Optical based force-torque sensor

Abstract

Systems relating to a force-torque sensor. A sensor that uses an optical-based system is disclosed. A light source emits a light that is received by an electrical component that produces a signal based on the amount of light received. The light may be received directly from the light source or after being reflected by a reflective surface. The light source and the electrical component may be embodied in a transducer. The sensor may use a flexure component that resiliently deforms when a force or moment is applied to the sensor. When the flexure component resiliently deforms, this causes the position and / or distance between the transducer and the reflective surface changes, thereby changing the signal produced by the transducer. By calibrating various forces and torques with signals from multiple transducers in the sensor, the sensor can be used to detect / assess directions and amounts of forces and torques applied to the sensor.

Description

OPTICAL BASED FORCE-TORQUE SENSORTECHNICAL FIELD

[0001] The present invention relates to a sensor for determining force and torque as applied to the sensor. More specifically, the present invention relates to a light or optical based force and torque sensor.BACKGROUND

[0002] With the expanding applications of robotics, robots are increasingly required to interact with people in unstructured environments. Ensuring user safety during Human-Robot Interaction (HRI) is a key concern in these scenarios. Robots can pose risks of physical injury to users through such events as unexpected collisions, pinching, and clamping.

[0003] These risks necessitate the design and implementation of comprehensive safety measures. To mitigate these risks, robots can be equipped with force sensors to detect their surroundings and these can help prevent accidents. Furthermore, when humans and robots are working together, they can accomplish tasks with greater efficiency than either can achieve alone. This enhanced efficiency motivates the integration of human-robot collaboration in manufacturing. Human-robot work cells can perform assembly tasks that typically require the separate efforts of humans and robots. By combining the strengths of humans and robots, human-robot work cells can achieve optimal performance.

[0004] Various attempts have been made to provide force and torque sensors. For example, sensors using strain gauges may be used to measure force and moments. However, it is crucial to keep the sensing element's displacement small while the structure endures significant external force and torque. This can be made possible by using a rigid metallic body and a specific sensor design. However, such measures can limit the sensor's use. The sensor's rigidity and size make it less suitable for applications needing human / machine interaction measurements.Hence, a flexible and lightweight sensor is more suitable for such applications that may involve human / machine interaction measurements or when robots interact with delicate objects with the potential of physical damage during contact.

[0005] One attempt at solving this issue may be found in US Patent 7,220,958. This reference discloses an external force detecting device comprises a hollow- cylindrical support section, an action section disposed centrally inside the support section, and an optical displacement sensor. The sensor includes, at the action section on its center axis: a light source to emit a light beam in a direction along the center axis of the action section, a light branching member to branch the light beam into three light beams to progress respectively in three directions oriented at an equiangular distance, and a light reflecting member to reflect the three light beams in a direction parallel to a plane perpendicular to the center axis. This sensor also includes, at the support section, three light receiving elements arranged in a rotation-symmetric manner at a 120 degree interval with their light receiving faces looking toward the center axis of the action section so as to receive respectively the three light beams reflected.

[0006] Another attempt at resolving these issues can be found in US Patent 9,989,427. This reference discloses a force sensor that includes: a base, a first movable portion arranged to face the base, a second movable portion arranged to face the first movable portion, a support that is provided on the base and that rockably supports the first movable portion and the second movable portion. The force sensor also includes a joint that is provided to the support and that rotatably supports the second movable portion, a first detection unit that can detect a force component causing the first movable portion and the second movable portion to rock, and a second detection unit that can detect a force component causing the second movable portion to rotate when external force is applied to at least one of the first movable portion and the second movable portion. In this system, the light emitter and the light sensor are within the same sensor.

[0007] A further system that relates to force sensors is disclosed in CN112213009. This reference discloses a multi-axis force sensor based on the optical principle. The sensor includes a sensing part and a cover part stacked on the upper side of thesensing part. The sensor has a hollow peripheral part and a bearing part arranged in the center of the peripheral part. The bearing part and the peripheral part are connected to the peripheral part through a plurality of elastic suspension beams evenly distributed on the outer peripheral side of the bearing part. The bearing part is under the action of external force deflection or movement relative to the peripheral portion. A first displacement detector for detecting the deflection or movement of the bearing part relative to the peripheral part is arranged between the cover part and the bearing part.

[0008] Another force sensor, disclosed in JP7013303, details a force sensor that comprises a support part, a force receiving part that is displaced with respect to the support part by action of an external force and an elastic connecting part for connecting the support part and the force receiving part. The sensor further comprises a displacement conversion part connected to the elastic connecting part and displaced in accordance with a load inputted to the force receiving part, a detection target provided in the displacement conversion part, a sensor substrate fixed to the support part, and a displacement detection element mounted on the sensor substrate. The detection target is arranged closer to a center axis of the force sensor than a junction vertical line passing through the center of a junction of the displacement conversion part and the elastic connecting part and parallel to the center axis, the normal of the detection target and the junction vertical line forming an angle larger than 0 degrees, the distance between the detection target and the support part in a direction in which the support part and the force receiving part are interconnected being made longer than the length of the displacement conversion part in a direction parallel to the junction vertical line.

[0009] While the above references disclose force sensors, none of these references disclose a force sensor that has multiple degrees of freedom and which can be used in multiple use cases. There is, therefore, a need for a force / torque sensor that is flexible in terms of applications and which can be adapted to different degrees of freedom.SUMMARY

[0010] The present invention provides systems and methods relating to a force-torque sensor. A sensor that uses an optical-based system is disclosed. A light source emits a light that is received by an electrical component that produces a signal based on the amount of light received. The light may be received directly from the light source or after being reflected by a reflective surface. The light source and the electrical component may be embodied in a transducer. The sensor may use a flexure component that resiliently deforms when a force or moment is applied to the sensor. When the flexure component resiliently deforms, this causes the position and / or distance between the transducer and the reflective surface changes, thereby changing the signal produced by the transducer. By judiciously calibrating various forces and torques with signals from multiple transducers in the sensor, the sensor can be used to detect / assess directions and amounts of forces and torques applied to the sensor.

