Contact sensor for mobile robot

Abstract

A robot includes a body and a bumper. The body is movable relative to a surface and includes a first portion of a sensor. The bumper is mounted on the body and is movable relative to the body and includes a support and a second portion of the sensor. The support is movable relative to the body in response to a force exerted on the bumper. The second portion of the sensor is attached to the support and is movable relative to the first portion of the sensor with the support in response to the force exerted on the bumper. The sensor is configured to output an electrical signal in response to movement of the support. The electrical signal is proportional to an amount of displacement of the second portion relative to the first portion.

Description

[0001] This application is a divisional application of the application patent application with the application date of November 20, 2015, the application number of 201511036126.5, and the invention name of "Contact sensor for mobile robot". TECHNICAL FIELD

[0002] This specification generally relates to contact sensors for mobile robots. BACKGROUND

[0003] Mobile robots operate by traveling around an environment. Mobile robots can include bumpers that contact obstacles encountered by the mobile robot in its travels. The mobile robot can modify its behavior in response to detection that the bumper has contacted an obstacle in the environment. For example, the mobile robot can return from the obstacle, or conversely change its path. In some mobile robots, the bumper includes a mechanical switch that provides a binary indication of whether the bumper has contacted an obstacle. SUMMARY

[0004] Bumpers of mobile robots can detect contact with obstacles in the environment using sensors that detect motion of the bumper. For example, each sensor can be a capacitive sensor having a plate that moves with the bumper relative to a chassis, and another plate that is fixed relative to the chassis. Due to movement of the bumper, movement of one plate relative to the other causes the capacitive sensor to output an electrical signal having a magnitude or value that is proportional to a distance between the plates. Thus, the electrical signal varies in value over a range depending on movement of the bumper. A controller interprets the electrical signal generated by the sensor to determine attributes of a force applied to the bumper, such as location, magnitude, and duration of the force. Various systems described herein are used to detect contact with a bumper of a mobile robot, forces applied to a bumper of a mobile robot, and displacement of a bumper of a mobile robot.

[0005] In one aspect, a robot includes a body and a bumper. The body is movable relative to a surface and includes a first portion of a sensor. The bumper is mounted on the body and is movable relative to the body and includes a carrier and a second portion of the sensor. The carrier is movable relative to the body in response to a force applied to the bumper. The second portion of the sensor is attached to the carrier and is movable relative to the first portion of the sensor with the carrier in response to the force applied to the bumper. The sensor is configured to output an electrical signal in response to movement of the carrier. The electrical signal is proportional to an amount of displacement of the second portion relative to the first portion.

[0006] In some cases, the sensor includes a capacitive sensor. The first portion can include a first plate of the capacitive sensor. The second portion can include a second plate of the capacitive sensor. The electrical signal can vary in proportion to an amount of displacement of the first plate relative to the second plate. The bracket can include rigid regions interconnected by a flexible region. At least one rigid region can include a stem that extends into and through a hole in the body. The second plate can be attached to the stem on a side of the body opposite the bracket. The second plate can move with the stem relative to the first plate. In some examples, the displacement of the first plate relative to the second plate can include a horizontal displacement parallel to the surface, and the electrical signal can vary in proportion to an amount of the horizontal displacement. In some examples, the displacement of the first plate relative to the second plate can include a vertical displacement perpendicular to the surface, and the electrical signal can vary in proportion to an amount of the vertical displacement.

[0007] The bumper can move between a compressed position and an uncompressed position. In some cases, in the uncompressed position, the first plate can contact the second plate, and in the compressed position, movement of the stem through the hole can cause separation between the first plate and the second plate. In some examples, in the uncompressed position, a distance between the first plate and the second plate is less than a distance between the first plate and the second plate in the compressed position.

[0008] In some examples, the first plate of the capacitive sensor can be attached to the body on a surface of the body facing the bracket, and the second plate can be attached to the bracket on a side of the bracket facing away from the body. A dielectric can be between the first plate and the second plate. The robot can include a spacer having a thickness. In some implementations, the spacer can connect the first plate to the body. A gasket can be between the first plate and the body. In some implementations, the gasket can connect the second plate to the bracket and can be between the second plate and the bracket.

[0009] The bracket can include an integrated structure having a substantially constant rigidity throughout. The bumper can have a generally rectangular shape. The bumper can include a skin covering at least a portion of the bracket, the skin being composed of a shock-absorbing material.

[0010] In some examples, the sensor can include an inductive sensor, the first portion of the sensor can include a coil of the inductive sensor, the second portion can include a core of the inductive sensor, and the electrical signal can vary in proportion to an amount of displacement of the coil relative to the core.

[0011] In other examples, the first portion of the sensor can include a Hall effect sensor, the second portion of the sensor can include a magnet, and the electrical signal can vary in proportion to an amount of displacement of the magnet relative to the Hall effect sensor.

[0012] In other aspects, a robot includes a body, a bumper, a first sensor, a second sensor, and a controller. The body is movable relative to a surface. The bumper is mounted on the body and movable relative to the body. The bumper includes a support movable relative to the body in response to a force exerted on the bumper. The first sensor outputs and / or is configured to output a first electrical signal that varies with an amount of movement of the bumper. At least a portion of the first sensor is mounted to the support. The second sensor outputs and / or is configured to output a second electrical signal that varies with the amount of movement of the bumper. At least a portion of the second sensor is mounted to the support. The controller receives and / or is configured to receive the first electrical signal and the second electrical signal. The controller determines and / or is configured to determine one or more properties of the force exerted on the bumper based on the first electrical signal and the second electrical signal.

[0013] The support can include a plurality of segments. The plurality of segments can include a first segment and a second segment. At least a portion of the first sensor is mounted to the first segment. At least a portion of the second sensor is mounted to the second segment. The plurality of segments can be interconnected by a connecting element to form an integrated structure. The connecting element can have a greater elasticity than the plurality of segments. The connecting element can include the same material as the plurality of segments. The connecting element can have a thickness less than a thickness of the plurality of segments. At least some of the plurality of segments can be separable from the remaining segments of the plurality of segments.

[0014] In some examples, the one or more properties can include a location of the force exerted on the bumper. The one or more properties can include a magnitude of the force exerted on the bumper. The one or more properties can include a frequency of the force exerted on the bumper, a duration of the force exerted on the bumper, and / or a dynamic response of the force exerted on the bumper.

[0015] The controller can be configured to execute instructions to determine the one or more properties by performing one or more interpolation processes based on the first and second electrical signals.

[0016] The support can have a first side in series with and angled relative to a second side. The support can include a first segment aligned with the first sensor on the first side and a second segment aligned with the second sensor on the second side. The first segment can be connected to the second segment by a connecting element having a length greater than a length from the first segment along the first side to the second segment along the second side. The connecting element can be angled away from the first segment on the first side. The connecting element can be angled away from the second segment on the second side. The connecting element can be curved relative to a path along the first side and the second side. The support can have a generally rectangular shape. The first side and the second side can be adjacent sides of the generally rectangular shape.

[0017] In some examples, the first and / or second electrical signal can vary linearly with movement of the bumper. In some examples, the first and / or second electrical signal can vary non-linearly with movement of the bumper.

[0018] The foregoing advantages can include, but are not limited to, the following: the sensor generates an electrical signal indicative of the angle of force caused by contact with an object in the environment, thus allowing the controller not only to detect whether the bumper is in contact with an object in the environment, but also to determine the location of the force on the bumper, the magnitude of the force on the bumper, and other properties of the force on the bumper. In response to detecting contact and determining properties of the contact, the controller can adjust the robot's behavior to avoid obstacles in the environment. The sensor system, which can also detect airborne obstacles, reduces the likelihood that the robot will become stuck between a hanging obstacle and a floor surface. In part due to the high sensitivity of the sensor, a bumper using the sensor described herein can reduce the number of movable components that are visible to a user of the robot. In addition, in part due to the high sensitivity of the sensor, small displacements (e.g., 1-3 mm) of the bumper's movable components can be accurately measured by the system, such that the total amount of movement of the movable components is reduced relative to a bumper based on mechanical switches. The sensor can be designed to obtain different degrees of responsiveness to forces along the bumper, thereby improving the robot's operation.

[0019] Any two or more of the features described in this specification, including in the SUMMARY section, can be combined to form implementations not specifically described herein.

[0020] The robots described in this specification, or aspects of their operation, can be implemented as, or controlled by, a computer program product including instructions stored on one or more non-transitory machine-readable storage media, and which is implemented on one or more processing devices to control (e.g., adjust) the operation of the robots described in this specification. The robots described in this specification, or aspects of their operation, can be implemented as part of a system or method that can include one or more processing devices and memory to store executable instructions to implement various operations.

[0021] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a perspective view of a mobile robot contacting an obstacle on the ground.

[0023] Figure 2 is a top cutaway view of a mobile robot including a bumper having a capacitive sensor.

