JP4876926B2 - Legged mobile robot and walking control method for legged mobile robot - Google Patents

Description

  The present invention relates to a legged mobile robot having legs for walking and a walking control method for the legged mobile robot.

  In recent years, leg portions for walking are provided, and these leg portions are driven based on predetermined gait data, and a foot portion connected to be rotated to the lower end of the leg portion is disposed on the floor portion. Therefore, legged mobile robots that perform walking movements have been developed.

  In such a legged mobile robot, first, the foot portion of the leg is brought into contact with the floor surface to form a supporting leg, and then the floor surface is pushed by the back of the foot to raise the entire leg portion (the entire robot). Thus, the next walking motion is performed by driving the legs. The driven leg portion is a free leg, while the other leg portion is a support leg. In this way, a walking motion can be performed by alternately switching the free leg and the support leg.

  In order to stably perform such a walking motion, it is necessary to control the position of the center of gravity of the entire robot and drive the leg portion. That is, in the case of a biped walking type legged mobile robot having legs on the left and right, the moment due to the center of gravity of the entire robot does not act on the ground contact surface of the foot portion of the supporting leg that contacts the floor surface on which it walks. A point (ZMP = Zero Moment Point) is located.

  By the way, when a legged mobile robot as described above performs a walking motion, when the leg is driven based on the gait data, it becomes a free leg due to the shape of the floor or the deflection of the leg itself. When the leg portion is switched to the support leg, the foot portion may come into contact with a position different from the ground contact position determined by the gait data. In this way, when the free leg is switched to the standing leg, a large reaction force is received from the floor surface via the foot, and this reaction force is transmitted as an impact to the entire robot and affects the walking motion.

Therefore, for example, as described in Patent Literature 1, 2, or 3, by providing a contact-type distance sensor or force sensor on the back surface of the foot portion that contacts the floor surface, contact between the foot portion and the floor surface can be achieved. It is known to perform walking control that detects and feeds back the detected result to leg drive control. By performing such walking control, the legged mobile robot can perform a stable walking motion.
JP-A-5-318336 JP 2001-353686 A Japanese Patent Laid-Open No. 62-187671

  However, by incorporating the distance sensor and force sensor as described above into the foot, the weight of the foot increases and the power required for the motor that drives the leg connected to the foot increases. It becomes. Furthermore, when walking control based on signals from such sensors is performed, there may be a delay in responsiveness due to a minute time difference required for signal transmission / reception, which may be an obstacle for performing high-speed walking motions. .

  The present invention has been made to solve such problems, and detects contact between the foot and the floor surface without using a contact-type sensor or the like for the foot when performing a walking motion. It is an object of the present invention to provide a legged mobile robot and a legged mobile robot walking control method capable of performing a stable walking motion.

  The legged mobile robot according to the present invention includes a leg portion that connects a foot portion that contacts a floor surface during walking, and performs a walking motion by driving the leg portion based on gait data. A mobile robot, comprising: a rotation part configured to be rotatable about a rotation axis with respect to a leg part, at least part of the foot part, and shape information of the rotation part Based on the storage unit that stores the relative position and orientation information for detecting the relative position and orientation information of the rotating unit with respect to the leg, the shape information of the rotating unit, and the relative position and orientation information A height calculation unit that calculates height information from the axis to the lowest point of the foot, and a height direction of the leg based on the gait data based on the height information calculated by the height calculation unit A drive amount correction unit for correcting the drive amount of A.

  According to such a legged mobile robot, it is possible to detect that the foot is in contact with the floor without using contact-type sensors, and the relative position and posture of the foot with respect to the leg. From the change, it is possible to grasp the relative positional relationship between the foot and the leg with respect to the floor surface. Therefore, the driving amount in the height direction of the leg determined by the gait data can be corrected so that the back surface of the foot part contacts the floor surface without receiving a large reaction force, As a result, a stable walking motion can be performed.

  Further, the rotating portion may be the entire foot portion, or a rotating shaft for rotating the entire foot portion may be provided at the ankle joint of the leg portion. In such a legged mobile robot, the entire foot portion can be used as a rotating portion that detects contact with the floor surface, so a special configuration can be added to the foot portion. It becomes unnecessary, and a legged mobile robot can be configured more easily.

  Moreover, it is preferable that the relative position / posture information is a degree of inclination relative to the leg portion. In particular, the difference between the inclination angle of the leg with respect to the vertical direction and the inclination angle with respect to the vertical direction of the reference line extending in the vertical direction from the surface of the rotating portion is obtained, and the difference between the inclination angles is used as relative position and orientation information. It is preferable. In this case, for example, when the rotating part is the entire foot part and the rotating shaft for rotating the entire foot part is provided at the ankle joint of the leg part, the tip of the foot part (toe) The height from the floor surface of the rotating part (ankle part) where the foot part rotates relative to the leg part, regardless of which of the part) and the rear end part (the heel part) comes into contact with the floor surface first It is possible to obtain the accuracy accurately.

  In addition, in such a legged mobile robot, when the rotating unit further includes a measuring unit that measures an angular velocity at which the rotating unit rotates with respect to the leg, and the angular velocity measured by the measuring unit exceeds a predetermined threshold value In addition, the driving amount in the height direction of the leg may be corrected. Such a legged mobile robot can determine that the foot portion is in contact with the floor surface only when the entire foot portion or a rotating portion that is a part of the foot portion is rotated at an angular velocity of a certain level or more. it can. Therefore, when the foot part is partially rotated due to a slight shaking during driving of the leg part, it is possible to perform a walking operation without erroneously detecting such rotation as contact with the floor surface. It becomes.

  In addition, such a legged mobile robot reduces the frictional force generated between the rotating part and the leg part (rotating shaft) as much as possible, and the reaction force received when the foot part contacts the floor surface. However, if the rotating part is configured to be able to freely rotate with respect to the leg part, it is preferable that the rotating part be floored by its own weight. The posture with respect to the surface is displaced, and the contact position with respect to the floor surface becomes unstable.

