Robots with dynamically controlled position of center of mass
11260545 · 2022-03-01
Inventors
Cpc classification
B25J9/0009
PERFORMING OPERATIONS; TRANSPORTING
H04L63/029
ELECTRICITY
G06F21/00
PHYSICS
International classification
B25J5/00
PERFORMING OPERATIONS; TRANSPORTING
B62D57/032
PERFORMING OPERATIONS; TRANSPORTING
B25J19/00
PERFORMING OPERATIONS; TRANSPORTING
B62D49/08
PERFORMING OPERATIONS; TRANSPORTING
G06F21/00
PHYSICS
Abstract
Dynamic control of a center of mass position is based on replacement of discrete motion of macro body (counterweighing solid or counterbalancing mechanisms) for continuous molecular flow of counterweighing liquid. Redistributing liquid counterweight between chambers attached to independently moving parts of robot allows its motion to new stable position without disruption in static stability and dynamic balance. Various embodiments include bipods/humanoids, wheeled locomotion robots and hybrid wheeled/multi-pod bio-like robotic systems; some embodiments allow reversible mutual reconfiguration between various structural arrangements. In humanoid embodiments, method allows moving on uneven terrain or ascending staircases while maintaining static stability; method also decreases the probability of fall and secures self-rising if a fall occurred. In some embodiments liquid counterweight may be transferred upon high barriers exceeding the height of robot by a few folds, such as walls of the building or ledge or steep slope in mountains, thus providing robots with capability principally not available to prior art.
Claims
1. A locomotion robot, comprising: a liquid counterweight, at least two cars each including a tank for said liquid counterweight and a liquid pump, each of said tanks being connected by a flexible pipe for transfer of said liquid counterweight, said liquid counterweight being transported and reversibly redistributed between corresponding chambers of said tanks, each of said two cars including a motor or engine, each of said at least two cars having double flexible joints allowing said two cars to alternatively lift each other over a ground surface and mutually change their relative altitudinal positions, one of said double flexible joints having a telescopic hydraulic cylinder fixed with its base on a first of said two cars and with its opposite end of a sliding rod being fixed on a second of said two cars, another of said double flexible joints having a hoister installed on a second of said two cars and with an end of a cable of said hoister being fixed on said first of said two cars, said liquid counterweight being transferred to and amassed in said tank in said first of said two cars resting on the ground surface while emptying said tank in said second car of said two cars, said second car with an emptied tank being lifted by said telescopic hydraulic cylinder up to or slightly above the ground surface at an elevated terrain, the first moving moves a robotic system to a position thereby allowing the second car to be grounded on said elevated terrain, the second car being grounded on said elevated terrain by said telescopic hydraulic cylinder, said liquid counterweight being transferred to and amassed in said tank of the second of said two cars resting on said ground surface on said elevated terrain while emptying said tank in said first car of said two cars, the first car with an emptied tank being lifted by said hoister up to or slightly above of the ground of said elevated terrain, said second car moving the robotic system to a position allowing the first car to be grounded on said elevated terrain, said first car being grounded on said elevated terrain by said hoister such that the robotic system is self-ascended upon said elevated terrain.
2. The locomotion robot according to claim 1, wherein said locomotion robot ascends vertical barriers exceeding a normal height of said robot as measured during its resting position or movement on an even terrain.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE INVENTION
(20) The key concept of present invention is transferable liquid counterweight wherein the transfer of said liquid counterweight substantially or virtually completely decoupled from the motion of the robot's arms and from the motion of its body.
(21) Fixed liquid counterweight is known by prior art, although not in robotic systems, but in industrial cranes. Fixed liquid counterweight provides some convenience during installation or transportation of cranes, but it neither improves, nor extend their useful functionalities.
