JP3864370B2 - Joint braking device for walking robot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joint device of a robot, and in particular, when the robot keeps a stationary posture, or when the motion direction of the joint coincides with the direction in which gravity acts even during motion, the braking force controlled by the joint is controlled. It is related with the joint braking device of the robot which can generate | occur | produce and hold | maintain an attitude | position or can save the energy required for the exercise | movement.
[0002]
[Prior art]
A legged mobile robot with multiple joints has an animal-like feature that consumes a lot of energy to support its weight even when it is stationary. This feature is a major disadvantage compared to not consuming energy while a wheeled mobile robot is stationary, but it has the advantage of a leg type that can move even if there are steps or steps, but it impedes its practical use It is one of the causes. In the first place, since a stationary robot has no external work, it is not necessary to consume these energies, and some improvement was required.
[0003]
Furthermore, even a robot whose moving means is a wheel has an arm made up of a plurality of joints on the upper body, and the same thing can be said when the arm holds a thing and keeps the arm in a predetermined posture against gravity. stay up. In other words, whether the moving means is a legged type or a wheeled type, the conventional technology consumes unnecessary energy as long as the robot maintains the same posture, and some improvement has been required.
[0004]
Considering the case where the legged robot is going down the stairs, the leg joint on the ground moves in the direction in which gravity acts while supporting the weight. It is rotating in the opposite direction while generating resisting torque. If you think physically, an object placed in the gravitational field releases potential energy when it moves in the direction of gravity, so you can recover potential energy in the form of power generation instead of using energy. It is a spear. However, in order to recover by power generation, this method cannot be used unless the rotation speed is sufficiently high, in other words, when the stairs are run down at a considerable speed. In the prior art, the same amount of energy was consumed when going up and down the stairs.
[0005]
The situation is exactly the same for industrial robots fixed to the ground. That is, when the work is held in a predetermined posture, or when a heavy work is moved in the direction of gravity, the above-described problem occurs as it is at the joint portion of the arm. However, in the case of industrial robots, replenishment of energy from the outside can be easily performed through a cable, and since the energy price (electricity charge) is also low at present, the problem has not been revealed.
[0006]
[Problems to be solved by the invention]
  In the present invention, a braking device capable of generating a controllable braking force can be incorporated into the joint, and most of the joint torque due to body weight is absorbed by the braking device. Since less output torque is generated, energy consumption can be reduced.walkingAn object of the present invention is to provide a joint braking device for a robot.
[0007]
In conventional robots, it has been proposed and implemented to provide a braking device at the joint. However, the conventional braking device is provided in order to prevent an arm holding a heavy object from falling and causing a personal injury in the event of an unexpected power failure. The principle is based on an electromagnetic clutch. Usually, a spring is provided in a direction in which a brake is applied, and an electromagnetic force is opposed to the spring force to release the clutch. Therefore, coils, steel plates, and the like that generate electromagnetic force are constituent members, which are very heavy devices, and there is no other way but to incorporate them for each joint. For example, an industrial robot with 6 degrees of freedom has an arm. There is a problem that six heavy braking devices are attached to each joint, and the joint driving motor of the robot having such a braking device is also increased in size. Therefore, it is not popular because of its weight, and it has not been applied to anything other than a very special purpose of emergency safety for robots that handle heavy objects. It is obvious that the energy consumption increases as the weight increases.
[0008]
Regarding the joint configuration of a walking robot, for example, there is a structure disclosed in Japanese Patent No. 2592340. This joint is used in combination with an electric motor and a harmonic reducer that can reduce and increase its output.
[0009]
In the configuration disclosed in this patent publication, when the robot is kept stationary, it is necessary to apply a so-called servo lock that keeps a current flowing through the motor of the leg joint to support its own weight. This is because the weight constantly works in the direction of bending the leg joint.
[0010]
In view of such problems, the present applicant has already filed Japanese Patent Application No. 2000-220936 and Japanese Patent Application No. 2000-284080 regarding a joint structure in which the joint is stabilized at a predetermined position and control of the joint. ing. In these prior applications, the position at which the joint is stable is determined, so that it can be used when resting in a specific posture such as a standing posture, but it cannot be used when the posture is not so. As for the ankle joint, it is sufficient if the ground at the point of rest is level, but there is a disadvantage that it cannot be used when it is tilted.
[0011]
Also consider each joint when this robot is going down the stairs. For example, considering the knee joint of the leg that is in contact with the ground, the joint is bent greatly, and the distance from the vertical line drawn from the center of the weight to the center position of the knee joint is the largest. Since the amount obtained by multiplying the distance by the weight is a moment for further bending the joint, the knee joint needs to bend the knee gradually while generating a torque that can counter this large moment. Therefore, the knee joint is consuming the most energy at this time.
[0012]
Here, if there is a large friction force at the knee joint, and if it can be configured so that this friction force takes over most of the moment generated by the body weight, a smaller current value will flow through the motor, saving energy. Can be achieved. In this case, since the moment generated by the body weight increases or decreases according to the bending angle of the knee joint, this frictional force should preferably be configured to be variable according to the joint angle. Furthermore, since this frictional force acts reversely when climbing the stairs and consumes more energy than before, it is desirable that there is no frictional force when climbing, so the frictional force can be varied from zero according to the situation. It is desirable that it can be configured.
[0013]
  The present invention has been made paying attention to the above circumstances, and a first object is to provide a controllable braking function to the joint portion of the robot, and when the robot takes a desired posture and stops, The joint can be locked, and the brake function can be suppressed to walk as in the past.walkingAn object of the present invention is to provide a joint braking device for a robot.
[0014]
  A second object of the present invention is to make it possible to substantially suppress an increase in the weight of the robot by configuring the braking device to be small and light.walkingAn object of the present invention is to provide a joint braking device for a robot.
