Biped locomotion robot

The movement analysis becomes easy and the control of all the movement systems is realized better through the initialization of the multiple coordinate systems. The fundamental body portion 6 is coupled to a foot portion 5 through a first joint portion 7, a first link 3, a second joint portion 8, a second link 4, and a third joint portion 9. The rigidity of the first link 3 is lower than that of the fundamental body portion 6, and the rigidity of the second link 4 is lower than that of the second link 4. It is possible to position the second link 4 and the foot portion 5 in a high precision to a mechanical origin which is predetermined to the fundamental body portion, for the reason of the rigidity relation. Handle portions 13 are coupled in two positions to the fundamental body portion 6. When the whole posture is initialized based on the mechanical origin, the center of gravity G of the whole robot is located between two vertical planes containing the two positions. In the initialization, a first joint portion 7, a second joint portion 8, and a third joint portion 9 are located between the two vertical planes. Thus, because the whole balance is taken, the origin adjustment is easy.

TECHNICAL FIELD

The present invention relates to a biped locomotion robot.

BACKGROUND ART

A humanoid robot, especially a biped locomotion robot, has being developed as an autonomous movement machine operable in environments where human beings have to execute difficult activities, such as care activity and in home and rescue activity in a fire scene. As shown inFIG. 1, such a robot is composed of an element system comprising a plurality of elements (head101, body102, and legs103) which are under subordinative control of each other based on multiple joints, and an element relating system which relates the element system (joints104,105,106,107,108, and109as 1-, 2- and 3-axis rotation systems). The whole control of the element system and the element relating system is described based on multiple variables belonging to each system and multiple parameters. However, it is difficult to separate independence and subordination between the multiple variables with high precision in the development phase. It is also difficult to describe a foot rising movement and a foot grounding movement that are associated with walking correctly.

When a theoretical walking movement and an actual walking movement do not coincide with each other, the cause of the discrepancy depends on some of the variables. Mechanical elements of the plurality of elements have physical parameters, and the rigidity and mass of each mechanical element have an important influence on the walking movement. For this reason, it is difficult to theoretically analyze whether the instability of control depends on the mass of the head or the rigidity of the body or leg. Additionally, it is difficult to analyze the discrepancy when each mechanical element is not manufactured according to theory.

Therefore, it is important to design a biped locomotion robot such that the changeable ranges of the parameters of all the elements are restricted in consideration of physical characteristics between the elements, for the purpose of facilitating the analysis and confirming the quality of the design. It is important to cause effective attenuation of influence between composite rotation systems. The definition of reasonable rules about the adjustment and initialization of a mechanical origin defining an initial condition of the movement is important to prove the quality of the design.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a self-controlled biped locomotion robot with a small size.

Another object of the present invention is to provide a biped locomotion robot in which movement analysis is easy.

Another object of the present invention is to provide a biped locomotion robot in which the initialization of composite coordinate systems is easy.

Another object of the present invention is to provide a biped locomotion robot in which the control of the whole movement system can be realized better.

In an aspect of the present invention, a biped locomotion robot is composed of a fundamental body portion, an upper body housing rigidly coupled to the fundamental body portion, two leg portions movably coupled to the fundamental body portion, a foot portion movably coupled to each of the two leg portions, a head portion movably coupled to the upper body housing, and two arm portions movably coupled to the upper body housing. It is desirable that the fundamental body portion functions as a mechanical origin.

The biped locomotion robot may be further composed of two handle portions provided for opposing attachment sections of the fundamental body portion. Thus, the workability and custody can be improved.

Also, the center of gravity of the biped locomotion robot is desirably located between vertical planes, each of which passes corresponding ends of the attachment sections of the handle portions to the fundamental body portion, when the biped locomotion robot is in an initial state.

Also, each of the two leg portions may be composed of a first link functioning to support the fundamental body portion through a first joint portion and a second link functioning to support the first link through a second joint portion. In this case, it is preferable that a horizontal rotation axis of the first joint portion and a horizontal rotation axis of the second joint portion are located between the vertical planes, each of which passes through corresponding ends of the attachment sections of the two handle portions to the fundamental body portion, when the biped locomotion robot is in the initial state. Moreover, each of the foot portions may support a corresponding one of the second links through a third joint portion. It is preferable that a horizontal rotation axis of the third joint portion is located between vertical planes, each of which passes through the corresponding ends of the attachment sections of the two handle portions to the fundamental body portion, when the biped locomotion robot is in the initial state.