[0024] Figure 3 is Figure 2 is a close-up view of a portion of the bumper.

[0025] Figure 4 is a perspective view of a bumper separated from a mobile robot. Figure 2Perspective view of the bumper.

[0026] Figure 5 Side perspective cutaway view of the capacitive sensor.

[0027] Figure 6 Figure 5 Side cutaway view of the capacitive sensor.

[0028] Figure 7 Block diagram of the mobile robot control system.

[0029] Figure 8A Figure 2 Top view of the mobile robot in contact with an object.

[0030] Figure 8B Figure 8A Graph of the electrical response due to contact between the mobile robot and an object in

[0031] Figure 9A Flowchart showing the flow applied by the mobile robot to detect contact with an obstacle.

[0032] Figure 9B Flowchart showing the flow to determine the location of contact in Figure 9A

[0033] Figure 9C Flowchart showing the flow to determine the size of contact in Figure 9B

[0034] Figures 10 to 12 Side cutaway view of an alternative capacitive sensor.

[0035] Figure 13 14 Top view of a mobile robot including an alternative bumper having a capacitive sensor.

[0036] Figure 15 16 Close-up view of a corner of an alternative bumper having a capacitive sensor.

[0037] Figure 17 Top view of the mobile robot in contact with an object.

[0038] Figure 18 Side view of an alternative capacitive sensor.

[0039] Figure 19 Figure 18 Perspective view of the capacitive sensor in

[0040] Figure 20 Side view of an alternative capacitive sensor. ​​​​​​​​

[0041] Figure 21 is Figure 20 perspective view of a capacitive sensor.

[0042] Figure 22 side view of a capacitive sensor.

[0043] Figure 23 side view of a mobile robot contacting an object.

[0044] Figure 24 side view of an inductive sensor for a bumper.

[0045] Figure 25 side view of a Hall effect sensor for a bumper. DETAILED DESCRIPTION

[0046] Described herein are example robots configured to move (or walk) back and forth on a surface, such as a floor, carpet, turf, or other material and perform various operations including, but not limited to, vacuuming, wet or dry mopping, polishing, etc. These robots can encounter obstacles that can impede their progress. For example, during operation, a robot can contact an obstacle, such as a chair or a wall. The robot determines that it has contacted the obstacle based on a force generated by contact between a bumper on the robot and the obstacle. A controller identifies the force based on signals output by a sensor that detects movement of the bumper in response to the force.

[0047] The sensor can employ various suitable sensing technologies. For example, a capacitive sensor can be used in which one plate of a capacitor is fixed relative to a chassis and the other plate of the capacitor moves relative to the chassis along with a bumper. The bumper can move in response to contact with an obstacle. The capacitive sensor outputs electrical signals that are proportional to displacement of the plates caused by movement of the bumper. These electrical signals can be interpreted (e.g., processed) by a controller to identify properties of the contact force, such as a location of the force and a magnitude of the force. Capacitive sensors such as those described herein, as well as other types of sensors also described herein, are advantageous because they can generate a range of electrical signals in response to contact and thus can provide improved obstacle detection.

[0048] Figure 1An example of a mobile robot 100 (also referred to as robot 100) that can detect contact with an obstacle in an environment and determine attributes of the contact is shown. In operation, the robot 100 travels along a floor 102 in an environment 103 and can contact an obstacle, such as a vertical surface, overhead surface, or other surface that can impede movement of the robot 100. During movement, a bumper 106 located in front of the robot 100 (relative to its direction of movement) contacts a chair 104. As the robot 100 contacts the chair 104, sensors in the robot 100 generate and output electrical signals that are proportional to the amount of movement of the bumper 106. A controller 110 in the robot 100 receives the electrical signals and uses them to determine one or more attributes of the force, such as the magnitude of the force, the direction of the force, the location of the force, or the duration of the force. Information such as the direction and location of the force can be used to determine the location of the obstacle in the environment 103 relative to the robot 100. The controller 110 can issue commands for travel and navigation based on the determined one or more attributes of the force. For example, the travel and navigation commands can instruct and cause the robot to avoid continued contact with the chair, travel along the chair, reduce the forward speed of travel, or perform other actions in response to the detection of contact with the chair 104.

[0049] Figure 2 and 3 An example structure of a bumper 200 mounted on a robot body 109 is shown. In this example, the bumper 200 is generally rectangular in shape. The bumper 200 is mounted on the front portion 108 of the robot and includes a front side 200F, a right side 200R, and a left side 200L. A left corner 201L connects the front side 200F and the left side 200L, and a right corner 201R connects the front side 200F and the right side 200R. The front side 200F and the sides 200R, 200L can be substantially perpendicular to each other, forming a partial (e.g., frontal) rectangular shape. The front side 200F can have a length between, for example, 15 cm and 30 cm, 30 cm and 45 cm, or 45 cm and 60 cm. The sides 200R, 200L can each have a length between, for example, 5 cm and 15 cm, 15 cm and 25 cm, or 25 cm and 35 cm. Generally, the front side 200F can extend across the entire width of the robot and be equal to the width of the robot and the sides 200R, 200L can be between 1 / 4 and 1 / 2 the length of the robot. For example, the sides 200R, 200L can have a length between 1 / 4 and 1 / 3 the length of the robot.

[0050] Although the bumper 200 has been described herein as being partially rectangular, it can also have other shapes described herein. In some embodiments, the angle between the front side 200F and the side 200R, 200L is any suitable angle, examples of which include, but are not limited to, angles between 85 and 95 degrees, 80 and 100 degrees, or 75 and 105 degrees. For any of the embodiments described herein, the front portion 108 of the robot body can be partially circular, semi-circular, triangular, Realeaux triangular, splined, or have any other suitable shape. In these cases, the bumper 200 can have a geometry that is different from the generally rectangular shape described herein.

[0051] The structure of the bumper 200 transfers the force resulting from contact such that the sensors in the bumper 200 can generate electrical signals based on the force. In particular, the sensors described herein can be used to detect a vertical force, a horizontal force, or a combination thereof, exerted on the bumper 200. With reference to Figure 2 The bumper 200 includes an outer skin 202 that at least partially (in this example, completely) covers the support 204. The support 204 is positioned between the robot body 109 and the outer skin 202. The outer skin 202 serves as the outer surface of the bumper 200 and comes into direct contact with objects located in the environment 103. Thus, when the outer skin 202 contacts an object in the environment 103, the outer skin 202 deforms, causing the support 204 to move closer to the robot body 109. The movement of the support 204 thereby causes the capacitive sensors 210a-210j (collectively referred to as capacitive sensors 210) of the bumper 200 to generate electrical signals that are responsive to the movement of the support 204. In some embodiments, the displacement of the support 204 relative to the robot body 109 is within a distance of, for example, 0 mm and 5 mm, 0 mm and 15 mm, and 0 mm and 25 mm. Due in part to the high sensitivity of the sensors, in some examples, the displacement of the support 204 relative to the robot body 109 is limited to between 1 mm and 5 mm to provide a bumper that appears substantially fixed to an observer.

[0052] The materials of the components of the bumper 200 can vary depending on the function of the component. The outer skin 202 can be a flexible, pliable material that allows forces applied to the outer surface of the bumper 200 that deform the outer skin 202 to be distributed relatively finely over small areas of the support 204. For example, the outer skin 202 can be an elastomeric or rubbery material such as polychloroprene, ethylene-propylene diene rubber, polyolefin thermoplastic elastomer, or thermoplastic vulcanizate. The outer skin 202 can have a low modulus of elasticity / modulus, such as 0.01 MPa to 1 MPa, 1 MPa to 10 MPa, or 10 MPa to 100 MPa. In some embodiments, the outer skin 202 is a single integrated element; however, the outer skin can be composed of two separate parts that split at the front side 200F of the bumper 200, each covering one of the sides 200R, 200L of the bumper 200.

[0053] All or part of the support 204 can be composed of a material that is stiffer than the outer skin 202. For example, the support can be composed of a rigid polymer such as polycarbonate, acrylonitrile butadiene styrene, or nylon; or the support can be composed of a sheet metal such as stainless steel and copper steel. In one particular embodiment, the support is composed of copper plated steel. In operation, the robot 100 contacts an object in the environment 103, the outer skin 202 deforms and transmits the force to the support 204, which reacts to the force by moving relative to the robot body 109. The outer skin 202 and the support 204 of the bumper 200 can have a similar geometry to the lower portion of the robot body 109. As a result, both the outer skin 202 and the support 204 can be partially rectangular in shape.