[0015]
  Furthermore, a third object of the present invention is to easily control the braking force, which can be adapted to various anticipated walking scenes and exhibit the optimum braking force.walkingAn object of the present invention is to provide a joint braking device for a robot.
[0016]
  Here, how to use the energy generated in the joint of the stationary robot will be described. The current joint control technology calculates the difference between the target joint angle and the current joint angle, and a constant proportional constant K is used as the difference. The proportional constant K is set to be large so as to guarantee good followability even when the maximum load is applied. The amount of energy consumed by the joint drive motor is determined according to this manipulated variable, in other words, the difference value x the proportionality constant, and at the same time, it is used to generate a motor torque according to the external load moment applied to the joint.Proportional to the current valueis there.
[0017]
Considering when the joint is stationary, if the proportional constant K is set large, the difference between the target joint angle and the current joint angle becomes small. Conversely, if the proportional constant K is set small, the difference becomes large, resulting in consumption. The energy (current value supplied to the motor) to be used does not change. That is, even if the proportionality constant K is changed, the energy consumption does not change theoretically.
[0018]
This is a story when an ideal joint without friction is in a stationary state, but the story changes considerably when friction force is assumed. If a stationary joint has a sufficiently large frictional force, it can support one's weight with only that frictional force, so once that posture can be taken, the posture can be maintained even after the current supply is stopped. Can be kept. In fact, legged robots that use screws as reduction gears reduce energy consumption in this way. However, using a reducer with a lot of friction, such as a screw, consumes a lot of energy even in the process of reaching the desired posture, so the energy used for walking increases this time, and it is impossible to reduce energy consumption comprehensively. There is. The above is the actual state of energy consumption occurring inside the joint.
[0019]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides the following:Walking having at least two legs that are connected to the torso and a plurality of joints.In the robot joint braking device,It is provided between the electric motor that generates a driving force that counteracts the gravitational moment acting on the joint and causes the joint to rotate relative to the member that causes the relative movement of the joint, and brakes against the gravitational moment. giveFriction engagement means and the friction engagement meansAnd a pneumatic pressure supply source for supplying pneumatic pressure to the pneumatic pressure pressing means, and simultaneously operating the driving force of the electric motor and the braking force of the frictional engagement means. Let the robot walk down the stairs or downhill to save energy consumption to drive the walking robotIt is characterized by that.
[0020]
  Claim 2In a joint braking device for a walking robot having at least two legs composed of a plurality of joints and connected to the body, a relative rotational movement of the joints against a gravitational moment acting on the joints A friction engagement means provided between the electric motor for generating the driving force to be driven, a member that causes relative movement of the joint portion, and applying braking against the gravitational moment; and the friction engagement means in the friction engagement direction. And a pneumatic pressure supply source for supplying pneumatic pressure to the pneumatic pressure means, and controlling the direction of decreasing the current value to the electric motor while the friction engagement means is operated. Maintaining the joint portion in a desired static posture and saving energy consumed to drive the walking robotIt is characterized by that.
[0021]
  Claim 3 is the claim 1 or 2,Air pressure supply source was installed on the bodyIt is characterized by that.
[0022]
  Claim 4 claimsThe joint portion of 1, 2 or 3 includes a speed reducer in which the rotational force of the electric motor is transmitted to a pulley via a belt, and the pneumatic pressure means applies a brake by pressing a friction plate against the pulley. It is characterized by.
[0023]
  Claim 5 is claim 1, 2 or 3 includes a speed reducer to which the rotational force of the electric motor is directly transmitted, and the air pressure pressing means applies a brake by pressing a friction plate against the rotating body of the speed reducer. Characterized by.
[0024]
  Claim 6 is claim 1, 2, 3, 4 or 5 is characterized in that it comprises a cylinder and a piston housed in the cylinder so as to be able to advance and retract..
[0025]
Since each joint part of the link can be braked, various energy savings can be executed by devising a control method. For example, when the walking robot takes a standing posture, the standing posture can be maintained even if the current value to the motor for driving the joint is completely eliminated after applying the joint braking.
[0026]
Therefore, there is an advantage that the energy consumption can be substantially zero as compared with the standing by the conventional servo lock. In addition, the current value is not made zero at all, but some flow is allowed, and by applying weak braking, the joint can be driven quickly when external force is applied inadvertently.
[0027]
Furthermore, when the robot is going down the stairs, by applying partial braking to each joint part on the stance side, the driving motor for each joint part can move down the stairs with a small amount of torque, in other words, with a small current. It also opens the way to get down.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
FIG. 1 is a perspective view showing a skeleton of a biped robot suitable for applying the present invention. As shown in FIG. 1, the walking robot 1 has six joint axes on the left leg 2L and the right leg 2R. The left leg 2L and the right leg 2R have symmetrical structures, and one of them will be described. The six joint axes are, in order from the top, the leg rotation joint axis 3, the crotch pitch direction joint axis 4, and the roll direction joint axis 5. The knee pitch direction joint shaft 6, the ankle portion pitch direction joint shaft 7, and the roll direction joint shaft 8 are provided, and a foot portion 10 is provided at a lower portion thereof via a six-axis force sensor 9.
[0030]
A waist plate link 12 corresponding to the pelvis of the human body is provided at the top of the left leg 2L and the right leg 2R. The waist plate link 12 is equipped with a power supply and an amplifier (amplifier) necessary for joint control, and an inclinometer 13 that detects an inclination of the robot with respect to the walking space and outputs it as an electric signal by means not shown.
[0031]
A hip joint portion 14 is configured by the leg rotation joint shaft 3, the crotch pitch direction joint shaft 4, and the roll direction joint shaft 5. Further, the knee joint portion 15 is constituted by the knee pitch direction joint shaft 6. Further, the ankle portion pitch direction joint shaft 7 and the roll direction joint shaft 8 constitute an ankle joint portion 16.
