Habitat for vibration powered device

A playset system for autonomous devices includes a communal area including a substantially horizontal and substantially planar area bounded by a plurality of side walls, a plurality of connectors, and a plurality of ports. Each port is disposed in a side wall, each port is situated adjacent to one of the connectors, and each port includes a gate adapted to open and close, to impede movement of the autonomous devices when closed, and to allow passage of the autonomous devices when open.

BACKGROUND

This specification relates to habitats for devices that move based on oscillatory motion and/or vibration.

One example of vibration driven movement is a vibrating electric football game. A vibrating horizontal metal surface induced inanimate plastic figures to move randomly or slightly directionally. More recent examples of vibration driven motion use internal power sources and a vibrating mechanism located on a vehicle.

One method of creating movement-inducing vibrations is to use rotational motors that spin a shaft attached to a counterweight. The rotation of the counterweight induces an oscillatory motion. Power sources include wind up springs that are manually powered or DC electric motors. The most recent trend is to use pager motors designed to vibrate a pager or cell phone in silent mode. Vibrobots and Bristlebots are two modern examples of vehicles that use vibration to induce movement. For example, small, robotic devices, such as Vibrobots and Bristlebots, can use motors with counterweights to create vibrations. The robots' legs are generally metal wires or stiff plastic bristles. The vibration causes the entire robot to vibrate up and down as well as rotate. These robotic devices tend to drift and rotate because no significant directional control is achieved.

Vibrobots tend to use long metal wire legs. The shape and size of these vehicles vary widely and typically range from short 2″ devices to tall 10″ devices. Rubber feet are often added to the legs to avoid damaging tabletops and to alter the friction coefficient. Vibrobots typically have 3 or 4 legs, although designs with 10-20 exist. The vibration of the body and legs creates a motion pattern that is mostly random in direction and in rotation. Collision with walls does not result in a new direction and the result is that the wall only limits motion in that direction. The appearance of lifelike motion is very low due to the highly random motion.

Bristlebots are sometimes described in the literature as tiny directional Vibrobots. Bristlebots use hundreds of short nylon bristles for legs. The most common source of the bristles, and the vehicle body, is to use the entire head of a toothbrush. A pager motor and battery complete the typical design. Motion can be random and directionless depending on the motor and body orientation and bristle direction. Designs that use bristles angled to the rear with an attached rotating motor can achieve a general forward direction with varying amounts of turning and sideways drifting. Collisions with objects such as walls cause the vehicle to stop, then turn left or right and continue on in a general forward direction. The appearance of lifelike motion is minimal due to a gliding movement and a zombie-like reaction to hitting a wall.

SUMMARY

In general, one innovative aspect of the subject matter described in this specification can be embodied in apparatus, systems, or kits that include a communal area including a substantially horizontal and substantially planar area bounded by a plurality of side walls, a plurality of connectors, and a plurality of ports. Each port is disposed in a side wall, and each port includes a gate adapted to open and close, to impede movement of the autonomous devices when closed, and to allow passage of the autonomous devices when open, and each port is situated adjacent to one of the connectors.

These and other embodiments can each optionally include one or more of the following features. Each autonomous device includes a vibration-powered drive. The kit includes at least one track adapted for traversal by the autonomous devices, and each track is adapted to connect to the communal area at one of the ports using one of the connectors. Each track includes a channel having vertical lateral sides, open ends, and a floor. The vertical lateral sides are spaced at a substantially consistent distance between the open ends. The floor includes a substantially planar surface and an upward curvature in a vicinity of where the floor meets the vertical lateral sides. The upward curvature is adapted to cause each autonomous device to tend to turn toward a centerline of the channel when the autonomous device moves toward the lateral side of the channel. Each track is adapted to connect to the communal area using one of the connectors on the communal area and a corresponding connector at one end of the channel such that the end of the channel substantially aligns horizontally with one of the ports and the floor of the channel substantially aligns vertically with the substantially planar area of the communal area. Each track includes a connector at each end of the channel and each of the connectors is adjacent to a port of the communal area is adapted to interlock with each connector at each end of the channel. The side walls are substantially straight along a horizontal dimension. The side walls of the communal area form a substantially regular polygon. The substantially regular polygon includes at least five sides. The substantially regular polygon includes six sides. The communal area includes a substantially planar open space and each side wall has a horizontal dimension that is at least three times a horizontal dimension of each of the plurality of ports. Each gate includes a lever and is pivotally attached to a portion of one of the side walls of the communal area, and each gate is adapted to be opened and closed by rotating the lever in an arc substantially perpendicular to the substantially planar area of the communal area.

In general, another innovative aspect of the subject matter described in this specification can be embodied in apparatus, systems, or kits that include at least one communal section having a communal area bounded by a plurality of vertical side walls, a plurality of connectors, and a plurality of ports. Each port is disposed in a side wall along one of the side walls of the communal area and each port is situated adjacent to one of the connectors. At least one track is adapted for traversal by vibration-powered devices and is adapted to connect to the communal area at one of the ports using one of the connectors. Each track includes a channel having vertical lateral sides, open ends, and a floor, wherein the vertical lateral sides are spaced at a substantially consistent distance between the open ends. The floor includes a substantially planar surface and an upward curvature in a vicinity of where the floor meets the vertical lateral sides.

These and other embodiments can each optionally include one or more of the following features. Each port includes a gate adapted to open and close, to impede movement of the vibration-powered devices when closed, and to allow passage of the vibration-powered devices when open. Each port is situated adjacent to one of the connectors. Each track includes a connector at each end of the channel and each of the connectors adjacent to a port of the communal area is adapted to interlock with the connectors at the ends of the channel. At least one vibration-powered device includes a body, a rotational motor coupled to the body, an eccentric load, and a plurality of legs. The rotational motor is adapted to rotate the eccentric load, and the plurality of legs each have a leg base and a leg tip at a distal end relative to the leg base. At least a portion of the plurality of legs are constructed from a flexible material, injection molded, integrally coupled to the body at the leg base, and include at least one driving leg configured to cause the vibration-powered device to move in a direction generally defined by an offset between the leg base and the leg tip as the rotational motor rotates the eccentric load.

In general, another innovative aspect of the subject matter described in this specification can be embodied in apparatus, systems, or kits that include at least one communal section including a communal area bounded by a plurality of vertical side walls, a plurality of connectors, and a plurality of ports. Each port is disposed in a side wall of the communal area and each port is situated adjacent to one of the connectors. Each port also includes a gate adapted to open and close, to impede movement of the vibration-powered devices when closed, and to allow passage of the vibration-powered devices when open. At least one track is adapted for traversal by vibration-powered devices, and each track is adapted to connect to the communal area at one of the ports using one of the connectors. Each track includes open ends, a floor, and a channel having lateral sides adapted to limit movement of the vibration-powered devices laterally with respect to a longitudinal dimension of the channel.

These and other embodiments can each optionally include one or more of the following features. The lateral sides are spaced at a substantially consistent distance between the open ends. The kit or system includes a plurality of tracks adapted for traversal by vibration-powered devices, including at least one straight track and at least one curved track. Each channel includes an upward curvature in a vicinity of at least one lateral side and the upward curvature is adapted to cause a vibration-powered device to tend to turn toward a centerline of the channel when the vibration-powered device moves forward at an angle relative to the lateral side of the channel.

In general, another innovative aspect of the subject matter described in this specification can be embodied in apparatus, systems, or kits that include a substantially planar floor disposed between longitudinal ends, a connector at each longitudinal end, and lateral sides adapted to limit movement of vibration-powered devices laterally with respect to a longitudinal dimension of the floor. The connector is adapted to interlock with a corresponding connector on another playset component. The lateral sides terminate at each longitudinal end to form an open end, and the floor includes an upward curvature in a vicinity of where the floor meets the lateral sides.

These and other embodiments can each optionally include one or more of the following features. The lateral sides are spaced at a substantially consistent distance between the open ends.

In general, another innovative aspect of the subject matter described in this specification can be embodied in methods for that include the acts of connecting at least one track component to a communal area component, repositioning at least one gate on one of the communal area component or one of the track components, and operating at least one self-propelled, vibration-driven device in at least one of the communal area component or one of the track components. The communal area component includes a communal area having a substantially horizontal and substantially planar area bounded by a plurality of side walls, a plurality of connectors, and a plurality of ports. Each port is disposed in a side wall, and each port includes a gate adapted to open and close, to impede movement of the autonomous devices when closed, and to allow passage of the autonomous devices when open. Each port is situated adjacent to one of the connectors, and at least one track component is adapted for traversal by vibration-powered devices. Each track component is adapted to connect to the communal area component at one of the ports using one of the connectors, and each track includes a channel having lateral sides adapted to limit movement of the vibration-powered devices laterally with respect to a longitudinal dimension of the channel, open ends, and a floor.

DETAILED DESCRIPTION

Small robotic devices, or vibration-powered vehicles, can be designed to move across a surface, e.g., a floor, table, or other relatively flat surface. The robotic device is adapted to move autonomously and, in some implementations, turn in seemingly random directions. In general, the robotic devices include a housing, multiple legs, and a vibrating mechanism (e.g., a motor or spring-loaded mechanical winding mechanism rotating an eccentric load, a motor or other mechanism adapted to induce oscillation of a counterweight, or other arrangement of components adapted to rapidly alter the center of mass of the device). As a result, the miniature robotic devices, when in motion, can resemble organic life, such as bugs or insects.

Movement of the robotic device can be induced by the motion of a rotational motor inside of, or attached to, the device, in combination with a rotating weight with a center of mass that is offset relative to the rotational axis of the motor. The rotational movement of the weight causes the motor and the robotic device to which it is attached to vibrate. In some implementations, the rotation is approximately in the range of 6000-9000 revolutions per minute (rpm's), although higher or lower rpm values can be used. As an example, the device can use the type of vibration mechanism that exists in many pagers and cell phones that, when in vibrate mode, cause the pager or cell phone to vibrate. The vibration induced by the vibration mechanism can cause the device to move across the surface (e.g., the floor) using legs that are configured to alternately flex (in a particular direction) and return to the original position as the vibration causes the device to move up and down.

Various features can be incorporated into the robotic devices. For example, various implementations of the devices can include features (e.g., shape of the legs, number of legs, frictional characteristics of the leg tips, relative stiffness or flexibility of the legs, resiliency of the legs, relative location of the rotating counterweight with respect to the legs, etc.) for facilitating efficient transfer of vibrations to forward motion. The speed and direction of the robotic device's movement can depend on many factors, including the rotational speed of the motor, the size of the offset weight attached to the motor, the power supply, the characteristics (e.g., size, orientation, shape, material, resiliency, frictional characteristics, etc.) of the “legs” attached to the housing of the device, the properties of the surface on which the device operates, the overall weight of the device, and so on.