[0054] The robot 100 includes a sensor system that can detect contact with objects in the environment 103. In this example, the sensor system includes capacitive sensors 210 distributed along the bumper 200. The capacitive sensors 210 output an electrical signal in response to movement of the support 204 (the support 204 moves when a force is applied to the bumper 200). Each electrical signal can be a current, voltage, or some other suitable signal that can vary with the capacitance of the capacitive sensor 210. The capacitive sensors 210 can be located on the front side 200F of the bumper 200, the right side 200R of the bumper 200, and / or the left side 200L of the bumper 200. The number of capacitive sensors 210 and the distribution of the capacitive sensors 210 along the length of the bumper 200 allows the sensor system to detect contact from multiple locations along the front and sides of the robot 100. For example, the capacitive sensors 210a, 210b, 210h, 210i respond to contact with objects on the sides 200R, 200L of the bumper 200, while the capacitive sensors 210c through 210g along the front side 200F of the bumper 200 respond to contact with objects on the front side 200F of the bumper 200.

[0055] The structure of the support 204 can be selected to adjust the responsiveness of the capacitive sensors 210 to forces along various locations of the bumper 200. Responsiveness includes the amount of change in the electrical signal for each change in a parameter, such as the magnitude of the force on a portion of the bumper 200. Thus, a capacitive sensor 210 that is more responsive to forces will produce a larger change in the electrical signal in response to a unit increase in force than a capacitive sensor that is less responsive to forces.

[0056] The support 204 can include rigid regions and other regions that are less rigid (referred to herein as flexible regions) that are coupled to one another such that the capacitive sensors 210 located in the rigid regions exhibit a stronger response to forces on the rigid regions to which they are attached. For example, in the example shown in Figure 3 , an enlarged view of a portion of the bumper 200 shown in Figure 2 , the support 204 can include a plurality of segments 206a-206g (each shown in Figure 3 and collectively referred to as segments 206) that are coupled to one another by connecting elements 208a-208f (each shown in Figure 2 and collectively referred to as connecting elements 208). The connecting elements 208 are flexible regions and can have more flexibility / less rigidity than the segments 206. Figure 3 In the example shown in

[0057] , the connecting elements 208 and the segments 206 are composed of the same material. The connecting elements 208 have a thickness that is less than the thickness of the segments 206 such that the connecting elements 208 are more flexible than the segments 206. In some embodiments, the material that composes the connecting elements 208 can be different than or more flexible than the segments 206. In such embodiments, the thickness of the segments 206 and the connecting elements 208 can be substantially the same or possibly less different than the thickness of both being composed of the same material. For example, the ratio of the thickness of the segments 206 to the connecting elements 208 can be between 1.1 and 2, 2 and 4, 4 and 6, or 6 and 8. The thickness of the segments 208 can be between 1 mm and 2 mm, 2 mm and 3 mm, or 3 mm and 4 mm. Figure 3 The plurality of segments 206 and connecting elements 208 form an integrated structure such that they can be manufactured as a single piece. In other embodiments, the segments and connecting elements are composed of a plurality of pieces.

[0058]

[0059] ​By way of example, since segments 206 are connected by flexible elements, the force on each segment 206 is essentially split into a force-bearing segment. The force-bearing segment is further compressed compared to the non-force-bearing segment. As a result, the capacitive sensor 210 responds more strongly to forces on the segments 206 to which it is directly attached, and less strongly (or not at all, depending on the level of isolation) to forces on the segments 206 to which it is not directly attached. In some embodiments, to implement this, the connecting elements 208 are less rigid than the segments 206 so as to reduce the transfer of force between segments 206. As described herein, since the capacitive sensor 210 has a different electrical response to forces at different locations along the bumper, the electrical signal generated by the capacitive sensor 210 can be used to infer the location of the force along the bumper 200.

[0060] As described elsewhere herein, the capacitive sensor 210 generates an electrical signal in response to movement of the plates of the capacitive sensor 210 relative to each other. Figures 3 to 5 In the example of Fig. 2, each capacitive sensor 210 comprises a fixed plate 216 and a movable plate 214 that is movable with the bumper 200. The fixed plate 216 is mounted on a portion of the main body that faces away from the support 204. The movable plate 214 is mounted on a rod 212 that is connected to a (rigid) segment of the support 204. The rod 212 can be connected to a segment 206 or form an integral part of a segment 206. The rod 212 is connected to the movable plate 214 through a hole 213 in the main body 109. As a result of this connection, movement of the segment 206 is transferred to the rod 212, and this movement is then transferred to the movable plate 214. Thus, in operation, in response to a force applied to the bumper 200, the segment 206 moves, causing the rod 212 to move, which in turn causes the movable plate 214 to move away from the fixed plate 216. Movement of the rod 212 through the hole 213 thus causes separation between the movable plate 214 and the fixed plate 216. The displacement of the plates 214, 216 caused thereby results in a change in the capacitance of the capacitive sensor 210. This change in capacitance is reflected by an output of an electrical signal that is proportional to the displacement, and thus to the movement.

[0061] The electrical signal generated by the capacitive sensor 210 can vary relative to a baseline electrical signal. When no force is applied, in which case the bumper 200 is in an uncompressed position, the plates 214, 216 are in contact or closer to each other than when a force is applied. The electrical signal generated is measured against the baseline electrical signal.

[0062] The movable plate 214 and the fixed plate 216 can be, for example, copper plates, thin film metal coated plates, or include some other suitable conductive material. The dielectric 500 between the plates 214 and 216 can be, for example, air, glass, ceramic, or some other insulating material. For example, when no force is applied, if the plates are in contact, the dielectric will be air. However, if there is some baseline separation between the plates, other dielectrics (and air) can be used. The movable plate 214 can be circular, rectangular, or any other suitable shape. The fixed plate 216 can be a shape that complements the shape of the movable plate 214 (such as a circular, rectangular, or any other suitable shape). In some cases, the movable plate 214 can be a circular shape determined by a radius between 5 mm and 35 mm (e.g., between 5 mm and 15 mm, between 15 mm and 25 mm, or between 25 mm and 35 mm). The fixed plate can be a circular shape determined by a radius between 5 mm and 15 mm, between 15 mm and 25 mm, or between 25 mm and 35 mm, for example. In the case where the movable plate 214 is rectangular in shape, the movable plate 214 may have a length and a width between 5 mm and 35 mm (e.g., between 5 mm and 15 mm, between 15 mm and 25 mm, or between 25 mm and 35 mm). In some examples, the movable plate may be a rectangular plate having a length to width ratio between 1.5:1 and 2:1. In one specific example, the length of the plate may be between approximately 15-25 mm and the width of the plate may be between 5-15 mm.

[0063] Figure 6 2 shows a schematic side view of an example of a capacitive sensor 210 including a movable plate 214 and a fixed plate 216. Figure 6 , the displacement of the movable plate 214 may include a horizontal displacement 605 that is generally parallel to the ground surface on which the robot 100 is traveling. For example, when the bumper 200 contacts a vertical surface extending from the ground, the displacement may include a horizontal displacement, thereby resulting in the horizontal displacement 605. Therefore, when the bumper 200 is in the unstressed position, the horizontal distance 600 between the movable plate 214 and the fixed plate 216 is smaller than the horizontal distance 600 between the movable plate 214 and the fixed plate 216 when the bumper 200 is in the stressed position.

[0064] The capacitance of the capacitive sensor is a parameter that varies over a continuous range. The capacitive sensor can therefore generate an analog electrical signal based on the capacitance. As noted, the electrical signal can be a voltage, a current, a frequency (arising from an RC circuit), or other suitable electrical signal that varies with capacitance. As the horizontal distance 600 increases, the capacitance of the capacitive sensor 210 decreases. As the horizontal distance 600 decreases, the capacitance of the capacitive sensor 210 increases. The continuous range of capacitance changes with the change in horizontal distance 600 between the unpressed position and the pressed position. The electrical signal indicative of the capacitance can be proportional to the horizontal displacement 605. In one example, the electrical signal of the capacitance can be inversely proportional to the horizontal displacement 605.

[0065] Figure 7 An example of a control system 700 is shown, which can be included in the robot 100, for example, in order to determine the properties of forces on the bumpers 200 of the robot 100 and to navigate the robot 100. The control system 700 includes a controller circuit 705 (also referred to herein as controller 705) that can be operated with a memory storage element 710 and a sensor system 715. The controller 705 receives electrical signals generated by sensors of the sensor system 715 on the robot 100 and selects and issues drive commands, travel commands, and other behavioral commands based on the electrical signals. The sensor system 715 includes a bumper contact sensor system 720, which includes, for example, the capacitive sensor 210 described herein. In conjunction with the electrical signals received by the sensor system 715, the controller 705 can detect obstacles and perform behaviors to avoid the obstacles.