[0032]
The hip joint 14 and the knee joint 15 are coupled by a thigh link 17, and the knee joint 15 and the ankle joint 16 are coupled by a shin link 18.
[0033]
The left leg 2L and the right leg 2R have a mirror image relationship and are symmetrical.
[0034]
The six-axis force sensor 9 is provided between the ankle joint portion 16 and the foot portion 10, and the moment generated by the vertical direction component Fz, the traveling direction component Fx, the lateral direction component Fy, and the floor reaction force of the floor reaction force F. The N vertical direction component Nz, the traveling direction component Nx, and the horizontal direction component Ny can be detected separately.
[0035]
FIG. 2 is a cross-sectional view of the hip joint 14 provided with a braking device, and the hip joint 14 of the right leg 2R is viewed from the front. First, in comparison with FIG. 1, the leg rotating joint shaft 3 is rotatably supported by two bearings 20 and 21, and is rotationally driven by a motor (not shown) via a speed reducer (not shown). Further, the lower part of the leg rotation joint shaft 3 is divided into upper and lower parts on the paper surface so as to constitute a yoke part 53 to be described later, and the housing part 31 is crotch roll direction joint axis clockwise or counterclockwise on the paper surface. 5 so as to be rotatable around.
[0036]
A hollow portion 22 is provided at an intermediate portion between the yoke portion 53 and the bearings 20 and 21, and a motor 23 is provided inside the hollow portion 22. The output of the motor 23 is increased by a speed reducer (not shown) via a pulley 24 and a timing belt 25 to rotationally drive the crotch roll direction joint shaft 5.
[0037]
A motor 26 for controlling the pitch motion of the hip joint is provided on the hip pitch direction joint axis 4 orthogonal to the hip roll direction joint axis 5, and this output shaft 27 is connected to a wave generator 28 of a harmonic reduction gear by a fastening screw 29. Are combined. A screw 30 is fixed to the tip of the output shaft 27 and supports the thrust of a piston 33 described later.
[0038]
  The flange portion 32 of the casing 31 to which the motor 26 is attached is provided with a cylinder portion 34 that slidably accommodates, for example, a donut-shaped piston 33 as volume changing means. The cylinder part 34 and the piston 33 are operated by air pressure.Pneumatic pressing meansAnd the friction plate 35 is pressed against the wave generator 28 to generate a braking force to be described later. Although it is necessary to provide a passage 36 for sending air under pressure in the cylinder portion 34, the cylinder portion 34 is made by joining two parts because it is necessary to design the passage in a compact manner in the axial direction. That is, the cylinder 34 is first made with a slightly larger diameter, a passage is provided there, and then closed with another cylinder component 37, and then the cylinder portion 34 is manufactured by precision machining. The passage 36 is connected via a control valve (not shown)Air pressure supply sourceIt is connected to the.
[0039]
The friction plate 35 is obtained by applying a friction material to a steel plate and finishing the surface after drying, and has a structure similar to that of a friction plate used in a clutch of an automobile transmission. A plurality of suitable return springs 38 are provided to help return the piston 33 to its original position after it is pressed to the right in FIG. 2 by air pressure. The return spring 38 is positioned by a through hole 40 provided in the circular ring 39 of the harmonic reduction gear. The output of the harmonic reduction gear is transmitted to the flex ring 41, and the thigh link 17 is driven through the reduction gear cover. The portion of the passage 36 shown in FIG. 2 actually shows a cross section having a 90 ° phase difference as clearly shown in FIG.
[0040]
  As shown in FIG.Upper partIs provided with a motor 43 for driving the knee joint 15, and its output is transmitted via a pulley 44 and a timing belt 45 to a harmonic reduction gear (not shown) arranged coaxially with the knee joint 15.
[0041]
FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and the cylinder portion 34 and the friction plate 35 are removed for convenience of explanation. 3, a cylindrical convex portion 46 is formed around the flange portion 32 of the housing 31, and screw holes 47 are formed in the convex portion 46 at intervals of 60 °. The circular ring 39 is fixed using the screw hole 47.
[0042]
The convex portion 46 is provided with three slots 48 at intervals of 120 °, and has a role of fixing the friction plate 35 in the circumferential direction. As shown in FIG. 4, the shape of the friction plate 35 is generally disc-shaped, but three claws 49 whose widths are managed so as to be slidably fitted into the slots 48 project radially. Therefore, when the friction plate 35 of FIG. 4 is inserted into the flange portion 32 of FIG. 3 and assembled, the friction plate 35 can move in the axial direction but is fixed in the circumferential direction.
[0043]
Returning to FIG. 3 again, the cylinder part 34 is scraped off lower than the convex part 46, but a part of the bottom part thereof is shaved lower by a milling cutter to form the concave part 50, thereby forming the compressed air passage. is doing. A passage 36 indicated by a dotted line is formed by a processing method such as a drill so as to communicate with the recess 50. As described above, the concave portion 50 is partially covered by the constituent member 37 (see FIG. 2) of the cylinder portion 34, and when completed, only the right portion of the concave portion 50 can be seen from the outside. A bearing member 51 of another component is fixed to the left side of the housing 31, and the passage 36 is connected to an appropriate conduit such as a hose as shown by an arrow through a passage provided on the bearing member 51 side. Connected to air pressure source and control valve. The bearing member 51 is supported by the yoke portion 53 through a bearing 52.