Also, when each of the two leg portions is composed of a first link provided to support the fundamental body portion through a first joint portion, and a second link provided to support the first link through a second joint portion, it is preferable that the rigidity of the first link is lower than that of the fundamental body portion, and the rigidity of the second link is lower than that of the first link. It is preferable that the first joint portion has a vertical rotation axis.

Also, it is desirable that the first joint portion has a vertical rotation axis.

Also, it is desirable that the upper body housing is coupled to the fundamental body portion to provide a gap region between the upper body housing and the fundamental body portion, and an energy source is arranged in the gap region.

Also, the biped locomotion robot may further include a control unit provided for a back of the upper body housing.

Also, in another aspect of the present invention, a biped locomotion robot is composed of a fundamental body portion, two first links to support the fundamental body portion through a first joint portion, and a second link to support a corresponding one of the first links through a second joint portion. The rigidity of the first link is lower than that of the fundamental body portion and the rigidity of the second link is lower than that of the first link. Also, the biped locomotion robot is further composed of a foot portion to support a corresponding one of the second links through a third joint portion. Mechanical stress transferred instantaneously through a double pendulum system (3,4,7,8) between the fundamental body portion and the foot portion is relaxed or damped on the grounding of the foot portion. Thus, the control of mechanical origin for a control system of the fundamental body portion becomes easy. As a result, it becomes easy to position the second link. Moreover, the positioning of the foot portion attached to the second link with the minimum rigidity becomes easy.

In another aspect of the present invention, the biped locomotion robot is composed of a fundamental body portion in which a mechanical origin is set, a first link to support the fundamental body portion through a first joint portion, a second link to support the first link through a second joint portion, and a third link to support the second link through a third joint portion. The fundamental body portion has handle portions, and the handle portions are coupled to the fundamental body portion at two positions. It is desirable that the center of gravity (G) of the robot is located between two vertical planes passing through the two positions in the initialization of the whole posture with respect to the mechanical origin. As a result, the rotation moment when the whole of robot is carried is small, so that the stability of the robot is high and the carrying of the robot is easy. In case of the initialization, it is desirable that the rotation axis of the first joint portion, the rotation axis of the second joint portion, and the rotation axis of the third joint portion are located between the two vertical planes. Especially, the two positions corresponding to the two vertical planes are determined as two separate positions in a front direction in case of the initialization. It is desirable that the handle portions form a reference plane to the mechanical origin in case of the initialization, and the grounding surface of the foot portion can be adjusted based on the reference surface of the handle portion. Especially, by adjusting the foot portions such that the reference surface of the handle portions is parallel to the grounding surfaces of the foot portions, the adjustment of the foot portions to the origin point becomes easy. The handle portions may be outside an exterior body such as a body section cover and may be exposed. Thus, the regular initialization work becomes easy.

In another aspect of the present invention, the biped locomotion robot is composed of a fundamental body portion, an upper body housing supported by the fundamental body portion, first links to respectively support the fundamental body portion through first joint portions, second links to respectively support the first links through second joint portions, foot portions to respectively support the second links through third joint portions, and an upper portion supported by the upper body housing through a fourth joint portion. The upper body housing is attached to the fundamental body portion with a high rigidity, and arm portions and a head portion are supported by the upper body housing through joint portions. In this way, the rigidity of the support structure to support the head portion and the arm portions can be maintained high. The upper body housing is supported by the fundamental body portion through side plate sections to form a gap region, and an energy source (cell battery and so on) is arranged in the gap region. Thus, the use efficiency of the space is high.

Many various holes and an attachment structure are provided for the fundamental body portion for attachment of the upper portion and the lower portion. Therefore, the fundamental body portion is formed of thick light alloy as a whole. A proper reinforcement structure may be used for the fundamental body portion.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a biped locomotion robot of the present invention will be described in detail with reference to the attached drawings.