In some implementations, the devices include features that are designed to compensate for a tendency of the device to turn as a result of the rotation of the counterweight and/or to alter the tendency for, and direction of, turning between different robotic devices. The components of the device can be positioned to maintain a relatively low center of gravity (or center of mass) to discourage tipping (e.g., based on the lateral distance between the leg tips) and to align the components with the rotational axis of the rotating motor to encourage rolling (e.g., when the device is not upright). Likewise, the device can be designed to encourage self-righting based on features that tend to encourage rolling when the device is on its back or side in combination with the relative flatness of the device when it is upright (e.g., when the device is “standing” on its leg tips). Features of the device can also be used to increase the appearance of random motion and to make the device appear to respond intelligently to obstacles. Different leg configurations and placements can also induce different types of motion and/or different responses to vibration, obstacles, or other forces. Moreover, adjustable leg lengths can be used to provide some degree of steering capability. In some implementations, the robotic devices can simulate real-life objects, such as crawling bugs, rodents, or other animals and insects.

FIG. 1is a diagram that illustrates an example device100that is shaped like a bug. The device100includes a housing102(e.g., resembling the body of the bug) and legs104. Inside (or attached to) the housing102are the components that control and provide movement for the device100, including a rotational motor, power supply (e.g., a battery), and an on/off switch. Each of the legs104includes a leg tip106aand a leg base106b. The properties of the legs104, including the position of the leg base106brelative to the leg tip106a,can contribute to the direction and speed in which the device100tends to move. The device100is depicted in an upright position (i.e., standing on legs104) on a supporting surface110(e.g., a substantially planar floor, table top, etc. that counteracts gravitational forces).

Overview of Legs

Legs104can include front legs104a,middle legs104b,and rear legs104c. For example, the device100can include a pair of front legs104athat may be designed to perform differently from middle legs104band rear legs104c. For example, the front legs104amay be configured to provide a driving force for the device100by contacting an underlying surface110and causing the device to hop forward as the device vibrates. Middle legs104bcan help provide support to counteract material fatigue (e.g., after the device100rests on the legs104for long periods of time) that may eventually cause the front legs104ato deform and/or lose resiliency. In some implementations, device100can exclude middle legs104band include only front legs104aand rear legs104c. In some implementations, front legs104aand one or more rear legs104ccan be designed to be in contact with a surface, while middle legs104bcan be slightly off the surface so that the middle legs104bdo not introduce significant additional drag forces and/or hopping forces that may make it more difficult to achieve desired movements (e.g., tendency to move in a relatively straight line and/or a desired amount of randomness of motion).

In some implementations, the device100can be configured such that only two front legs104aand one rear leg104care in contact with a substantially flat surface110, even if the device includes more than one rear leg104cand several middle legs104b. In other implementations, the device100can be configured such that only one front leg104aand two rear legs104care in contact with a flat surface110. Throughout this specification, descriptions of being in contact with the surface can include a relative degree of contact. For example, when one or more of the front legs104aand one or more of the back legs104care described as being in contact with a substantially flat surface110and the middle legs104bare described as not being in contact with the surface110, it is also possible that the front and back legs104aand104ccan simply be sufficiently longer than the middle legs104b(and sufficiently stiff) that the front and back legs104aand104cprovide more support for the weight of the device100than do the middle legs104b,even though the middle legs104bare technically actually in contact with the surface110. In some implementations, even legs that have a lesser contribution to support of the device may nonetheless be in contact when the device100is in an upright position, especially when vibration of the device causes an up and down movement that compresses and bends the driving legs and allows additional legs to contact the surface110. Greater predictability and control of movement (e.g., in a straight direction) can be obtained by constructing the device so that a sufficiently small number of legs (e.g., fewer than twenty or fewer than thirty) contact the support surface110and/or contribute to the support of the device in the upright position when the device is either at rest or as the rotating eccentric load induces movement. In this respect, it is possible for some legs to provide support even without contacting the support surface110(e.g., one or more short legs can provide stability by contacting an adjacent longer leg to increase overall stiffness of the adjacent longer leg). Typically, however, each leg is sufficiently stiff that four or fewer legs are capable of supporting the weight of the device without substantial deformation (e.g., less than 5% as a percentage of the height of the leg base106bfrom the support surface110when the device100is in an upright position).

Different leg lengths can be used to introduce different movement characteristics, as further discussed below. The various legs can also include different properties, e.g., different stiffnesses or coefficients of friction, as further described below. Generally, the legs can be arranged in substantially parallel rows along each lateral side of the device100(e.g.,FIG. 1depicts one row of legs on the right lateral side of the device100; a corresponding row of legs (not shown inFIG. 1) can be situated along the left lateral side of the device100).

In general, the number of legs104that provide meaningful or any support for the device can be relatively limited. For example, the use of less than twenty legs that contact the support surface110and/or that provide support for the device100when the device100is in an upright position (i.e., an orientation in which the one or more driving legs104aare in contact with a support surface) can provide more predictability in the directional movement tendencies of the device100(e.g., a tendency to move in a relatively straight and forward direction), or can enhance a tendency to move relatively fast by increasing the potential deflection of a smaller number of legs, or can minimize the number of legs that may need to be altered to achieve the desired directional control, or can improve the manufacturability of fewer legs with sufficient spacing to allow room for tooling. In addition to providing support by contacting the support surface110, legs104can provide support by, for example, providing increased stability for legs that contact the surface110. In some implementations, each of the legs that provides independent support for the device100is capable of supporting a substantial portion of the weight of the device100. For example, the legs104can be sufficiently stiff that four or fewer legs are capable of statically (e.g., when the device is at rest) supporting the device without substantial deformation of the legs104(e.g., without causing the legs to deform such that the body of the device100moves more than 5% as a percentage of the height of the leg base106bfrom the support surface).

As described here at a high level, many factors or features can contribute to the movement and control of the device100. For example, the device's center of gravity (CG), and whether it is more forward or towards the rear of the device, can influence the tendency of the device100to turn. Moreover, a lower CG can help to prevent the device100from tipping over. The location and distribution of the legs104relative to the CG can also prevent tipping. For example, if pairs or rows of legs104on each side of the device100are too close together and the device100has a relatively high CG (e.g., relative to the lateral distance between the rows or pairs of legs), then the device100may have a tendency to tip over on its side. Thus, in some implementations, the device includes rows or pairs of legs104that provide a wider lateral stance (e.g., pairs of front legs104a,middle legs104b,and rear legs104care spaced apart by a distance that defines an approximate width of the lateral stance) than a distance between the CG and a flat supporting surface on which the device100rests in an upright position. For example, the distance between the CG and the supporting surface can be in the range of 50-80% of the value of the lateral stance (e.g., if the lateral stance is 0.5 inches, the CG may be in the range of 0.25-0.4 inches from the surface110). Moreover, the vertical location of the CG of the device100can be within a range of 40-60% of the distance between a plane that passes through the leg tips106aand the highest protruding surface on the top side of the housing102. In some implementations, a distance409aand409b(as shown inFIG. 4) between each row of the tips of legs104and a longitudinal axis of the device100that runs through the CG can be roughly the same or less than the distance406(as shown inFIG. 4) between the tips106aof two rows of legs104to help facilitate stability when the device is resting on both rows of legs.

The device100can also include features that generally compensate for the device's tendency to turn. Driving legs (e.g., front legs104a) can be configured such that one or more legs on one lateral side of the device100can provide a greater driving force than one or more corresponding legs on the other lateral side of the device100(e.g., through relative leg lengths, relative stiffness or resiliency, relative fore/aft location in the longitudinal direction, or relative lateral distance from the CG). Similarly, dragging legs (e.g., back legs104c) can be configured such that one or more legs on one lateral side of the device100can provide a greater drag force than one or more corresponding legs on the other lateral side of the device100(e.g., through relative leg lengths, relative stiffness or resiliency, relative fore/aft location in the longitudinal direction, or relative lateral distance from the CG). In some implementations, the leg lengths can be tuned either during manufacturing or subsequently to modify (e.g., increase or reduce) a tendency of the device to turn.

Movement of the device can also be influenced by the leg geometry of the legs104. For example, a longitudinal offset between the leg tip (i.e., the end of the leg that touches the surface110) and the leg base (i.e., the end of the leg that attaches to the device housing) of any driving legs induces movement in a forward direction as the device vibrates. Including some curvature, at least in the driving legs, further facilitates forward motion as the legs tend to bend, moving the device forward, when vibrations force the device downward and then spring back to a straighter configuration as the vibrations force the device upward (e.g., resulting in hopping completely or partially off the surface, such that the leg tips move forward above or slide forward across the surface110).

The ability of the legs to induce forward motion results in part from the ability of the device to vibrate vertically on the resilient legs. As shown inFIG. 1, the device100includes an underside122. The power supply and motor for the device100can be contained in a chamber that is formed between the underside122and the upper body of the device, for example. The length of the legs104creates a space124(at least in the vicinity of the driving legs) between the underside122and the surface110on which the device100operates. The size of the space124depends on how far the legs104extend below the device relative to the underside122. The space124provides room for the device100(at least in the vicinity of the driving legs) to move downward as the periodic downward force resulting from the rotation of the eccentric load causes the legs to bend. This downward movement can facilitate forward motion induced by the bending of the legs104.

The device can also include the ability to self-right itself, for example, if the device100tips over or is placed on its side or back. For example, constructing the device100such that the rotational axis of the motor and the eccentric load are approximately aligned with the longitudinal CG of the device100tends to enhance the tendency of the device100to roll (i.e., in a direction opposite the rotation of the motor and the eccentric load). Moreover, construction of the device housing to prevent the device from resting on its top or side (e.g., using one or more protrusions on the top and/or sides of the device housing) and to increase the tendency of the device to bounce when on its top or side can enhance the tendency to roll. Furthermore, constructing the legs of a sufficiently flexible material and providing clearance on the housing undercarriage that the leg tips to bend inward can help facilitate rolling of the device from its side to an upright position.

FIG. 1shows a body shoulder112and a head side surface114, which can be constructed from rubber, elastomer, or other resilient material, contributing to the device's ability to self-right after tipping. The bounce from the shoulder112and the head side surface114can be significantly more than the lateral bounce achieved from the legs, which can be made of rubber or some other elastomeric material, but which can be less resilient than the shoulder112and the head side surface114(e.g., due to the relative lateral stiffness of the shoulder112and the head side surface114compared to the legs104). Rubber legs104, which can bend inward toward the body102as the device100rolls, increase the self-righting tendency, especially when combined with the angular/rolling forces induced by rotation of the eccentric load. The bounce from the shoulder112and the head side surface114can also allow the device100to become sufficiently airborne that the angular forces induced by rotation of the eccentric load can cause the device to roll, thereby facilitating self-righting.