[0044]
As shown in FIG. 5A, the constituent member 37 of the cylinder portion 34 shows the shape of the constituent member 37 incorporated in the cylinder portion 34 of FIG. ) Shows the back side of the component member 37. That is, two shallow grooves 54a and 54b are formed in the component member 37 so that compressed air is supplied and discharged quickly through the grooves 54a and 54b. Further, a chamfer 55 is provided around the outside of the component member 37, and this chamfer 55 also helps to quickly supply and discharge air.
[0045]
When compressed air is sent into the pressure chamber constituted by the cylinder portion 34 and the piston 33, the piston 33 moves to the right in FIG. 2 and presses the friction plate 35 against the wave generator 28, so that a braking force is obtained. The braking force is expanded according to the reduction gear ratio of the speed reducer and transmitted to the speed reduction cover 42 to stop the movement of the thigh link 17 in the pitch direction.
[0046]
The magnitude of the braking force is determined by two factors, the effective area of the piston 33 and the air pressure. That is, if these two elements are designed to be large, a large braking force is generated and the force for stopping the movement of the thigh link 17 in the pitch direction is strengthened. The resulting torque is basically a small torque, and so a large braking force is not necessary for the purpose of reducing energy consumption at the time of standing. Also, regarding the braking force when going down the stairs, if the braking force is designed too large, the joint itself will not move, and it will not be possible to walk. Therefore, it is only necessary to obtain a moderate braking force at this time. Accordingly, the effective area and air pressure of the piston 33 may be small.
[0047]
Conversely, designing with a small braking force has the following good results. When the robot is standing by braking force, assuming that external force is inadvertently applied from the side, it is ideal that the joint drive starts after releasing the braking force and the posture is stabilized. Even if it is appropriate, there may be a case where there is not enough time. If the braking force is designed to be weak, the stability of the robot can be restored to the joint if the driving force of the motor 26 is set larger than the braking force even when the release of the braking force does not end in such an emergency. Can be driven in the direction of
[0048]
  As shown in FIG.A driven pulley 56 that transmits the output of the motor 23 via the timing belt 25 is provided on the right side portion 53 a of the yoke portion 53. The output shaft 57 rotates the wave generator 58 of the harmonic speed reducer. Upon receiving the output of the speed reducer, the casing 31 rotates around the crotch pitch direction joint shaft 4 by the two bearings 52 and 59 of the yoke portion 53. It becomes like this.
[0049]
  further,As shown in FIG. 6A, a cover 60 that rotatably supports the output shaft 57 is provided with a cylinder portion 62 that houses a donut-shaped piston 61, and pressure air is guided to a chamber on the left side of the piston 61. Then, the piston 61 moves to the right and presses the friction plate 63 against the driven pulley 56. This movement causes a braking force to act on the driven pulley 56.
[0050]
In order to prevent the friction plate 63 from rotating while being dragged by the frictional force, the friction plate 63 is provided with a pair of radially extending ear portions 64 as shown in FIG. One of them has a perfect hole 65a, and the other ear 64 has an oval hole 65. In the holes 65 and 65a, a pin 66 having a size to be closely engaged is driven into the cover 60. Torque generated during braking is absorbed by the pin 66, and a desired braking force is obtained. In order to exhaust the compressed air and completely remove the braking force of the driven pulley 56, the friction plate 63 needs to be separated from the driven pulley 56. In order to ensure that, FIG. As indicated by a broken line in a), a plurality of return springs 67 made by bending a steel plate may be provided.
[0051]
In this embodiment, there are basically few space restrictions and the driven pulley 56 can have a large diameter, so that the diameter of the friction plate 63 and the diameter of the piston 61 can be increased. Increasing the diameter of the driven pulley 56 increases the transmitted torque, but the relationship is merely a proportional relationship (only proportional to the first power of the diameter). On the other hand, the increase in the diameter of the piston 61 means that the pressure receiving area increases in proportion to the square of the diameter, so that the braking force is increased to the first power of the subtracted diameter even if the amplified torque is taken into consideration. Proportionally strong design. For example, since a large bending torque acts on the knee joint when moving up and down the stairs, a structure in which a large torque is also generated is desirable. When the torque to be transmitted by the driven pulley 56 can be amplified, there is an advantage that the braking force can be designed to be larger than that of the embodiment shown in FIG.
[0052]
The robot shown in FIG. 1 has 12 joints, each of which has a braking device of any type described above.
[0053]
FIG. 7 is a pneumatic circuit diagram of a control system for sending compressed air to a braking device provided at each joint.
[0054]
In FIG. 7, the compressor 200 is driven by a DC motor 201 and stores energy in the form of pressure in a surge tank 204 via a check valve 202. Although the surge tank 204 also exhibits the effect of leveling the pulsation of the compressor 200, the surge tank 204 stores energy produced over a long period of time by the small-capacity compressor 200 and the DC motor 201, so that a large amount of energy is consumed in a short time. Have a guarantee.
[0055]
An accumulator with a built-in piston or metal spring may be used in place of the surge tank 204. However, when it is mounted on a mobile robot, it must be lightweight and the air pressure is relatively low. For the two reasons that the level is acceptable, a tank type with only a hollow is illustrated. A suitable pressure sensor 203 is provided to detect the pressure level inside the surge tank 204 and stop the DC motor 201.
[0056]
  Since a control technique for stopping the DC motor 201 in accordance with the output of the pressure sensor 203 is known, it is not shown. These DC motor 201, compressor 200, surge tank 204, etc.Air pressure sourceIs preferably fixed to the waist plate link 12 of the robot.