FIG. 2is a perspective view of the biped locomotion robot according to an embodiment of the present invention. Referring toFIG. 2, the biped locomotion robot of the present invention is composed of a fundamental body portion6, and a body section1and two leg portions2with respect to the fundamental body portion6. A control unit26is provided on the rear side of the body section1. InFIG. 2, only one leg portion is shown.

Referring toFIG. 3, the fundamental body portion6is a highly rigid body. The fundamental body portion6is supported by 2-axis rotatably by each of the leg portions2. Each leg portion2is supported by 2-axis rotatably by a foot portion5. Also, the fundamental body portion6is provided with two side plate sections12(not shown inFIG. 3) for a gap to stand up in both side ends of the fundamental body portion6, as shown inFIG. 4.

Each leg portion2has a first leg portion3or first link3and a second leg portion4or second link4. The first leg portion3or first link3is coupled to the fundamental body portion6through a 2-axis rotatable first joint portion7. The second leg portion4or second link4is coupled to the first leg portion3through a 1-axis rotatable second joint portion8. The foot portion5is coupled to the second leg portion4through a 2-axis rotatable third joint portion9. The foot portion5partially has a flat foot back surface contacting a flat floor or flat ground. It should be noted that in this example, the leg portion2and the foot portion5are coupled 2-axis rotatably. However, the leg portion2and the foot portion5may be coupled 1-axis rotatably.

In this way, the second leg portion4is supported by the foot portion5through the third joint portion9, and the first leg portion3is supported by the second leg portion4through the second joint portion8. Moreover, the fundamental body portion6is supported by the first leg portions3through the first joint portions7.

As shown inFIG. 4, the body section1has an upper body housing11. The upper body housing11is formed of light alloy as a unit. The upper body housing11has a proper thickness and is formed to have a high rigidity. The upper body housing11is rigidly coupled to the fundamental body portion6with the side plate sections12for the gap and is supported by the fundamental body portion6. The upper body housing11is separated from an upper portion of the fundamental body portion6in an upper vertical direction by the side plate sections12. A battery cell case17is detachably provided in the gap region formed between the upper portion of the fundamental body portion6and the lower portion of the upper body housing11.

As shown inFIG. 4, the upper body housing11has a head attachment hole19in the upper portion18. Also, the upper body housing11has arm attachment holes23in the side portions11.

Two handle portions13are provided for attachment portions corresponding to the side plate sections12on both sides of the fundamental body portion6. In more detail, the two handle portions13are firmly attached to attachment portions14on the both side edges of the fundamental body portion6to oppose to each other. Each of the two handle portions13is attached to the attachment portion14at two positions P and Q. It is preferable that the two corresponding positions P and the two corresponding positions Q are located on a same plane. Also, it is desirable that the plane is parallel to a horizontal plane, namely, is orthogonal to a vertical axis. Especially, it is desirable that the two positions P and Q are located on a reference plane which passes a mechanical origin to be described later. As shown inFIG. 3, it is desirable that the center of gravity G of the total mass when the biped locomotion robot is complete is positioned on a vertical plane which passes a middle point of the two positions P and a middle point of the two positions Q, or in the neighborhood of the vertical plane.

As shown inFIG. 5, the fundamental body portion6and the upper body housing11are covered by a body section cover16.FIG. 6andFIG. 7show the whole biped locomotion robot when the body section cover16is attached to the fundamental body portion6in this way. In this case, only one leg portion2is shown inFIG. 7. The handle portion13is exposed outside the body section cover16. The body section cover16has openings corresponding to the head attachment hole and arm attachment holes24in the upper body housing11.

As shown inFIG. 8, the head portion22is attached to the upper body housing11such that the head portion22is adjusted in axis to the head attachment hole19of the upper body housing11through the body section cover16and is supported in the vertical direction. Like the head portion22, the arm portions25are adjusted in axis to the arm attachment holes23and24of the upper body housing11through the body section cover16, and is attached to the upper body housing112-axis rotatably. That is, as shown inFIG. 8, the arm portion25has the degrees of freedom in multiple axes and is attached to the upper body housing11freely in swing and turning. The carrying type control unit26is arranged on the back side of the body section cover16and is attached to the fundamental body portion6, as shown inFIG. 2.