(22) Partially movable solid counterweight is known by prior art in robotic systems, however a motion of solid counterweight is strictly specified for every particular configuration of a robot's arm and/or its body, and the allowable motion of solid counterweight is narrow limited; besides, it requires additional complex mechanical subsystem and corresponding complex control and supporting mathematical apparatus.
(23) Contrarily to these particularities and limitations of the prior arts, the transferable liquid counterweight brings to robots and robotic systems the following advantages: 1. A change of CoM position is not directly bounded with functional configuration or functional motion of robot; instead, accordingly to the present invention, the dynamically adaptive change of CoM position is achieved by continuous molecular flow of liquid mass that does neither disturb nor restrict the structural body motions and only defined by the requirement of the designated useful task. 2. If required, the necessary change of CoM position may be conducted while the arms and body of robot remain immovable; alternatively, if required, the necessary change of CoM position may be conducted in real time of the robot's motion. 3. Substantial decoupling of COM position from the robot's motion allows significant simplifications in the mathematical model of the robot's dynamics and its control and design. Contrarily to the counterbalancing methods and apparatuses known by prior art wherein the dynamical balance of a robotic system every moment depends on the momentary velocity vector of counterweighing solid body or counterbalancing mechanism and their momentary position and, thus, depends on the trajectory of said solid body or mechanism motion, the trajectory of liquid flow is simply defined by a flexible connecting pipe and does not influence the robotic system dynamic balance. 4. The transferable liquid counterweight allows motion of a humanoid robot under condition of continuous static stability keeping its safely to the pathway even on strongly uneven terrains, such as ruins, or in mountains or while rising upstairs. 5. In spite the liquid counterweight increases the general mass of robot, it allows avoiding certain relatively heavy and complex structural components. 6. Replacement of mechanical counterbalance for the transferable liquid counterweight also decreases vibrations, thus additionally simplifying the dumping system and supporting smooth motion of the robot. 7. The transferable liquid counterweight allows continuous maintaining the lowest possible position of COM thus significantly decreasing possibility of the fall. 8. If a fall occurred, the flexible liquid jackets cushion a shock thus protecting the robot structure and sensitive apparatuses; then, the liquid may be redistributed effectively supporting self-rising of the robot. 9. During the robot's ascending, the transferable liquid counterweight may be lifted upstairs, or uphill, or on the sharp high barrier even greater by several folds than the height of the robot, such as wall of the building or ledge in mountains, thus providing robots with capability not available for robots designed based on the prior art. 10. For humanoids and other bio-like robots, the transferable liquid counterweight represents a significant further approach to the natural balancing mechanisms acting in the live organisms.
(24) The disclosed robot with a transferable liquid counterweight includes at least one pump, and at least two independently moving parts of the body, each comprises at least one liquid chamber.
(25) The method consists of redistributing of liquid counterweight between the liquid chambers amassing the major portion of the liquid counterweight in the liquid chamber located in the part of the robot resting on stable support while partially or completely emptying the liquid chamber located in the other part of the robot thus maintaining the Center of Mass of the robot in the margin of stable support and allowing motion of the other movable part of the robot to new stable position without disruption of the dynamic balance of the robot; the method then applies to transfer the liquid counterweight and amass it in the other part; such operations repeated alternatively; a series of such alternating operations allows to move the robot over uneven terrain or to raise the robot uphill while continuously maintaining its dynamic balance and stability of its proper position in space.
(26) Method allows various embodiments including legged, wheeled and reconfigurable locomotion robots. Some embodiments of the disclosed method and apparatuses may comprise a plurality of movable parts, each part contains its liquid chamber or chambers.
(27) There are variety of liquid pumps known of the prior art, the highly effective miniature pumps are readily available from the industry, and any person of ordinary skill in the pertinent area could make and use the invention without extensive experimentation. The preferable pump depends on specific technical task and may be selected by such person of ordinary skill. Generally, gas-powered liquid transfer pump may be preferred in most implementations of the present invention due to simplicity of the pump and entire liquid transfer system. It is important that gas-powered liquid transfer pumps are functioning from compressed air; thus, the liquid counterweight may be transferred on substantial height practically without limitation.