[0057]
The cylinder unit 62 and the piston 61 of the brake device described above are prepared for each joint, but there are six joints for the left leg, so six sets of brake devices are prepared. For example, since the hip joint portion 14 is composed of a leg rotation joint shaft 3, a hip pitch direction joint shaft 4, and a roll direction joint shaft 5, three sets of braking devices 208-1, 2 and 3 are provided. It has been. Here, the brake device 208-1 will be briefly described. When the piston 61 is slidably accommodated inside the cylinder portion 62 to form a pneumatic chamber, and when pressurized air is fed into the pneumatic chamber, the piston 61 moves to the right and exerts a braking force by pressing a friction plate (not shown) against the rotating member. Brake device 208-4 is the knee joint portion 15, and 208-5 and 208-6 are the brake devices of the foot joint portion 16. The pneumatic chambers of these braking devices are pressure-connected to each other by a hose, and can be selectively connected to the surge tank 204 or opened to the atmosphere by a common electromagnetic valve 206. The state shown in the figure is a state in which the solenoid valve 206 is energized and the pressure air is sent from the surge tank 204 to the pneumatic chamber of each brake device. When the energization of the solenoid valve 206 is stopped, the left side of the solenoid valve 206 is changed by the force of the spring 206a, and the pneumatic chamber is opened to the atmosphere via the solenoid valve 206.
[0058]
Since the robot has both legs, the same system is prepared for the right leg, and a braking device shown in 207-1 to 6-6 and an electromagnetic valve 205 are provided for controlling these braking devices.
[0059]
Next, the operation of the system shown in FIG. 7 will be described. When a computer for walking control (not shown) outputs a walking mode for standing and stationary, the computer also excites the two electromagnetic valves 205 and 206 to operate the braking device. When the output of the excitation command to the electromagnetic valves 205 and 206 is completed, the computer reduces the control gain of the joint driving motor, and consequently saves the energy consumed by the motor.
[0060]
A technique for saving the motor energy consumption by changing the gain is disclosed in detail in Japanese Patent Application No. 2000-284080 described above. The technology disclosed in this prior application was designed to reduce the supply current value to the motor in order to save energy. However, the present invention is not limited to this. For example, the braking force of the braking device is designed with a certain level of magnitude. In this case, it is needless to say that energy saving can also be achieved by stopping the energization of the motor on and off after sending the excitation command to the solenoid valves 205 and 206.
[0061]
  As can be seen from this embodiment, according to the present invention, the system can be configured with only one heavy component compressor 200 and DC motor 201, and the conventional braking device needs to provide a heavy electromagnetic clutch for each joint. The whole can be designed lighter than there was. Further, the place where the compressor 200 and the DC motor 201 are installed can be provided on the waist plate link 12 which is relatively slow in acceleration / deceleration. Arm and legmotorThere is an advantage that it is possible to do without enlarging the capacity.
[0062]
Further, another use of this system will be described. When going down the stairs, when the walking control computer outputs a gait suitable for going down the stairs to the motors of each joint, the six axes shown in FIG. By energizing the solenoid valve 205 or 206 of the leg from which the output from the force sensor 13 is obtained, the joints in the stance phase are driven while a predetermined braking force is generated in the six joints.
[0063]
  In this way, the joints in the stance phasemotorIt is sufficient to bear only the remaining torque borne by the braking device among the torques that support the weight, and energy saving is achieved. Especially in this control,motorThere is no need to lower the gain ofmotorAutomatically according to the control law of position controlmotorThe power supplied to is reduced. However, in the illustrated system, it is impossible to cope with the fact that the load torque due to the body weight increases as the angle of the knee joint portion 15 increases, and the torque borne by the braking device is always constant. Needless to say, near the end of the stance phase, the walking control computer demagnetizes the solenoid valve to remove the braking force from the braking device.
[0064]
In addition, although the electromagnetic valves 205 and 206 shown in FIG. 7 are those that generate a braking force when energized, reversing the connection so that the braking force is generated when demagnetized is related to the technology. It is common sense in the field. For example, in the case of an industrial robot, a braking device using an electromagnetic clutch or a brake has already been put into practical use as a device for preventing an unexpected accident due to the arm falling during a power failure. Applying it to the joint part of the arm of an industrial robot and connecting it to the solenoid valves 205 and 206 in reverse to FIG. 7 to use it for joint braking of the industrial robot can achieve the same performance and function as before, Furthermore, robots can be designed to be smaller and lighter than before, and accidents during power outages can be prevented while maintaining cost and quality. In an industrial robot, a pipe stretched around in a factory is immediately beside it, so that compressed air can be easily obtained through the pipe, and it becomes simpler when actually applied.
[0065]
  FIG. 8 shows another embodiment in which the braking force can be made variable in response to a change in the angle of the knee joint 15. In FIG. 8, only the left leg control circuit is shown for the sake of simplicity, and the right leg is omitted. In FIG. 8, a second electromagnetic valve 219 is added between the brake device 218-4 of the knee joint portion 15 and the electromagnetic valve 216 of the entire leg and capable of continuously controlling the pressure. Such a solenoid valve 219 is a proportional solenoid valve.OrServo valveEtc.The output pressure can be arbitrarily changed according to the current value supplied to the solenoid valve. In order to accurately control the level of the output pressure, a pressure sensor 219S is connected in parallel with the braking device 218-4, and control by feedback is performed. This type of solenoid valve and its feedback control device are also known. 8 is basically the same as the system of FIG. 7 except that it is surrounded by a dotted line.The compressor 210, DC motor 211, check valve 212, pressure sensor 213, and surge tank 214 perform the same functions as the compressor 200, DC motor 201, check valve 202, pressure sensor 203, and surge tank 204 of FIG. To do.