[0066] The controller 705 can access the memory storage element to execute signal processing programs stored on the memory storage element 710. The memory storage element 710 can store interpolation programs that can allow the controller 705 to better determine the properties of forces from obstacles in the environment, static sensor calibration values, and low pass filter programs. The interpolation programs can be used to determine the properties of forces from obstacles in the environment. The controller 705 can use the static sensor calibration values to determine the magnitude of forces corresponding to the magnitude of the electrical signals from the bumper contact sensor system 720. The controller 705 can use the low pass filter programs to set the resolution of the bumper contact sensor system 720. In some implementations, the controller can execute a filter program to set the frequency resolution of the bumper sensor. A high pass filter program can be set such that the controller determines that contact has occurred if the force on the bumper exceeds a frequency of 0.1 Hz to 0.5 Hz, 0.5 Hz to 2 Hz, or 2 Hz to 5 Hz. The high pass filtering can be advantageous to allow the system to sense forces above the frequency.

[0067] Referring back to Figure 2Each capacitive sensor 210a-210i can independently generate an electrical signal in response to the bumper 200 contacting an object in the environment 103. When the bumper 200 is in an uncompressed position, which generally indicates that the bumper 200 is not contacting an object in the environment and no force is being applied, the capacitive sensors 210a-210i generate similar electrical signals that the controller 705 can interpret as baseline neutral signals representing the bumper 200 in the uncompressed position. Thus, as the robot 100 travels around the environment 103 without contacting objects in the environment 103, the controller 705 can dynamically calibrate each capacitive sensor 210a-210i to these neutral signals. Changes in the electrical signals (also referred to as electrical responses) from the baseline neutral signals can be indicative of the bumper 200 being compressed.

[0068] Figure 8A The robot 100 is shown contacting an object 800, which exerts a force 805 on the bumper 200 of the robot 100 that is parallel or substantially parallel to the ground. In response to the force 805, the bumper 200 moves such that the segments 206 of the brace 204 move, which causes the capacitive sensors 210 to output electrical signals. The force 805 can include properties such as magnitude, direction, and location along the bumper 200.

[0069] Each capacitive sensor 210a-210i can generate an electrical signal that can change in properties of voltage, current, or other electrical signals depending on the properties of the force. The reaction of the capacitive sensors 210 to the force can vary depending on the location of the force 805. For example, as the distance between the location of the force 805 and the location of the capacitive sensors 210 increases, the displacement caused by the force 805 decreases. Thus, each capacitive sensor 210 generates an electrical signal depending on the location of the force 805. The more proximate the location of the force 805 to a given capacitive sensor 210, the more intense the electrical reaction generated by the capacitive sensor as the force 805 acts on the bumper 200. In some examples, the more proximate the location of the force 805 to the capacitive sensor 210, the more intense the reaction of the capacitive sensor 210 to the magnitude of the force 805.

[0070] As Figure 8A shown in the example, the capacitive sensors 210c and 210d, which are located proximate to the force 805, react more intensely to the force 805 than the other capacitive sensors 210a-210b and 210e-210i. Figure 8BThe plot 819 of the capacitive sensors 210a-210i shows the electrical responses 820a-820i- which can be represented as changes in voltage, current, or other appropriate electrical signal from a neutral baseline signal- of each of the capacitive sensors 210a-210i. Each of the capacitive sensors 210a-210i is located at a position 822 along the bumper 200, which is a linear, one-dimensional position measured along the bumper 200. Thus, the electrical responses 820a-820i can be associated with the position of the capacitive sensors 210a-210i, respectively.

[0071] Because the position of the force 805 is between the positions of the capacitive sensors 210c and 210d, the electrical responses 820c and 820d are greater than the other electrical responses 820a-820b and 820e-820i. Moreover, the capacitive sensors 210c and 210d, by both being coupled to the same segment (e.g., segment 206c) of the support 204 (shown), are more sensitive to the force 805 per unit of force than the other capacitive sensors 210a-210b and 210e-210i. As described herein, because the flexible connecting elements 208b, 208c separate the segment 206c from the other segments 206, the electrical responses 820c and 820d can exhibit greater changes in response to the force 805. Figure 2

[0072] Based on the electrical responses 820a-820i, the controller 705 can determine properties of the force 805 resulting from contact with the object 800. For example, the controller 705 can determine the position and magnitude of the force 805. The controller 705 can determine that the general position of the force 805 is near the segment 206c because the electrical responses 820c and 820d from the capacitive sensors 210c and 210d are greater than the electrical responses 820a-820b and 820e-820i from the other capacitive sensors 210a-210b and 210e-210i, respectively. The controller 705 can perform an interpolation process based on the electrical responses 820c and 820d from the capacitive sensors 210c and 210d to identify the precise position of the force 805 along the segment 206c. The interpolation can be a linear interpolation. In some cases, the interpolation can account for non-linear changes in stiffness, elasticity, and geometry along the segment 206c and thus can be a non-linear interpolation, such as a polynomial interpolation.

[0073] In one example, the controller 705 can calculate the slope 830 of the interpolation line 825 between the electrical responses 820c and 820d to determine the position along the segment 206c to which the capacitive sensors 210c and 210d are attached. Generally, if the slope 830 is 0, the controller 705 can determine that the force 805 is at a point substantially equidistant from each of the capacitive sensors 210c and 210d. If the slope 830 is positive, the controller 705 can determine that the force 805 is closer to the capacitive sensor 210d. If the slope 830 is negative (e.g., if the slope 830 is -1), the controller 705 can determine that the force 805 is closer to the capacitive sensor 210c. Figure 8A ​Based on the electrical responses 820a through 820i, the controller 705 can also determine the magnitude of the force 805. For example, the controller 705 can calculate the average of the electrical responses 820c and 820d. The controller 705 can then calculate the difference between the average and a predetermined reference average stored on the memory storage element 710. The predetermined reference average defines a relationship between the magnitude of the force (e.g., the magnitude of the force 805) and the average of two electrical responses (e.g., the electrical responses 820a through 820i). Thus, the calculated difference can represent the magnitude of the force 805. Accordingly, the controller 705 can determine the magnitude of the force 805 acting on the bumper 200 from the calculated difference.

[0074] In other examples, the controller 705 can determine the ratio of the electrical response 820c to the electrical response 820d to determine the position of the force 805 along the bumper 200. A ratio of one can indicate that the position of the force 805 is equidistant from the capacitive sensor 210c and the capacitive sensor 210d. A ratio greater than one can indicate that the position of the force 805 is closer to the capacitive sensor 210c, and a ratio less than one can indicate that the position of the force 805 is closer to the capacitive sensor 210d. The system can calculate the ratio of the electrical responses and determine the position of the contact based at least in part on the ratio.

[0075] Based on the electrical responses 820a through 820i, the controller 705 can also determine the magnitude of the force 805. For example, the controller 705 can calculate the average of the electrical responses 820c and 820d. The controller 705 can then calculate the difference between the average and a predetermined reference average stored on the memory storage element 710. The predetermined reference average defines a relationship between the magnitude of the force (e.g., the magnitude of the force 805) and the average of two electrical responses (e.g., the electrical responses 820a through 820i). Thus, the calculated difference can represent the magnitude of the force 805. Accordingly, the controller 705 can determine the magnitude of the force 805 acting on the bumper 200 from the calculated difference.

[0076] In some additional examples, the magnitude of the force can be calculated based on the summation of a plurality of sensor values. The individual responses of the plurality of sensors can also be used to determine whether the force is acting on a localized small area or distributed over a large area, which occurs on a soft barrier. Thus, when only one to two sensors show a strong response, the system can determine that contact with a small object (e.g., a pole, a chair leg, a table leg). However, if a large number of sensors (e.g., 3 or more sensors) show a strong response, the system can determine that it has contacted a large barrier, such as a well. Similarly, if a large number of sensors show a weak response, the system can determine that the robot has contacted a soft or flexible surface.

[0077] Figure 9AA flowchart is shown that illustrates a process 900 of issuing one or more travel instructions in response to detecting contact along a bumper of a robot, such as robot 100, such as bumper 200.

[0078] According to step 902, the controller controls 905 the robot to travel around an environment. The controller can issue travel, drive, and motion instructions to effect the control. During the travel, the controller also calibrates 910 a bumper sensor of a bumper of the robot. The controller can intermittently (e.g., at a frequency of 0.01 Hz to 0.1 Hz, 0.1 Hz to 1 Hz, or 1 Hz to 10 Hz) and dynamically (e.g., as the robot travels around the environment) calibrate the bumper sensor to a baseline signal. During the dynamic calibration, the bumper is unpressurized. Thus, the electrical signal received by the controller serves as a baseline signal against which other electrical signals are compared. In some implementations, the controller can implement a low-pass filtering procedure such that the controller filters out signals above a threshold frequency. Thus, the controller can set the baseline signal to a sample below the threshold frequency of the low-pass filtering procedure, which can be between 0.01 Hz to 0.1 Hz, 0.1 Hz, or 1 Hz to 10 Hz, for example. In some examples, the frequency can be adjusted based on the speed of the robot to filter out noise at undesirable frequencies of the contact signal.

