JPH0585853B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a force/torque detection device for detecting the magnitude of force or torque (six-axis force) applied to the wrist in an assembly robot or the like. [Prior art] Generally, when using robots to perform assembly work, etc., if there is a misalignment of parts,
Unreasonable force may be applied to the parts, causing them to break. Conventionally, in order to prevent this, a method has been used to detect the force or moment applied to parts during assembly and adjust the position and attitude of the robot. In such a case, it is necessary to measure the forces x, y, z in the directions of the three orthogonal axes X, Y, Z, and the moments Mx, My, Mz around each axis. For example, as shown in FIG. 6, if we consider the case where a robot's hand 1 grasps a component 2 and inserts it into a hole 3, if the insertion is performed normally as shown in FIG. 6a, No extra force is applied to the hand portion 1 and the component 2, and the component 2 will not be damaged. However, as shown in FIG. 6b, if the grasping state (posture) of the component 2 by the hand section 1 changes or the positioning shifts, the hand section 1
Also, excessive force may be applied to the part 2, resulting in damage to the part 2. Therefore, when inserting the part 2, it is necessary to detect the force and moment acting on the hand part 1 and control the position and posture of the hand part 1 so that the part 2 can be inserted smoothly. be. FIG. 7 is a configuration diagram showing an example of a conventional force/torque detection device. The device shown in the figure has connecting members 4 and 5 connected to the arm side and the hand side, respectively.
are connected by a plurality of beams 6 to 13, and strain gauges 14 are attached to each beam 6 to 13.
21 is attached to detect the force in the six axial directions. That is, the connecting members 4, 5
When a force is applied between the
The force components in each axial direction are measured via. [Problems to be solved by the invention] However, the power and
In the torque detection device, since the magnitude of force is measured using the distortion of beams 6 to 13, the diameters of beams 6 to 13 must be made small, which has the disadvantage of being weak against impact force. are doing. In other words, in robots, collisions of the hand due to incorrect operation cannot be avoided, and if the hand collides with surrounding machinery, there is a high probability that beam 6~
13 will be damaged or permanent distortion will remain, resulting in a change in zero output. This is done in beam 6 to increase detection sensitivity.
This is because the amount of distortion of 13 is increased. Generally, the maximum amount of strain to avoid leaving permanent strain is about 1000μ strain, so considering the margin of impact force by 10 times this, beams 6 to 13 are strained to 100μ.
If used within the strain, 1 of the microwave
To read the %, a distortion of 1μ strain must be detected. Even when the applied voltage is 5 [V] and the gauge factor is 2, the voltage generated in strain gauges 14 to 21 due to the strain of 1μ strain is as follows:
The voltage is as small as 10 [μv], which is the limit of detection. Therefore, at the expense of impact resistance, the strain amount of beams 6 to 13 is set to 1000μ strain, and 0.1
It is common to obtain a practical resolution of %,
If a force of about 10,000 μ strain is applied due to a collision, the beams 6 to 13 will be damaged or permanently deformed. Furthermore, increasing the distortion of the beams 6 to 13 reduces the rigidity of the beams 6 to 13, which is not preferable for robots that perform highly accurate positioning. The present invention aims to eliminate the drawbacks of the conventional devices as described above, to detect force with a small amount of distortion, and to realize a highly rigid force/torque detection device with a simple configuration. It is. [Means for Solving the Problems] The force/torque detection device of the present invention has two connecting members connected to the arm side and the hand side, respectively, formed so as to have parallel hexagonal opposing surfaces. At the same time, six vibrating force detectors are arranged in different directions on the diagonals of each rectangular side surface of a hexagonal cylinder whose bottom surface is assumed to be these opposing surfaces. [Operation] The force/torque detection device configured as described above can convert forces in the six axial directions into force components in the axial direction where the vibrating force detector is arranged, and the force acting on the hand section can be It can be detected with high precision.
Further, since the vibrating force detector can detect force with an extremely small amount of distortion, a highly rigid force/torque detection device can be realized. [Embodiment] FIG. 1 is a configuration diagram showing an embodiment of the force/torque detection device of the present invention. In the figure, 22, 24
are two connecting members having parallel hexagonal opposing surfaces 23 and 25 and connected to the arm side and the hand side, respectively, and 26 to 31 are hexagonal cylinders that are assumed to have these opposing surfaces 23 and 25 as the bottom surface. Six vibrating force detectors are arranged diagonally on each rectangular side surface in different directions. FIG. 2 is a developed view showing an outline of the arrangement of the vibration force detectors 26 to 31. In the force/torque detection device in which the vibrating force detectors 26 to 31 are arranged as described above, when a force acts on the hand-side connecting member 24, this force is applied to each vibrating force detector 26 to 31 in the axial direction. The force is divided into force components and detected by each of the vibrating force detectors 26 to 31. For example, if an axial force z acts on the connecting member 24 in the Z direction, this axial force z is balanced with the axial forces 1 to 6 of the six vibrating force detectors 26 to 31, and this relationship can be expressed as , is expressed as the following equation. Fz=K31.1+K32.2+K33.3+K34.4 +K35.5+K36.6 Here, K31 to K36 are coefficients, which are uniquely determined according to the shape of the force/torque detection device. Further, a similar formula holds true for x, y, Mx, My, and Mz, and if these relationships are expressed in a matrix, they can be expressed as the following formula.

[Table] In other words, K11 to K66 are constants determined by the geometrical shape of the force/torque detection device, and can be calculated by substituting outputs 1 to 6 of each vibrating force detector 26 to 31 into the above formula. Therefore, the force x ~ Mz in the six axial directions is
can be found. Furthermore, in actual working conditions, as shown in FIG.
It is necessary to measure Mz′, but these forces are the forces detected by the force/torque detection device S.
It can be obtained from x~Mz as follows. Now, let us consider the relationship between x~Mz and x′~Mz′.

〔Effect of the invention〕

As explained above, in the force/torque detection device of the present invention, the two connecting members connected to the arm side and the hand side, respectively, are formed to have parallel hexagonal opposing surfaces, and Six vibrating force detectors are arranged in different directions on the diagonal of each rectangular side view of a hexagonal cylinder whose bottom surface is assumed to be the opposite surface of the hexagonal tube. It can be converted into a force component in the axial direction where the force detector is placed, and the force acting on the hand can be detected with high precision by the vibrating force detector, so force can be detected with a small amount of distortion. In addition, a highly rigid force/torque detection device can be realized with a simple configuration.

[Brief explanation of the drawing]

1 to 5 are block diagrams showing one embodiment of the force/torque detection device of the present invention, and FIGS. 6 and 7 are block diagrams showing an example of the conventional force/torque detection device. 4, 5, 22, 24... connection member, 6-13...
...Beam, 14-21...Strain gauge, 26-3
DESCRIPTION OF SYMBOLS 1... Vibrating force detector, 32... String, 33... Shell, 34... Insulating material, 35... Magnet, 36 Mounting part, 37... Resonating part, 38, 39... Piezoelectric element.

Claims (1)

[Claims] 1 having parallel hexagonal opposing surfaces and connected to the arm side and the hand side, respectively.
and six vibrating force detectors arranged in different directions on the diagonal of each rectangular side of a hexagonal tube whose opposing surfaces are assumed to be the bottom surface. Detection device.