[0066]
  Next, the operation of the system shown in FIG. 8 will be described. The gait when the walking control computer goes down the stairs is shown.kneeJoint15When the left foot is in the stance phase, the amount of the joint angle commanded to the motor 43 of the knee joint 15 is multiplied by a proportional constant to the second solenoid valve 219 as a command pressure. Output. (To be precise, if the knee joint angle is θ, the load torque of the knee joint portion 15 is proportional to sinθ, but for simplicity of explanation, the above amount is used.) The second value given this target value The electromagnetic valve 219 is a pressure sensor for adjusting the pressure level of the pressure chamber of the brake device of the knee joint 15 to a target value.219STherefore, proportional control is performed with reference to the output information, and the braking torque corresponding to the increasing load torque is generated in the knee joint portion 15.Motor 43The power (energy) supplied to the can be kept at a low level.In FIG. 8, reference numerals 218-1 to 218-6 denote pneumatic pressing means.
[0067]
  Connecting the second solenoid valve 219 in parallel with the first solenoid valve 216 has the same effect. However, this type of proportional control valve is often designed to control while consuming pressure air, so in the case of parallel connection, even when demagnetized, the surge tank214The air pressure is slightly consumed. By connecting in series with the first electromagnetic valve 216 as shown in FIG. 8, it is possible to avoid wasting compressed air in order to demagnetize the first electromagnetic valve 216 during the swing phase.
[0068]
  FIG. 9 shows yet another embodiment. As described above, the proportional control valve performs control by discarding a part of the pressure air during the control, but the on / off control valve shown in FIG. In the example of FIG. 9, the pressure air supplied to the braking device 228-4 of the knee joint portion 15 is controlled to have a predetermined output pressure level by the electromagnetic valve 229. The solenoid valve 229 can create three phases by a pair of solenoid valves performing coordinated control. When the solenoid valve 229 is in the illustrated phase, the pressure in the surge tank 224 is directlyPneumatic pressing means228-4, but by limiting the time to a very short time,Pneumatic pressing meansWhile the pressure inside 228-4 does not rise, it switches to the middle phase. In this second phasePneumatic pressing means228-4 is left in an isolated state so that its pressure level remains constant. When it is determined that the pressure level of the pressure sensor 229S has not reached the predetermined level, the first phase shown in the figure is realized again in a short time to try to increase the pressure level.229SWhen it is detected that the pressure level exceeds the predetermined level and becomes too high, the left solenoid is excited to discharge a part of the pressure and approach the predetermined level. Of the knee joint 15Pneumatic pressing meansExcept for the above, it is basically the same as FIG. 7, and the control circuit for the right leg is omitted for the sake of simplicity.9, the compressor 220, the DC motor 221, the check valve 222, the pressure sensor 223, and the surge tank 224 are the same as the compressor 200, the DC motor 201, the check valve 202, the pressure sensor 203, and the surge tank 204 of FIG. Perform the same function. Reference numerals 228-1 to 228-6 are air pressure pressing means.
[0069]
  Such a technique of continuously changing the output pressure level using the electromagnetic valve 229 having an on / off characteristic is widely used as duty ratio control and is well known. Using this duty ratio control, a pressure level corresponding to an increase in the angle of the knee joint portion 15 is generated in the braking device of the knee joint portion 15, and the knee joint portion 15 is correspondingly increased.Motor 43Power consumption can be saved.
[0070]
FIG. 10 shows yet another embodiment. FIG. 10 also shows only the left leg control circuit as in the previous embodiment. Although the pressure level inside the surge tank 234 should be kept at a substantially constant value by the pressure sensor 233, the general pressure control principle is a starting pressure level for driving the DC motor 231 to prevent hunting. The pressure level when the DC motor 231 is stopped is set to a different level. That is, the internal pressure of the surge tank 234 is between these two levels and constantly fluctuates.
[0071]
The fluctuation of the pressure level means that the braking force generated by the braking device also fluctuates, and this fluctuation of the braking force may not be desirable. For example, the case where the knee joint part 15 rotates under a braking force, such as when going down stairs, corresponds.
[0072]
The embodiment shown in FIG. 10 is made for the purpose of preventing such fluctuations and performing stable walking, and the electromagnetic valve 236 that controls on and off is provided. Although it is the same as the example, pressure reducing valves 239-a and 239-b are provided in series with the electromagnetic valve 236 so that the output pressure of these pressure reducing valves 239-a and 239-b is supplied to the braking device. Configured.
[0073]
More specifically, the first pressure reducing valve 239-a controls the pressure levels of the five joints of the hip joint and the ankle joint to be constant, and the second pressure reducing valve 239-b is the knee joint. The pressure level of the 15 braking devices 238-4 is maintained at a predetermined pressure level. As described above, it is desirable that the knee joint portion 15 exerts a larger braking force as the knee joint portion 15 is bent. Therefore, a linear solenoid capable of changing the output pressure level by electromagnetic force is adopted. Has been.
[0074]
  When the electromagnetic coil is energized, an electromagnetic force corresponding to the flowing current value is applied to the spring force, and the circuit is not closed unless the opposing output pressure (indicated by a dotted line in the figure) becomes stronger. Such linear solenoids are also provided for public use and need no further explanation. For knee joint disclosed in FIG.Pneumatic pressing meansSince the quality of the linear solenoid 239-b is stable at the pressure level of 238-4, the pressure sensor shown in FIG. 9 is omitted in this example.10, the compressor 230, the DC motor 231, the check valve 232, the pressure sensor 233, and the surge tank 234 are the same as the compressor 200, the DC motor 201, the check valve 202, the pressure sensor 203, and the surge tank 204 in FIG. Perform the same function. Reference numerals 238-1 to 238-6 are air pressure pressing means.
[0075]
As described above in detail, the braking device according to the present invention is based on air pressure in principle, and is lighter than the case where a conventional electromagnetic clutch is mounted integrally with a drive motor, and the inertia of the leg of the robot when completed. Since there is almost no increase in moment, there is no contradiction that adding a braking device further increases the capacity of the drive motor and increases energy consumption. Moreover, since the air pressure constantly supplies fresh and cold air to the braking device, the joint portion can be simultaneously cooled, and the motor can be used more severely.