(28) It is also important, that the liquid transfer pumps are energetically exceptionally effective, and energy effectiveness up to about 98% is practically achievable.
(29) The liquid counterweight, depending on specific designation, kind and dimension of the robots, may be lightweight—as water or oil, medium heavyweight—as bromoform (also known as Tribromomethane, CHBr3; specific gravity 2.89), heavyweight, as liquid gallium, or ultra-heavyweight, as mercury. All these liquid matters are readily available from the industry.
(30) In some embodiments, the same liquid, in particularly oil, may be also employed in hydraulic power transmission systems driving or reconfiguring the robots.
(31) Particular embodiments of the present invention will be clear in specific details from the following examples:
(32) The
(33) The
(34) The
The Humanoid Robots Embodiments
Example 1
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(36) The structural components of the body and mechanisms made of magnesium-lithium alloys with density range 1.4-1.6. Such alloys with reliable protective coatings are known by the prior art and readily available on the industrial market. The magnesium alloys are also known by the prior art as the materials with the superior values of specific stiffness even with comparison with the high quality steel and titanium alloys.
(37) The “bones” of robot are tubular, thus assuring the utmost maximal specific stiffness of the structure. The exterior made of carbon-fiber composites, the elastic chambers made of fiber-reinforced plastics, both kinds of the ultra-light materials known by the prior art. The height of robot in this example (not including the bottom chamber under foot in correspondingly designed robots) is 160 cm. Total structural (solid) mass of robot, not including liquid load, is 50 kg.
(38) Table shows the required volume of different liquids at different relative mass of liquid load vs. body of robot with solid mass 50 kg.
(39) TABLE-US-00001 TABLE Relative mass Volume of liquid load, liters for M.sub.sol = 50 kg of liquid Tribromomethane Liquid counterweight (bromoform) gallium Mercury M.sub.liq/M.sub.sol × 100% 2.89 kg/l 6.095 kg/l 13.546 kg/l 100 17.3 8.20 3.69 80 13.8 6.56 2.95 50 8.65 4.1 1.85 25 4.33 2.05 0.92
(40) In the shown example, internal dimensions of each of the bottom (rigid) chambers 108 are: length L=38 cm, height H=16 cm, width W=22 cm; the corners are slightly rounded, and the actual internal volume 13 liters; maximal liquid mass is 37.57 kg of bromoform in each chamber 108. The actual maximal volume of each flexible chambers 109b 4.3 liters; maximal liquid mass is 12.43 kg of bromoform in each chamber 109b.
(41) The shown example illustrates the maximal liquid load equal to the solid mass of robot, in specific example 50 kg; the liquid counterweight in shown example is the medium heavyweight bromoform (Tribromomethane, CHBr.sub.3; specific gravity 2.89).
(42) It is important to note that a smaller relative amounts of liquid load, such as 25% of the solid mass of robot, that is 12.5 kg, will be sufficient for substantial improvement of stability and dynamic balance of robot; however maximal amount of liquid shown on example allows maintaining static stability with substantial margin even during ascending. It is also important to note, that the maximal relative amount of liquid counterweight implies slightly more complex design; the shown examples on
(43) Referring to
(44) In the initial position of robot, phase A1, at front of the step, the total load of counterweighing liquid is equalized between both legs, and liquid partially filled both rigid chambers 108, while both flexible chambers 109 are emptied and deflated. Ground projections of three CoM are closely positioned between the foots inside, and specifically in the center of the ground support polygon of the robot (polygons are not marked to prevent unnecessary complexity of the figure, that is for its better visibility).