  Therefore, such a legged mobile robot further includes a torque control unit that controls the torque supplied to the foot when the rotating unit rotates with respect to the leg. It is preferable that a torque having a magnitude proportional to an angular velocity at which the rotating unit rotates with respect to the leg portion is supplied to the foot portion by the control unit in a state where the rotating unit is separated from the floor surface. If it does in this way, the suitable torque according to the angular velocity at the time of rotation of a rotation part will be loaded, and the posture at the time of contacting the floor of a rotation part will be fixed. Therefore, the contact position of the rotating part to the floor surface does not change, and a stable walking motion can be performed.

  As described above, it is preferable that the reaction force generated when the foot part contacts the floor is not propagated to the leg part and the robot body as much as possible. Therefore, it is more preferable that the torque control unit supplies a larger magnitude of torque to the rotating unit when the rotating unit is separated from the floor surface than when the rotating unit is grounded to the floor surface. . By controlling the torque supplied to the rotating portion in this way, it is possible to further reduce the impact received from the floor surface when performing a walking motion.

  It should be noted that the torque control unit described above is sized so that the rotation unit can rotate about the leg portion almost immediately before it is determined, for example, that the rotation unit contacts the floor surface based on gait data. In addition, it may be controlled to reduce the magnitude of the torque supplied to the foot. In this way, when the moving floor surface is substantially flat, the reaction force received when the rotating part contacts the floor surface is greatly suppressed, and a more stable walking motion can be performed. .

  The present invention also provides a walking control method for a legged mobile robot, comprising a leg portion that rotatably connects a foot portion that contacts a floor surface during walking, A leg that is at least a part and includes a rotation part configured to be rotatable around a rotation axis with respect to the leg part, and performs a walking motion by driving the leg part based on gait data In the walking control method of the mobile robot, the step of detecting the relative position and orientation of the rotating unit with respect to the legs before the rotating unit is brought into contact with the floor, and the shape information of the rotating unit stored in advance A step of calculating a height from the rotation axis to the lowest point of the foot portion based on the detected relative position and orientation of the rotation portion; and a step of calculating the gait data based on the calculated height. Correcting the driving amount in the height direction of the leg based on, and correction And the foot based on the driving amount is characterized in that comprises a step of contacting the floor surface.

  According to such a walking control method, it is possible to detect that the rotating unit has come into contact with the floor surface without using contact-type sensors, and to change the relative position and posture of the rotating unit with respect to the legs. From this, it is possible to grasp the relative positional relationship between the rotating part and the leg part with respect to the floor surface. Therefore, the driving amount in the height direction of the leg determined by the gait data can be corrected so that the back surface of the foot part contacts the floor surface without receiving a large reaction force, As a result, a stable walking motion can be performed.

  Further, the rotating portion may be the entire foot portion, or a rotating shaft for rotating the entire foot portion may be provided at the ankle joint of the leg portion. If it does in this way, since the whole foot part can be used as a rotation part which detects having contacted with respect to the floor surface, it becomes unnecessary to add a special structure to a foot part.

  The walking control method further includes a step of measuring an angular velocity at which the rotating portion rotates with respect to the leg portion, and when the measured angular velocity exceeds a predetermined threshold, the height of the leg portion is increased. The driving amount in the vertical direction may be corrected. According to such a walking control method, even if the relative position and orientation of the rotating part with respect to the leg part is slightly displaced due to its own weight or the like, the displacement is erroneously detected as contact with the floor surface. Disappears.

  In addition, it is preferable that the walking control method further includes a step of supplying a torque having a magnitude proportional to the measured angular velocity of the rotating part to the foot part in a state where the rotating part is separated from the floor surface. . If it does in this way, the suitable torque according to the angular velocity at the time of rotation of a rotation part will be loaded, and the posture at the time of contacting the floor of a foot part will be fixed. Therefore, the contact position of the rotating part to the floor surface does not change, and a stable walking motion can be performed.

  Furthermore, such a walking control method supplies a larger torque to the leg portion of the rotating portion when the rotating portion is separated from the floor surface than when the rotating portion is in contact with the floor surface. It is preferable to provide a step of controlling the magnitude of the torque to be supplied. By controlling the torque supplied to the rotating portion in this way, it is possible to further reduce the impact received from the floor surface when performing a walking motion.

  Furthermore, in such a walking control method, just before it is determined that the rotating part comes into contact with the floor surface, the size of the rotating part is such that the rotating part can freely rotate with respect to the leg part. It is preferable to further include a step of reducing the magnitude of the torque supplied to the rotating unit. In this way, when the moving floor surface is substantially flat, the reaction force received when the rotating part contacts the floor surface is greatly suppressed, and a more stable walking motion can be performed. .

  Furthermore, in such a walking control method, it is preferable that the relative position and orientation to be detected is a relative inclination degree with respect to the leg portion of the rotating portion. In particular, the difference between the inclination angle of the leg with respect to the vertical direction and the inclination angle with respect to the vertical direction of the reference line extending in the vertical direction from the surface of the foot is obtained, and the difference between the inclination angles is used as relative position and orientation information. It is preferable. In this case, for example, when the rotating part is the entire foot part and the rotating shaft for rotating the entire foot part is provided at the ankle joint of the leg part, the tip of the foot part (toe) The floor surface of the rotating part (ankle part) in which the foot part rotates relative to the leg part, regardless of which of the part) and the rear end part (the heel part) comes into contact with the floor surface first It is possible to accurately determine the height from.

  As described above, according to the present invention, when a walking motion is performed, the contact between the foot and the floor surface is detected without using a contact-type sensor or the like on the foot, and a stable walking motion is achieved. It becomes possible to do.

Embodiment 1 of the Invention
A legged mobile robot (hereinafter simply referred to as a robot) according to a first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a schematic diagram schematically showing the robot 1 as viewed from the front, and shows the robot 1 walking on the floor F. FIG. In FIG. 1, for convenience of explanation, the direction in which the robot 1 travels (front-rear direction) is the x-axis, and the direction perpendicular to the horizontal direction (left-right direction) is the y-axis with respect to the direction in which the robot 1 travels. The direction (vertical direction) extending in the vertical direction from the plane to be performed is defined as the z axis, and a description will be made using a coordinate system composed of these three axes. That is, in FIG. 1, the x-axis indicates the depth direction of the paper surface, the y-axis indicates the left-right direction toward the paper surface, and the z-axis indicates the vertical direction in the paper surface.