[0076]
Since the motor and the compressor are installed on the body portion that does not relatively accelerate and decelerate, there is almost no inevitability in increasing the capacity of the joint drive motor, although this weight increase occurs. For example, in the case of walking (gait) in which the torso is moved at a constant speed, the weight increase of the torso is basically not a burden on the leg joint drive motor (the necessary torque to support the body weight is naturally Although it increases, it has less impact than the conventional electromagnetic clutch / brake system that provides everything in the part with intense acceleration / deceleration. Above all, compared to the conventional system requiring one set for each joint, the motor and compressor The biggest advantage is that only one set is required).
[0077]
Furthermore, when the robot is used as an industrial robot fixed to the ground instead of a mobile robot, compressed air is easily supplied from the factory air piping, so not only a compressor but also no surge tank is required. become. In this case, since the compressed air is abundant, there are no restrictions when selecting the solenoid valve to be used, and the degree of freedom in design is increased.
[0078]
Although all the embodiments used in the above description use air pressure, the use of pressure liquid has almost the same effect although it is somewhat heavier than air. Japanese Patent Laid-Open No. 8-126984 discloses an example of a technique that uses a pressure liquid and installs a large and heavy part in another place and transmits it to a desired joint.
[0079]
When this technology is applied to the present invention, the pressure source is shared, and the output is branched and transmitted to the piston chamber of the brake device of each joint. If a liquid is used as a working fluid, the liquid has no compressibility, so that the responsiveness is improved. Since the liquid can be used at a higher pressure level, there is an advantage that the pressure receiving area of the piston can be reduced accordingly.
[0080]
On the other hand, when air is selected as the working fluid, the air is basically clean, and the advantage is that it does not pollute the environment even in the event of a leak failure. Also, since air is compressible, it is possible to store energy simply by preparing a surge tank, and there is an advantage that the intended purpose can be achieved with a smaller motor and compressor. When using liquid as the working fluid, the surge tank must be changed to an accumulator, but the disadvantage is that the accumulator becomes heavy. In short, it is only necessary to decide which fluid to select according to the purpose of use of the robot.
[0081]
In any of the above-described embodiments, a fluid under pressure is supplied to a braking device including a cylinder and a piston to obtain a predetermined braking force. However, this technical concept is a large and heavy part, and mechanical actuation force is increased. Install the source of the operating force that can be generated away from the joint that needs to move violently, and transmit the operating force to the braking device via appropriate transmission means (in this case, pressure air and hose) This minimizes the increase in weight of parts such as legs that are subject to rapid acceleration / deceleration. In the example, taking advantage of the fact that cylinders and pistons can be made of light materials such as light alloys and engineering plastics, these are provided at each joint. Heavy motors and compressors are first reduced in number (in the embodiment, It has succeeded in suppressing the overall weight increase.
[0082]
Furthermore, this technical concept allows a plurality of braking devices to be actuated by the output of a single actuating force generator, so when applied to an articulated arm or leg, the conventional electromagnetic clutch / brake is used. Compared to braking devices, the overall weight increase can be remarkably suppressed, and there is no restriction on the installation location, so it is possible to select parts with less acceleration / deceleration, so the capacity (weight) of the joint drive motor is also increased. Inevitably less.
[0083]
Considering the above points, the power transmission device need not be limited to a combination of pressurized air and a hose. Another embodiment will be shown and described below.
[0084]
  FIGS. 11 to 13 show embodiments using tendons (cables) as transmission means other than pressurized air and hoses. Figure 116A joint portion in the case where power is transmitted through the driven pulley 56 shown in FIG. In other words, the cylindrical portion 302 protrudes from the side surface of the driven pulley 304 that rotates.
[0085]
On the other hand, as shown in FIG. 12, a pair of pins 306 and 307 are driven into the speed reducer cover 300 which is a fixed portion, and half-moon shaped braking segments 308 and 309 are provided to be rotatable around the pins 306 and 307. It has been. A hole 312 through which the wire 310 is passed is formed below the braking segment 308, and the wire 310 that has passed through the hole 312 passes through the hole 314 of the counterpart segment 309 and then has a diameter larger than that of the wire 310. The fastening part 316 is coupled with appropriate means such as solder.
[0086]
A sheath 318 is provided on the outside of the wire 310, and if the wire 310 is pulled to the right in FIG. 12 so that a relative displacement occurs between the wire 310 and the sheath 318, the two segments 308 and 309 become the pins 306 and 307. Is caused to rotate, and the cylinder portion 302 is contacted to generate a braking force. Such a wire 310 having a sheath 318 and a braking method using the wire 310 are widely used in bicycle brakes and the like. In this mechanism, it is possible to use a light alloy or a resin as the material of the segment, and it can be said that it is a very preferable mechanism for disposing it in a joint portion that does not want to increase in weight.
[0087]
FIG. 13 shows a drive system for the wire 310. FIG. 13 schematically shows only two joint braking devices. That is, a first braking device 320 and a second braking device 322 are provided. These braking devices 320 and 322 schematically depict the configuration shown in FIG. 12. Briefly describing the first braking device 320, the pair of segments 328 and 329 are respectively rotatable by pins 326 and 327. If the wire 330 is supported and pulled to the right in the figure, a braking force is generated. The second braking device 322 basically has the same configuration, and a wire 330a for operating the second braking device 322 is provided.
[0088]
If the two wires 330 and 330a are coupled to holes provided at both ends of the lever 340, and the lever 340 is pulled to the right side by the third wire 342, the first and second braking devices 320 and 322 operate together. It becomes a state. In this case, the tension acting on the first wire 330 that operates the first braking device 320 and the second wire 330a that operates the second braking device 322 is arbitrarily designed according to the position of the fulcrum C of the lever 340. The ratio can be changed. As shown in the figure, when the distance AC is equal to the distance BC, equal tension is generated in the two wires 330 and 330a. When a large load moment acts on any joint part, the design requirement can be easily satisfied by changing the position of the fulcrum C.