(45) In the preparatory position of robot, phase B1, all amount of liquid counterweight transferred to the chambers 108 and 109b of the left leg; the chambers 108 and 109a of the right leg emptied. The position of ground projection of CoM of solid body was not changed, the position of ground projection of CoM of liquid counterweight shifted to center of ground projection of lest foot, the position of ground projection of general CoM also shifted inside of the ground projection of the left foot.
(46) In the critical phase C1, when the right foot does not touch the ground, the position of ground projection of general CoM remains inside of the ground projection of the left foot.
(47) In the phase D1, the right foot touches the ground, and all amount of liquid counterweight transferred to the chambers 108 and 109b of the right leg, while the chambers 108 and 109a of the left leg emptied. The position of ground projection of general CoM shifted inside of the ground projection of the right foot.
(48) In the critical phase E1, when the left foot does not touch the ground, the position of ground projection of general CoM remains inside of the ground projection of the right foot until the left foot touches the ground in phase E1.
(49) In the final phase F1 the total load of counterweighing liquid is equalized between both legs as it was in the initial position of robot, phase A1.
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(52) Specifically: On the top diagram, the curve 301 shows the time dependence of the altitudinal position of the solid body CoM, the curve 302 shows the time dependence of the altitudinal position of CoM for the entire robotic system including both solid body and liquid counterweight, and the curve 303 shows the time dependence of the altitudinal position of the liquid counterweight CoM; line 304 shows the level of new step. It is clear from the top diagram that the altitudinal position of COM of the entire robotic system is nearly 50% lower than of the altitudinal position of the solid body CoM, that is the CoM position of a robot with transferable liquid counterweight during the all ascending is almost two-fold lower than the CoM position of a conventional similar robot known from prior art without a transferable liquid counterweight.
(53) On the bottom diagram, the shadowed areas 305a and 305b shows the width of the left support when the left foot of the robot is touching the ground, the shadowed areas 306a and 306b shows the width of the right support when the right foot of the robot is touching the ground, the curve 307 shows the time dependence of the ground projection of the solid body CoM, the curve 308 shows the time dependence of the ground projection of the CoM position for the entire robotic system, and the curve 309 shows the time dependence of the ground projection of the CoM position for the liquid counterweight relatively to the ground support areas. It is apparent from the bottom diagram that a robot with transferable liquid counterweight retains static stability during the entire ascending including the time intervals when right or left foot are detached from ground, while a conventional similar robot known from prior art without a transferable liquid counterweight during said interval must be supported with complex and less reliable dynamic balancing system.
(54) It is evident from these examples that a transferable liquid counterweight allows a robot to maintain a quasi-static state and stability during its motion on uneven terrain or ascending the stairs, that is to adjust its CoM to new designated position while the solid body of a robot remains in static state and move the solid body to new designated position while retaining the ground projection of CoM in the ground support polygon and, hence, to retain its static stability during the motion.
(55) The flowchart shown on
(56) It is important to note that the examples shown on
(57) Referring to
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(59) The average thickness of the walls of chambers 3 mm. The external dimensions of four chambers are shown on
(60) Besides the lowest CoM position, the advantages of this design are equal volumes of all chambers and their positioning outside of the main structure of the robot.
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(62) In specific example proportionally illustrated by
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(64) The advantages of the design shown on
(65) Alternatively,
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(67) The transferable liquid counterweight disclosed in this patent document provides the manifold empowering for the robots' maneuverability and stability while not implying any additional load on the robot mechanics during its motion on uneven terrain or during ascending. However, such substantial additional load is not However, such substantial liquid load is not commonly required during the robots' motion on even terrain.
(68) As it will be clear from the following disclosure, there are various embodiments of the present inventions supporting effective motion of the robots with the transferable liquid counterweight on the even terrains.