[0011] In a first aspect, the present invention provides a force-torque sensor comprising:- at least one light source for emitting light;- at least one electrical component that produces an electrical signal that is proportional (but not necessarily linear) to a light input that said electrical component receives;- at least one reflecting surface for reflecting light from said light source to said at least one electrical component;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one reflecting surface and one of: said at least one electrical component and said at least one light source; wherein said light source emits light that is reflected by said at least one reflecting surface to said at least one electrical component, thereby causing said at least one electrical component to produce said electrical signal based on how much light is reflected to said at least one component by said at least one reflecting surface; andwherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one reflecting surface and said at least one electrical component, thereby changing how much light is reflected to said at least one electrical component by said at least one reflecting surface.

[0012] In a second aspect, the present invention provides a force-torque sensor comprising:- at least one light source for emitting light;- at least one electrical component that produces an electrical signal that is proportional to a light input that said electrical component receives;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one light source and said at least one electrical component; wherein said light source emits light to said at least one electrical component, thereby causing said at least one electrical component to produce said electrical signal based on how much light is received by said at least one component; and wherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one light source and said at least one electrical component, thereby changing how much light is received by said at least one electrical component.

[0013] In a third aspect, the present invention provides a force-torque sensor comprising:- at least one transducer, said at least one transducer comprising a light source for emitting light and at least one electrical component that produces an electrical signal that is proportional to a light input that said electrical component receives;- at least one reflecting surface for reflecting light from said light source to said at least one electrical component;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one reflecting surface said at least one transducer; wherein, for each transducer, said light source emits light that is reflected by a corresponding reflecting surface to said at least one electrical component on said transducer, thereby causing said at least one electrical component on said transducer to produce said electrical signal based on how much light is reflected to said at least one component by said at least one reflecting surface; and wherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one reflecting surface and said at least one transducer, thereby changing how much light is reflected to said at least one transducer by said at least one reflecting surface.

[0014] In a further aspect, the sensor comprises a plurality of transducers and a plurality of reflecting surfaces and each transducer comprises at least one of said at least one light source and at least one of said at least one electrical component and each specific transducer emits a light from said at least one light source on said specific transducer that is reflected from a corresponding reflecting surface to an electrical component on said specific transducer.

[0015] As another aspect, the sensor comprises a single flexure component and said single flexure component has a perimeter section that encompasses at least a part of a perimeter of said flexure component, a central section; and connecting sections that couple said center section to said perimeter section. At least one of said perimeter section, central section, and connecting sections is resiliently deformable. In one variant, the connecting sections are resiliently deformable.

[0016] In a further aspect, each electrical component in said plurality of transducers has an axis of sensing that is perpendicular to a face of said electrical component and wherein, for at least one specific transducer in said plurality of transducers, an axis of sensing of an electrical component in said at least one specific transduceris perpendicular to an axis of sensing of at least one other transducer in said plurality of transducers.

[0017] As yet another aspect, at least one of said plurality of reflecting surfaces is mounted directly on said at least one flexure component.

[0018] In a further aspect, when said at least one flexure component resiliently deforms, said resilient deformation changes a position or a distance between said at least one reflecting surface and said at least one electrical component.

[0019] Yet another aspect provides that when said at least one flexure component resiliently deforms, said resilient deformation changes a position or a distance between said at least one reflecting surface and said at least one light source.

[0020] In another aspect, the sensor comprises one or more end stops that control an extent by which a position or distance between said at least one transducer and a corresponding reflective surface changes when said flexure component resiliently deforms.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The embodiments of the present invention will now be described by reference to the following figures, in which identical reference numerals in different figures indicate identical elements and in which:FIGURES 1-5 are schematic diagrams illustrating the various transducer concepts embodied in the present invention;FIGURES 6-7 illustrates a configuration of a sensor that uses a flexure component and transducers;FIGURES 8-11 illustrates different configurations for transducer placement;FIGURE 12 shows a configuration that uses multiple flexure components;FIGURES 13-22 illustrate different configurations for various flexure components;FIGURE 23 shows a configuration for a transducer holder for multiple transducers;FIGURE 24 is an exploded view of a sensor that uses the transducer holder shown in Fig. 23;FIGURE 25 shows another configuration for a transducer holder according to another aspect of the present invention;FIGURE 26 is an exploded view of a sensor that uses the transducer holder shown in Fig. 25;FIGURE 27 shows another configuration for a transducer holder according to a further aspect of the present invention;FIGURE 28 is an exploded view of a sensor that uses the transducer holder illustrated in Fig. 27;FIGURE 29 is an exploded view of another configuration for a transducer holder;FIGURE 30 illustrates the transducer holder in Fig. 29 integrated with a flexure component;FIGURE 31 is a top down view of the transducer holder shown in Fig. 29;FIGURE 32 is an exploded view of a sensor that incorporates the transducer holder shown in Fig. 29;FIGURE 33 is a view of a transducer that has multiple light sources (LEDs) and multiple LTVs;FIGURE 34 is a view of a transducer with a single LED and two LTVs;FIGURE 35 illustrates another transducer holder with multiple vertical and horizontal transducers;FIGURE 36 shows the transducer holder shown in Fig. 35 integrated with a flexure component;FIGURE 37 is an exploded view of a sensor that uses the transducer holder shown in Fig. 35;FIGURE 38 illustrates a further configuration for another transducer holder;FIGURE 39 is an exploded view of another sensor that uses the transducer holder shown in Fig. 38;FIGURE 40 is a detailed view of a portion of a transducer and a corresponding reflective surface mounted directly on a flexure component; andFIGURES 41-50 are exploded and side cutaway views of different configurations for sensors according to different aspects of the present invention.DETAILED DESCRIPTION

[0022] The force-torque sensor of one aspect of the present invention operates by using a light source, an electrical component that provides a signal (a voltage or a current) based on the amount of light the electrical component receives, a reflective surface, and a flexure component that resiliently deforms when a force or a torque (or a moment) is applied to the sensor. In operation, the light source emits a light that is reflected off of the reflective surface and the reflected light is received by the electrical component. The reflected light received by the electrical component causes the electrical component to produce a proportional signal. With no force or moment applied to the sensor, this proportional signal can operate as a baseline. When a force or torque is applied to the sensor, the flexure component resiliently deforms and the sensor is configured such that this resilient deformation changes or affects the relative distance or position betweenthe light source and the reflective surface or the relative distance or position between the reflective surface and the electrical component. The change in the relative distance or position caused by the resilient deformation affects the amount of reflected light received by the electrical component and, as such, affects the signal produced by the electrical component. Accordingly, by careful and judicious calibration between the baseline and the different forces applied to the sensor (and the differing signals produced by the electrical component for each of the different forces), the sensor can be used to determine an amount of force or moment (or torque) that is applied to the sensor.