The device can also be configured to include a degree of randomness of motion, which can make the device100appear to behave like an insect or other animate object. For example, vibration induced by rotation of the eccentric load can further induce hopping as a result of the curvature and “tilt” of the legs. The hopping can further induce a vertical acceleration (e.g., away from the surface110) and a forward acceleration (e.g., generally toward the direction of forward movement of the device100). During each hop, the rotation of the eccentric load can further cause the device to turn toward one side or the other depending on the location and direction of movement of the eccentric load. The degree of random motion can be increased if relatively stiffer legs are used to increase the amplitude of hopping. The degree of random motion can be influenced by the degree to which the rotation of the eccentric load tends to be either in phase or out of phase with the hopping of the device (e.g., out of phase rotation relative to hopping may increase the randomness of motion). The degree of random motion can also be influenced by the degree to which the back legs104ctend to drag. For example, dragging of back legs104con both lateral sides of the device100may tend to keep the device100traveling in a more straight line, while back legs104cthat tend to not drag (e.g., if the legs bounce completely off the ground) or dragging of back legs104cmore on one side of the device100than the other can tend to increase turning.

Another feature is “intelligence” of the device100, which can allow the device to interact in an apparently intelligent manner with obstacles, including, for example, bouncing off any obstacles (e.g., walls, etc.) that the device100encounters during movement. For example, the shape of the nose108and the materials from which the nose108is constructed can enhance a tendency of the device to bounce off of obstacles and to turn away from the obstacle. Each of these features can contribute to how the device100moves, and will be described below in more detail.

FIG. 1illustrates a nose108that can contribute to the ability of the device100to deflect off of obstacles. Nose left side116aand nose right side116bcan form the nose108. The nose sides116aand116bcan form a shallow point or another shape that helps to cause the device100to deflect off obstacles (e.g., walls) encountered as the device100moves in a generally forward direction. The device100can includes a space within the head118that increases bounce by making the head more elastically deformable (i.e., reducing the stiffness). For example, when the device100crashes nose-first into an obstacle, the space within the head118allows the head of the device100to compress, which provides greater control over the bounce of the device100away from the obstacle than if the head118is constructed as a more solid block of material. The space within the head118can also better absorb impact if the device falls from some height (e.g., a table). The body shoulder112and head side surface114, especially when constructed from rubber or other resilient material, can also contribute to the device's tendency to deflect or bounce off of obstacles encountered at a relatively high angle of incidence.

In some implementations, the device100includes a receiver that can, for example, receive commands from a remote control unit. Commands can be used, for example, to control the device's speed and direction, and whether the device is in motion or in a motionless state, to name a few examples. In some implementations, controls in the remote control unit can engage and disengage the circuit that connects the power unit (e.g., battery) to the device's motor, allowing the operator of the remote control to start and stop the device100at any time. Other controls (e.g., a joy stick, sliding bar, etc.) in the remote control unit can cause the motor in the device100to spin faster or slower, affecting the speed of the device100. The controls can send the receiver on the device100different signals, depending on the commands that correspond to the movement of the controls. Controls can also turn on and off a second motor attached to a second eccentric load in the device100to alter lateral forces for the device100, thereby changing a tendency of the device to turn and thus providing steering control. Controls in a remote control unit can also cause mechanisms in the device100to lengthen or shorten one or more of the legs and/or deflecting one or more of the legs forward, backward, or laterally to provide steering control.

Leg Motion and Hop

FIGS. 2A through 2Dare diagrams that illustrate example forces that induce movement of the device100ofFIG. 1. Some forces are provided by a rotational motor202, which enable the device100to move autonomously across the surface110. For example, the motor202can rotate an eccentric load210that generates moment and force vectors205-215as shown inFIGS. 2A-2D. Motion of the device100can also depend in part on the position of the legs104with respect to the counterweight210attached to the rotational motor202. For example, placing the counterweight210in front of the front legs104awill increase the tendency of the front legs104ato provide the primary forward driving force (i.e., by focusing more of the up and down forces on the front legs). For example, the distance between the counterweight210and the tips of the driving legs can be within a range of 20-100% of an average length of the driving legs. Moving the counterweight210back relative to the front legs104acan cause other legs to contribute more to the driving forces.

FIG. 2Ashows a side view of the example device100shown inFIG. 1and further depicts a rotational moment205(represented by the rotational velocity ωmand motor torque Tm) and a vertical force206represented by Fv.FIG. 2Bshows a top view of the example device100shown inFIG. 1and further shows a horizontal force208represented by Fh. Generally, a negative Fvis caused by upward movement of the eccentric load as it rotates, while a positive Fvcan be caused by the downward movement of the eccentric load and/or the resiliency of the legs (e.g., as they spring back from a deflected position).

The forces Fvand Fhcause the device100to move in a direction that is consistent with the configuration in which the leg base106bis positioned in front of the leg tip106a. The direction and speed in which the device100moves can depend, at least in part, on the direction and magnitude of Fvand Fh. When the vertical force206, Fv, is negative, the device100body is forced down. This negative Fvcauses at least the front legs104ato bend and compress. The legs generally compress along a line in space from the leg tip to the leg base. As a result, the body will lean so that the leg bends (e.g., the leg base106bflexes (or deflects) about the leg tip106atowards the surface110) and causes the body to move forward (e.g., in a direction from the leg tip106atowards the leg base106b). Fv, when positive, provides an upward force on the device100allowing the energy stored in the compressed legs to release (lifting the device), and at the same time allowing the legs to drag or hop forward to their original position. The lifting force Fvon the device resulting from the rotation of the eccentric load combined with the spring-like leg forces are both involved in allowing the vehicle to hop vertically off the surface (or at least reducing the load on the front legs104a) and allowing the legs104to return to their normal geometry (i.e., as a result of the resiliency of the legs). The release of the spring-like leg forces, along with the forward momentum created as the legs bend, propels the vehicle forward and upward, based on the angle of the line connecting the leg tip to the leg base, lifting the front legs104aoff the surface110(or at least reducing the load on the front legs104a) and allowing the legs104to return to their normal geometry (i.e., as a result of the resiliency of the legs).

Generally, two “driving” legs (e.g., the front legs104a,one on each side) are used, although some implementations may include only one driving leg or more than two driving legs. Which legs constitute driving legs can, in some implementations, be relative. For example, even when only one driving leg is used, other legs may provide a small amount of forward driving forces. During the forward motion, some legs104may tend to drag rather than hop. Hop refers to the result of the motion of the legs as they bend and compress and then return to their normal configuration—depending on the magnitude of Fv, the legs can either stay in contact with the surface or lift off the surface for a short period of time as the nose is elevated. For example, if the eccentric load is located toward the front of the device100, then the front of the device100can hop slightly, while the rear of the device100tends to drag. In some cases, however, even with the eccentric load located toward the front of the device100, even the back legs104cmay sometimes hop off the surface, albeit to a lesser extent than the front legs104a. Depending on the stiffness or resiliency of the legs, the speed of rotation of the rotational motor, and the degree to which a particular hop is in phase or out of phase with the rotation of the motor, a hop can range in duration from less than the time required for a full rotation of the motor to the time required for multiple rotations of the motor. During a hop, rotation of the eccentric load can cause the device to move laterally in one direction or the other (or both at different times during the rotation) depending on the lateral direction of rotation at any particular time and to move up or down (or both at different times during the rotation) depending on the vertical direction of rotation at any particular time.

Increasing hop time can be a factor in increasing speed. The more time that the vehicle spends with some of the leg off the surface110(or lightly touching the surface), the less time some of the legs are dragging (i.e., creating a force opposite the direction of forward motion) as the vehicle translates forward. Minimizing the time that the legs drag forward (as opposed to hop forward) can reduce drag caused by friction of the legs sliding along the surface110. In addition, adjusting the CG of the device fore and aft can effect whether the vehicle hops with the front legs only, or whether the vehicle hops with most, if not all, of the legs off the ground. This balancing of the hop can take into account the CG, the mass of the offset weight and its rotational frequency, Fvand its location, and hop forces and their location(s).

Turning of Device

The motor rotation also causes a lateral force208, Fh, which generally shifts back and forth as the eccentric load rotates. In general, as the eccentric load rotates (e.g., due to the motor202), the left and right horizontal forces208are equal. The turning that results from the lateral force208on average typically tends to be greater in one direction (right or left) while the device's nose108is elevated, and greater in the opposite direction when the device's nose108and the legs104are compressed down. During the time that the center of the eccentric load210is traveling upward (away from the surface110), increased downward forces are applied to the legs104, causing the legs104to grip the surface110, minimizing lateral turning of the device100, although the legs may slightly bend laterally depending on the stiffness of the legs104. During the time when the eccentric load210is traveling downward, the downward force on the legs104decreases, and downward force of the legs104on the surface110can be reduced, which can allow the device to turn laterally during the time the downward force is reduced. The direction of turning generally depends on the direction of the average lateral forces caused by the rotation of the eccentric load210during the time when the vertical forces are positive relative to when the vertical forces are negative. Thus, the horizontal force208, Fh, can cause the device100to turn slightly more when the nose108is elevated. When the nose108is elevated, the leg tips are either off the surface110or less downward force is on the front legs104awhich precludes or reduces the ability of the leg tips (e.g., leg tip106a) to “grip” the surface110and to provide lateral resistance to turning. Features can be implemented to manipulate several motion characteristics to either counteract or enhance this tendency to turn.

The location of the CG can also influence a tendency to turn. While some amount of turning by the device100can be a desired feature (e.g., to make the device's movement appear random), excessive turning can be undesirable. Several design considerations can be made to compensate for (or in some cases to take advantage of) the device's tendency to turn. For example, the weight distribution of the device100, or more specifically, the device's CG, can affect the tendency of the device100to turn. In some implementations, having CG relatively near the center of the device100and roughly centered about the legs104can increase a tendency for the device100to travel in a relatively straight direction (e.g., not spinning around).

Tuning the drag forces for different legs104is another way to compensate for the device's tendency to turn. For example, the drag forces for a particular leg104can depend on the leg's length, thickness, stiffness and the type of material from which the leg is made. In some implementations, the stiffness of different legs104can be tuned differently, such as having different stiffness characteristics for the front legs104a,rear legs104cand middle legs104b. For example, the stiffness characteristics of the legs can be altered or tuned based on the thickness of the leg or the material used for the leg. Increasing the drag (e.g., by increasing a leg length, thickness, stiffness, and/or frictional characteristic) on one side of the device (e.g., the right side) can help compensate for a tendency of the device to turn (e.g., to the left) based on the force Fhinduced by the rotational motor and eccentric load.

