim 14, wherein first and second portions are included in a part of the robot that is: a soft robotics component of the robot, an articulated soft robotics component of the robot, a continuum soft robotics component of the robot, a rigid robotics component of the robot, a robotic limb driven by hydraulic or pneumatic actuators, or a compliant mechanism.

16. Computer readable instructions that, when performed by a processing device, cause the processing device to carry out the computer implemented method of any one of claims 1 to 15.

17. A computer readable storage medium storing instructions that, when performed by a processing device, cause the processing device to carry out the computer implemented method of any one of claims 1 to 15.

18. A processing device arranged to determine a configuration of a deformable object, the device comprising: memory circuitry to store instructions; and processing circuitry to perform the instructions, wherein the instructions are to cause the processing circuitry to: receive data indicative of propagation of magnetoinductive or electroinductive waves in a magnetoinductive or electroinductive waveguide, the waveguide including a plurality of resonator elements, the plurality of resonator elements including at least first and second resonator elements, the first and second resonator elements are arranged to change their relative pose when the configuration of the deformable object is changed, wherein the relative pose describes at least one of (i) relative positions of the first and second resonator elements, and (ii) relative orientations of the first and second resonator elements; and determine, based on the received data, information indicative of the configuration of the deformable object.

19. A robotic component comprising: a first portion; a second portion, the second portion moveable relative to the first portion; and a pose sensor, the pose sensor comprising: a magnetoinductive or electroinductive waveguide comprising a plurality of magnetoinductively or electroinductively coupled resonant elements, the resonant elements including a first resonant element and a second resonant element, the first resonant element arranged to move with the first portion and the second resonant element arranged to move with the second portion.

20. The robotic component of claim 19, further comprising an input component and a receiver component, the input component to supply at least one of power and data to the waveguide, and the receiver component to receive the at least one of power and data via the waveguide.21 . The robotic component of claim 19 or claim 20, wherein the robotic component is selected from: a complaint mechanism, a soft robotic limb, a articulated soft robotic limb, a continuum soft robotic limb, a rigid robotic limb, or a robotic limb driven by hydraulic or pneumatic actuators.

22. The robotic component of any one of claims 19 to 21 , further comprising processing circuitry arranged to receive data describing propagation of magnetoinductive or electroinductive waves in the waveguide and to determine a pose of the robotic component based on the received data.

23. The robotic component of any one of claims 19 to 22, wherein at least one of: the first resonant element, or a carrier of the first resonant element is slidably in contact with the second resonant element, or a carrier of the second resonant element; the first and second resonant elements are arranged relative to each other in a scale-like or shingle-like arrangement; the first and second resonant elements overlap in a direction perpendicular to the first resonant element, a direction perpendicular to the second resonant element, and a direction perpendicular to a line between the respective centres of the first and second resonant elements; the first resonant element obliquely overlaps the second resonant element; the first and second resonant elements are parallel and offset, or parallel and staggered.

24. The robotic component of any one of claims 19 to 22, wherein the first and second resonator elements are arranged obliquely on a substrate, such that the first and second resonator elements overlap each other.

25. A method of producing a configuration sensor for a robot, the method comprising: providing, a first resonant element that is arranged to move with a first portion of the robot, the first resonant element being a resonant element of a magnetoinductive or electroinductive waveguide of resonant elements; and providing a second resonant element that is arranged to move with a second portion of the robot, the second resonant element being a resonant element of the waveguide of resonant elements, wherein magnetoinductive or electroinductive coupling between the first and second resonant elements is dependent on a relative pose of the first and second elements.

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