[0023] It should, of course, be clear that the above concept can be extended to use transducers or devices that incorporate a light source and one or more electrical components. Multiple transducers, with suitable corresponding reflective surfaces can be incorporated into the sensor with suitably resiliently deformable flexure components to produce a sensor that not only can measure force and / or torque as applied to the sensor but can also provide an indication as to the direction of such force and / or torque.

[0024] Referring to Figs. 1-5, illustrated are different schematic drawings that explain the above concept. However, it should be noted that the drawings in Figs. 1-5 do not illustrate the flexure component that resiliently deforms when a force or torque is applied to the sensor.

[0025] For clarity, the term “resiliently deforms” or “resilient deformation” refers to a characteristic of a component such that when a force is applied to the component, at least a portion of that component elastically deforms. When the force is removed, the portion of the component that has deformed springs back or adjusts to the former configuration or shape prior to the application of that force. This feature or characteristic is similar to that of a coiled spring - when a force is applied to one end of the coiled spring, the spring compresses and, as the spring compresses, it deforms. Once the force has been removed, the spring resiliently returns to the former configuration it had prior to the application of force.

[0026] Referring to Fig. 1, illustrated are two platforms 10, 20. On platform 10 is a light source 30 adjacent an electrical component 40. As explained above, the electricalcomponent 40 produces a signal that is proportional to the amount of light it receives. In Fig. 1, a reflective surface 50 is on the underside of platform 10. The light source 30 produces a light that is reflected from the reflective surface and the reflected light is received by the electrical component. The component then produces its corresponding signal based on the amount of light it receives. If a force or torque is applied to the platform 10 and if a flexure component (that is resiliently deformable) is between the platforms 10, 20, the distance between platforms 10, 20 would be changed / adjusted. This would change the amount of light received by the component 40 as the distance between the light source and the reflective surface (and the distance between the component 40 and the reflective surface) would be changed.

[0027] Referring to Fig. 2, illustrated is another configuration of the concept illustrated in Fig. 1. However, in this configuration, a single light source 30 will have its light reflected from the reflective surface 50 to multiple components 40. Again, a flexure component is not illustrated but, as force or torque is applied to one or both of the platforms 10, 20, the distance and the relative position between the light source, the reflective surface, and the various components 40 are changed / affected. This causes the amount of reflected light received by the components 40 to change, thereby changing the signal produced by each of the components 40.

[0028] Referring to Fig. 3, illustrated is yet another configuration of the concept illustrated and applied in the present invention. In this configuration, instead of a single light source, there are light source-electrical component pairs. Each light source-component pair may have a dedicated corresponding reflective surface or the whole underside of the platform 10 may be reflective. As can be seen, there are 3 light source-component pairs A, B, C. Depending on the configuration of the flexure components used, different signals may result from the various electrical components depending on the amount, location, and direction of force or torque applied to the platform 10. By properly calibrating component outputs with the amount, direction, and location of forces / torques, the system in Fig. 3 can be used to determine the force / torque applied to the platform 10.

[0029] Referring to Fig. 4, illustrated is a configuration that does not use a reflective surface. As can be seen, the light source 30 is placed directly opposite the electrical component 40. Changes in position / distance between the platforms 10, 20 would change the amount of light that the component 40 receives directly from the light source.

[0030] Referring to Fig. 5, yet another configuration is illustrated. In this configuration, again without a reflective surface, a single light source 40 provides light that is received by different electrical components 40. As with Fig. 4, the components 40 are positioned on the underside of platform 10 while the light source is placed atop platform 20. For this configuration, all the components 40 receive light from the light source. As can be imagined, any sideways directed force on the platform 10 would cause the components 40 to receive more or less light relative to baseline / no force applied. This would, of course, cause the different components to produce different signal values. Again, by judiciously calibrating the resulting signals with the forces / directi on of forces applied, the system can be used to determine an amount and / or direction of forces / torques applied to the system.

[0031] Referring to Fig. 6 and Fig. 7, illustrated is an implementation of the present invention. For this implementation, however, transducers are used. For clarity, each transducer is a device that combines a light source with an electrical component as explained above. Transducers are used with one or more reflective surfaces to reflect the light produced from the light source back to the transducer to be received by the electrical component in the transducer. As can be seen in Fig. 6, each transducer 60 has a corresponding reflective surface 50. The surface 50 reflects the light from the transducer back to the transducer. As can also be seen in Fig. 6, a flexure component 70 is present and is illustrated. In this implementation, the flexure component 70 is a coiled spring. As will be explained below, the flexure component may take other forms / configurations.

[0032] Referring to Fig. 7, illustrated is the sensor in Fig. 6 when a force is applied to the sensor. As can be seen, the force is directed to the right of the figure and is greater on the right side of platform 10 than on the left side of platform 10. This force would, as can be seen, change the position and distance between the varioustransducers and their corresponding reflective surfaces. This would cause signals from the components that would be different from when the sensor has no force applied to it. By careful and judicious calibration between the different signals from the different components for different forces / torques, the sensor can be used to determine not just the amount of force applied to the sensor but also the direction of the force and / or torque applied to the sensor.

[0033] For clarity, each electrical component would have an axis of sensing - an axis that is normal to the plane of the electrical component’s light sensor. Thus, light directly on this axis of sensing would, depending on the brightness of the light, would result in the largest signal generated by the electrical component.

[0034] Referring to Fig. 8, illustrated is a configuration for paired transducers. Each transducer 100A in Fig. 8 is paired with another transducer 100B. Paired transducers may have their axes of sensing be at right angles or be perpendicular to one another. Thus, as can be seen in Fig. 8, for each pair of transducers, one transducer 100A has an axis of sensing that is parallel to the plane of the plate 10 (and tangential to the center axis of the plate 20) while another transducer 100B has an axis of sensing that perpendicular to the plane of the plate 20. Each transducer has, of course, a corresponding reflective surface. The use of three paired transducers, each pair being positioned at an arc of 120 degrees from adjacent pairs, allows for suitable coverage regardless of the force or torque applied. This configuration ensures that any force or torque that is applied to the sensor, as long as the force or torque has a component that is parallel or perpendicular to any of the axes of sensing of the various transducers, causes that force or torque to be detected. This detection causes a change in the signal output of one or more transducers and forces that cause this can thus be adjusted or calibrated for.