Altering the position of the rear legs104cis another way to compensate for the device's tendency to turn. For example, placing the legs104further toward the rear of the device100can help the device100travel in a more straight direction. Generally, a longer device100that has a relatively longer distance between the front and rear legs104cmay tend to travel in more of a straight direction than a device100that is shorter in length (i.e., the front legs104aand rear legs104care closer together), at least when the rotating eccentric load is located in a relatively forward position on the device100. The relative position of the rearmost legs104(e.g., by placing the rearmost leg on one side of the device farther forward or backward on the device than the rearmost leg on the other side of the device) can also help compensate for (or alter) the tendency to turn.

Various techniques can also be used to control the direction of travel of the device100, including altering the load on specific legs, adjusting the number of legs, leg lengths, leg positions, leg stiffness, and drag coefficients. As illustrated inFIG. 2B, the lateral horizontal force208, Fh, causes the device100to have a tendency to turn as the lateral horizontal force208generally tends to be greater in one direction than the other during hops. The horizontal force208, Fhcan be countered to make the device100move in an approximately straight direction. This result can be accomplished with adjustments to leg geometry and leg material selection, among other things.

FIG. 2Cis a diagram that shows a rear view of the device100and further illustrates the relationship of the vertical force206Fvand the horizontal force208Fhin relation to each other. This rear view also shows the eccentric load210that is rotated by the rotational motor202to generate vibration, as indicated by the rotational moment205.

Drag Forces

FIG. 2Dis a diagram that shows a bottom view of the device100and further illustrates example leg forces211-214that are involved with direction of travel of the device100. In combination, the leg forces211-214can induce velocity vectors that impact the predominant direction of travel of the device100. The velocity vector215, represented by Tload, represents the velocity vector that is induced by the motor/eccentricity rotational velocity (e.g., induced by the offset load attached to the motor) as it forces the driving legs104to bend, causing the device to lunge forward, and as it generates greater lateral forces in one direction than the other during hopping. The leg forces211-214, represented by F1-F4, represent the reactionary forces of the legs104a1-104c2, respectively, that can be oriented so the legs104a1-104c2, in combination, induce an opposite velocity vector relative to Tload. As depicted inFIG. 2D, Tloadis a velocity vector that tends to steer the device100to the left (as shown) due to the tendency for there to be greater lateral forces in one direction than the other when the device is hopping off the surface110. At the same time, the forces F1-F2for the front legs104a1and104a2(e.g., as a result of the legs tending to drive the device forward and slightly laterally in the direction of the eccentric load210when the driving legs are compressed) and the forces F3-F4for the rear legs104c1and104c2(as a result of drag) each contribute to steering the device100to the right (as shown). (As a matter of clarification, becauseFIG. 2Dshows the bottom view of the device100, the left-right directions when the device100is placed upright are reversed.) In general, if the combined forces F1-F4approximately offset the side component of Tload, then the device100will tend to travel in a relatively straight direction.

Controlling the forces F1-F4can be accomplished in a number of ways. For example, the “push vector” created by the front legs104a1and104a2can be used to counter the lateral component of the motor-induced velocity. In some implementations, this can be accomplished by placing more weight on the front leg104a2to increase the leg force212, represented by F2, as shown inFIG. 2D. Furthermore, a “drag vector” can also be used to counter the motor-induced velocity. In some implementations, this can be accomplished by increasing the length of the rear leg104c2or increasing the drag coefficient on the rear leg104c2for the force vector804, represented by F4, inFIG. 2D. As shown, the legs104a1and104a2are the device's front right and left legs, respectively, and the legs104c1and104c2are the device's rear right and left legs, respectively.

Another technique for compensating for the device's tendency to turn is increasing the stiffness of the legs104in various combinations (e.g., by making one leg thicker than another or constructing one leg using a material having a naturally greater stiffness). For example, a stiffer leg will have a tendency to bounce more than a more flexible leg. Left and right legs104in any leg pair can have different stiffnesses to compensate for the turning of the device100induced by the vibration of the motor202. Stiffer front legs104acan also produce more bounce.

Another technique for compensating for the device's tendency to turn is to change the relative position of the rear legs104c1and104c2so that the drag vectors tend to compensate for turning induced by the motor velocity. For example, the rear leg104c2can be placed farther forward (e.g., closer to the nose108) than the rear leg104c1.

Leg Shape

Leg geometry contributes significantly to the way in which the device100moves. Aspects of leg geometry include: locating the leg base in front of the leg tip, curvature of the legs, deflection properties of the legs, configurations that result in different drag forces for different legs, including legs that do not necessarily touch the surface, and having only three legs that touch the surface, to name a few examples.

Generally, depending on the position of the leg tip106arelative to the leg base106b, the device100can experience different behaviors, including the speed and stability of the device100. For example, if the leg tip106ais nearly directly below the leg base106bwhen the device100is positioned on a surface, movement of the device100that is caused by the motor202can be limited or precluded. This is because there is little or no slope to the line in space that connects the leg tip106aand the leg base106b. In other words, there is no “lean” in the leg104between the leg tip106aand the leg base106b. However, if the leg tip106ais positioned behind the leg base106b(e.g., farther from the nose108), then the device100can move faster, as the slope or lean of the legs104is increased, providing the motor202with a leg geometry that is more conducive to movement. In some implementations, different legs104(e.g., including different pairs, or left legs versus right legs) can have different distances between leg tips106aand leg bases106b.

In some implementations, the legs104are curved (e.g., leg104ashown inFIG. 2A, and legs104shown inFIG. 1). For example, because the legs104are typically made from a flexible material, the curvature of the legs104can contribute to the forward motion of the device100. Curving the leg can accentuate the forward motion of the device100by increasing the amount that the leg compresses relative to a straight leg. This increased compression can also increase vehicle hopping, which can also increase the tendency for random motion, giving the device an appearance of intelligence and/or a more life-like operation. The legs can also have at least some degree of taper from the leg base106bto the leg tip106a,which can facilitate easier removal from a mold during the manufacturing process.

The number of legs can vary in different implementations. In general, increasing the number of legs104can have the effect of making the device more stable and can help reduce fatigue on the legs that are in contact with the surface110. Increasing the number of legs can also affect the location of drag on the device100if additional leg tips106aare in contact with the surface110. In some implementations, however, some of the legs (e.g., middle legs104b) can be at least slightly shorter than others so that they tend not to touch the surface110or contribute less to overall friction that results from the leg tips106atouching the surface110. For example, in some implementations, the two front legs104a(e.g., the “driving” legs) and at least one of the rear legs104care at least slightly longer than the other legs. This configuration helps increase speed by increasing the forward driving force of the driving legs. In general, the remaining legs104can help prevent the device100from tipping over by providing additional resiliency should the device100start to lean toward one side or the other.

In some implementations, one or more of the “legs” can include any portion of the device that touches the ground. For example, the device100can include a single rear leg (or multiple rear legs) constructed from a relatively inflexible material (e.g., rigid plastic), which can resemble the front legs or can form a skid plate designed to simply drag as the front legs104aprovide a forward driving force. The oscillating eccentric load can repeat tens to several hundred times per second, which causes the device100to move in a generally forward motion as a result of the forward momentum generated when Fvis negative.

Leg geometry can be defined and implemented based on ratios of various leg measurements, including leg length, diameter, and radius of curvature. One ratio that can be used is the ratio of the radius of curvature of the leg104to the leg's length. As just one example, if the leg's radius of curvature is 49.14 mm and the leg's length is 10.276 mm, then the ratio is 4.78 . In another example, if the leg's radius of curvature is 2.0 inches and the leg's length is 0.4 inches, then the ratio is 5.0 . Other leg104lengths and radii of curvature can be used, such as to produce a ratio of the radius of curvature to the leg's length that leads to suitable movement of the device100. In general, the ratio of the radius of curvature to the leg's length can be in the range of 2.5 to 20.0 . The radius of curvature can be approximately consistent from the leg base to the leg tip. This approximate consistent curvature can include some variation, however. For example, some taper angle in the legs may be required during manufacturing of the device (e.g., to allow removal from a mold). Such a taper angle may introduce slight variations in the overall curvature that generally do not prevent the radius of curvature from being approximately consistent from the leg base to the leg tip.

Another ratio that can be used to characterize the device100is a ratio that relates leg104length to leg diameter or thickness (e.g., as measured in the center of the leg or as measured based on an average leg diameter throughout the length of the leg and/or about the circumference of the leg). For example, the length of the legs104can be in the range of 0.2 inches to 0.8 inches (e.g., 0.405 inches) and can be proportional to (e.g., 5.25 times) the leg's thickness in the range of 0.03 to 0.15 inch (e.g., 0.077 inch). Stated another way, legs104can be about 15% to 25% as thick as they are long, although greater or lesser thicknesses (e.g., in the range of 5% to 60% of leg length) can be used. Leg104lengths and thicknesses can further depend on the overall size of the device100. In general, at least one driving leg can have a ratio of the leg length to the leg diameter in the range of 2.0 to 20.0 (i.e., in the range of 5% to 50% of leg length). In some implementations, a diameter of at least 10% of the leg length may be desirable to provide sufficient stiffness to support the weight of the device and/or to provide desired movement characteristics.

Leg Material

The legs are generally constructed of rubber or other flexible but resilient material (e.g., polystyrene-butadiene-styrene with a durometer near 65, based on the Shore A scale, or in the range of 55-75, based on the Shore A scale). Thus, the legs tend to deflect when a force is applied. Generally, the legs include a sufficient stiffness and resiliency to facilitate consistent forward movement as the device vibrates (e.g., as the eccentric load210rotates). The legs104are also sufficiently stiff to maintain a relatively wide stance when the device100is upright yet allow sufficient lateral deflection when the device100is on its side to facilitate self-righting, as further discussed below.

The selection of leg materials can have an effect on how the device100moves. For example, the type of material used and its degree of resiliency can affect the amount of bounce in the legs104that is caused by the vibration of the motor202and the counterweight210. As a result, depending on the material's stiffness (among other factors, including positions of leg tips106brelative to leg bases106a), the speed of the device100can change. In general, the use of stiffer materials in the legs104can result in more bounce, while more flexible materials can absorb some of the energy caused by the vibration of the motor202, which can tend to decrease the speed of the device100.