  As shown in FIG. 1, the robot 1 has a head 2, a trunk 3, a waist 4 coupled to the trunk 3, a right arm 5, a left arm 6, and a waist 4 connected to the trunk 3. A legged mobile robot (hereinafter simply referred to as a robot). Details will be described below.

  The head 2 includes a pair of left and right imaging units 2 a and 2 b for visually capturing an environment around the robot 1, and the head 2 is rotated around an axis parallel to the trunk 3 in the vertical direction. The surrounding environment is widely imaged by rotating the lens to the right. Image data indicating the captured surrounding environment is transmitted to the control unit 130 described later, and is used as information for determining the operation of the robot 1.

  The trunk 3 houses therein a control unit 130 that controls the operation of the robot 1, a battery (not shown) for supplying power to a leg motor and the like. As shown in FIG. 2, the control unit 130 drives the leg unit 10 and stores a gait data for moving the robot 1, etc., and a storage area 131 as a storage unit, and the steps stored in the storage area 131. An arithmetic processing unit 132 that reads the condition data and a motor driving unit 133 that drives a motor included in the leg unit 10 are provided. Each of these components operates by being supplied with electric power from a battery (not shown) provided inside the trunk 3.

  The arithmetic processing unit 132 reads the gait data stored in the storage area 131 and calculates the joint angle of the leg 10 necessary to realize the posture of the robot 1 specified by the read gait data. To do. The gait data is associated with the amount of movement of the leg 10 specified by the signal sent from the operation unit 113, and the position of the tip (toe) of the foot (right foot 26, left foot 36) of the leg 10 is detected. And the position of the mobile body (the placement unit 11 in the present embodiment) are indicated over time in a coordinate system (for example, an xyz coordinate system) that defines a space in which the robot 1 moves. Then, a signal based on the joint angle calculated in this way is transmitted to the motor driving unit 133. As will be described later, the arithmetic processing unit 132 is configured to calculate the shape information such as the length, width, and thickness of the foot portion provided in the leg portion 10 and the relative position and orientation information as relative position and posture information with respect to the leg portion of the foot portion. Based on the degree of inclination, based on the calculated height information, a height calculation unit that calculates height information from the pivot part to the foot of the foot part to the lowest point of the foot part, It also functions as a driving amount correction unit that corrects the driving amount of the leg in the height direction based on the gait data. Details of the operation of the arithmetic processing unit 132 will be described later.

  Based on the signal transmitted from the arithmetic processing unit 132, the motor drive unit 133 specifies the drive amount of each motor for driving the leg portion, and outputs a motor drive signal for driving the motor with these drive amounts. Send to each motor. As a result, the driving amount at each joint of the leg 10 is changed, and the movement of the robot 1 is controlled.

  The arithmetic processing unit 132 instructs the motor to be driven based on the read gait data, and receives a signal from a sensor (not shown) such as a gyroscope or an accelerometer built in the robot 1. Adjust the drive amount of the motor. Thus, the robot 1 can be maintained in a stable state by adjusting the joint angle of the leg 10 according to the external force acting on the robot 1 detected by the sensor, the posture of the robot 1, and the like.

  The right arm 5 and the left arm 6 are pivotally connected to the trunk 3, and perform the same movement as a human arm portion by driving joint portions provided at the elbow portion and the wrist portion. Can do. Further, the hand part connected to the tip of the wrist part has a hand structure for gripping an object (not shown), and by driving a plurality of finger joints incorporated in the hand structure, various kinds of parts are provided. It becomes possible to grip an object having a shape.

  The lumbar part 4 is connected to the trunk 3 so as to rotate, and the driving energy necessary for driving the leg part 10 can be obtained by combining the rotational action of the lumbar part 4 when performing a walking action. Can be reduced.

  A leg 10 (right leg 20 and left leg 30) for bipedal walking is composed of a right leg 20 and a left leg 30. Specifically, as shown in FIG. 21, the right leg 20 includes a right hip joint 21, an upper right thigh 22, a right knee joint 23, a right lower leg 24, a right ankle joint 25, and a right foot 26. The right foot 26 is pivotally connected to the right ankle joint at the tip of the right leg 20. Similarly, the left leg 30 includes a left hip joint 31, a left upper thigh 32, a left knee joint 33, a left lower thigh 34, a left ankle joint 35, and a left foot 36, and the left foot 36 rotates around a rotation axis included in the left ankle joint. Connected movably. That is, in the right leg and the left leg, the rotation shaft included in each ankle joint acts as a rotation part for rotating each foot part.

  In this embodiment, when the leg 10 (the right leg 20 and the left leg 30) lifts the lower leg to the front side around the knee joint, the upper leg and the lower leg are placed rearward like a human leg. It is in an open state (a state where the lower leg rotates around the knee joint on the rear side of the extension line of the upper leg). In addition, as described above, the driving amount and the driving angular velocity of each joint of the leg 10 are controlled by a motor (not shown) based on the signal transmitted from the motor driving unit 133.

  In the storage area 131 described above, gait data for the robot 1 to perform a walking motion, shape information of the foot portions (the right foot 26 and the left foot 36), and the like are stored. The shape information of such a foot part (right foot 26, left foot 36) is the length of each foot part in the front-rear direction (the length from the toe to the buttocks) and the thickness of each foot part. Necessary information about the shape, such as the distance from the bottom surface to the top surface when in surface contact with the floor, and the length in the left-right direction (the direction perpendicular to the length direction in the plane of the foot) It is what you point to. It should be noted that it is possible to appropriately change which information among such information is stored according to the structural features and form of the robot.

  Next, the structure of the foot portions (the right foot 26 and the left foot 36) provided in the leg portion 10 will be described in detail with reference to FIG. Since the right foot 26 and the left foot 36 have the same symmetrical structure, only the detailed structure of the right foot 26 will be described here, and the description of the left foot 36 will be omitted. . FIG. 3 is a side view showing the right foot 26 as seen from the side (right side).