[0035] Referring to Fig. 9, illustrated is another configuration for transducers. As can be seen, this configuration uses three transducers, with each transducer having an axis of sensing that is perpendicular to the axes for the other transducers. As with the configuration in Fig. 8, each transducer in this configuration would have a corresponding reflective surface. The configuration in Fig. 9 would allow for greater sensitivity to different forces and torques applied to the sensor.

[0036] Referring to Fig. 10, illustrated is a schematic configuration for transducers. In this configuration, each transducer is provided with a corresponding reflective surface. The bottom transducer allows for vertical forces to be detected and quantified while the four horizontal transducers (each having an axis of sensing that is orthogonal to that of the bottom transducer) allows for greater sensitivity to directional forces and / or torques applied to the sensor. For clarity, each of the transducers in this configuration may have more than one electrical component to sense the reflected light.

[0037] Referring to Fig. 11, illustrated is a configuration similar to that in Fig. 8 but which allows for greater sensitivity to the forces and torques applied to the sensor. When calibrating a sensor with transducers in this configuration, the calibration is easier than with the configuration in Fig. 8 as the greater number of transducers allow for a larger data set of resulting signals for each applied force / torque.

[0038] Referring to Fig. 12, illustrated is a configuration that uses coiled springs as the flexure components. This configuration features an array of legs 110 that connect a top plate 10 with a bottom plate 20. In one configuration, the bottom plate is a fixed base part and the top plate is a moving tool mounting part. The legs 110 would have a certain spring rate that would create a usable displacement for the transducers for a given load. The pitch circle for the mounting of the legs allows for the customization of the rotational stiffness for the sensor. In this configuration, the farther the legs are spread from the center of the sensor, the stiffer the sensor is in all three of its rotational axes. While only three legs are shown, more legs may be used to generate a more uniform stiffness matrix. Different materials for the legs may be selected depending on the application. When impact resistance is crucial and hysteresis is not an issue, the legs may be made from an elastomer or soft polymer. In use cases where rigidity and low hysteresis is required, metallic springs may be used as the legs.

[0039] Referring to Figs. 13-22, illustrated are different configurations for different flexure components that may be used as part of sensors according to the present invention. These flexure components are configured to be underneath the top plate / gasket / adaptor of a sensor and either above or at the same level as thereflective surfaces and / or the transducers. To reiterate, these flexure components are configured such that any force or torque applied to the sensor causes a change in position and / or distance between a reflective surface and a transducer. As can be seen, these flexure components are configured such that a force or a torque on any part of the plate / gasket / adaptor of the sensor causes resilient deformation of at least part of the flexure component. This resilient deformation of the flexure component causes a change in the relative positions of at least one transducer (in the sensor) and its associated or corresponding reflective surface and / or causes a change in the distance between at least one transducer (in the sensor) and its associated or corresponding reflective surface.

[0040] As can be seen, the flexure components in Figs. 13-22 have a configuration that is a spring plate. The configuration of the spring plate may be selected depending on the desired stiffness matrix of the sensor so as to generate uniform displacements according to different loading scenarios. Parametric values can be manipulated in each design to further refine the performance of the sensor. Generating uniform displacements allows the sensor to increase its resolution, resulting in more accurate and less noisy data. The sensor may be configured to use mechanical end stops that are either integrated into the flexure component design or configured to work with the flexure component to protect the sensor from overloading. Such mechanical end stops allow the sensor to not rely on the designed safety factor of spring legs (incorporated into the sensor) for its overload capacity.

[0041] The material for the flexure component may be carefully chosen. For example, according to one embodiment of the present invention, the material for the flexure component may be a heat treated steel alloy to meet the demanding requirements of robotic applications, ensuring that the component can withstand repeated loading. Choice of material for the flexure component would preferably strike a balance between durability and flexibility, while also minimising hysteresis and creep. Both material selection and manufacturing process take these factors into consideration to achieve optimal performance, thus a material that is similar to or different from heat treated steel alloys may be used. Other materials such carbon-fibre reinforced plastics may, of course, be used. Materialsthat have the properties of stiffness and elasticity, as well as durability and flexibility, may be used.

[0042] For clarity, it can be seen from Figs. 13-22 that each flexure component has a center portion 200, a perimeter portion 210, and connecting sections 220. The center portion 200 is connected to the perimeter portion 210 by way of the connecting sections 220. It can also be seen that, for at least some of the flexure component configurations, the connecting sections are sinuous or serpentine in configuration. All or at least some of these portions (the center portion, perimeter portion, and connecting sections) may be resiliently deformable such that at least part of the flexure component resiliently deforms to reflect a force or torque applied to the sensor. The perimeter portion encompasses or surrounds at least part of the perimeter of the flexure component. There may, of course, be gaps in the perimeter portion such that not all of the flexure component’s perimeter is covered / encompassed. The connecting sections 220 may be serpentine or sinuous in configuration.

[0043] It should be clear that the electrical component may be a light-to-voltage (LTV) converter and the light source may be a LED (light emitting diode). Accordingly, each transducer may include one or more light emitter diodes (or LED) and one or more LTVs, where light emitted from the light transceiver is reflected at a corresponding reflective surface and back to the light transceiver, where the LTV(s) would generate output dependent on the distance between the light transceiver and the reflective surface. Of course, an electrical component that produces a current dependent on the light received may also be used.

[0044] For a calibrated sensor with multiple transducers, the outputs of all the transducers would be passed to a function / model running on a data processor and the function / model would generate data relating to forces and estimated displacements (and / or torque directions / force amounts). The resulting data can then be communicated through analog or digital interfaces to a computer or robot controller. The function / model may be an executable / computer implemented system / method, which may be executed on a processing unit, such as microprocessor, digital signal processor, etc. To achieve required accuracy, thefunction / model would be built through a calibration / optimization algorithm / process.