Frictional Characteristics

Friction (or drag) force equals the coefficient of friction multiplied by normal force. Different coefficients of friction and the resulting friction forces can be used for different legs. As an example, to control the speed and direction (e.g., tendency to turn, etc.), the leg tips106acan have varying coefficients of friction (e.g., by using different materials) or drag forces (e.g., by varying the coefficients of friction and/or the average normal force for a particular leg). These differences can be accomplished, for example, by the shape (e.g., pointedness or flatness, etc.) of the leg tips106aas well as the material of which they are made. Front legs104a,for example, can have a higher friction than the rear legs104c. Middle legs104bcan have yet different friction or can be configured such that they are shorter and do not touch the surface110, and thus do not tend to contribute to overall drag. Generally, because the rear legs104c(and the middle legs104bto the extent they touch the ground) tend to drag more than they tend to create a forward driving force, lower coefficients of friction and lower drag forces for these legs can help increase the speed of the device100. Moreover, to offset the motor force215, which can tend to pull the device in a left or right direction, left and right legs104can have different friction forces. Overall, coefficients of friction and the resulting friction force of all of the legs104can influence the overall speed of the device100. The number of legs104in the device100can also be used to determine coefficients of friction to have in (or design into) each of the individual legs104. As discussed above, the middle legs104bdo not necessarily need to touch the surface110. For example, middle (or front or back) legs104can be built into the device100for aesthetic reasons, e.g., to make the device100appear more life-like, and/or to increase device stability. In some implementations, devices100can be made in which only three (or a small number of) legs104touch the ground, such as two front legs104aand one or two rear legs104c.

The motor202is coupled to and rotates a counterweight210, or eccentric load, that has a CG that is off axis relative to the rotational axis of the motor202. The rotational motor202and counterweight210, in addition to being adapted to propel the device100, can also cause the device100to tend to roll, e.g., about the axis of rotation of the rotational motor200. The rotational axis of the motor202can have an axis that is approximately aligned with a longitudinal CG of the device100, which is also generally aligned with a direction of movement of the device100.

FIG. 2Aalso shows a battery220and a switch222. The battery220can provide power to the motor202, for example, when the switch222is in the “ON” position, thus connecting an electrical circuit that delivers electric current to the motor202. In the “OFF” position of the switch222, the circuit is broken, and no power reaches the motor202. The battery220can be located within or above a battery compartment cover224, accessible, for example, by removing a screw226, as shown inFIGS. 2A and 2D. The placement of the battery220and the switch222partially between the legs of the device100can lower the device's CG and help to prevent tipping. Locating the motor202lower within the device100also reduces tipping. Having legs104on the sides of a vehicle100provides a space (e.g., between the legs104) to house the battery220, the motor204and the switch222. Positioning these components204,220and222along the underside of the device100(e.g., rather than on top of the device housing) effectively lowers the CG of the device100and reduces its likelihood of tipping.

The device100can be configured such that the CG is selectively positioned to influence the behavior of the device100. For example, a lower CG can help to prevent tipping of the device100during its operation. As an example, tipping can occur as a result of the device100moving at a high rate of speed and crashing into an obstacle. In another example, tipping can occur if the device100encounters a sufficiently irregular area of the surface on which it is operating. The CG of the device100can be selectively manipulated by positioning the motor, switch, and battery in locations that provide a desired CG, e.g., one that reduces the likelihood of inadvertent tipping. In some implementations, the legs can be configured so that they extend from the leg tip106abelow the CG to a leg base106bthat is above the CG, allowing the device100to be more stable during its operation. The components of the device100(e.g., motor, switch, battery, and housing) can be located at least partially between the legs to maintain a lower CG. In some implementations, the components of the device (e.g., motor, switch and battery) can be arranged or aligned close to the CG to maximize forces caused by the motor202and the counterweight210.

Self-righting, or the ability to return to an upright position (e.g., standing on legs104), is another feature of the device100. For example, the device100can occasionally tip over or fall (e.g., falling off a table or a step). As a result, the device100can end up on its top or its side. In some implementations, self-righting can be accomplished using the forces caused by the motor202and the counterweight210to cause the device100to roll over back onto its legs104. Achieving this result can be helped by locating the device's CG proximal to the motor's rotational axis to increase the tendency for the entire device100to roll. This self-righting generally provides for rolling in the direction that is opposite to the rotation of the motor202and the counterweight210.

Provided that a sufficient level of roll tendency is produced based on the rotational forces resulting from the rotation of the motor202and the counterweight210, the outer shape of the device100can be designed such that rolling tends to occur only when the device100is on its right side, top side, or left side. For example, the lateral spacing between the legs104can be made wide enough to discourage rolling when the device100is already in the upright position. Thus, the shape and position of the legs104can be designed such that, when self-righting occurs and the device100again reaches its upright position after tipping or falling, the device100tends to remain upright. In particular, by maintaining a flat and relatively wide stance in the upright position, upright stability can be increased, and, by introducing features that reduce flatness when not in an upright position, the self-righting capability can be increased.

To assist rolling from the top of the device100, a high point120or a protrusion can be included on the top of the device100. The high point120can prevent the device from resting flat on its top. In addition, the high point120can prevent Fhfrom becoming parallel to the force of gravity, and as a result, Fhcan provide enough moment to cause the device to roll, enabling the device100to roll to an upright position or at least to the side of the device100. In some implementations, the high point120can be relatively stiff (e.g., a relatively hard plastic), while the top surface of the head118can be constructed of a more resilient material that encourages bouncing. Bouncing of the head118of the device when the device is on its back can facilitate self-righting by allowing the device100to roll due to the forces caused by the motor202and the counterweight210as the head118bounces off the surface110.

Rolling from the side of the device100to an upright position can be facilitated by using legs104that are sufficiently flexible in combination with the space124(e.g., underneath the device100) for lateral leg deflection to allow the device100to roll to an upright position. This space can allow the legs104to bend during the roll, facilitating a smooth transition from side to bottom. The shoulders112on the device100can also decrease the tendency for the device100to roll from its side onto its back, at least when the forces caused by the motor202and the counterweight210are in a direction that opposes rolling from the side to the back. At the same time, the shoulder on the other side of the device100(even with the same configuration) can be designed to avoid preventing the device100from rolling onto its back when the forces caused by the motor202and the counterweight210are in a direction that encourages rolling in that direction. Furthermore, use of a resilient material for the shoulder can increase bounce, which can also increase the tendency for self-righting (e.g., by allowing the device100to bounce off the surface110and allowing the counterweight forces to roll the device while airborne). Self-righting from the side can further be facilitated by adding appendages along the side(s) of the device100that further separate the rotational axis from the surface and increase the forces caused by the motor202and the counterweight210.

The position of the battery on the device100can affect the device's ability to roll and right itself. For example, the battery can be oriented on its side, positioned in a plane that is both parallel to the device's direction of movement and perpendicular to the surface110when the device100is upright. This positioning of the battery in this manner can facilitate reducing the overall width of the device100, including the lateral distance between the legs104, making the device100more likely to be able to roll.

FIG. 4shows an example front view indicating a center of gravity (CG)402, as indicated by a large plus sign, for the device100. This view illustrates a longitudinal CG402(i.e., a location of a longitudinal axis of the device100that runs through the device CG). In some implementations, the vehicle's components are aligned to place the longitudinal CG close to (e.g., within 5-10% as a percentage of the height of the vehicle) the physical longitudinal centerline of the vehicle, which can reduce the rotational moment of inertia of the vehicle, thereby increasing or maximizing the forces on the vehicle as the rotational motor rotates the eccentric load. As discussed above, this effect increases the tendency of the device100to roll, which can enhance the self-righting capability of the device.FIG. 4also shows a space404between the legs104and the underside122of the vehicle100(including the battery compartment cover224), which can allow the legs104to bend inward when the device is on its side, thereby facilitating self-righting of the device100.FIG. 4also illustrates a distance406between the pairs or rows of legs104. Increasing the distance406can help prevent the vehicle100from tipping. However, keeping the distance406sufficiently low, combined with flexibility of the legs104, can improve the vehicle's ability to self-right after tipping. In general, to prevent tipping, the distance406between pairs of legs needs to be increased proportionally as the CG402is raised.

The vehicle high point120is also shown inFIG. 4. The size or height of the high point120can be sufficiently large enough to prevent the device100from simply lying flat on its back after tipping, yet sufficiently small enough to help facilitate the device's roll and to force the device100off its back after tipping. A larger or higher high point120can be better tolerated if combined with “pectoral fins” or other side protrusions to increase the “roundness” of the device.

The tendency to roll of the device100can depend on the general shape of the device100. For example, a device100that is generally cylindrical, particularly along the top of the device100, can roll relatively easily. Even if the top of the device is not round, as is the case for the device shown inFIG. 4that includes straight top sides407aand407b,the geometry of the top of the device100can still facilitate rolling. This is especially true if distances408and410are relatively equal and each approximately defines the radius of the generally cylindrical shape of the device100. Distance408, for example, is the distance from the device's longitudinal CG402to the top of the shoulder112. Distance410is the distance from the device's longitudinal CG402to the high point120. Further, having a length of surface407b(i.e., between the top of the shoulder112and the high point120) that is less than the distances408and410can also increase the tendency of the device100to roll. Moreover, if the device's longitudinal CG402is positioned relatively close to the center of the cylinder that approximates the general shape of the device100, then roll of the device100is further enhanced, as the forces caused by the motor202and the counterweight210are generally more centered. The device100can stop rolling once the rolling action places the device100on its legs104, which provide a wide stance and serve to interrupt the generally cylindrical shape of the device100.

FIG. 5shows an example side view indicating a center of gravity (CG)502, as indicated by a large plus sign, for the device100. This view also shows a motor axis504which, in this example, closely aligns with the longitudinal component of the CG502. The location of the CG502depends on, e.g., the mass, thickness, and distribution of the materials and components included in the device100. In some implementations, the CG502can be farther forward or farther back from the location shown inFIG. 5. For example, the CG502can be located toward the rear end of the switch222rather than toward the front end of the switch222as illustrated inFIG. 5. In general, the CG502of the device100can be sufficiently far behind the front driving legs104aand the rotating eccentric load (and sufficiently far in front of the rear legs104c) to facilitate front hopping and rear drag, which can increase forward drive and provide a controlled tendency to go straight (or turn if desired) during hops. For example, the CG502can be positioned roughly halfway (e.g., in the range of roughly 40-60% of the distance) between the front driving legs104aand the rear dragging legs104c. Also, aligning the motor axis with the longitudinal CG can enhance forces caused by the motor202and the counterweight. In some implementations, the longitudinal component of the CG502can be near to the center of the height of the device (e.g., within about 3% of the CG as a proportion of the height of the device). Generally, configuring the device100such that the CG502is closer to the center of the height of the device will enhance the rolling tendency, although greater distances (e.g., within about 5% or within about 20% of the CG as a proportion of the height of the device) are acceptable in some implementations. Similarly, configuring the device100such that the CG502is within about 3-6% of the motor axis504as a percentage of the height of the device can also enhance the rolling tendency.

FIG. 5also shows an approximate alignment of the battery220, the switch222and the motor202with the longitudinal component of the CG502. Although a sliding switch mechanism506that operates the on/off switch222hangs below the underside of the device100, the overall approximate alignment of the CG of the individual components220,222and202(with each other and with the CG502of the overall device100) contributes to the ability of the device100to roll, and thus right itself. In particular, the motor202is centered primarily along the longitudinal component of the CG502.