  As shown in FIG. 3, the right foot 26 is constituted by a substantially flat plate member extending in the horizontal direction connected to the right ankle joint 25 connected to the right lower leg 24 via a rotation shaft 25 a. ing. The right foot 26 includes a rear end portion 261b that first comes into contact with the floor surface when the bottom surface 26a switches from a free leg to a standing leg during walking. The rear end 261b is formed to extend in the left-right direction at the rear end of the bottom surface 26a of the right foot 26, and is made of a material such as a slightly elastic resin. Then, when the robot 1 performs a walking motion on the floor surface F, an appropriate elastic force is applied to the right foot 26 when contacting the floor surface, and a part of the impact when contacting the floor surface is absorbed. For convenience of explanation, the rear end portion 261b is described so as to protrude from the bottom surface 26a of the right foot 26. However, in actuality, only a very small amount protrudes from the bottom surface 26a of the right foot, and It is configured to be deformed by the elastic force so as not to prevent the bottom surface 26a of the right foot 26 from being in surface contact with the floor surface.

  The front end of the right foot 26 is provided with a sliding portion 262a having a substantially curved cross section when viewed from the side at the front end of the bottom surface 26a. The frictional force generated between the floor and the floor is reduced. For convenience of explanation, the sliding portion 262a is shown protruding from the bottom surface 26a of the right foot 26, but actually only a very small amount protrudes from the bottom surface of the right foot 26, and the bottom surface 26a of the right foot 26 is the floor. It is comprised so that the state which surface-contacts with respect to a surface may not be prevented.

  The right leg 20 includes an encoder (not shown) as a measurement unit that measures an angular velocity at which the right foot 26 rotates around a rotation shaft 25 a provided at the right ankle joint 25. For this encoder, for example, a general-purpose device such as a tachometer can be adopted, and the measurement value obtained by measuring the angular velocity of the right foot 26 that is output from these encoders is transmitted to the arithmetic processing unit 132 described above. Is done. Then, the arithmetic processing unit 132 obtains the degree of inclination relative to the leg part of the right foot from the transmitted angular velocity information of the right foot, and from this degree of inclination, the right leg (right ankle joint) is obtained. Height information from the pivot shaft 25a to the lowest point of the foot 26 is calculated. Then, based on the calculated height information, the amount of driving in the height direction of the leg determined based on the gait data so that the bottom surface of the right foot contacts without receiving a large reaction force from the floor surface F. And the leg is driven based on the corrected driving amount. The driving of the leg is obtained as a result of the driving force from a motor (not shown) being transmitted through a pulley and a belt (not shown) so that each joint operates at a desired angle. Details of these controls will be described later.

  For the drive control of the right foot 26 at the right ankle joint 25, control for applying friction compensation torque is used. That is, the motor that drives the right foot 26 is controlled so that torque corresponding to the drive amount (rotation angular velocity) of the rotation shaft 25a of the right ankle joint 25 is supplied to the right foot 26. Such a friction compensation torque τ is set as shown in the following equation 1, for example, where θ is the rotation angle of the right foot from the initial state. By controlling the supply of torque for driving the right foot in this way, the amount of impact transmitted to the leg when the right foot 26 comes into contact with the floor surface F due to friction on the rotation shaft 25a of the right foot 26 is suppressed. Is done.

  As described above, the arithmetic processing unit 132 according to the present embodiment calculates the angular velocity at which the foot portion rotates based on the angular velocity of the right foot 26 (foot portion) output from the encoder, and the leg portion. It acts as a relative position and orientation detection unit that detects a relative inclination degree (relative position and orientation).

  Then, the arithmetic processing unit 132 determines the right foot 26 based on the shape information of the right foot 26 stored in the storage area 131 serving as a storage unit and the degree of relative inclination (relative position and orientation information) with respect to the leg. It acts as a height calculation unit that calculates height information from the rotation axis 25a (rotation unit) to the right leg 20 to the lowest point of the right foot 26. Hereinafter, the case where the height information from the rotating part of the foot part to the lowest point of the foot part when the right foot comes in contact with the floor surface F will be described with reference to FIGS. 4 and 5.

  As shown in FIG. 4, first, the robot 1 moves the right foot 26 of the leg portion (right leg 20) in a free leg state to a predetermined posture (in this embodiment, the front end of the bottom surface 26a of the foot 26). It is brought close to contact with the floor surface F in a state (tilted so that the back surface of the toe is positioned most vertically downward). At this time, the amount of rotation about the rotation axis 25a of the right ankle joint 25 that determines the posture of the right foot 26, that is, the relative posture of the right foot 26 with respect to the right leg 20 is determined by predetermined gait data. It is determined based on.

  Next, FIG. 5 shows a state in which the front end of the bottom surface 26a located at the lowest point of the right foot 26 approaching the floor surface F in such a posture comes into contact with the floor surface F. As shown in FIG. 5, when the front end of the bottom surface 26a comes into contact with the floor surface F, the entire right foot 26 moves in the direction in which the rear end of the bottom surface 26a moves vertically downward with the grounded front end as a fulcrum. It rotates around 25a. At this time, the encoder provided in the right foot 26 measures the angular velocity rotating with respect to the leg portion of the right foot 26, and transmits the measured value to the arithmetic processing unit 132. The arithmetic processing unit 132 obtains the angular velocity at which the right foot rotates from the measurement value transmitted from the encoder, and when the value of the angular velocity exceeds a predetermined threshold stored in the storage area, the right foot 26 It is determined that the floor surface F has been touched. The height from the floor surface F of the ankle joint 25 of the right foot 26 at the time of contact with the floor surface is obtained by the following procedure.

FIG. 6 is a side view schematically showing the right foot 26 shown in FIGS. 4 and 5. As shown in FIG. 6, the height from the floor surface F to the rotation shaft 25 a of the right ankle joint 25 when the front end of the right foot 26 contacts the floor surface F is h. The length of the foot portion from the front end of the right foot 26 to the rotation shaft 25a is a, and the height from the bottom surface of the right foot 26 to the rotation shaft 25a is b. The length “a” and the height “b” of the foot are specified by the foot shape information stored in the storage unit in advance. Furthermore, when viewed from the side, the degree of inclination (inclination angle) from the right ankle joint 25 of the right lower leg 24 from the vertical direction is θ ₁ , and the degree of inclination of the straight line extending vertically from the upper surface of the right foot 26 from the right lower leg 24 ( When the inclination angle) and theta _2, the arithmetic processing unit 132 can be calculated by the measurement value transmitted a tilt angle from the encoder as described above.

  Then, the height h from the floor surface F to the pivot shaft 25a of the right ankle joint 25 when the front end of the bottom surface 26a of the right foot 26 contacts the floor surface F is calculated based on the following formula 2.