[0045] As will be explained below, the various implementations of the present invention may use a transducer holder component. Such a component operates by holding in place at least some of the sensor’s transducers such that the flexure component(s), when resiliently deforming, changes the position or distance of one or more reflective surfaces. Accordingly, transducer holders are the structural components that hold the transducers in the sensor. These holders can be one or more components that hold the LTV (the electrical component) devices and may also hold the reflectors (providing the reflective surfaces) at their respective location inside the sensor. The transducer holder may be mounted inside the sensor and may be mounted such that the holder is fixed inside the sensor while the flexure component provides at least some of the movable / deformable parts of the sensor. For such a configuration, the reflective surfaces may be mounted on the flexure component or on a sensor part that moves / deforms with the resilient deformation of the flexure component. Such a mounting and such movable characteristic of the reflective surfaces causes the differing signals from the transducers resulting from applied forces and / or moments to the sensor. The transducers can be installed onto the holders in a variety of ways including mechanical snap-in or bolting to bonding by way of adhesive or soldering. The material of the holder may be composed of polymer, composite, and / or metallic materials.

[0046] It should be clear that the transducer holder component may be designed as a distinct unit to simplify the individual installation of transducers.

[0047] Referring to Fig. 23, illustrated is one configuration for a transducer holder component. As can be seen, multiple windows are provided on the holder 260 such that transducers 270 can be mounted on the holder 260. The windows allow each transducer’s light to shine on a reflective surface and for the reflected light to return to the transducer. For clarity, the holder in Fig. 23 uses 9 transducers divided into three groups of transducers, each group having a bottom transducer (with an axis of sensing that is coplanar with the sensor’s vertical axis), and two horizontal transducers with axes of sensing that are perpendicular to each otherand to the axis of sensing of the bottom transducer. For clarity, window 250A is for a bottom transducer while windows 250B, 250C are for the horizontal transducers.

[0048] Referring to Fig. 24, illustrated is an exploded view and an assembled view of a sensor according to one implementation of the present invention. As can be seen, the sensor uses stacked layers that include the flexure component 280, the holder 260, a top plate (adaptor) 290, a gasket 300, and a base 310.

[0049] Referring to Fig. 25, illustrated is an exploded view and an assembled view of another transducer holder according to another aspect of the present invention. As can be seen, this holder 315 uses eight transducers, with three vertical transducers 320 and five horizontal transducers 330. As explained above, a vertical transducer has an axis of sensing that is parallel to a vertical axis of the sensor while a horizontal transducer has an axis of sensing that is perpendicular to the vertical axis of the sensor.

[0050] Referring to Fig. 26, illustrated is an exploded view of a sensor that uses the transducer holder shown in Fig. 25. As can be seen, this sensor uses a gasket clamp 335, a top plate 340, a gasket 345, a flexure component 350, multiple mirrors 355, multiple transducers 360, a transducer holder 365, and a base 370. The sensor illustrated in Fig. 26 also uses a stacked configuration with the flexure component 350 being sandwiched between the holder 365 and the top plate 340. The various components such as the holder 365 and the flexure component are contained within the base 370.

[0051] Referring to Fig. 27, illustrated is another assembled configuration for a reflective surface holder combined with flexure components and a transducer holder. For clarity, this configuration is similar to that illustrated in Fig. 8 with three sets of paired transducers. As can be seen, there are two flexure components 380 illustrated with another one not being visible in Fig. 27. One paired set of transducers is visible with a vertical transducer 385 having a light emitter 390 and an LTV (electrical component) 400. The other transducer in this paired set is a horizontal transducer 405 and its corresponding reflective surface 410 is visible.Also visible is a holder 415 for the reflective surfaces. As can be seen, the flexure components may be springs.

[0052] Referring to Fig. 28, illustrated is an exploded view of a sensor that uses the assembly pictured in Fig. 27. This sensor includes a stacked configuration with a top plate 420, a reflective surface holder 425, flexure components 430, and transducer holder 435.

[0053] Referring to Fig. 29, illustrated is another configuration for a transducer holder according to another aspect of the present invention. As can be seen, the transducer holder 440 is three-sided (triangular) with a cavity 445 at each of the three sides to hold a transducer 450. A bottom transducer 455 is present that operates as a vertical transducer. The three transducers 450 are horizontal transducers. In the middle of the holder 440 is a cavity 460 for holding a multisided reflective surface holder. For clarity, each of the transducers 450, 455 have a corresponding reflective surface that is held / positioned on the reflective surface holder.

[0054] Referring to Fig. 30, illustrated is the transducer holder 440 underneath a flexure component 465. A better view of the transducer holder 440 is provided in Fig. 31. Fig. 31 is a top down view of the transducer holder 440 clearly illustrating the cavity 460 and the reflecting surface holder 470. As can be imagined, the reflecting surface holder 470 has four reflecting surfaces, each of which faces one of the transducers 450, 455. In one implementation of this configuration, each transducer contains two sets of LED / LTV sensors and the orientation of the sensors is selected such that every motion of the reflective surface holder due to external loads can be identified effectively. For instance, the vertical motion of the reflective surface holder can be detected by the set of LED / LTV sensors located at the bottom of the holder. Also, the lateral motion of the reflective surface holder can be detected by either of the side transducer boards depending on the direction of the motion. Furthermore, any rotational movement of the reflective surface holder will be detected through the combination of transducers in three different planes.

[0055] It should be clear that the reflective surface holder may be incorporated with the transducer holder and may be directly mounted on the surrounding sections of the flexure component to form an integrated flexure and sensing component. This particular combination streamlines the assembly process and enhances the precision of the reflected light direction by eliminating the effect of manufacturing and assembly tolerances.

[0056] Referring to Fig. 32, illustrated is an exploded diagram of a sensor that incorporates the components illustrated in Figs. 30-32. The sensor has a stacked configuration and includes a top plate (loading adaptor) 475, a gasket clamp 480, a sealing gasket 485, a flexure component 490, a reflecting surface holder 470, a transducer holder 440, and transducers 450. These components are held in a base 495.

[0057] Referring to Fig. 33, illustrated is one configuration for a transducer. As can be seen, this transducer has multiple LED elements 500 and multiple electrical components 505 that generate signals based on the amount of light it receives. Referring to Fig. 34, illustrated is another configuration for a transducer. In this configuration, only one LED 500 is present while there are two transducers 505. These transducers have axes of sensing that are parallel but the presence of two transducers allow for greater data gathering capabilities. It should be clear that, to facilitate the process of optical sensitivity analysis, a set of LED / LTV pairs may be assembled in the transducer. Based on the size of the force / torque sensor and the stiffness of the flexure component that dictates the maximum displacement of the reflective surface holder, one can choose how many and how far apart each set of LED / LTV pairs must be selected to provide the best output signal.