[0089]
When the number of joints further increases, the second lever 350 may be provided and the fourth wire 330b may be pulled. The second lever 350 is activated by a rightward actuating force acting on the fulcrum F by a pneumatic cylinder 360 and a fifth wire 362 coupled to its piston, which force is applied to the two wires 342 and 330b. Are distributed and transmitted at a ratio determined by the ratio of the fulcrum distance FD / FE. It goes without saying that the pneumatic cylinder 360 is selectively supplied with an appropriate air pressure through a hose 364 via an appropriate distributor valve.
[0090]
In the embodiment using this cable, the mechanical force generating means is not limited to the air cylinder, and the cable may be pulled by a worm gear that rotates by receiving the output of the motor, for example. Since the worm gear has a large internal friction, the engagement force can be continuously generated even if the power to the motor that drives the worm gear is stopped when the friction engagement force is generated. However, in this case, since the worm gear is not compressible unlike air pressure, it is more desirable to insert a mechanical spring in series with the worm gear in the middle of the cable as a supplement.
[0091]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to brake each joint without substantially increasing the weight of the leg or arm, in other words, without increasing the moment of inertia. Various energy savings can be executed by devising. For example, when the walking robot takes a standing posture, the standing posture can be maintained even if the current value to the motor for driving the joint is completely eliminated after applying the joint braking. There is an advantage that the energy consumption can be reduced to substantially zero as compared with the standing by the conventional servo lock. In addition, the current value is not made zero at all, but some flow is allowed, and by applying weak braking, the joint can be driven quickly when external force is applied inadvertently.
[0092]
In addition, when the robot is going down the stairs, it applies partial braking to each joint on the stance side, so that the driving motor for each joint can go down the stairs with less torque by the amount of this braking force, in other words, with less current. It also opens the way for you.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a skeleton of a biped walking robot according to a first embodiment of the present invention.
FIG. 2 is a front view showing a cross section of a part of a hip joint portion including the braking device according to the embodiment;
3 is a cross-sectional view taken along the line AA of FIG. 2 showing the embodiment.
FIG. 4 is a front view of the friction plate, showing the embodiment.
5A is a front view of a component member incorporated in a cylinder portion, and FIG. 5B is a rear view of the component member.
6A and 6B show another embodiment of the braking device, where FIG. 6A is a cross-sectional view of the braking device, and FIG. 6B is a front view showing a friction plate.
FIG. 7 is a pneumatic circuit diagram of a control system for sending the compressed air of the embodiment to a braking device provided at each joint.
FIG. 8 is a pneumatic circuit diagram showing another example of a control system for sending compressed air to a braking device provided at each joint.
FIG. 9 is a pneumatic circuit diagram showing another example of a control system for sending compressed air to a braking device provided at each joint.
FIG. 10 is a pneumatic circuit diagram showing another example of a control system for sending compressed air to a braking device provided at each joint.
FIG. 11 is a front view of a section of a braking device.
12 is a sectional view taken along line BB in FIG.
FIG. 13 is a configuration diagram showing a power transmission mechanism.
[Explanation of symbols]
14 ... Hip joint
15 ... Knee joint
16 ... Ankle joint
17 ... Thigh link
18 ... Knee links
26, 43 ... Motor
35, 63 ... friction plate

Claims (6)

In a joint braking device for a walking robot having at least two legs connected to the body part and the body part and comprising a plurality of joint parts ,
An electric motor that generates a driving force that counteracts the gravitational moment acting on the joint and causes the joint to rotate relative to each other.
Friction engagement means provided between members that cause relative movement of the joint part, and applying braking against the gravitational moment ;
Air pressure pressing means for pressing the friction engagement means in the friction engagement direction;
An air pressure supply source for supplying air pressure to the air pressure pressing means;
The walking is characterized in that the walking power of the electric motor and the braking force of the friction engagement means are simultaneously actuated to cause the robot to walk down the stairs or downhill, thereby saving energy consumed to drive the walking robot. Robot joint braking device. In a joint braking device for a walking robot having at least two legs connected to the body part and the body part and comprising a plurality of joint parts,
An electric motor that generates a driving force that counteracts the gravitational moment acting on the joint and causes the joint to rotate relative to each other.
Friction engagement means provided between members that cause relative movement of the joint part, and applying braking against the gravitational moment;
Air pressure pressing means for pressing the friction engagement means in the friction engagement direction;
An air pressure supply source for supplying air pressure to the air pressure pressing means;
In a state where the friction engagement means is operated, the current value to the electric motor is controlled in a decreasing direction to maintain the joint portion in a desired stationary posture, and energy consumption for driving the walking robot is saved. A joint braking device for a walking robot. The joint braking device for a walking robot according to claim 1 or 2, wherein the air pressure supply source is installed in the body part . The joint portion includes a speed reducer in which a rotational force of the electric motor is transmitted to a pulley through a belt, and the pneumatic pressure pressing unit applies a brake by pressing a friction plate against the pulley. The joint braking device for a walking robot according to claim 1, 2 or 3 . The joint portion includes a speed reducer to which the rotational force of the electric motor is directly transmitted, and the air pressure pressing unit applies braking by pressing a friction plate against a rotating body of the speed reducer. Item 4. The joint braking device for a walking robot according to Item 1, 2 or 3 . 6. The joint braking device for a walking robot according to claim 1, 2, 3, 4, or 5, wherein the air pressure pressing means comprises a cylinder and a piston housed in the cylinder so as to be able to advance and retreat .

Images