FIG. 9shows a method of adjusting a mechanical origin. An element system is composed of a fundamental body portion system S1, first link systems S2, second link systems S3and foot systems S4. The state shown in the figure is when a walking examination is carried out with an arm system omitted. The first link system S2, the second link system S3and the foot system S4are provided for either side but are treated as a single system.

As shown inFIG. 10, the handle portion13has a unitary body of transverse bar portions13A extending in transverse directions and a bridge portion13B extending in a front direction. The surface of the bridge portion13B, especially, the lower surface of the bridge portion13B is formed as the reference surface SS1for the mechanical origin. A reference surface SS2corresponding to the reference surface SS1for the mechanical origin on either side is formed as the upper surface of a rigid body pillar31which stands up from a reference horizontal floor surface SS3. The coincidence of the reference surface SS1for the mechanical origin and the reference surface SS2may be detected by a touch sensor (not shown) which detects contact of the rigid body pillar31and the handle portion13.

The biped locomotion robot has a weight to the extent for a human being, and is carried by using the handle portions13on both sides such that the reference surface SS1for the mechanical origin is made to coincide with the reference surface SS2of the two rigid pillars31. Or, the biped locomotion robot is operated by a remote radio control such that the reference surface SS1for the mechanical origin is made to coincide with the reference surface SS2of the two rigid pillars. After that, the three coordinate systems S2, S3, and S4are initialized using the coordinate system S1as reference. That is, in the initial state, the element system is reset to the origins of all the coordinate systems S1, S2, S3, S4.

FIGS. 11A and 11Bshow an allowable range of the mechanical origin. The space formed between a vertical plane32containing both points P and P of the handle portions13on both sides and a vertical plane33containing both points Q and Q of the handle portions13on both sides is defined as the allowable range. The control target is that the horizontal rotation axis10extending in a horizontal direction in the first joint portion7, the horizontal rotation axis8H extending in a horizontal direction in the second joint portion8, and the horizontal rotation axis9H extending in a horizontal direction in the third joint portion are located between the two vertical planes32and33. It is not necessary that the horizontal rotation axes7H,8H and9H are located on a single vertical plane. Rather, it leads excellent stability that the horizontal rotation axes7H,8H and9H are not located on the single vertical plane. The whole mass distribution in the robot is designed such that the center of gravity G of the whole biped locomotion robot is in the allowable range when the horizontal rotation axes7H,8H and9H are in such an allowable range. The grounding surface of the foot portion5is contained in this allowable range. The rotation position of a servomotor or rotation drive section corresponding to each joint portion is rest and initialized when the adjustment of the center of gravity is ended.

It should be noted that in this example, the handle portions13are attached to the side portions14of the fundamental body portion6. However, the handle portions13may be provided as protrusion sections (not shown). Also, it is not necessary that the handle portions13are on a same horizontal plane. If the position of the center of gravity is located on a slant plane passing through the handle portions13, it is possible to stabilize the posture of the robot easily. The adjustment of the origin by the robot itself is possible by using the handle portions and the reference surface.

Various parameters are contained in the walking control. It has been proved that impact relaxation, proper rigidity and the optimization of mass of a movement body are important physical factors for the walking control. In the biped locomotion robot of the present invention, the following relations are set.(1) The rigidity of the fundamental body portion6or the rigidity of the fundamental body portion6and the object rigidly coupled to the fundamental body portion6>the rigidity of the first leg portion3>the rigidity of the second leg portion4,(2) The total mass of all the objects weighting on the fundamental body portion6>the mass of the first leg portion3>the mass of the second leg portion4, and(3) The condition (1)+the condition (2)