[0058] Referring to Fig. 35, illustrated is another configuration for a transducer holder according to another aspect of the present invention. As can be seen, this transducer holder 510 uses three grouped transducers with each group having three transducers - a vertical transducer 515 and two horizontal transducers 520A, 520B.

[0059] Referring to Fig. 36, illustrated is the transducer holder 510 in Fig. 35 integrated with a suitably configured flexure component 525. As can be seen, each transducer has a corresponding reflective surface that is mounted on a suitable reflective surface holder 530. The components illustrated in Fig. 35 and Fig. 36 are incorporated in the exploded view of a sensor in Fig. 37.

[0060] Referring to Fig. 37, the sensor illustrated uses a stacked configuration with an upper and a lower limiter or end stop. These upper and / or tower limiters may be used to ensure that the transducers do not overload. As should be clear, if the reflective surface is too close to the LTV / electrical component, the LTV may overload and the signal generated may be an erroneous one. Accordingly, the limiter(s) ensures that the flexure component does not resiliently deform so much that errors are generated / overloads occur with the LTV / electrical component. The sensor in Fig. 37 includes an upper limiter 535, a loading adaptor / top plate 540, a flexure component 550, a reflective surface holder 555, a transducer holder 560, transducers 565, a lower limiter 570, a ring 575, and a base 580. As can be imagined, overloads can occur if the reflective surface is too far from the LTV or too close to the LTV. Accordingly, to prevent both possibilities, upper and lower limiters (or end stops) may be used.

[0061] Referring to Fig. 38, a further configuration for a transducer holder 590 is illustrated. This configuration uses three horizontal transducers 600A, 600B, 600C each at an edge of the holder 590. Each of these three horizontal transducers is paired with an adjacent vertical transducer 610A, 610B, 610C. In the middle of the holder 590 are three further horizontal transducers in a triangular configuration, with two of these horizontal transducers 620A, 620B having a single LTV and one horizontal transducer 620C having two parallel LTVs. Fig. 38 shows, using arrows, the axes of sensing for these transducers.

[0062] Referring to Fig. 39, illustrated is an exploded view of a sensor that uses the transducer 590 as shown in Fig. 38. As can be seen, the sensor uses a loading adapter (top plate) 630, a gasket clamp 640, a gasket seal 650, the flexure component 660, a reflective surface component 670, the transducer holder 590, the horizontal transducers 600, and a base 680 to hold the various components.

[0063] Referring to Fig. 40, illustrated is a detail in the assembled sensor shown in Fig. 39. As can be seen, one of the horizontal transducers 600 is shown adjacent to its corresponding reflective surface 690. This reflective surface 690 is attached / placed on a wing or protruding part of the flexure component 660. As can be seen, any resilient deformation or movement of the flexure component changes the position and / or distance between the transducer and the reflective surface, thereby changing the signal produced by the transducer.

[0064] Referring to Fig. 41, illustrated is an exploded view of a sensor that uses a spring plate design for the flexure component. In this configuration, the reflective surface holder is mounted on the flexure component and the transducer holder is mounted onto a fixed base. This sensor configuration uses 3 vertical transducers, 3 horizontal transducers, and 2 radial transducers. The sensor uses a seal cap 700, a tool side adaptor (top plate) 705, a seal / gasket 710, a flexure component 715, an upper transducer holder 720, a reflective surface holder 725, a lower transducer holder 730, multiple transducers 735, and a fixed base 740. As can be seen, there are two transducer holders that sandwich the reflective surface holder. Fig. 42 is a side cutaway view of the assembled sensor.

[0065] Referring to Fig. 43 and Fig. 44 illustrates a sensor configuration that also uses a spring plate design for the flexure component. For this sensor, the reflective surface holder is mounted on the flexure component. As well, the transducer holder is mounted onto a fixed section of the flexure component. The sensor uses three vertical transducers, three horizontal transducers, and two radial transducers. Hard stops are utilized to prevent overloading. Fig. 43 and Fig. 44 shows the seal cap 750, the tool side adapter 755, a vertical hard stop 760, a seal 765, the flexure component 770 with integrated horizontal hard stops, the upper transducer holder 775, a reflective surface holder 780, a lower transducer holder 785, multiple transducers 790, and a fixed base 800.

[0066] As can be seen, Fig. 44 shows a portion of the inner workings of the sensor illustrated in Fig. 43. Fig. 44 is a close up view of the vertical hard stop, the flexure component, and of the upper and lower transducer holders. Similar to the configuration in Fig. 41, this configuration sandwiches the reflective surface holder between the upper and lower transducer holders. However, unlike theconfiguration in Fig. 41, this configuration uses vertical and horizontal hard stops. As well, in this configuration, the lower transducer holder is mounted directly onto the fixed portions of the flexure component instead of being mounted on to the fixed base. This mounting arrangement reduces the sensor’s sensitivity to thermal expansion by the structural components / parts.

[0067] Referring to Fig. 45 and Fig. 46, illustrated is another configuration for a sensor. For this sensor, the reflecting surfaces are directly mounted on resiliently deformable sections of the flexure component. This configuration does not have a reflective surface holder. This configuration uses four vertical transducers and four horizontal transducers, with the transducer holder being attached or coupled to the flexure component. Unlike other configurations, the horizontal transducers are located in the middle of the flexure component and this arrangement has the effect of reducing signal cross talk across different axes of motion. Hard stops or end stops are used to prevent overloading in all directions. As can be seen, the sensor has a tool side adaptor (top plate) 805, a seal 810, multiple vertical end stops 815, a flexure component 820, multiple reflective surfaces 825, multiple transducers 830, a transducer holder 835, and a fixed base 840. Fig. 46 is a side cutaway view of the assembled sensor.

[0068] Referring to Fig. 47 and Fig. 48, illustrated is a further sensor according to the present invention. In this configuration, the reflective surfaces are, again, mounted directly on the resiliently deformable sections of the flexure component and a separate reflective surface holder is not used. It should be noted that this sensor uses multiple separate transducer holders, each holder having a vertical and a horizontal transducer. Also, each transducer holder is coupled to a fixed section (a non-deformable section) of the flexure component. The sensor configuration uses four vertical transducers and four horizontal transducers. It should, however, be noted that the multiple transducer holders can be replaced by a single transducer holder to hold all the transducers. Much like the above sensors, this configuration uses hard stops to prevent overloading.