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(70) In the embodiments illustrated by
(71) In the embodiments illustrated by
(72) In the embodiments illustrated by
(73) The advantage of this design is possibility of a normal motion of the robot on even as well as on slightly uneven terrain where the embodiment shown on
(74) It is evident from the disclosure provided above that the transferable liquid counterweight provides significant enhancing of stability and dynamic balance for the bipod humanoid robot thus decreasing the risk of fall. Moreover, in the falling occurrence the transferable liquid counterweight and supporting devices decrease the probability of serious damage of the falling robot and provide effective means for its self-rising (or self-righting, using different term for this action).
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(77) The Locomotion Wheeled Robots Embodiments
(78) The locomotion wheeled robots on even or slightly uneven terrains usually retain condition of static mobility maintaining the ground projection of the center of mass in the margins of the Ground Support Polygon, but there are relatively strict limitations of accessibility of uneven terrain for the wheeled robots.
(79) As it will become clear from the following examples, the transferable liquid load significantly extends the scope of capabilities of the wheeled robots.
Example 1 a Relatively Light Wheeled Locomotion Robot Embodiment of the Invention
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(81) The locomotion robot consists of two cars 801 and 802. Each car has tank for liquid counterweight 803 and 804 of equal capacities. Specifically, on
(82) For a specific example, the following characteristics of apparatus are in geometric proportions to the shown on
(83) Motors: motor on the left car used as the main driving motor of the robot and for hydraulic cylinder (alternatively) 500 W, 25 kg; driving motor on the right car 300 W, 15 kg; motor of the electrical hoister 400 W, 20 kg.
(84) Telescopic cylinder: 3 stages, diameters 90 mm; 70 mm; 50 mm; stroke 3,150 m m; closed length 1,320 mm; hydraulic oil capacity 13.5 liters; total weight of telescopic hydraulic system 30 kg.
(85) Three Lithium-ion battery:
(86) 1. main battery powering the hydraulic lifting system and drivetrain in the left car—20 kg, 2.56 kWh.
(87) 2. electrical hoister, 10 kg, 1.28 kWh
(88) 3. drivetrain in the right car, 4 kg, 0.5 kWh
(89) Other components—2 kg on each car.
(90) Total weight of cars:
(91) Left car without water: 108 kg; right car without water: 77 kg.
(92) Maximal speed of the entire robot on even road 5 km/h without liquid counterweight and without cargo; 4 km/h with 80 kg liquid counterweight without cargo; 3 with 90 kg liquid counterweight with cargo up to 50 kg on right car and up to 100 kg on right car (up to 150 kg total).
(93) Maximal speed during the maneuvering motions of the right car 0.5 km/h.
(94) Maximal allowed cargo with 90 liter counterweight: left up to 50 kg+right car up to 100 kg, up to 150 kg total.
(95) Maximal height in a one-step rising: 3 meters, that is over free folds greater than the maximal height of the exemplified mobile robotic system on an even terrain.
Example 2 a Relatively Heavy Wheeled Locomotion Robot Embodiment of the Invention
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(97) The main difference of relatively heavy wheeled locomotion robot embodiment is employment of a powerful multi-stage telescopic hydraulic cylinder providing a significantly greater stroke, as well rigidity of extended cylinder; this, in turn, allows substantially higher altitude in one-step rising action as well as greater cargo.
(98) The components of system are principally the same: the locomotion robot consists of two cars 901 and 902. Each car has tank for liquid counterweight 903 and 904 of equal capacities. Specifically, on
(99) The exemplified specific characteristics in geometric proportions as shown on
(100) The width of each car 1000 mm
(101) The length of each car 2000 mm
(102) The maximal capacity of the each water tank: 400 liters; actual liquid load in the example: 250 liters.
(103) Telescopic cylinder: 10 stages (the outer diameters, mm) 52×66×80×94×109×125×141×158×178×200;
(104) closed length 780 mm; stroke 5,200 mm
(105) hydraulic oil capacity 41 liters; total weight of telescopic hydraulic system 87 kg.
(106) Total weight of the cars
(107) Left car without water: 220 kg
(108) Right car without water: 120 kg
(109) Maximal allowed cargo with 400 liter counterweight: left up to 100 kg and right car up to 250 kg, up to 350 kg total.