In some implementations, the high point120can be located behind the CG502, which can facilitate self-righting in combination with the eccentric load attached to the motor202being positioned near the nose108. As a result, if the device100is on its side or back, the nose end of the device100tends to vibrate and bounce (more so than the tail end of the device100), which facilitates self-righting as the forces of the motor and eccentric load tend to cause the device to roll.

FIG. 5also shows some of the sample dimensions of the device100. For example, a distance508between the CG502and a plane that passes through the leg tips106aon which the device100rests when upright on a flat surface110can be approximately 0.36 inches. In some implementations, this distance508is approximately 50% of the total height of the device (seeFIGS. 7A & 7B), although other distances508may be used in various implementations (e.g., from about 40-60%). A distance510between the rotational axis504of the motor202and the same plane that passes through the leg tips106ais approximately the same as the distance508, although variations (e.g., 0.34 inches for distance510vs. 0.36 inches for distance508) may be used without materially impacting desired functionality. Greater variations (e.g., 0.05 inches or even 0.1 inches) may be used in some implementations.

A distance512between the leg tip106aof the front driving legs104aand the leg tip106aof the rearmost leg104ccan be approximately 0.85 inches, although various implementations can include other values of the distance512(e.g., between about 40% and about 75% of the length of the device100). In some implementations, locating the front driving legs104abehind the eccentric load210can facilitate forward driving motion and randomness of motion. For example, a distance514between a longitudinal centerline of the eccentric load210and the tip106aof the front leg104acan be approximately 0.36 inches. Again, other distances514can be used (e.g., between about 5% and about 30% of the length of the device100or between about 10% and about 60% of the distance512). A distance516between the front of the device100and the CG502can be about 0.95 inches. In various implementations, the distance516may range from about 40-60% of the length of the device100, although some implementations may include front or rear protrusions with a low mass that add to the length of the device but do not significantly impact the location of the CG502(i.e., therefore causing the CG502to be outside of the 40-60% range).

FIGS. 9A and 9Bshow example devices100yand100zthat include, respectively, a shark/dorsal fin902and side/pectoral fins904aand904b. As shown inFIG. 9A, the shark/dorsal fin902can extend upward from the body102so that, if the device100ytips, then the device100ywill not end up on its back and can right itself. The side/pectoral fins904aand904bshown inFIG. 9Bextend partially outward from the body102. As a result, if the device100zbegins to tip to the device's left or right, then the fin on that side (e.g., fin904aor fin904b) can stop and reverse the tipping action, returning the device100zto its upright position. In addition, the fins904aand904bcan facilitate self-righting by increasing the distance between the CG and the surface when the device is on its side. This effect can be enhanced when the fins904aand904bare combined with a dorsal fin902on a single device. In this way, fins902,904aand904bcan enhance the self-righting of the devices100yand100z. Constructing the fins902,904aand904bfrom a resilient material that increases bounce when the fins are in contact with a surface can also facilitate self-righting (e.g., to help overcome the wider separation between the tips of the fins902,904aand904b). Fins902,904aand904bcan be constructed of light-weight rubber or plastic so as not to significantly change the device's CG.

Random Motion

By introducing features that increase randomness of motion of the device100, the device100can appear to behave in an animate way, such as like a crawling bug or other organic life-form. The random motion can include inconsistent movements, for example, rather than movements that tend to be in straight lines or continuous circles. As a result, the device100can appear to roam about its surroundings (e.g. in an erratic or serpentine pattern) instead of moving in predictable patterns. Random motion can occur, for example, even while the device100is moving in one general direction.

In some implementations, randomness can be achieved by changing the stiffness of the legs104, the material used to make the legs104, and/or by adjusting the inertial load on various legs104. For example, as leg stiffness is reduced, the amount of device hopping can be reduced, thus reducing the appearance of random motion. When the legs104are relatively stiff, the legs104tend to induce hopping, and the device100can move in a more inconsistent and random motion.

While the material that is selected for the legs104can influence leg stiffness, it can also have other effects. For example, the leg material can be manipulated to attract dust and debris at or near the leg tips106a,where the legs104contact the surface110. This dust and debris can cause the device100to turn randomly and change its pattern of motion. This can occur because the dust and debris can alter the typical frictional characteristics of the legs104.

The inertial load on each leg104can also influence randomness of motion of the device100. As an example, as the inertial load on a particular leg104is increased, that portion of the device100can hop at higher amplitude, causing the device100to land in different locations.

In some implementations, during a hop and while at least some legs104of the device100are airborne (or at least applying less force to the surface110), the motor202and the counterweight210can cause some level of mid-air turning and/or rotating of the device100. This can provide the effect of the device landing or bouncing in unpredictable ways, which can further lead to random movement.

In some implementations, additional random movement can result from locating front driving legs104a(i.e., the legs that primarily propel the device100forward) behind the motor's counterweight. This can cause the front of the device100to tend to move in a less straight direction because the counterweight is farther from legs104that would otherwise tend to absorb and control its energy. An example lateral distance from the center of the counterweight to the tip of the first leg of 0.36 inches compared to an example leg length of 0.40 inches. Generally, the distance514from the longitudinal centerline of the counterweight to the tip106aof the front leg104amay be approximately the same as the length of the leg but the distance514can vary in the range of 50-150% of the leg length.

In some implementations, additional appendages can be added to the legs104(and to the housing102) to provide resonance. For example, flexible protrusions that are constantly in motion in this way can contribute to the overall randomness of motion of the device100and/or to the lifelike appearance of the device100. Using appendages of different sizes and flexibilities can magnify the effect.

In some implementations, the battery220can be positioned near the rear of the device100to increase hop. Doing so positions the weight of the battery220over the rearmost legs104, reducing load on the front legs104a,which can allow for more hop at the front legs104a. In general, the battery220can tend to be heavier than the switch222and motor202, thus placement of the battery220nearer the rear of the device100can elevate the nose108, allowing the device100to move faster.

In some implementations, the on/off switch222can be oriented along the bottom side of the device100between the battery220and the motor204such that the switch222can be moved back and forth laterally. Such a configuration, for example, helps to facilitate reducing the overall length of the device100. Having a shorter device can enhance the tendency for random motion.

Speed of Movement

In addition to random motion, the speed of the device100can contribute to the life-like appearance of the device100. Factors that affect speed include the vibration frequency and amplitude that are produced by the motor202and counterweight210, the materials used to make the legs104, leg length and deflection properties, differences in leg geometry, and the number of legs.

Vibration frequency (e.g., based on motor rotation speed) and device speed are generally directly proportional. That is, when the oscillating frequency of the motor202is increased and all other factors are held constant, the device100will tend to move faster. An example oscillating frequency of the motor is in the range of 7000 to 9000 rpm.

Leg material has several properties that contribute to speed. Leg material friction properties influence the magnitude of drag force on the device. As the coefficient of friction of the legs increases, the device's overall drag will increase, causing the device100to slow down. As such, the use of leg material having properties promoting low friction can increase the speed of the device100. In some implementations, polystyrene-butadiene-styrene with a durometer near 65 (e.g., based on the Shore A scale) can be used for the legs104. Leg material properties also contribute to leg stiffness which, when combined with leg thickness and leg length, determines how much hop a device100will develop. As the overall leg stiffness increases, the device speed will increase. Longer and thinner legs will reduce leg stiffness, thus slowing the device's speed.

Appearance of Intelligence

“Intelligent” response to obstacles is another feature of the device100. For example, “intelligence” can prevent a device100that comes in contact with an immoveable object (e.g., a wall) from futilely pushing against the object. The “intelligence” can be implemented using mechanical design considerations alone, which can obviate the need to add electronic sensors, for example. For example, turns (e.g., left or right) can be induced using a nose108that introduces a deflection or bounce in which a device100that encounters an obstacle immediately turns to a near incident angle.

In some implementations, adding a “bounce” to the device100can be accomplished through design considerations of the nose and the legs104, and the speed of the device100. For example, the nose108can include a spring-like feature. In some implementations, the nose108can be manufactured using rubber, plastic, or other materials (e.g., polystyrene-butadiene-styrene with a durometer near 65, or in the range of 55-75, based on the Shore A scale). The nose108can have a pointed, flexible shape that deflects inward under pressure. Design and configuration of the legs104can allow for a low resistance to turning during a nose bounce. Bounce achieved by the nose can be increased, for example, when the device100has a higher speed and momentum.

In some implementations, the resiliency of the nose108can be such that it has an added benefit of dampening a fall should the device100fall off a surface110(e.g., a table) and land on its nose108.

FIG. 6shows a top view of the vehicle100and further shows the flexible nose108. Depending on the shape and resiliency of the nose108, the vehicle100can more easily deflect off obstacles and remain upright, instead of tipping. The nose108can be constructed from rubber or some other relatively resilient material that allows the device to bounce off obstacles. Further, a spring or other device can be placed behind the surface of the nose108that can provide an extra bounce. A void or hollow space602behind the nose108can also contribute to the device's ability to deflect off of obstacles that are encountered nose-first.

Alternative Leg Configurations

FIGS. 3A-3Cshow various examples of alternative leg configurations for devices100a-100k. The devices100a-100kprimarily show leg104variations but can also include the components and features described above for the device100. As depicted inFIGS. 3A-3C, the forward direction of movement is left-to-right for all of the devices100a-100k,as indicated by direction arrows302a-302c. The device100ashows legs connected with webs304. The webs304can serve to increase the stiffness of the legs104while maintaining legs104that appear long. The webs304can be anywhere along the legs104from the top (or base) to the bottom (or tip). Adjusting these webs304differently or on the device's right versus the left can serve to change leg characteristics without adjusting leg length and provide an alternate method of correcting steering. The device100bshows a common configuration with multiple curved legs104. In this implementation, the middle legs104bmay not touch the ground, which can make production tuning of the legs easier by eliminating unneeded legs from consideration. Devices100cand100dshow additional appendages306that can add an additional life-like appearance to the devices100cand100d. The appendages306on the front legs can resonate as the devices100cand100dmove. As described above, adjusting these appendages306to create a desired resonance can serve to increase randomness in motion.

Additional leg configurations are shown inFIG. 3B. The devices100eand100fshow leg connections to the body that can be at various locations compared to the devices100a-100dinFIG. 3A. Aside from aesthetic differences, connecting the legs104higher on the device's body can serve to make the legs104appear to be longer without raising the CG. Longer legs104generally have a reduced stiffness that can reduce hopping, among other characteristics. The device100falso includes front appendages306. The device100gshows an alternate rear leg configuration where the two rear legs104are connected, forming a loop.