[0079] In response to the force exerted on the bumper, the bumper sensor generates an electrical signal that is distinct from the calibrated electrical signal, and the controller receives 915 the electrical signal. The electrical signal can be an analog signal (e.g., a voltage, a current, or other appropriate electrical signal), for example. The analog signal can be responsive to a parameter that varies continuously over a range, such as a capacitance, an inductance, a magnetic field, a distance, a displacement, or other appropriate continuous parameter. The electrical signal can be directly or inversely proportional to the amount of displacement of the bumper or the amount of force acting on the bumper. In some examples, the electrical signal can be associated with the amount of displacement of the bumper through a non-linear smoothing function, such as a polynomial, a spline, an exponential, or the like. Thus, the electrical signal can vary continuously as the amount of displacement varies.

[0080] Upon receiving 915 the electrical signal, the controller determines 920 whether the bumper of the robot is in contact with an object in the environment, for example. The controller can do so by determining 922 that the electrical signal does not exceed a threshold difference from the calibrated electrical signal. In this case, the controller instructs the robot to continue traveling around the environment under operation 905.

[0081] If the electrical signal exceeds the threshold difference, the controller can determine 924 that the bumper is in contact. The controller then determines 925 properties of the contact, examples of which are described herein with reference to Figure 9B and 9C For example, the controller can determine a location of the contact along the bumper, a magnitude of the force caused by the contact, or a duration of the contact.

[0082] The controller issues (930) a command to the robot based on the determined property. For example, the controller, based on determining the location of the contact, can issue a travel command instructing the robot to turn around from the location of the contact. In some examples, the controller can instruct the robot to travel along an object that the robot has contacted. For example, the object can be a wall, and the controller can instruct the robot to perform a travel-along-wall behavior, in which the robot moves along the wall. While the robot performs the travel-along-wall behavior, the controller can instruct the robot to maintain the magnitude of the force within a predetermined force range. After the controller has issued a command in response to the contact, the robot continues to travel around the environment.

[0083] When the controller determines (925) a property of the contact, the controller can perform different procedures to determine different properties of the contact. The controller can perform multiple such procedures to determine (925) the property of the contact using variations in the electrical signal over a continuous range. Figure 9B An example flowchart is shown that illustrates a procedure 935 in which the controller determines a location of a contact based on the received (915) electrical signals.

[0084] According to step 937, the controller selects (940) two electrical signals received (915) from two bumper sensors. The controller can select (940) the two electrical signals based on the strength of the two electrical signals. For example, the controller can select (940) the two electrical signals that have the two greatest strengths, which can indicate that the two bumper sensors that generated the two electrical signals are closer to the location of the contact.

[0085] After the controller selects (940) the two electrical signals, the controller computes (943) a location-indicating value based at least in part on the two electrical signals. For example, the location-indicating value can be the difference between the two electrical signals. The controller can associate the two electrical signals with the locations of the bumper sensors that generated the two electrical signals. The locations of the bumper sensors can be measured as the locations of the bumper sensors along the bumper of the robot. The electrical signals and the locations of the bumper sensors can thus form ordered pairs. The controller can compute (943) the location-indicating value to be a slope based on the two electrical signals and the two locations along the bumper of the two bumper sensors that generated the two electrical signals. In this case, the controller can perform linear interpolation between the two ordered pairs of the two electrical signals.

[0086] Thereafter, the controller can determine (945) the location of the contact based on the location indication value. The controller can compare the location indication value to a reference value. Based on the difference between the location indication value and the reference value, the controller can determine the location of the contact. For example, if the location indication value is a difference between two electrical signals, the controller can compare the difference to a reference difference. The reference difference can be an estimated difference between two electrical signals that is expected for a contact at a certain location along the bumper. In another example, the controller can perform interpolation. If the location indication value is a slope, the controller can perform interpolation and compare the slope from the interpolation to a reference slope. The reference slope can be an estimated slope between two electrical signals that is expected for a contact at a certain location along the bumper.

[0087] In some embodiments, the controller can select (940) three or more electrical signals from three or more bumper sensors. For example, the controller can perform interpolation based on readings from all sensors whose electrical signals exceed a threshold reading. The interpolation can thus be a polynomial interpolation or other interpolation of the data set.

[0088] Figure 9C Another example flowchart is shown, which illustrates a flow 950 in which the controller determines a magnitude of the force based on the received (915) electrical signals.

[0089] According to flow 952, the controller calculates (955) a magnitude indication value based on the received (915) electrical signals. The magnitude indication value can be, for example, an average of the electrical signals in the received (915) electrical signals, a subset average of the electrical signals, a maximum of the electrical signals, or a sum of the electrical signals.

[0090] The controller can determine (960) the magnitude of the contact force based on the magnitude indication value. The controller can compare the magnitude indication value to a reference value. For example, if the magnitude indication value is an average of the received (915) electrical signals, the reference value can be a predetermined average that is expected for a known magnitude of the contact force. In some cases, the controller performs flow 952 after the controller determines (945) the location of the contact. Thus, the reference value can be a predetermined value that is expected for a known magnitude of the contact force at a known location. In this case, the magnitude indication value can be a single electrical signal, such as a maximum of the electrical signals. The controller can interpret a greater difference between the magnitude indication value and the reference value to indicate a greater magnitude of the force.

[0091] Other and alternative embodiments of the robot, sensors, and methods are also provided. For example, the structure of the capacitive sensors described herein can be varied. In Figure 5 In the example of FIG. 2, the movable plate 214 is adjacent to a side of the body 109 opposite the support 204, and the fixed plate 216 is attached to a side of the body 109 opposite the support 204. Figures 10 to 12Alternative embodiments are shown. In these alternative embodiments, the movable plates are attached to the side of the body facing away from the holder and the fixed plates are attached to the side of the body facing the holder. This embodiment is also different in how the capacitance changes with movement of the holder relative to the body. For example, in the embodiment of Figures 10 to 12 the compression between the holder and the body causes the plates to move closer to each other, while in the embodiment of Figure 5 the compression between the holder and the body causes the plates to move apart or away from each other.

[0092] The geometry of the movable and fixed plates results in a capacitor. The movable plates can be circular, rectangular, or some other shape that complements the shape of the fixed plates. The fixed plates can be circular, rectangular, or some other shape that complements the portion of the body on which the fixed plates are mounted. Each movable plate can have an area between, for example, 100 square millimeters and 1000 square millimeters or 1000 square millimeters and 2000 square millimeters. The fixed plates can have an area between, for example, 100 square millimeters and 1000 square millimeters or 1000 square millimeters and 2000 square millimeters.

[0093] Referring to Figure 10 , the movable plates 1000 attached to the holder 1010 face the robot body 1005, and the fixed plates 1015a, 1015b on the robot body 1005 face the holder 1010. Dielectrics 1020a, 1020b separate the fixed plates 1015a, 1015b from the movable plates 1000. The dielectrics 1020a, 1020b can be a deformable material, such as foam. Each fixed plate 1015a, 1015b, each dielectric 1020a, 1020b, and the movable plates 1000 make up a capacitive sensor 1022a, 1022b. To protect the fixed plates 1015a, 1015b from magnetic fields generated by sources other than the movable plates 1000, a grounded metal plate 1030 can cover the side of each fixed plate 1015a, 1015b opposite the movable plates 1000. A force 1025 on the holder 1010 causes displacement of the movable plates 1000 relative to the fixed plates 1015a, 1015b. The position of the force 1025 along the holder 1010 can affect the response of each capacitive sensor 1022a, 1022b to the force 1025. For example, the force 1025 on the holder 1010 is closer to the capacitive sensor 1022a than to the capacitive sensor 1022b. Thus, the capacitive sensor 1022a is more responsive to the force 1025. In the case where the force 1025 is equidistant from the capacitive sensors 1022a, 1022b, the sensors 1022a, 1022b are equally responsive to the magnitude of the force 1025 and are equally active for a given magnitude. In any case, a controller can determine, based on the measurements of the force, where along the holder 1010 the force occurred.

[0094] Referring to Figure 11 The movable plate 1100 attached to the bracket 1110 faces the robot body 1105, and the stationary plates 1115a, 1115b on the spacers 1116a, 1116b attached to the robot body 1105 face the bracket 1110. Air separates the movable plate 1100 from the stationary plates 1115a, 1115b and acts as a dielectric for the capacitive sensors 1122a, 1122b. A grounded metal plate 1130 shields the back side of each stationary plate 1115a, 1115b from the movable plate 1100. The height of the spacers 1116a, 1116b reduces the distance between the movable plate 1100 and the stationary plates 1115a, 1115b so that a small change in distance results in a large change in capacitance for the sensors 1122a, 1122b. As a result, the spacers 1116a, 1116b allow each capacitive sensor 1122a, 1122b to be more sensitive to forces 1125 on the bracket 1110.