  In the present embodiment, the height h is determined when the front end of the foot is grounded to the floor surface F. However, the present invention is not limited to this, and the grounding from the heel member to the floor surface is performed. Even in this case, the height of the right ankle joint 25 from the floor surface F can be obtained in the same manner. In the above-described embodiment, the rotation axis 25a of the right ankle joint 25 is a single axis extending in the left-right direction of the right foot 26. However, the rotation axis 25a of the right ankle joint 25 is the other direction. It may be a case with other rotating shafts extending in the direction. For example, when the right foot is configured to be turnable in the left-right direction with respect to a turning shaft extending in the front-rear direction of the right foot 26, the ankle portion when either of the right and left ends of the right foot touches the floor F You can also ask for the height. As described above, when the right foot is configured to be rotatable with respect to the plurality of rotation shafts, in which direction the right foot is rotated with respect to the plurality of rotation shafts (that is, the direction in which the right foot is rotated and the direction of the rotation). By detecting the angular velocity of rotation, it is possible to determine the location of the bottom surface of the foot that is in contact with the floor surface.

  The arithmetic processing unit 132 also calculates the driving amount of the leg in the height direction based on the gait data based on the calculated height information from the rotation axis 25a of the right ankle joint to the lowest point of the right foot 26. A drive amount correction unit for correcting When the robot 1 walks on the floor F, calculating height information from the rotation shaft 25a (rotation unit) of the right foot 26 to the right leg 20 to the lowest point of the right foot 26; A procedure for correcting the driving amount of the right leg in the height direction based on the gait data will be described in detail with reference to FIGS.

First, when the robot 1 is moving by walking motion, the target height of the pivot shaft 25a of the right ankle joint determined based on the gait data is h _ref , and the bottom surface of the right foot 26 is the floor. The state which contacted the surface F is represented. The height of the ankle portion when the bottom surface of the right foot 26 contacts the floor surface F is _{defined as hmes} . FIG. 7 shows a state in which the bottom surface of the right foot 26 is in contact with the floor surface F earlier than expected in the walking motion determined based on the gait data. In this case, the arithmetic processing unit 132 calculates the height h _mes of the ankle when the bottom surface of the right foot 26 contacts the floor surface F based on the position and posture of the right foot as described above, and the right leg ankle A correction amount (Δh = h _ref −h _mes ) for the current position in the height direction of the part is obtained. Then, based on this correction amount, the driving amount of each joint in the leg portion for bringing the next right foot portion close to the floor surface is determined, and an operation of switching the right leg, which is a free leg, to the standing leg is performed.

Similarly, when the right foot 26 does not contact the floor at the planned height in the walking motion determined based on the gait data, as shown in FIG. The right foot 26 is moved downward in the height direction until the bottom surface of 26 comes into contact with the floor surface F. When the bottom surface of the right foot 26 comes into contact with the floor surface F, the height h _mes of the ankle when the bottom surface of the right foot 26 contacts the floor surface F is calculated based on the position and orientation of the right foot 26 at that time. Then, a correction amount (Δh = h _mes −h _ref ) for the current position in the height direction of the ankle portion of the right leg is obtained. Then, based on this correction amount, the driving amount of each joint in the leg portion for bringing the next right foot portion close to the floor surface is determined, and an operation of switching the right leg, which is a free leg, to the standing leg is performed.

  In the robot 1 configured as described above, a part of the foot part comes into contact with the floor surface by obtaining the actual height of the ankle part before the bottom surface of the foot part comes into contact with the floor surface. The difference (error) between the target height and the actual height can be detected without using a sensor or the like. And based on the detected error in the height direction, by driving each joint in the leg in the direction that the difference becomes smaller, the impact received from the floor via the foot is suppressed, and stable walking is performed. The effect that it becomes possible to obtain is obtained.

  The description so far relates to the structure, operation and control of the right foot and right ankle joint provided in the right leg, but the same structure applies to the left foot and left ankle joint provided in the left leg. It is assumed that operation and control are provided.

  Next, walking control when the legged mobile robot configured as described above performs a walking motion will be described with reference to the flowchart shown in FIG.

First, the robot 1 drives the right leg and the left leg based on the stored gait data, but moves the leg on the free leg side toward the floor surface F (STEP 101). Then, from the amount of rotation of each joint, the shape of each link (upper thigh, lower thigh, etc.) and each joint (hip joint, knee joint, ankle joint, etc.), etc., the height h _ref of the rotation axis at the ankle joint on the free leg side Is estimated (STEP 102). The estimated height of the rotating shaft is stored in the storage area.

  Then, when the gait data is stored, the drive torque at the ankle joint on the free leg side is reduced when the free leg is in front of the floor F for a predetermined time (or a predetermined distance) (STEP 103). The timing for reducing the drive torque is preferably performed at a time sufficiently away from the floor surface. For example, the drive torque may be continuously reduced while the leg portion is a free leg. At this time, as described above, since the friction compensation torque acts on the rotation shaft that connects the foot portion and the ankle joint, the posture of the foot portion does not change even if the driving torque is reduced. No.

  Further, when the foot portion is made to approach the floor surface in this way, an angular velocity that rotates around the rotation axis of the foot portion is detected by the encoder (STEP 104). When it is detected that the angular velocity detected by the encoder is equal to or greater than a predetermined threshold (STEP 105), the posture of the foot portion at that time is estimated by a method such as integrating the detection value from the encoder (STEP 106). ).

Then, the lowest point of the foot is identified from the identified posture of the foot (STEP 107), and the actual height h _mes of the rotation axis of the ankle joint is calculated in the manner described above (STEP 108). Then, the height h _ref of the rotating shaft estimated in STEP 102 is compared with the actual height h _mes, and the amount (drive amount in the height direction) for driving each joint of the free leg is corrected based on the difference. (STEP 109), the free leg is driven based on the corrected driving amount, and the bottom surface of the foot is brought into contact with the floor F (STEP 110). In this way, by correcting the driving amount of the free leg based on the height information from the floor surface obtained when a part of the foot portion contacts the floor surface, the foot portion contacts the floor surface. It is possible to reduce the impact received.

