Methods and systems for calibrating deformable sensors using camera

#Embodiments described herein generally relate to calibrating contact sensors and, more particularly, to systems and methods for calibrating deformable contact and geometry/pose sensors using an imaging sensor.

#Contact sensors are used to determine whether or not one object is in physical contact with another object. For example, robots often use contact sensors to determine whether a portion of the robot is in contact with an object. Control of the robot may then be based at least in part on signals from one or more contact sensors. Robots are commonly equipped with end effectors that are configured to perform certain tasks. For example, an end effector of a robotic arm may be configured as a human hand, or as a two-fingered gripper. However, robots do not have varying levels of touch sensitivity as do humans. End effectors may include sensors such as pressure sensors, but such sensors provide limited information about the object that is in contact with the end effector. Thus, a deformable end effector may be desirable in robot-human interactions.

#In one embodiment, a system for calibrating a deformable sensor is provided. The system includes a deformable sensor including a housing, a deformable membrane coupled to an upper portion of the housing, and an enclosure defined by the housing and the deformable member; an imaging sensor configured to capture an image of the deformable membrane of the deformable sensor; and a controller. The enclosure is configured to be filled with a medium. The controller is configured to: receive the image of the deformable membrane of the deformable sensor; determine whether a contour of the deformable membrane in the image of the deformable membrane of the deformable sensor corresponds to a predetermined contour; and adjust a volume of the medium in the enclosure of the deformable sensor in response to the determination that the contour of the deformable membrane is different from the predetermined contour.

#The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

#FIG. 1A schematically depicts an elevation view of an example deformable sensor according to one or more embodiments described and illustrated herein;

#FIG. 1B schematically depicts a top perspective view of the example deformable sensor depicted by FIG. 1A according to one or more embodiments described and illustrated herein;

#Embodiments of the present disclosure are directed to calibrating a shape and/or size of deformable/compliant contact and/or geometry sensors (hereinafter “deformable sensors”) that detect contact. In order to appropriately detect the pressure or force by the deformable sensors, the deformable membrane of the deformable sensor may be maintained at a desired shape and/size. Embodiments of the present disclosure calibrate the size and shape of the deformable sensors using an imaging sensor external to the deformable sensors or an imaging sensor embedded within the deformable sensors. Particularly, the present disclosure provides a system for calibrating a deformable sensor. Systems of the present disclosure include a deformable sensor including a housing, a deformable membrane coupled to an upper portion of the housing, and an enclosure defined by the housing and the deformable member; an imaging sensor configured to capture an image of the deformable membrane of the deformable sensor; and a controller. The enclosure is configured to be filled with a medium. The controller is configured to receive the image of the deformable membrane of the deformable sensor, determine whether a contour of the deformable membrane in the image of the deformable membrane of the deformable sensor corresponds to a predetermined contour, and adjust a volume of the medium in the enclosure of the deformable sensor in response to the determination that the contour of the deformable membrane is different from the predetermined contour. By adjusting the volume of the medium in the deformable sensor based on the comparison between the captured image and the predetermined contour, the embodiments appropriately sets the size and shape of the deformable sensor before detecting an object using the deformable sensor. This allows precise sensing of an external object by the deformable sensor.

#Referring now to FIGS. 1A and 1B, an example deformable sensor 100 is schematically illustrated. FIG. 1A is a front elevation view of the example deformable sensor 100 and FIG. 1B is a top perspective view of the example deformable sensor 100. The example deformable sensor 100 generally comprises a housing 110 and a deformable membrane 120 coupled to the housing 110, such as by an upper portion 111 of the housing 110. The housing 110 and the deformable membrane 120 define an enclosure 113 that is filled with a medium through one or more passthroughs 112, which may be a valve or any other suitable mechanism. The passthrough 112 may be utilized to fill or empty the enclosure. In one example, the medium is gas, such as air. Thus, air may be pumped into the enclosure 113 to a desired pressure such that the deformable membrane 120 forms a dome shape as shown in FIG. 1, although any suitable shape may be utilized in other embodiments. The passthrough 112 may be connected to a pump 115 which provides gas, such as air, into the enclosure 113 or sucks the gas from the enclosure 113 to adjust the shape and/or size of the deformable membrane 120. In another example, the medium is a gel, such as silicone or other rubber-like substance. In some embodiments a substance such as solid silicone may be cast in a given shape before assembly of the deformable sensor 100. In various embodiments, the medium may be anything that is transparent to an internal sensor (discussed in more detail below), such as to a wavelength of a time of flight sensor. The medium may include clear/transparent rubbers in some embodiments. In other embodiments, the medium may be a liquid. In some examples, the deformable membrane 120 and the medium within the enclosure 113 may be fabricated of the same material, such as, without limitation, silicone. In some embodiments the deformable sensor 100 may be mountable. For example, the enclosure 113 may include brackets to be mounted any suitable object (such as a robot) or material. The deformable membrane 120 may be a latex or any other suitable material, such as a suitably thin, non-porous, rubber-like material.

#The deformability of the deformable sensor 100 may be tuned/modified by changing the material of the deformable membrane 120 and/or the pressure within the enclosure 113. By using a softer material (e.g., soft silicone), the deformable sensor 100 may be more easily deformed. Similarly, lowering the pressure within the enclosure 113 may also cause the deformable membrane 120 to more easily deform, which may in turn provide for a more deformable sensor 100. In some embodiments, robots feature varying touch sensitivity due to varying spatial resolution and/or depth resolution.