(110) Maximal height in a one-step rising: 5 meters.
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(121) The stages 11a to 11i are similar to the above described stages 10a-10i, however, the height of the ledge is 5 meters, the telescopic lifting system is substantially more powerful and significantly more rigid, the greater length of the cars and greater absolute and relative counterbalancing liquid mass provide highly-secured ascending and ability to carry not only cargo, but also passengers.
(122) The Hybrid Wheeled/Bio-Like Robotic Systems' Embodiments
(123) The transferable liquid counterbalancing methods also allow embodiments practically realizing various Hybrid Robotic Systems, such as Wheeled/Bio-like Locomotion Robots, beneficially combining technical and natural configurations and reconfigurable systems, thus, bringing to practice the respective advantages.
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(127) Accordingly to the present invention, the robotic train is capable to use any of three modes of motion depending on the practical task in progress and the current conditions of a terrain: 1. on even terrains, the preferable mode is the motion as common train with all hydraulic telescopic cylinders in retracted state; 2. on uneven terrains and while ascending the slopes, the preferable mode is the wave-like motion empowered by the consecutively extending hydraulic systems; 3. in some particular conditions, such as particularly steep slopes, the motion empowered by concurrently extending a few or all hydraulic systems is possible and may be preferable. The self-descriptive
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(130) It is important to note that while in the illustrating example for the purpose of visibility shown only 3 intermediate cars, the number of the practical intermediate cars in the robotic train accordingly to the present invention and correspondingly the available height of ascending may be significantly greater. Moreover, the cars may be equipped with anchors (or paws, using bio-like terms) allowing ascending the slope exceeding the fully extended length of the train.
(131) It is preferable accordingly to the present invention that all solid components of robotic systems, when their functionality allows, are made from ultra-light materials, such as magnesium and magnesium alloys, including lithium-magnesium alloys, and carbon-fiber composites. The maximal allowed length of the train, in particularly the number of intermediate cars, and hence—the maximal difference of the altitudes between the successive plateaus is defined by ratio of the combined mass of the front locomotive car with liquid counterweight and the combined mass of the intermediate cars and the rear car without liquid load.
(132) In specific example proportionally corresponding to
(133) The disclosed transferable liquid counterbalancing methods method and apparatuses also imply the embodiments with structurally reconfigurable robots including hybrid manned-robotic systems, bio-like multi-pod robotic devices as caterpillar or spider and also allows reversible mutual transforming between various bio-like arrangements practically beneficially actualizing real and imaginative bio-forms, such as centaurs. Some embodiments of the disclosed method and apparatuses may comprise a plurality of movable parts, each part contains its chamber. Below, some examples are given for illustration.
(134) The Hybrid Manned/Autonomous Robotic Systems' Embodiments
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(137) The Reconfigurable Bio-Like Robotic Systems' Embodiments
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(140) Although the primary goal of this invention is providing technical means preventing risk for human lives and health in the harsh environment and challenging task, the relatively small or miniature models of the disclosed apparatuses may be employed as the children toys and for various entertainments including competitive games for people of various ages.
(141) Applications of the disclosed methods and apparatuses can be realized in life-threatening circumstances, including natural and man-made disasters and battle fields. Application of the disclosed methods and apparatuses can be realized in circumstances demanding strong requirements for reliability and smoothness of the robot motion, including in a medical hospital, such as field hospitals. Applications of disclosed methods and apparatuses can be realized in an environment and under work conditions implying risk for human life or health, such as mining, chemical factories, and nuclear power stations. Applications of relatively small or miniature models of the disclosed apparatuses can be realized in the form of children's toys and entertainments. All provided specific embodiments, examples and illustrations in this patent disclosure should be considered as explanatory illustrations that neither limit nor exhaust the possible implementations of present invention in the entire scope of its claims.