  In the present embodiment, the case has been described where the height information of the leg portion is obtained using the rotational movement of the foot portion in the front-rear direction, but the present invention is not limited to this and the foot portion is not limited thereto. You may use the rotation motion about the left-right direction of a part, or you may use both the motion which rotates these front-back directions and left-right directions together. In this way, it is possible to determine where the foot portion contacts the floor surface, so even if the floor surface is uneven, a special sensor or the like is not provided on the foot portion. The effect that the floor surface shape can be estimated is obtained.

  In the present embodiment, the torque for driving the foot is reduced immediately before the free leg comes into contact with the floor (or during the free leg state). The present invention is not limited to the one that complies with the friction compensation torque as described above. That is, the foot part keeps its posture substantially constant, and when the foot part contacts the floor surface, the foot part rotates without transmitting excessive shock from the foot part to the leg part. What is necessary is just to be comprised so that the torque of the magnitude | size to perform may be provided.

  Further, in the present embodiment, when the value of the angular velocity at which the foot part rotates exceeds a predetermined threshold value, it is determined that the right foot is in contact with the floor surface. However, the present invention is not limited to this. It is not something that can be done. For example, when the foot part rotates more than a predetermined angle, it may be determined that the foot part is in contact with the floor surface.

Embodiment 2 of the Invention
Next, a second embodiment according to the present invention will be described with reference to FIGS. The legged mobile robot (robot 1 ′) in the present embodiment has the same or similar configuration as the main configuration of the legged mobile robot described in the first embodiment. Are denoted by the same reference numerals and the description thereof will be omitted.

  In FIG. 10, the structure of the right foot 26 ′ is schematically shown in order to describe the structure of the foot portions (the right foot 26 and the left foot 36) provided in the leg portion 10. Since the right foot and the left foot have the same symmetrical structure, only the detailed structure of the right foot will be described in this embodiment, and the description of the left foot will be omitted. 10 is a side view showing a state where the right foot 26 'is viewed from the side (right side), and FIG. 11 is a schematic view showing a state where the right foot 26' is viewed from above. To do.

  As shown in FIGS. 10 and 11, the right foot 26 ′ is a substantially plate-like heel extending in the horizontal direction connected to the right ankle joint 25 connected to the right lower leg 24 via a rotation shaft 25 a. A member 261 and a substantially plate-like toe member 262 are provided. The saddle member 261 includes a rear end portion 261b that first contacts the floor surface when the bottom surface 261a switches from a free leg to a standing leg during walking. The rear end 261b is formed to extend in the left-right direction (y direction) at the rear end of the bottom surface 261a of the flange member 261, and is made of a material such as a slightly elastic resin. Then, when the robot 1 performs a walking motion on the floor surface F, an appropriate elastic force is applied to the eaves member 261 when contacting the floor surface, and a part of the impact when contacting the floor surface is absorbed. For convenience of explanation, the rear end portion 261b is described so as to protrude from the bottom surface 261a of the flange member 261. However, in reality, only a very small amount protrudes from the bottom surface 261a of the flange member 261. The elastic member is deformed by the elastic force so that the bottom surface 261a of the flange member 261 does not interfere with the surface contact with the floor surface.

  A protrusion 261c provided with a rotation axis P is formed at the tip of the collar member 261 so as to extend in the y direction in FIG. The toe member 262 is configured to be rotatable upward from a horizontal state with respect to the convex portion 261c. And although illustration is abbreviate | omitted, the motor which rotates the toe member 262 around the rotating shaft P and the encoder as a measurement part for detecting the angular velocity which rotates are provided.

  The toe member 262 is provided with a sliding portion 262a having a substantially curved cross section when viewed from the side at the front end bottom surface. When the toe member 262 comes into contact with the floor surface, the contact area is reduced. The frictional force generated between them is suppressed. For convenience of explanation, the sliding portion 262a is shown protruding from the bottom surface of the toe member 262, but actually only a very small amount protrudes from the bottom surface of the toe member 262. It is comprised so that the state which carries out surface contact may not be prevented.

  Further, a concave portion 262b that engages with the convex portion 261c of the above-described collar member is provided at a substantially central portion of the rear end of the toe member 262, and the above-described rotation shaft P is provided on the inner surface of the concave portion 262b. It is fixed. The toe member 262 rotates in accordance with the movement of the rotation shaft P rotated by the motor described above, and changes its posture. Thus, in the present embodiment, the toe member 262 that is a part of the right foot 26 acts as a rotating portion that rotates around the rotation axis P.

  In the present embodiment, the torque output of the motor is controlled so that the above-mentioned friction compensation torque is applied in a direction in which the front end of the toe member 262 is changed in the vertical direction around the rotation axis P. The details of the control for applying the friction compensation torque have been described in the above-described embodiment, and thus detailed description thereof is omitted here.

  The right foot includes an encoder (not shown) as a measurement unit that measures an angular velocity at which the toe member 262 rotates about the rotation axis P, and the angular velocity output from these encoders. The measurement value is transmitted to the arithmetic processing unit 132 described above. Then, the arithmetic processing unit 132 obtains a relative inclination degree with respect to the leg portion of the toe member 262 from the transmitted angular velocity information of the toe member 262 flat, and the right leg (right ankle) from the inclination degree. The height information from the rotation axis 25a of the joint) to the lowest point of the foot is calculated. Then, gait data is used so that the bottom surface of the right foot 26 comes into contact with the floor surface F without receiving a large reaction force based on the calculated height information using the method described in the above-described embodiment. The driving amount in the height direction of the leg determined based on the correction is corrected, and the leg is driven based on the corrected driving amount.

  In the present embodiment, the motor that outputs torque to the toe member and the motor control unit may be provided inside the foot part or inside the leg part such as the lower leg. In particular, because the foot part is subjected to a lot of impact and the number of impacts caused by walking motion, if it is installed in a place other than the foot portion, the possibility of failure of these components due to impact received by walking motion, etc. is reduced. Can do.

  As described above, also in the present embodiment, the arithmetic processing unit 132 calculates the angular velocity at which the foot portion rotates based on the angular velocity of the toe member 262 (rotating portion) output from the encoder, Acts as a relative position and orientation detection unit that detects a relative inclination degree (relative position and orientation) with respect to the leg.