[0069] As can be seen in Fig. 47 and Fig. 48, the sensor has a tool side adaptor (top plate) 845, a seal 850, multiple vertical end / hard stops 855, multiple reflective surfaces 860, a flexure component 865, multiple transducers 870, multipletransducer holders 875, and a fixed base 880. Fig. 48 is a side cutaway view of the assembled sensor.

[0070] Referring to Fig. 49 and Fig. 50, illustrated is a sensor that is similar to the configuration shown in Fig. 32. This configuration uses a single reflective surface holder in the middle of a transducer holder similar to the configuration shown in Fig. 10. This configuration uses three to four horizontal transducers and one vertical transducer. Ideally, each transducer has at least two LTVs oriented all orthogonally to detect six degrees of freedom forces.

[0071] As can be seen from Fig. 49, this sensor has a tool side adapter (top plate) 885, a seal clamp 890, a seal 895, a flexure component 900, a reflective surface holder 905, a transducer holder 910, multiple transducers 915, and a fixed base 920. Fig. 50 is a side cutaway view of the assembled sensor.

[0072] In one embodiment, the sensor is a compliant six-degree freedom force / torque sensor that consists of a compliant mechanism that deflects under applied loads. The deflections can be measured through an array of eight optical displacement sensors (LTV boards) which are strategically placed in the sensor. Using calibration methods, reference data from another sensor and knowledge of the flexible stiffness, forces, and torques are calculated from the displacements observed by the optical sensors.

[0073] In one variant, the transducer holder is integrated with the flexure component. Such a configuration may effectively isolate any undesired slippage of the flexure component with respect to the sensor body from the transducer holder. Furthermore, installation of the transducers on the holder from the back side of the cavity may save the transducers from damage in the event of overloading and collision of the reflecting surface holder with the transducer.

[0074] It should also be noted that the orientation of the light source and / or electrical components on the transducer may be deliberately selected to be at desired angles to achieve different performance levels. For example, a perpendicular orientation for a double-LTV can enhance the sensor's sensitivity in horizontal and / or vertical directions.

[0075] Similarly, the position of a light source (e.g. an LED) on the transducers can be selected to optimize various performance measures, for example, to maximise the reflected light reaching the LTVs while ensuring isolation between each LTV.

[0076] Multiple transducers may be used to improve performance by providing the benefits of redundancy in sensing. A redundancy resolution / optimization or sensing fusion strategy can be used to process the information in case of redundancy in the number of transducers.

[0077] To counteract environmental temperature variations, the sensor may incorporate one or more temperature transducers. The temperature transducers may be positioned near the transducer holder and / or at the sensor's centre. These temperature transducers may be used when compensating for temperature changes. Through the calibration process, the sensor may be configured to efficiently nullify any temperature-related discrepancies, ensuring accurate and reliable performance across various applications.

[0078] For calibration, various measurements may be made under certain conditions. For example, the sensor may be provided with no displacement (i.e. 0 force / 0 torque). The light emitted from each LED would be reflected off from the corresponding reflecting surface, and reflected light may be reflected back to a specific portion / area of the LED / LTV transducer. Each LTV measures the light intensity and a record is made of the measurement as 0 force / 0 torque. This type of controlled measurements would be made through a number of specific force and torque conditions for calibration purposes. Calibration measurements may also be made through a temperature range to compensate for the environmental factor(s) for the measurement during its operation. These measurements are characterized and used as compensation values / factors for accurately measuring the toque / force under certain environmental conditions. Calibration data may be stored in a computing device, which may be on board with the sensor, or remotely located away from the sensor.

[0079] A sensor system that includes a sensor according to the present invention may include the force and torque sensor, a sensor box that is in communication withthe sensor and the sensor’s control system. Such a system may, of course, integrate a power supply / power adaptor from which the system receives power.

[0080] For such a system, the sensor box receives force and torque measurement data / information from the sensor and samples the data at specified frequencies and provides measured data to the control system. Calibration compensation may be carried out within the sensor box or / and the controller system. The sensor box may include the processor or micro controller such that it may incorporate all of or part of the features of the controller system. Additional or various interfaces may also be provided at the sensor box or / and the controller system including network interface (wired or wireless data communication). A terminal or a server may be used to communicate remotely with the sensor box and / or the controller system by way of a network. Of course, the sensor box may be located internal or external to the sensor assembly.

[0081] The sensor according to one aspect of the present invention uses transducers that have one or more light sources (such as LEDs) and one or more electrical components that produce a signal proportional to the amount of light that it receives. The light may be reflected from a reflective surface or the light may be received directly from a light source such as an LED. The sensor may use multiple transducers, each transducer having an axis of sensing that is perpendicular to a face or a plane of the transducer. The transducers may be grouped such that vertical transducers are grouped with horizontal transducers or a group may only use horizontal transducers. Horizontal transducers have their axes of sensing to be perpendicular to a vertical axis of the sensor while vertical transducers have their axes of sensing to be parallel to the vertical axis of the sensor. The axes of sensing for horizontal transducers may be perpendicular to the axes of sensing for vertical transducers. The sensor may be configured to have multiple layers and the sensor may use a flexure component with sections or portions of the flexure component being resiliently deformable. The whole flexure component may be resiliently deformable. When a flexure component resiliently deforms, this causes a change in the position and / or distance between a transducer and its corresponding reflective surface, thereby changing the signal produced by the transducer. Of course, resilient deformation of at least a portionof the flexure component may cause the position and / or distance between multiple transducers and their respective corresponding reflective surfaces to change, thereby changing the signals produced by these transducers. The resilient deformation of the flexure component occurs when a force, a moment, or a torque is applied to the sensor. By calibrating signals caused by specific forces / torques applied to the sensor, the sensor can be used to detect and quantify the force and / or torque applied to the sensor. To prevent overload conditions occurring on the sensor, the sensor may be equipped with horizontal and / or vertical hard stops. These hard stops are designed to limit the amount by which sections or portions of a flexure component resiliently deforms, thereby limiting the amount by which the position and / or distance between transducers and their corresponding reflective surfaces changes. Such hard stops prevent the transducers from being too close or too far from their corresponding reflective surfaces. Horizontal hard stops prevent too much change in this position and / or distance between transducers and reflective surfaces in a horizontal direction.Vertical hard stops prevent too much change in this position and / or distance between transducers and reflective surfaces in a vertical direction. For clarity, the sensor may use reflective surface holders and / or transducer holders. These may be incorporated in one or more layers of the assembled sensor. The reflective surfaces may, of course, be mounted directly on the flexure component. The transducer holders may take the form of multiple holders or may be a single component / layer in the assemble sensor.