The rigidities may be defined based on the flexural rigidity or the torsional rigidity when the both ends of each object are supported and a load or pressure is applied to a predetermined position or region. It is important that the rigidity of the object coupled to the fundamental body portion6and located in a further distance downwardly from the fundamental body portion6is lower and smaller in mass. The conditions (1), (2) and/or (3) facilitate the analysis of the variable dependence and parameter dependence in the directional control. For example, when the mass of the foot portion5is larger, the movement of the foot portion5has a large influence on the control of the whole of systems. Thus, it is difficult to determine whether the movement of the whole of systems depends on the pursuit of the servomotor or the centrifugal movement of the foot portion5with a large inertia (inertia mass). However, if the mass of the foot portion5is set small, it can be determined that the movement of the whole of systems depends on the pursuit of the servomotor largely. This depends strongly on the rigidity of each system especially. The first and second links are properly given with high rigidities and the rigidities of them are designed to be lower than the rigidity of the fundamental body portion.

When the attachment portions of the handle portion are determined for the gravity center to be located in the neighborhood of a horizontal region containing the handle portions13, the stability is good when the whole robot is carried by using the handle portions13. Especially, when the robot is installed on the stiff pillar by using the handle portions13, it is easy to adjust the positions of the foot portions5to the handle portions13such that the grounding surfaces of the foot portions5are parallel to the reference plane of the handle portions13.

In case that the arm portions25and the head portion22are attached freely in swinging to the fundamental body portion6with the highest rigidity or the upper body housing11having of a high rigidity and coupled to the fundamental body portion6in the robot, the light weight of the whole system can be realized. The cell battery is inserted between the fundamental body portion6and the upper body housing11and use efficiency of the space can be improved while keeping the rigidity.

FIG. 12shows the body section cover16and the carrying type control unit26.FIG. 13shows a part of the fundamental body portion6when an upper portion26A of the carrying type control unit26is removed and a part of the body section cover16is opened.FIG. 14is a perspective view of the whole of fundamental body portion6. InFIG. 14, the arrow F shows the front direction. The fundamental body portion6is formed of light alloy casting as a unit to have a high rigidity and a proper thickness in the vertical direction. Two positioning holes41corresponding to the two leg portions are formed in the fundamental body portion6. To position each leg portion, a positioning pin hole45is formed. The two leg portions are firmly coupled to the fundamental body portion6with bolts passing through bolt holes44which are formed in the fundamental body portion6. A reinforcement rib49is formed in a cross in each of the two positioning holes41.

FIGS. 15 and 16show a structural section52of the first joint portion7. The structural section52of the first joint portion7has a fixation section52A and a rotation section52B. The top section of the fixation section52aof the structural section52is formed to have an outer circular cylinder surface54. The circular cylinder surface54is fit to the positioning hole41shown inFIG. 14coaxially. In case of the attachment of the first joint portion7, the positioning pin55which stands upwardly from a surface of the fixation section52ais inserted in the positioning pin hole45ofFIG. 14to determine the position relation of the structural section52and the fundamental body portion6. The structural section52and the fundamental body portion6is coupled firmly in a high rigidity with bolts (not shown) passing through bolt hole56on the side of the structural section52and the bolt holes44on the side of the fundamental body portion6.

The foot portion5is provided apart from the center of gravity G and is controlled to have the degrees of freedom of multiple axes through the first leg portion3and the second leg portion4. Therefore, the movement control of the foot portion5in case of the foot rising movement and the foot grounding movement is more faithfully carried out with respect to the reference coordinate system which is fixed on the fundamental body portion6, comparing a case that the first leg portion3and the second leg portion4have higher rigidities than the fundamental body portion6. Thus, the first joint portion7is rotatable with respect to the fundamental body portion6in one axis or two axes.

In the biped locomotion robot of the present invention, the origin adjustment can be carried out easily in a high precision. Especially, the rigidity is lower in a portion further distant from the mechanical origin. Therefore, the grounding impact can be attenuated easily at the portion further distant from the mechanical origin. The control of the rotation moment in the floating state of the foot portion becomes easy because of the lower rigidity and the fact that the portion further distant from the mechanical origin has a smaller mass. As a result, the initialization of the control on the grounding of the foot portion becomes easy. The handle portions are provided on positions near the center of gravity so that the stability is good. When the biped locomotion robot is in the stationary condition by fixing the mechanical origin using the handle portions, the initialization of the system of the robot is carried out. Therefore, the initialization work is simple.