  And the arithmetic processing part 132 is based on the shape information of the right foot 26 (toe member 262) memorize | stored in the said memory | storage area | region 131 as a memory | storage part, and the relative inclination degree (relative position and orientation information) with respect to a leg part. Thus, it acts as a height calculation unit that calculates height information from the rotation axis P of the toe member 262 to the right leg 20 to the lowest point of the toe member 262. Hereinafter, the case where the height information from the lowest point of the toe member (rotating part) to the pivot axis P point when the right foot contacts the floor surface F will be described with reference to FIGS. 12 and 14. To do.

  As shown in FIG. 12, first, the robot 1 moves the right foot 26 of the leg portion (the right leg 20) in the free leg state to a predetermined posture (in this embodiment, the toe member 262 of the foot 26). The front end is inclined so as to be located at the lowest vertical position, and the toe member 262 and the heel member 261 are brought into contact with each other toward the floor surface F in a state where the bottom surfaces thereof are substantially identical. At this time, the amount of rotation of the ankle joint 25 about the rotation axis 25a that determines the posture of the right foot 26, that is, the relative posture of the right foot 26 with respect to the right leg is based on predetermined gait data. It has been established.

  Next, FIG. 13 shows a state where the front end of the toe member located at the lowest point of the right foot 26 approaching the floor surface F in such a posture is in contact with the floor surface. As shown in FIG. 13, when the front end of the toe member 262 contacts the floor surface F, the entire right foot 26 is centered on the rotation shaft 25a so that the entire right foot 26 moves vertically downward with the front end as a fulcrum. As it begins to rotate. At this time, the encoder provided in the right foot measures the angular velocity rotating with respect to the leg portion of the right foot 26 and transmits the measured value to the arithmetic processing unit 132. The arithmetic processing unit 132 determines that the right foot 26 is in contact with the floor surface F when the measured value transmitted from the encoder exceeds a predetermined threshold, and the floor surface F of the rotating shaft P at the time of the contact is determined. Calculate the height from. As a method for calculating the height, a geometric calculation method such as that used in the above-described embodiment or other methods may be used.

  Then, as shown in FIG. 14, the toe member 262 rotates around the rotation axis P until the bottom surface of the toe member 262 becomes substantially horizontal with the floor surface and comes into surface contact. A slight torque may be applied to the toe member 262 by a motor in a direction opposite to the rotation operation so as to buffer an impact generated when the toe member 262 contacts the floor surface. In the present embodiment, the height of the leg from the actual floor surface is calculated based on the degree of rotation of the toe member (that is, the relative position and orientation of the toe member with respect to the leg), and the drive amount of the leg is calculated. Description of the control step for correction is omitted. The description in this embodiment relates to the structure, operation and control of the right foot and right ankle joint provided in the right leg, but the same applies to the left foot and left ankle joint provided in the left leg. Needless to say, structure, operation and control are provided.

  In the present embodiment, the initial state is a state in which the bottom surface of the toe member and the bottom surface of the heel member are substantially the same surface, but the present invention is not limited to this. That is, as shown in FIG. 15, the initial state may be a state in which the front end of the toe member is slightly inclined downward in the vertical direction. Then, the relative position and posture of the toe member may be obtained by detecting the amount of rotation of the toe member so that the bottom surface of the toe member and the bottom surface of the heel member are substantially flush with each other. . In such a case, the toe member is grounded on the floor surface, and the toe member can rotate freely on the bottom surface of the toe member so that the toe member moves smoothly on the floor surface until the foot makes surface contact with the floor surface. A roller may be provided. In such a configuration, after the foot comes into surface contact with the floor surface, the roller is fixed so that the toe member does not slip on the floor surface when the foot is stepped on from the floor surface on the back surface of the foot. It is preferable to do.

  In the above-described embodiment, an example is shown in which a motor is used as means for applying torque until the toe member comes into surface contact. Instead, for example, an external force is applied as shown in FIG. The toe member using a leaf spring S having one end fixed to a rotation shaft P provided integrally with the heel member so that the toe member can assume a substantially constant posture with respect to the heel member in a state where the toe member is not Alternatively, a torque against the floor surface may be applied. As a result, when an external force is applied in the direction of rotation via the leaf spring S or the like, a substantially constant elastic force is applied as a reaction force, and when the external force disappears, the toe member can return to the original posture. .

  As described above, the legged mobile robot according to the present invention detects the contact between the foot and the floor surface without using a contact sensor or the like for the foot when performing a walking motion. And stable walking motion.

  In the embodiment described above, a biped walking robot is used as an example of a so-called legged mobile robot, but the present invention is not limited to this. That is, the present invention can also be applied to other legged mobile robots such as four-legged walking.

  Such a legged mobile robot may be a so-called boarding robot that moves with a human being as an operator. When the present invention is applied to such a robot, the impact received by the robot from the floor surface is reduced, so that the impact received by the person on board is reduced, and the ride comfort is improved.

  In addition, the leg structure of such a legged mobile robot is not the same as that of a human, but the upper and lower legs are open toward the front side (frontward from the extension line of the upper leg). On the side, a state in which the lower leg rotates around the knee joint), a so-called “bird leg state”, may be adopted. By configuring the leg portion in this way, when configuring a robot in the form of boarding a human as described above, even if the rider bends the knee joint of the leg portion to get on and off the placing portion, Since the lower leg and the lower leg are located behind the placing portion, the bent leg portion does not come into contact with the placing portion that descends. Therefore, the mounting portion can be sufficiently lowered to a position where the passenger can easily get on and off.