Additional leg configurations are shown inFIG. 3C. The device100hshows the minimum number of (e.g., three) legs104. Positioning the rear leg104right or left acts as a rudder changing the steering of the device100h. Using a rear leg104made of a low friction material can increase the device's speed as previously described. The device100jis three-legged device with the single leg104at the front. Steering can be adjusted on the rear legs by moving one forward of the other. The device100iincludes significantly altered rear legs104that make the device100iappear more like a grasshopper. These legs104can function similar to legs104on the device100k,where the middle legs104bare raised and function only aesthetically until they work in self-righting the device100kduring a rollover situation.

In some implementations, devices100can include adjustment features, such as adjustable legs104. For example, if a consumer purchases a set of devices100that all have the same style (e.g., an ant), the consumer may want to make some or all of the devices100move in varying ways. In some implementations, the consumer can lengthen or shorten individual leg104by first loosening a screw (or clip) that holds the leg104in place. The consumer can then slide the leg104up or down and retighten the screw (or clip). For example, referring forFIG. 3B, screws310aand310bcan be loosened for repositioning legs104aand104c,and then tightened again when the legs are in the desired place.

In some implementations, screw-like threaded ends on leg bases106balong with corresponding threaded holes in the device housing102can provide an adjustment mechanism for making the legs104longer or shorter. For example, by turning the front legs104ato change the vertical position of the legs bases106b(i.e., in the same way that turning a screw in a threaded hole changes the position of the screw), the consumer can change the length of the front legs104a,thus altering the behavior of the device100.

In some implementations, the leg base106bends of adjustable legs104can be mounted within holes in housing102of the device100. The material (e.g., rubber) from which the legs are constructed along with the size and material of the holes in the housing102can provide sufficient friction to hold the legs104in position, while still allowing the legs to be pushed or pulled through the holes to new adjusted positions.

In some implementations, in addition to using adjustable legs104, variations in movement can be achieved by slightly changing the CG, which can serve to alter the effect of the vibration of the motor202. This can have the effect of making the device move slower or faster, as well as changing the device's tendency to turn. Providing the consumer with adjustment options can allow different devices100to move differently.

Device Dimensions

FIGS. 7A and 7Bshow example dimensions of the device100. For example, a length702is approximately 1.73 inches, a width704from leg tip to leg tip is approximately 0.5 inches, and a height706is approximately 0.681 inches. A leg length708can be approximately 0.4 inches, and a leg diameter710can be approximately 0.077 inches. A radius of curvature (shown generally at712) can be approximately 1.94 inches. Other dimensions can also be used. In general, the device length702can be in the range from two to five times the width704and the height706can be in the approximate range from one to two times the width704. The leg length708can be in the range of three to ten times the leg diameter710. There is no physical limit to the overall size that the device100can be scaled to, as long as motor and counterweight forces are scaled appropriately. In general, it may be beneficial to use dimensions substantially proportional to the illustrated dimensions. Such proportions may provide various benefits, including enhancing the ability of the device100to right itself after tipping and facilitating desirable movement characteristics (e.g., tendency to travel in a straight line, etc.).

Construction Materials

Material selection for the legs is based on several factors that affect performance. The materials main parameters are coefficient of friction (COF), flexibility and resilience. These parameters in combination with the shape and length of the leg affect speed and the ability to control the direction of the device.

COF can be significant in controlling the direction and movement of the device. The COF is generally high enough to provide resistance to sideways movement (e.g., drifting or floating) while the apparatus is moving forward. In particular, the COF of the leg tips (i.e., the portion of the legs that contact a support surface) can be sufficient to substantially eliminate drifting in a lateral direction (i.e., substantially perpendicular to the direction of movement) that might otherwise result from the vibration induced by the rotating eccentric load. The COF can also be high enough to avoid significant slipping to provide forward movement when Fvis down and the legs provide a forward push. For example, as the legs bend toward the back of the device100(e.g., away from the direction of movement) due to the net downward force on the one or more driving legs (or other legs) induced by the rotation of the eccentric load, the COF is sufficient to prevent substantial slipping between the leg tip and the support surface. In another situation, the COF can be low enough to allow the legs to slide (if contacting the ground) back to their normal position when Fvis positive. For example, the COF is sufficient low that, as the net forces on the device100tend to cause the device to hop, the resiliency of the legs104cause the legs to tend to return to a neutral position without inducing a sufficient force opposite the direction of movement to overcome either or both of a frictional force between one or more of the other legs (e.g., back legs104c) in contact with the support surface or momentum of the device100resulting from the forward movement of the device100. In some instances, the one or more driving legs104acan leave (i.e., hop completely off) the support surface, which allows the driving legs to return to a neutral position without generating a backward frictional force. Nonetheless, the driving legs104amay not leave the support surface every time the device100hops and/or the legs104may begin to slide forward before the legs leave the surface. In such cases, the legs104may move forward without causing a significant backward force that overcomes the forward momentum of the device100.

Flexibility and resilience are generally selected to provide desired leg movement and hop. Flexibility of the leg can allow the legs to bend and compress when Fvis down and the nose moves down. Resilience of the material can provide an ability to release the energy absorbed by bending and compression, increasing the forward movement speed. The material can also avoid plastic deformation while flexing.

Rubber is an example of one type of material that can meet these criteria, however, other materials (e.g., other elastomers) may a have similar properties.

FIG. 8shows example materials that can be used for the device100. In the example implementation of the device100shown inFIG. 8, the legs104are molded from rubber or another elastomer. The legs104can be injection molded such that multiple legs are integrally molded substantially simultaneously (e.g., as part of the same mold). The legs104can be part of a continuous or integral piece of rubber that also forms the nose108(including nose sides116aand116b), the body shoulder112, and the head side surface114. As shown, the integral piece of rubber extends above the body shoulder112and the head side surface114to regions802, partially covering the top surface of the device100. For example, the integral rubber portion of the device100can be formed and attached (i.e., co-molded during the manufacturing process) over a plastic top of the device100, exposing areas of the top that are indicated by plastic regions806, such that the body forms an integrally co-molded piece. The high point120is formed by the uppermost plastic regions806. One or more rubber regions804, separate from the continuous rubber piece that includes the legs104, can cover portions of the plastic regions806. In general, the rubber regions802and804can be a different color than plastic regions806, which can provide a visually distinct look to the device100. In some implementations, the patterns formed by the various regions802-806can form patterns that make the device look like a bug or other animate object. In some implementations, different patterns of materials and colors can be used to make the device100resemble different types of bugs or other objects. In some implementations, a tail (e.g., made of string) can be attached to the back end of the device100to make the device appear to be a small rodent.

The selection of materials used (e.g., elastomer, rubber, plastic, etc.) can have a significant effect on the vehicle's ability to self-right. For example, rubber legs104can bend inward when the device100is rolling during the time it is self-righting. Moreover, rubber legs104can have sufficient resiliency to bend during operation of the vehicle100, including flexing in response to the motion of (and forces created by) the eccentric load rotated by the motor202. Furthermore, the tips of the legs104, also being made of rubber, can have a coefficient of friction that allows the driving legs (e.g., the front legs104) to push against the surface110without significantly slipping.

Using rubber for the nose108and shoulder112can also help the device100to self-right. For example, a material such as rubber, having higher elasticity and resiliency than hard plastic, for example, can help the nose108and shoulder112bounce, which facilitates self righting, by reducing resistance to rolling while the device100is airborne. In one example, if the device100is placed on its side while the motor202is running, and if the motor202and eccentric load are positioned near the nose108, the rubber surfaces of the nose108and shoulder112can cause at least the nose of the device100to bounce and lead to self-righting of the device100.

In some implementations, the one or more rear legs104ccan have a different coefficient of friction than that of the front legs104a. For example, the legs104in general can be made of different materials and can be attached to the device100as different pieces. In some implementations, the rear legs104ccan be part of a single molded rubber piece that includes all of the legs104, and the rear legs104ccan be altered (e.g., dipped in a coating) to change their coefficient of friction.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. Other alternative embodiments can also be implemented. For example, some implementations of the device100can omit the use of rubber. Some implementations of the device100can include components (e.g., made of plastic) that include glow-in-the-dark qualities so that the device100can be seen in a darkened room as it moves across the surface110(e.g., a kitchen floor). Some implementations of the device100can include a light (e.g., an LED bulb) that blinks intermittently as the device100travels across the surface110.

FIG. 10is a flow diagram of a process1000for operating a vibration-powered device100(e.g., a device that includes any appropriate combination of the features described above). The device can include any appropriate combination of features, as described above. In various embodiments, different subsets of the features described above can be included.

Initially, a vibration-powered device is placed on a substantially flat surface at1005. Vibration of the device is induced at1010to cause forward movement. For example, vibration may be induced using a rotational motor (e.g., battery powered or wind up) that rotates a counterweight. The vibration can induce movement in a direction corresponding to an offset between the leg bases and the leg tips of one or more driving legs (i.e., the forward direction). In particular, this vibration can cause resilient legs to bend in one direction, at1015, as the net downward forces cause the device to move downward. This bending, along with using a material with a sufficiently high coefficient of friction to avoid substantial slipping, can cause the device to move generally forward.

As the vibration causes net upward forces (e.g., due to the vector sum of the forces induced by the rotating counterweight and the spring effect of the resilient legs) that cause the driving legs to leave the surface or to come close to leaving the surface, the tips of the one or more driving legs move in the forward direction (i.e., the leg deflects in the forward direction to return to a neutral position) at1020. In some implementations, the one or more driving legs can leave the surface at varying intervals. For example, the driving legs may not leave the surface every time the net forces are upward because the forces may not overcome a downward momentum from a previous hop. In addition, the amount of time the driving legs leave the surface may vary for different hops (e.g., depending on the height of the hop, which in turn may depend on the degree to which the rotation of the counterweight is in phase with the spring of the legs).

During the forward motion of the device, different drag forces on each lateral side of the device can be generated at1025. Generally, these different drag forces can be generated by rear legs that tend to drag (or at least that drag more than front driving legs) and alter the turning characteristics of the device (e.g., to counteract or enhance turning tendencies). Typically, the legs can be arranged in (e.g., two) rows along each lateral side of the device, such that one or more of the legs in one row drag more than corresponding legs in another row. Different techniques for causing the device to generate these different drag forces are described above.

If the device overturns, rolling of the device is induced at1030. In general, this rolling tendency can be induced by the rotation of the counterweight and causes the device to tend to independently right itself. As discussed above, the outer shape of the device along the longitudinal dimension (e.g., substantially parallel to the axis of rotation and/or the general forward direction of movement of the device) can be shaped to promote rolling (e.g., by emulating longitudinal “roundness”). Rolling of the device can also be stopped by a relatively wide spread between the rows of legs at1035. In particular, if the legs are wide enough relative to the COG of the device, the rotational forces generated by the rotating counterweight are generally insufficient (absent additional forces) to cause the device to roll over from the upright position.