[0095] Referring to Figure 12 The movable plate 1200 attached to the bracket 1210 faces the robot body 1205, and the stationary plates 1215a, 1215b, 1215c on the spacers 1217a, 1217b, 1217c attached to the robot body 1205 face the bracket 1210. A grounded metal plate 1230 shields the back side of each stationary plate 1215a, 1215b, 1215c from the movable plate 1200. The movable plate 1200 can be capacitively coupled to the stationary plate 1215b, which can be grounded using a wire connected to ground. As a result, in this embodiment, the movable plate 1200 can float so that the movable plate 1200 does not need to be connected to a wire that also moves with the movable plate 1200. As such, the spacers 1217a, 1217b, 1217c make the sensors 1222a, 1222b, 1222c more sensitive to forces 1225 on the bracket 1210.

[0096] Figure 13 and 14 An alternative bumper is depicted having a capacitive sensor that changes position and a bracket that changes structure. In one embodiment, Figure 13 The robot 1300 shown in FIG. 13 uses capacitive sensors 1315a through 1315j (collectively referred to as capacitive sensors 1315) to detect forces along a bumper 1310 mounted on a body 1312, the capacitive sensors 1315a through 1315j being of the type described in Figures 10 to 12 FIG. 12.

[0097] and Figure 2In contrast to the segments 206 shown in FIG. , which are continuously connected to each other via connecting elements 208, the bumper 1310 includes discontinuous bracket segments 1314a through 1314f (collectively, bracket segments 1314). As a result, forces acting on one bracket segment 1314 are generally not transmitted to other bracket segments 1314. The capacitive sensor 1315 may include a movable plate connected to the bracket segments 1314 and a fixed plate connected to the main body 1312 of the robot 1400. In one example, a force acting on segment 1314a causes the electrical signals generated by the capacitive sensors 1315a and 1315b to change more than the electrical signals generated by the capacitive sensors 1315c through 1315j. As a result, the capacitive sensor 1315 is more sensitive to forces acting on the segment 1314 to which it is attached than to forces acting on segments 1314 to which it is not attached.

[0098] refer to Figure 13 Capacitive sensors 1315c and 1315h are located at the left corner 1350L and right corner 1350R of bumper 1310, respectively. Thus, capacitive sensors 1315c and 1315h may include a non-planar fixed plate and a non-planar movable plate that conform to the curved shape of corners 1350L and 1350R. Capacitive sensors 1315c and 1315h are more responsive to forces on corners 1350L and 1350R of bumper 1310 than capacitive sensors 1315a to 1315b, 1315d to 1315f, and 1315h to 1315j. Furthermore, segment 1314b at left corner 1350L and segment 1314e at right corner 1350R may be thinner to increase their resilience, thereby improving their responsiveness to forces on corners 1350L and 1350R.

[0099] Figure 14 In another embodiment shown, the bumper 1410 of the robot 1400 includes a bracket 1414 that includes continuous segments 1416F, 1416R, 1416L, 1417L, 1417R of varying thickness to achieve varying stiffness. The bracket 1414 may be made of a rigid material such as polycarbonate, sheet metal, or some other hard material. The robot 1400 includes a bracket 1414 relative to the robot 1400. Figures 10 to 12 Capacitive sensors 1415a to 1415e of the type described herein (collectively, capacitive sensors 1415) may include a movable plate (e.g., a movable plate) coupled to a support 1414. Figures 10 to 12 The movable plates 1000, 1100, 1200, respectively) and the fixed plate 1418 connected to the main body 1418 of the robot 1400 (such as Figures 10 to 12 Corresponding fixing plates 1015, 1115, 1215).

[0100] The front segment 1416F, right segment 1416R, and left segment 1416L of the bracket 1414 can have greater stiffness than the left corner segment 1417L and right corner segment 1417R of the bracket 1414 to reduce the amount of force transmitted between the segments 1416F, 1416R, 1416L. The bracket 1414, including the movable plate of the capacitive sensors 1415a-1415e, can be decoupled from the robot body 1418, including the fixed plate of the capacitive sensors 1415, by the supports 1420a-1420d (collectively referred to as supports 1420). Thus, when the bracket 1414 deforms, the movable plate and the fixed plate move relative to each other. The supports 1420 further act as reference locations and / or boundary conditions when a controller (e.g., controller 705) of the robot 1400 interpolates the electrical signals generated by the capacitive sensors 1415a-1415e.

[0101] In some embodiments, the geometry of the bracket can affect the response of the capacitive sensors to forces along the bumper at particular locations. Figures 15 to 16 Alternative embodiments of different geometries of a bumper bracket at a corner of a bumper are shown. The structure of the bracket in the corner can determine the amount of force transmitted from the side to the front of the bracket. The structure of the bracket at the corner can be designed to reduce the amount of force transmitted between the sides.

[0102] A bumper can include a bracket with a corner geometry that mitigates the transmission of forces between the front and sides of the bumper. The bracket can include an element that is elongated, thin, or incorporates other features into the corner geometry such that the corner geometry is more elastic than the adjacent geometry of the front and sides. Thus, the bracket can mechanically decouple the front and sides of the bumper by significantly reducing the transmission of forces between the front and sides. The effect of forces applied on a segment on adjacent segments is reduced, allowing for easier determination of the location of the applied force.

[0103] Figure 15 A zoomed-in top view of a robot is shown at a left corner 1550L of a bumper 1510 of the robot, including a feature that reduces the transmission of forces between a front side 1512F of the bracket 1512 and a side 1512 of the bracket 1512. The bumper 1510 is mounted on a robot body 1511. At the corner 1550L, the bracket 1512 of the bumper 1510 includes segments 1516a, 1516b, and 1516c connected to each other in series. The connecting segment 1516b connects a side segment 1516a of the side 1512L of the bracket 1512 and a front segment 1516c of the front side 1512F of the bracket 1512 as a connecting element. A capacitive sensor 1515a includes a movable plate (e.g., movable plate 1000, 1100, 1200) connected to the side segment 1516a and a fixed plate (e.g., fixed plate 1000, 1100, 1200) connected to the robot body 1511. Figures 10 to 12 A zoomed-in top view of a robot is shown at a left corner 1550L of a bumper 1510 of the robot, including a feature that reduces the transmission of forces between a front side 1512F of the bracket 1512 and a side 1512 of the bracket 1512. The bumper 1510 is mounted on a robot body 1511. At the corner 1550L, the bracket 1512 of the bumper 1510 includes segments 1516a, 1516b, and 1516c connected to each other in series. The connecting segment 1516b connects a side segment 1516a of the side 1512L of the bracket 1512 and a front segment 1516c of the front side 1512F of the bracket 1512 as a connecting element. A capacitive sensor 1515a includes a movable plate (e.g., movable plate 1000, 1100, 1200) connected to the side segment 1516a and a fixed plate (e.g., fixed plate 1000, 1100, 1200) connected to the robot body 1511. Figures 10 to 12fixed plate 1015, 1115, 1215). Capacitive sensor 1515b includes a movable plate (e.g., a flexible membrane) connected to front segment 1516c and a fixed plate (e.g., a rigid plate) connected to the robot body 1511 (e.g., as shown in movable plate 1000, 1100, 1200 and fixed plate 1015, 1115, 1215, respectively). Figures 10 to 12 respectively). Capacitive sensor 1515b includes a movable plate (e.g., a flexible membrane) connected to front segment 1516c and a fixed plate (e.g., a rigid plate) connected to the robot body 1511 (e.g., as shown in movable plate 1000, 1100, 1200 and fixed plate 1015, 1115, 1215, respectively). Figures 10 to 12 respectively). Capacitive sensor 1515b includes a movable plate (e.g., a flexible membrane) connected to front segment 1516c and a fixed plate (e.g., a rigid plate) connected to the robot body 1511 (e.g., as shown in movable plate 1000, 1100, 1200 and fixed plate 1015, 1115, 1215, respectively).

[0104] The geometry of the connecting segment 1516b allows the connecting segment 1516b to act as a flexure that absorbs force from adjacent segments. In particular, the connecting segment 1516b can reduce the amount of force transmitted from the front side 1512F to the side 1512L or can reduce the amount of force transmitted from the side 1512L to the front side 1512F. As shown in FIG. 15B, the connecting segment 1516b is curved (e.g., concave or convex) relative to the passage between the front side 1512F and the side 1512L. Figure 15 As described, to extend the length of the connecting segment 1516c, the connecting segment 1516b is curved (e.g., concave or convex) relative to the passage between the front side 1512F and the side 1512L. The length of the connecting segment 1516b is longer than the length of the passage 1517 and is angled away from the front segment 1516c and the side segment 1516a. In some cases, the length of the connecting segment 1516b is 1.1 to 1.5 times, 1.5 to 3 times, 3 to 4.5 times the length of the passage 1517.