1 is an overall schematic view schematically showing the whole legged mobile robot according to a first embodiment of the present invention. FIG. 2 is a block diagram conceptually showing the inside of a control unit provided inside the legged mobile robot shown in FIG. 1. It is a side view which shows roughly the structure of the foot (right foot) part with which the leg part of the leg type mobile robot shown in FIG. FIG. 2 is a side view schematically showing a state in which the right leg of the legged mobile robot shown in FIG. 1 is in a free leg state and the right foot approaches the floor surface. FIG. 5 is a side view schematically showing a state in which a right foot tip of a right leg of the legged mobile robot shown in FIG. 4 is in contact with a floor surface. FIG. 6 is a side view shown for geometrically calculating the height between the pivot axis of the ankle joint and the floor surface in a state where the right foot of the legged mobile robot is in contact with the floor surface. FIG. 6 is a side view schematically showing a state where the right foot of the legged mobile robot is in contact with the floor surface earlier than estimated from the gait data. It is a side view which shows roughly the state where the right foot of the legged mobile robot contacted the floor surface later than estimated from the gait data. It is a flowchart which shows the flow which correct | amends about the drive amount of a height direction in the walk control at the time of the leg-type mobile robot shown in FIG. 1 performing a walk operation. It is a side view which shows roughly the structure of the right foot with which the leg part of the leg type mobile robot which concerns on 2nd Embodiment was equipped by side view. FIG. 5 is a top view schematically showing a structure of a right foot provided in a leg portion of the legged mobile robot shown in FIG. 4 in a top view. FIG. 12 is a side view schematically showing how the right foot of the legged mobile robot shown in FIGS. 10 and 11 approaches the floor surface. FIG. 13 is a side view schematically showing a state where the tip of the right foot of the legged mobile robot shown in FIG. 12 is in contact with the floor surface. FIG. 14 is a side view schematically showing a state in which the right foot tip of the legged mobile robot shown in FIG. 13 rotates after contacting the floor surface. It is a side view showing roughly other embodiments of a foot part of a legged mobile robot concerning the present invention. It is a side view explaining the detailed structure of the foot part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Leg type mobile robot 10 ... Leg part 130 ... Control part 131 ... Storage area (storage part)
132... Arithmetic processing unit (relative position and orientation detection unit, height detection unit, drive amount correction unit)
133: Motor drive unit 25: Ankle joint (right ankle joint)
25a: Rotating shaft 26, 26 '... Foot part (right foot)
26a ... bottom surface 261 ... heel member 262 ... toe member F ... floor surface

Claims (14)

A legged mobile robot that includes a leg portion that connects a foot portion that contacts a floor surface during walking, and that performs a walking motion by driving the leg portion based on gait data,
A rotation portion that is at least a part of the foot portion and is configured to be rotatable around a rotation axis with respect to the leg portion; and
A storage unit for storing shape information of the rotating unit;
A relative position and orientation detection unit that detects relative position and orientation information with respect to the legs of the rotating unit;
A height calculation unit that calculates height information from the rotation axis to the lowest point of the foot, based on the shape information of the rotation unit and the relative position and orientation information;
It is determined based on the gait data when the front end of the foot part contacts the floor surface with respect to the height information calculated by the height calculation unit when the front end of the foot part contacts the floor surface. A driving amount correction unit that calculates an error in height information targeted by the rotation axis and corrects the driving amount in the height direction of the leg based on the gait data in a direction in which the error is reduced ; A legged mobile robot characterized by comprising:   The leg-type movement according to claim 1, wherein the turning portion is the entire foot portion, and a turning shaft for turning the entire foot portion is provided at the ankle joint of the leg portion. Type robot.   The legged mobile robot according to claim 1, wherein the relative position and orientation information is a relative inclination degree with respect to the leg portion.   The rotation unit further includes a measurement unit that measures an angular velocity at which the rotation unit rotates with respect to the leg unit, and when the angular velocity measured by the measurement unit exceeds a predetermined threshold, the driving amount in the height direction of the leg unit The legged mobile robot according to any one of claims 1 to 3, wherein:   A torque control unit for controlling a torque supplied to the rotation unit when the rotation unit rotates with respect to the leg unit, the torque control unit being in a state in which the rotation unit is separated from the floor surface The legged mobile robot according to claim 4, wherein a torque having a magnitude proportional to an angular velocity measured by the measuring unit is supplied to the rotating unit.   The torque control unit supplies a larger torque to the rotating unit when the rotating unit is separated from the floor surface than when the rotating unit is grounded to the floor surface. 5. A legged mobile robot according to 5.   The torque control unit is configured so that the rotation unit has a size that allows the rotation unit to rotate almost freely with respect to the leg portion immediately before the rotation unit is determined to contact the floor surface. The legged mobile robot according to claim 5, wherein the magnitude of torque supplied to the robot is reduced. A leg part that rotatably connects a foot part that contacts the floor surface during walking is provided, and is at least a part of the foot part, and is configured to be rotatable about a rotation axis with respect to the leg part. A walking control method for a legged mobile robot that includes a rotating unit and performs a walking motion by driving the leg based on gait data,
Detecting the relative position and orientation of the rotating unit with respect to the leg before contacting the rotating unit with the floor surface;
Calculating the height from the pivot axis to the lowest point of the foot part based on the shape information of the pivot part stored in advance and the detected relative position and orientation of the pivot part;
The rotation axis defined based on the gait data when the front end of the foot part contacts the floor surface with respect to height information calculated when the front end of the foot part contacts the floor surface. Calculating the target height information error, and correcting the driving amount of the leg in the height direction based on the gait data in a direction in which the error becomes smaller ;
And a step of driving the leg based on the corrected driving amount. A walking control method for a legged mobile robot, comprising:   9. The leg-type movement according to claim 8, wherein the turning portion is the entire foot portion, and a turning shaft for turning the entire foot portion is provided at the ankle joint of the leg portion. Type robot walking control method.   10. The walking control method for a legged mobile robot according to claim 8, wherein the detected relative position and orientation is a degree of relative inclination with respect to the leg of the rotating unit.   The method further includes a step of measuring an angular velocity at which the rotating portion rotates with respect to the leg portion, and correcting the driving amount in the height direction of the leg portion when the measured angular velocity exceeds a predetermined threshold value. The walking control method for a legged mobile robot according to claim 8, wherein the walking control method is for a legged mobile robot.   12. The method according to claim 11, further comprising: supplying a torque having a magnitude proportional to the measured angular velocity of the rotating unit to the rotating unit in a state where the rotating unit is separated from the floor surface. Control method for legged mobile robots.   The magnitude of the torque to be supplied so that smaller torque is supplied to the legs of the rotating unit when the rotating unit is separated from the floor surface than when the rotating unit is in contact with the floor surface. The walking control method for a legged mobile robot according to any one of claims 8 to 12, further comprising a step of controlling the height.   Immediately before it is determined that the rotating part comes into contact with the floor surface, the torque supplied to the rotating part is adjusted so that the rotating part can rotate freely with respect to the leg part. The walking control method for a legged mobile robot according to any one of claims 8 to 13, further comprising a step of reducing the size.

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