[0082] Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. The examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, as used herein, the term “or” is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other.Additionally, when the term “data” is used, it should be appreciated that the data may in some cases include simply data or a particular type of data generated based on operation of algorithms and computational services, or, in some cases, the data may actually provide computations, results, algorithms and / or the like that are provided as services.

[0083] A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above all of which are intended to fall within the scope of the invention as defined in the claims that follow.

Claims

We claim:

1. A force-torque sensor comprising:- at least one light source for emitting light;- at least one electrical component that produces an electrical signal that is proportional to a light input that said electrical component receives;- at least one reflecting surface for reflecting light from said light source to said at least one electrical component;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one reflecting surface and one of: said at least one electrical component and said at least one light source; wherein said light source emits light that is reflected by said at least one reflecting surface to said at least one electrical component, thereby causing said at least one electrical component to produce said electrical signal based on how much light is reflected to said at least one component by said at least one reflecting surface; and wherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one reflecting surface and said at least one electrical component, thereby changing how much light is reflected to said at least one electrical component by said at least one reflecting surface.

2. The sensor according to claim 1 wherein said sensor comprises a plurality of transducers and a plurality of reflecting surfaces; wherein each transducer comprises at least one of said at least one light source and at least one of said at least one electrical component; andwherein each specific transducer emits a light from said at least one light source on said specific transducer that is reflected from a corresponding reflecting surface to an electrical component on said specific transducer.

3. The sensor according to claim 1 wherein said sensor comprises a single flexure component and said single flexure component comprises:- a perimeter section that encompasses at least a part of a perimeter of said flexure component;- a central section; and- connecting sections that couple said center section to said perimeter section.

4. The sensor according to claim 3 wherein at least one of said perimeter section, central section, and connecting sections is resiliently deformable.

5. The sensor according to claim 3 wherein said connecting sections are resiliently deformable.

6. The sensor according to claim 2 wherein each electrical component in said plurality of transducers has an axis of sensing that is perpendicular to a face of said electrical component and wherein, for at least one specific transducer in said plurality of transducers, an axis of sensing of an electrical component in said at least one specific transducer is perpendicular to an axis of sensing of at least one other transducer in said plurality of transducers.

7. The sensor according to claim 2 wherein at least one of said plurality of reflecting surfaces is mounted directly on said at least one flexure component.

8. The sensor according to claim 1 wherein when said at least one flexure component resiliently deforms, said resilient deformation changes a position or a distance between said at least one reflecting surface and said at least one electrical component.

9. The sensor according to claim 1 wherein when said at least one flexure component resiliently deforms, said resilient deformation changes a position or a distance between said at least one reflecting surface and said at least one light source.

10. A force-torque sensor comprising:- at least one light source for emitting light;- at least one electrical component that produces an electrical signal that is proportional to a light input that said electrical component receives;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one light source and said at least one electrical component; wherein said light source emits light to said at least one electrical component, thereby causing said at least one electrical component to produce said electrical signal based on how much light is received by said at least one component; and wherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one light source and said at least one electrical component, thereby changing how much light is received by said at least one electrical component.

11. The sensor according to claim 10 wherein, before being received by said at least one electrical component, light from said at least one light source is reflected by at least one reflecting surface to said at least one electrical component.

12. The sensor according to claim 10 wherein said sensor comprises a single flexure component and said single flexure component comprises:- a perimeter section that encompasses at least a part of a perimeter of said flexure component;- a central section; and- connecting sections that couple said center section to said perimeter section.

13. The sensor according to claim 12 wherein at least one of said perimeter section, central section, and connecting sections is resiliently deformable.

14. The sensor according to claim 12 wherein said connecting sections are resiliently deformable.

15. A force-torque sensor comprising:- at least one transducer, said at least one transducer comprising a light source for emitting light and at least one electrical component that produces an electrical signal that is proportional to a light input that said electrical component receives;- at least one reflecting surface for reflecting light from said light source to said at least one electrical component;- at least one flexure component that resiliently deforms when a force or a torque is applied to said sensor such that a resilient deformation of said at least one flexure component changes a position or a distance between said at least one reflecting surface said at least one transducer; wherein, for each transducer, said light source emits light that is reflected by a corresponding reflecting surface to said at least one electrical component on said transducer, thereby causing said at least one electrical component on said transducer to produce said electrical signal based on how much light is reflected to said at least one component by said at least one reflecting surface; and wherein when said force or torque is applied to said sensor, said at least one flexure component resiliently deforms to change said position or distance between said at least one reflecting surface and said at least one transducer, thereby changing how much light is reflected to said at least one transducer by said at least one reflecting surface.

16. The sensor according to claim 15 wherein said sensor comprises a single flexure component and said single flexure component comprises:- a perimeter section that encompasses at least a part of a perimeter of said flexure component;- a central section; and- connecting sections that couple said center section to said perimeter section.

17. The sensor according to claim 16 wherein at least one of said perimeter section, central section, and connecting sections is resiliently deformable.

18. The sensor according to claim 17 wherein said connecting sections are resiliently deformable.

19. The sensor according to claim 15 wherein each electrical component in said at least one transducer has an axis of sensing that is perpendicular to a face of said electrical component and wherein, for at least one other specific transducer, an axis of sensing of an electrical component in said at least one other specific transducer is perpendicular to an axis of sensing of at least one other transducer.

20. The sensor according to claim 15 wherein at least one of said plurality of reflecting surfaces is mounted directly on said at least one flexure component.

21. The sensor according to claim 15 wherein when said at least one flexure component resiliently deforms, said resilient deformation changes a position or a distance between said at least one reflecting surface and said at least one transducer.

22. The sensor according to claim 15 further comprising one or more end stops that control an extent by which a position or distance between said at least one transducer and a corresponding reflective surface changes when said flexure component resiliently deforms.

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