[0105] The connecting segment 1516b is shown with a concave geometry, although in other cases the connecting segment 1516b can be convex, triangular, zig-zag, or have other geometries that increase the length of the connecting segment 1516b. In other embodiments, the connecting segment 1516b can include multiple curves or spline curves that increase the length of the connecting segment 1516b relative to the length of the passage 1517.

[0106] In some cases, a bumper can include a bumper sensor associated with a corner, and the geometry of the bumper at the corner can be designed to reduce the transmission of force between the corner and the sides of the bumper and between the sides of the bumper. For example, the corner segment can be lengthened, divided, or thinned to make the bumper more flexible near the corner so that the segments of the bumper can move independently of each other in response to an applied force. Without this special treatment of the corner, in some examples, the bumper near the corner is somewhat rigid and the segments of the bumper are difficult to move independently of each other. As a result of this mechanical decoupling, the influence of each segment on the sensor relative to adjacent segments is reduced, which makes it easier to determine the location of the applied force. Figure 16 An example of reducing force transmission is shown. Figure 16A top view of the robot is shown, enlarged at the left corner 1650L of the robot's bumper 1610. The bumper 1610 is mounted on the robot body 1611. At the corner 1650L, the bracket 1612 of the bumper 1610 includes bracket segments, a side segment 1616a, a corner segment 1616b, and a front segment 1616c, which are connected to each other in series by connection elements 1617a, 1617b. The connection element 1617a connects the side segment 1616a and the corner segment 1616b. The connection element 1617b connects the corner segment 1616b to the front segment 1616c. The capacitive sensors 1615a, 1615b, 1615c include movable plates (e.g., movable plates 1000, 1100, 1200) connected to the side segment 1616a, the corner segment 1616b, and the front segment 1616c, respectively, and fixed plates (e.g., fixed plates 1015, 1115, 1215) connected to the robot body 1611. Figures 10 to 12 Figures 10 to 12

[0107] The connection elements 1617a, 1617b lengthen the connection between the segments 1616 and reduce the force transfer between the segments 1616a, 1616b, 1616c. The connection element 1617a has a curvature such that the length of the connection element 1617a is longer than the length of a straight connection between the side segment 1616a and the corner segment 1616b. Similarly, the connection element 1617b has a curvature such that the length of the connection element 1617b is longer than the length of a straight connection between the corner segment 1616b and the front segment 1616c. For example, the connection element 1617a is angled away from the front segment 1616c and the side segment 1616a. Thus, the connection element 1617a reduces the amount of force transfer between the side segment 1616a and the corner segment 1616b. The connection element 1617b reduces the amount of force transfer between the front segment 1616c and the corner segment 1616b. The connection elements 1617a, 1617b isolate the force in each side segment 1616a, corner segment 1616b, and front segment 1616c. The connection elements 1617a, 1617b thus allow each capacitive sensor 1615a, 1615b, 1615c to more accurately detect the force applied to the segment 1616a, 1616b, 1616c to which its movable plate is connected.

[0108] Although the connection elements 1617a, 1617b are shown as concave to achieve this purpose, in some embodiments, the connection elements 1617a, 1617a (should be 1617b) can be convex. In other embodiments, the connection elements 1617a, 1617b can include multiple curves or splines that lengthen the connection elements 1617a, 1617b.

[0109] ​​Due to contact with an object near the left corner 1650L of the bumper 1610, for example, Figure 17 Potential locations of the side force 1705a, corner force 1705b, and forward force 1705c experienced by the left corner 1650L of the bumper 1610 of the robot 1600 are shown. If the side force 1705a is applied to the bumper 1610, the capacitive sensor 1615a responds to a greater electrical response than either of the capacitive sensors 1615b, 1615c. If the corner force 1705b is applied to the bumper 1610, the capacitive sensor 1615b responds to a greater electrical response than either of the capacitive sensors 1615a, 1615c. If the forward force 1705c is applied to the bumper 1610, the capacitive sensor 1615c responds to a greater electrical response than either of the capacitive sensors 1615a, 1615b. Due to the length, curvature, and other geometric aspects of the connecting elements 1617a, 1617b, as Figure 16 shown, the forces 1705a, 1705b, 1705c do not readily transfer between segments 1616a, 1616b, 1616c.

[0110] While the movable plate is described as responding to a horizontal force pushing the movable plate inward relative to the fixed plate, in some embodiments, the movable plate can include a coupling mechanism that allows forces having a non-horizontal component to cause the movable plate to move relative to the fixed plate. In Figure 5 the example shown, a rod 212 connected to the movable plate 214 extends toward the body 109 and through a hole 213 in the robot body 109 to control movement of the movable plate relative to the fixed plate. Figures 18 to 21 Alternative embodiments of the movable plate are shown that allow forces having a non-horizontal component to cause the movable plate to move relative to the fixed plate.

[0111] A coupling mechanism incorporated into the movable plate structure can allow forces having a non-horizontal component to cause the movable plate to move horizontally relative to the fixed plate. As Figure 18 , 19 shown, which shows a portion of the bracket 1800, the bracket 1800 of a bumper (such as the bumper 200) can include a coupling mechanism 1805 connected to a rod 1810. The rod 1810 extends through a hole 1813 in the robot body 1814 and is connected to a movable plate 1816 of a capacitive sensor 1822. A fixed plate 1818 connected to the robot body 1814 faces the movable plate 1816. A force 1825 applied to the bracket 1800 that includes a horizontal component and a vertical component can be transferred through the coupling mechanism 1805 to the rod 1810, causing horizontal displacement of the movable plate 1816. The coupling mechanism 1805 can thus act as a spring to transfer vertical and horizontal forces to the movable plate 1816.

[0112] The geometry of the coupling mechanism 1805 can facilitate the transmission of forces through the bracket 1800 to the movable plate 1816. The coupling mechanism 1805 can form an angle 1830 with the rod 1810 such that forces forming a similar angle to the angle 1830 are readily transmitted through the coupling mechanism 1805 to the rod 1810. The angle 1830 can be between 100 degrees and 120 degrees, 120 degrees and 140 degrees, 140 degrees and 160 degrees. The coupling mechanism 1805 can connect the bracket 1800 to the rod 1810 along a concave, convex, linear, or other path. In some cases, the coupling mechanism 1805 connects to an end of the bracket 1800, and in other cases, the coupling mechanism 1805 can connect to a point between the ends of the bracket 1800.

[0113] The bend can be incorporated into the structure of the bracket such that the bracket favors horizontal motion and disfavors non-horizontal motion. Referring to Figure 20 and 21 The bracket 2000 of a bumper (such as the bumper 200) can include a bend 2005a and a bend 2005b. The bracket 2000 also includes a rod 2010 that passes through a hole 2013 of a robot body 2014 and connects to a movable plate 2016 of a capacitive sensor 2022. A fixed plate 2018 is connected to the robot body 2014 facing the movable plate 2016. The bends 2005a, 2005b in combination with the robot body 2014 cause a force 2025 on the bracket 2000 that includes a non-horizontal component to cause the bends 2005a, 2005b to resist the non-horizontal force, thereby reducing the non-horizontal displacement of the movable plate 2016.

[0114] In some cases, the capacitive sensor can allow for lateral motion or sliding motion of the fixed plate relative to the movable plate and generate various electrical signals caused by the lateral motion. Figure 22 A capacitive sensor 2200 is shown, which can generate electrical signals in response to lateral movement of a movable plate 2218 of the capacitive sensor 2200 relative to a fixed plate 2216 of the capacitive sensor 2200. A robot (such as the robot 200) can include the capacitive sensor 2200. Figure 23The hole 2225 of the body 2223 of the capacitive sensor 2200 allows the rod 2227 to be connected to the movable plate 2218 to move in the hole 2225. As such, the movable plate 2218 can slide relative to the fixed plate 2216, which can cause a change in capacitance of the capacitive sensor 2200 and thereby a change in the electrical signal generated by the capacitive sensor 2200. The capacitance can vary depending on the vertical distance 2205 between the movable plate 2218 and the fixed plate 2216. The vertical displacement 2250 can increase the vertical distance 2205, which effectively reduces the capacitive area of the capacitive sensor 2200. As a result, the capacitance of the capacitive sensor 2200 decreases as the vertical distance 2205 increases. As the vertical distance 2205 decreases, the capacitance of the capacitive sensor 2200 increases. Thus, the electrical signal indicative of the capacitance can be proportional to the vertical displacement 2250. In one example, the electrical signal indicative of the capacitance can be inversely proportional to the vertical displacement 2250.

[0115] Thus, the capacitive sensor 2200 can generate an electrical response indicative of the vertical displacement 2250, which a controller can determine that the robot 2300 has contacted an object in the environment. Figure 22 The lateral motion shown in FIG. 23 includes a generally horizontal motion that is generally perpendicular to the vertical displacement 2250 of the robot 2300 traveling around the surface of the ground. Figure 23 The vertical displacement 2250 of the robot 2300 shown in FIG. 23 can be caused by the robot’s bumper 2310 contacting an aerial object 2320, for example. Figure 23 A side view of the robot 2300 contacting the aerial object 2320 is shown. When the bumper 2310 of the robot 2300 contacts the object 2320, a vertical force 2330 is applied to the bumper 2310. The vertical force 2330 causes a vertical displacement, and in this regard, the description of the capacitive sensor 2200, the vertical displacement 2250 can cause the capacitive sensor (e.g., the capacitive sensor 2200) of the bumper 2310 to generate an electrical signal indicative of the bumper 2310 being under the force 2330. In some cases, the electrical signal from the capacitive sensor can be indicative of the force 2330 being a vertical force. Figure 22 The vertical displacement 2250 of the robot 2300 shown in FIG. 23 can be caused by the robot’s bumper 2310 contacting an aerial object 2320, for example.

[0116] In some cases, the direction of a horizontal force on a robot (e.g., the robot 2300) includes a lateral component that can cause a sliding motion of a capacitive sensor (e.g., the capacitive sensor 2200) that results in a sliding displacement of the movable plate and the fixed plate relative to each other. In this regard, the description of the capacitive sensor 2200, the sliding displacement can cause the capacitive sensor 2200 to generate an electrical signal indicative of the robot 2300 being under the force. Figure 23The displacement described by the vertical displacement 2250 can similarly cause the movable plate (e.g., movable plate 2218) and the fixed plate (e.g., fixed plate 2216) to displace such that the lateral component changes the effective capacitance area of the capacitive sensor. As a result, as the amount of the lateral component increases, the capacitance area decreases and the capacitance decreases. As the amount of the lateral component decreases, the capacitance area increases and the capacitance increases. The sliding motion can cause a similar difference in the electrical signals from two or more capacitive sensors, such that the controller (e.g., controller 705) can determine that the force includes a lateral component.

[0117] Although described herein with respect to capacitive sensors, in other embodiments, other electrical sensors that generate electrical signals in response to movement of a bumper relative to a robot body can be used. For example, with reference to Figures 1 to 23 The contact sensors described can be capacitive sensors, but in other embodiments, other electrical sensors that generate electrical signals in response to movement of a bumper relative to a robot body can be used. For example, with reference to Figure 24 The bracket 2400 of a bumper (e.g., bumper 200) can include an inductive sensor 2405. The inductive sensor includes a core 2410 attached to the bracket 2400 and a coil 2420 attached to the robot body 2430. The core 2410 and the coil 2420 form an inductor, and the inductive sensor 2405 generates an electrical signal based on the inductance of the inductor. A force 2450 on the skin 2455 of the bumper is transferred to the bracket 2400, causing the bracket 2400 to move relative to the body. Thus, as the bracket 2400 moves, the core 2410 passes through the coil 2400. As more of the core 2410 advances through the coil 2420, the inductance of the inductor increases. Thus, the electrical signal from the inductive sensor 2405 is proportional to the amount of displacement of the core 2410 relative to the coil 2420. In some cases, the core 2410 can be attached to the robot body 2430, and the coil 2420 can be attached to the bracket 2400. In these cases, the electrical signal from the inductive sensor 2405 will similarly vary in proportion to the amount of displacement of the core 2410 relative to the coil 2420.

[0118] With reference to Figure 25The standoff 2500 of a bumper (e.g., bumper 200) can include a magnet 2505 coupled to a rod 2510 that passes through a hole 2515 of a robot body 2530. The magnet 2505 is located at an initial distance from a Hall effect sensor 2550 coupled to the robot body 2530. The Hall effect sensor 2550 generates an electrical signal in response to the strength of the magnetic field generated by the magnet 2505 located at the position of the Hall effect sensor 2550. In one example, a force 2560 on the outer skin 2565 of the bumper is transferred to the standoff 2500 such that the standoff 2500 moves relative to the body 2530. As a result, the distance of the magnet 2505 and the Hall effect sensor 2550 standoff changes with the movement of the standoff 2500. As a result, the electrical signal generated by the Hall effect sensor 2550 changes in direct proportion to the amount of displacement of the magnet 2505 relative to the Hall effect sensor 2550 by the force 2560.

[0119] The robots described herein can be controlled, at least in part, using one or more computer program products, such as one or more tangible computer program storage media storing computer programs, for example, non-transitory machine-readable media having stored thereon computer program instructions, for execution by one or more data processing apparatus, such as one or more programmable processors, computers, a plurality of computers, and / or programmable logic elements.

[0120] A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0121] The operations described herein related to controlling a robot can be performed by one or more programmable processors executing one or more computer programs to perform the functions described herein. All or part of the control of a robot described herein can be implemented using special purpose logic circuitry, such as an FPGA (field programmable gate array) and / or an ASIC (application-specific integrated circuit).

[0122] By way of example, a processor suitable for the execution of a computer program includes the general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer include one or more processors for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also includes, or is operatively coupled to receive data from or transfer data to, or both, one or more machine-readable media, such as a mass storage device for storing data like a large PCB, magnetic, magneto-optical disks, or optical disks. Machine-readable media suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks or removable hard disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0123] The elements of different implementations described herein can be combined to form further implementations not specifically described herein. In addition, the elements and / or functions of one specific implementation can be combined in one or more systems and / or methods.

Claims

1. Autonomous mobile robots, including: a body that is movable relative to a surface; a bumper mounted on the main body and movable relative to the main body, the bumper having a front side, side sides, and corners, the bumper comprising: a bracket including a front portion at a front side of the bumper, side portions at sides of the bumper, and corner portions at corners of the bumper, the corner portions connecting the front portion and the side portions and configured to suppress transmission of a force applied to the front portion of the bracket to the side portions, and suppress transmission of a force applied to the side portions of the bracket to the front portion; a sensor system comprising a first sensor at a corner of the bumper to detect a force applied to the corner of the bumper; and A controller is operable to move the body based on the electrical signals from the sensor system.

2. The autonomous mobile robot according to claim 1, wherein: The sensor system further comprises: a second sensor proximate the front side of the bumper to detect a force applied to the front side of the bumper, and A third sensor is located near the side of the bumper to detect the force applied to the side of the bumper.

3. The autonomous mobile robot according to claim 2, wherein: The controller is configured to: determining a location of a force applied to a crash avoider based on electrical signals from the first, second, and third sensors of the sensor system; Start moving the body based on the position of the force.

4. The autonomous mobile robot according to claim 3, wherein: The controller is configured to determine that the location of the force applied to the bumper is at a corner of the bumper based on the electrical signal from the first sensor being greater than the electrical signal from the third sensor and the electrical signal from the second sensor.

5. The autonomous mobile robot according to claim 3, wherein: The electrical signal varies linearly with the movement of the bumper.

6. The autonomous mobile robot according to claim 1, wherein: An angle between a front side of the bumper and a side surface of the bumper is in a range of 75 degrees to 105 degrees.

7. The autonomous mobile robot according to claim 1, wherein: The bumper forms a partial frontal rectangular shape.

8. The autonomous mobile robot according to claim 1, wherein: The bracket includes rigid regions interconnected by flexible regions to inhibit forces applied to a front portion of the bracket from being transmitted to the corner portions and to inhibit forces applied to side portions of the bracket from being transmitted to the corner portions.

9. The autonomous mobile robot according to claim 1, wherein: Corner portions of the bracket are thinner than side portions of the bracket and a front portion of the bracket.

10. The autonomous mobile robot according to claim 1, wherein: The corner portion includes a corner segment and a connecting segment connecting the corner segment to the side portion of the bracket, wherein the length of the connecting segment is greater than the distance between the corner segment and the side portion, thereby suppressing the force applied to the side from being transmitted to the corner segment, and The first sensor includes a portion attached to a corner segment of the bracket.

11. The autonomous mobile robot according to claim 10, wherein: The connecting section is concave relative to the shape of the bumper.

12. The autonomous mobile robot according to claim 1, wherein: The corner portion includes a connecting segment connecting the corner segment to the front portion, the length of the connecting segment being greater than the distance between the corner segment and the front portion, thereby suppressing the force applied to the front portion from being transmitted to the corner portion, and The first sensor includes a portion attached to a corner segment of the bracket.

13. The autonomous mobile robot according to claim 1, wherein: The first sensor includes a first portion attached to the body and a second portion attached to the corner portion, the second portion of the first sensor being movable relative to the first portion of the first sensor to generate an electrical signal in response to contact between the corner portion of the bumper and an obstacle.

14. The autonomous mobile robot according to claim 1, wherein: The first sensor includes a capacitive sensor having a first plate attached to the body and a second plate attached to the bracket.

15. The autonomous mobile robot according to claim 14, wherein: At least one of the first plate or the second plate is non-planar.

16. The autonomous mobile robot according to claim 1, wherein: The autonomous mobile robot is an autonomous cleaning robot configured to perform a cleaning operation on the surface.

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