At1040, resiliency of the nose of the device can induce a bounce when the device encounters an obstacle (e. g., a wall). This tendency to bounce can facilitate changing directions to turn away from an obstacle or toward a higher angle of incidence, particularly when combined with a pointed shaped nose as discussed above. The resilient nose can be constructed from a elastomeric material and can be integrally molded along with lateral shoulders and/or legs using the same elastomeric material. Finally, lateral drifting can be suppressed at1045based on a sufficiently high coefficient of friction at the leg tips, which can prevent the legs from tending to slide laterally as the rotating counterweight generates lateral forces.

FIG. 11is a flow diagram of a process1100for constructing a vibration-powered device100(e.g., a device that includes any appropriate combination of the features described above). Initially, the device undercarriage is molded at1105. The device undercarriage can be the underside122shown inFIG. 1and can be constructed from a hard plastic or other relatively hard or stiff material, although the type of material used for the underside is generally not particularly critical to the operation of the device. An upper shell is also molded at1110. The upper shell can include a relatively hard portion of the upper body portion of the housing102shown inFIG. 1, including the high point120. The upper shell is co-molded with an elastomeric body at1115to form the device upper body. The elastomeric body can include a single integrally formed piece that includes legs104, shoulders112, and nose108. Co-molding a hard upper shell and a more resilient elastomeric body can provide better constructability (e.g., the hard portion can make it easier to attach to the device undercarriage using screws or posts), provide more longitudinal stiffness, can facilitate self-righting (as explained above), and can provide legs that facilitate hopping, forward movement, and turning adjustments. The housing is assembled at1120. The housing generally includes a battery, a switch, a rotational motor, and an eccentric load, which may all be enclosed between the device undercarriage and the upper body.

The ability of the device to simulate life-like features can be extended by providing a user configurable playset (e.g., that imitates and insect colony or ant farm). The playset can be used to study cause and effect in autonomous vehicle interaction and flow where the user provides flow control and colony configuration. For example, the playset can contain various flow elements that can be pieced together to direct devices along particular paths (e.g., similar to slot car tracks or toy train tracks). The flow elements can include straight and curved pieces as desired. Unlike train sets and/or slot car sets, however, the playset of the present invention can also include communal areas designed to allow autonomous vehicle gathering and interaction. These communal areas can contain one or more in/out ports that allow the connection of flow elements. The communal area can include an internal open space or features that alter vehicle interactions, such as an array of posts, mazes, or other features. The in/out ports may contain flow control gates that block vehicles from passing, if desired. These gates can allow ports without a connected flow element to be blocked, ensuring that vehicles do not escape the playset. The gates can also be used to create communal areas with more or less in/out ports, thus allowing the studying of cause and effect relationship of autonomous vehicle flow.

FIG. 12is a perspective view of a communal area playset component1200. The communal area component1200includes a substantially horizontal planar floor1202and multiple side walls1204. In some implementations, the side walls1204of the communal area component1200are straight along the inside of the communal area and form a substantially regular polygon. In some implementations, the side walls1204form a polygon having at least five or six sides such that the corners where the side walls1204meet form an angle that helps prevent vibration-powered devices from getting stuck in the corner. The side wall components1204can be substantially perpendicular to the floor1202or can at least be sufficiently vertical to cause vibration-driven devices to deflect off of the side wall1204(e.g., by bouncing off the side wall1204with a resilient nose) or to otherwise turn back toward the middle of the communal area component1200. The communal area component1200further includes a plurality of connectors1206that facilitate connecting the communal area component1200to another communal area component or to tracks, as further described below. In some implementations, each connector1206is shaped such that it is capable of interlocking with another identically shaped connector1206. Each connector can also include tabs1218that are shaped to guide and hold the interlocking connectors1206in a proper position, while still allowing the interlocking connectors1206to be separated if sufficient force is applied (i.e., in the vertical direction for the type of connector illustrated).

Adjacent to each connector1206(or to at least some of the connectors) is a port1208that allows vibration-powered devices to pass through (e.g., either into or out of the communal area component1200). The ports1208are disposed in a side wall1204. In some implementations, the ports1208are a third or less of the width of the side wall1204on each side of the communal area component1200. Each port can include a gate1210that can rotate or pivot between a closed position (as indicated1210a), a partially open position (as indicated at1210b), and a fully open position (as indicated at1210c). Each side wall1204(at least on one side of the port1208) includes a slot1216into which the gate1210for that side wall1204can rotate (or slide, in some implementations) to provide an open port1208through which vibration-powered devices can travel. The gate1210can include a lever projection1212that can make the gate easier to rotate (e.g., with a user's finger), and the side wall1204can include an indentation1214that makes the lever projection1212easier to contact (e.g., again with the user's finger) when the gate1210is in the fully open position. For example, each gate1210is adapted to be opened and closed by rotating the lever projection1212in an arc substantially perpendicular to the substantially planar area1202of the communal area1200.

FIG. 13Ais a perspective view of a straight track playset component1300. The straight track component1300includes a substantially planar floor1302and side walls1304that form a U-shaped channel1308with open ends1310. The side walls1304can be substantially vertical or at least sufficiently vertical to cause a vibration-powered device to deflect off of the side wall1304or to otherwise turn toward the middle of the track. In some implementations, the side walls1304of the straight track component1300are separated by a substantially consistent distance between the open ends1310. In some implementations, the side walls1304are spaced apart at a distance that is sufficiently wider than a vibration-powered device for which the track is designed (e.g., sold with the track or for which the track is an accessory) that the device can move back and forth to some degree. In some implementations, the channel1308is narrow enough to prevent the vibration-powered device from being able to turn around on the straight track component1300(e.g., the device is longer than the channel1308is wide).

The straight track component1300also includes connectors1306, which can match the connectors1206of the communal area component1200. When connected together in this manner, the end of the channel1308may substantially aligns horizontally with one of the ports1208and the floor1302of the channel substantially aligns vertically with the substantially planar area1202of the communal area component1200. The straight track component1300can further have tabs1312(matching the tabs1218inFIG. 12) that mate with portions of another connector1206(seeFIG. 12),1306, or1406(seeFIG. 14) to “lock” the connectors in place. In particular, a projection on the lower end of the tabs1312can catch on the lower edge of a surface1330adjacent to the tab1312on a different connector1306. The connector1306, along with adjacent surfaces1316, can interlock or mate with another connector1306and corresponding surfaces1316in a manner that substantially prevents the two interlocking components from twisting laterally relative to the other connector1306. The straight track component1300can also include slots1314in the side walls1306along at least a portion (or portions) of the length of the component that facilitate insertion of accessories or other objects (e.g., to build taller walls or tunnels).

A vibration-powered vehicle, as described above behaves in a significantly different manner than a slot car or train in a track due to the existence of side forces Fh and at least slightly random, not straight, movement of the vehicle. These side forces can cause significant collisions with the track side walls1304in a channel-shaped track. These collisions (e.g., both on the right and left) cause the vehicle to oscillate sideways in the track and slow the motion of the vehicle due to friction during the collisions, particularly when the vehicle is constructed from rubber or other relatively higher friction material.

FIG. 13Bis an end view of one implementation of a straight track component1300. In this implementation, the side walls1304of the channel1308and the floor1302meet (at138) at substantially a right angle. Such a construction tends to result in greater numbers of collisions with the side walls1304.

An alternative track cross-section that eliminates side-to-side oscillation can also be used. An ordinary channel-shaped track, such as that shown inFIG. 13B, uses the sidewalls to deflect the vehicle body. This direct on or off contact causes undesired reflectance.

FIG. 13Cis an end view or cross section of an alternative track channel1308for reducing side wall collisions. In this configuration, the floor1302includes an upward curvature1320adjacent to the side walls1304. This upward curvature1320forms an altered (or alternative) floor that interacts with the vehicle legs. Viewed in a different manner, the track channel1308ofFIG. 13Cincludes depression in the floor was added with gradual curves1320on the right and left sides. When the gradual curves1320contact the legs, the vehicle is gradually deflected toward a centerline1322of the channel1308to the correct course proportionally with its directional error, eliminating or at least reducing the oscillation. In some implementations, the upward curvature1320that is adjacent to the side wall1304can terminate in a flat horizontal surface as depicted inFIG. 13C, while in other cases the upward curvature1320can meet the corresponding adjacent side wall1304. In some cases the upward curvature1320, rather than being truly curve, can be formed by a flat surface at an angle to the floor1302and side wall1304(e.g., at a 45 degree angle to the plane of the side wall1304and the plane of the floor1302) or by a series of flat surfaces that, when the channel is viewed in cross section, emulate a curve by forming a gradually steeper surface as the surfaces approach the side wall1304.

FIG. 14is a perspective view of a curved track playset component1400. The curved track component1400includes a substantially planar floor1402, an outer side wall1404a,an inner side wall1404b,and connectors1406on each end. Generally, the curved track component1400includes features similar to those shown and described for the straight track component1300. For example, the curved track component1400can include any one or more features described above for the straight track component1300. In some implementations, the curved track component1400may include an upward curvature1320on only one side (e.g., adjacent to outer side wall1404a) of the curved track component1400, although such a feature is also possible on the straight track component1300.

FIG. 15shows a multi-component playset1500. The playset1500includes multiple communal area components1200, straight track components1300, and curved track components1400. As depicted, the floors1202,1302, and1402of the various components generally meet in substantially the same plane when the components are connected together using the connectors1206,1306, and1406. Generally, the relative dimensions of the components are selected to facilitate interconnection of components in multiple configurations (e.g., such that the components tend to meet at connectors rather than needing different lengths or different curvatures to make components properly match up at the connectors). Moreover, the gates1210of the communal area component1200can be used to control flow or movement of vibration powered devices through the playset1500. In some implementations, any of the components (e.g., straight track components1300or curved track components1400) can also or alternatively include gates or other flow control features (e.g., one-way gates that swing in one direction but not the other to allow passage of devices in only one direction). The playset1500or portions thereof can be part of a kit (e.g., sold together) for use in constructing playsets of arbitrary size and configuration.

FIG. 16is a flow diagram of a process1600for using a playset for autonomous devices. The process1600includes connecting at least one track component (e.g., straight track component1300or curved track component1400) to a communal area component (e.g., communal area component1200) at1605. Varying numbers of components can be connected together to form playsets with many different configurations. The various components can include any one or more of the component features described above. At least one gate on one of the components (e.g., communal area component1200) is manually opened or closed (e.g., by a user) at1610. Finally, at least one self-propelled vibration-driven device is operated in at least one of the communal area component or the track component at1615.

Thus, particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims.