JP7602235B2 - Parallel Wire Mechanism - Google Patents

Description

This disclosure relates to a parallel wire mechanism that suspends and moves a work object.

Various devices for suspending and moving a work object have been known in the past. Patent Document 1 describes a hoist equipped with a balancing cylinder. This hoist includes multiple guide rollers that roll along a guide rail, a drum that is connected to the multiple guide rollers via a vertical plate and a support vertically below the multiple guide rollers, a wire that extends vertically downward from the drum, and a hook attached to the lower end of the wire. With this hoist, after an object is hooked onto the hook, the wire is wound onto the drum to raise the object, and in this state the multiple guide rollers are rolled along the guide rail to move the object to a specified location.

Patent Document 2 describes a balancer that moves a load suspended from a hook. The balancer includes a support pillar that is erected on a base with wheels, a rod-shaped arm that can rotate horizontally at the upper end of the support pillar, a trolley that moves along the arm and extends vertically downward from the arm, a movable pulley that is attached to the lower end of the trolley, and a hook that extends further vertically downward from the movable pulley.

The balancer further comprises a hoist located on the opposite side of the support arm, and a rope that extends from the hoist along the arm and is connected to the trolley and the movable pulley. The hoist has a drum connected to the arm via the rope, and a hoist body located below the drum. When the drum is rotated with a load hooked on the hook, the hook rises as the rope is wound up, and the load is lifted. In this state, the trolley is moved along the arm to move the load to a specified location.

Japanese Utility Model Application Publication No. 58-71094 Publication No. 3027081

With the hoists and balancers described above, it is possible to hang an object on the hook and move it along the guide rail or arm. However, with the hoists described above, objects can only be moved within the range in which the guide rail is installed. Also, with the balancers described above, there can be a problem in that objects can only be moved within the range of movement of the arm.

In the balancer described above, a cart is attached to the base from which the support poles extend, but depending on the conditions at the construction site, the base may not be easily moved. For example, if the ground or floor surface at the site is uneven or there are steps, the cart cannot be moved easily. Therefore, when using the hoist or balancer described above, there is a problem that although it is possible to move a load within a small area, it is not possible to easily move the load over a wide area. In particular, at construction sites, there is a demand to move work objects over a wide area, but the current situation is that it is not possible to easily move work objects over a wide area.

The objective of this disclosure is to provide a parallel wire mechanism that can move a work object over a wide area and easily in the direction in which a force is applied to the work object.

The parallel wire mechanism according to the present disclosure includes a plurality of wires installed at a construction site, a plurality of winches each having a motor provided on each of the plurality of wires for winding and unwinding the wires, a work object connected to the plurality of wires and supported by the plurality of wires, a sensor for measuring the force acting on the work object, a first calculation unit for calculating at least one of virtual inertia, viscosity, and spring constant based on the force measured by the sensor to calculate at least one of a target position, a target speed, and a target acceleration of the work object, a second calculation unit for calculating at least one of the unwinding length, unwinding speed, and unwinding acceleration of each wire for moving the work object at at least one of the target position, target speed, and target acceleration for each motor of each winch, an output unit for outputting at least one of command values of the unwinding length, unwinding speed, and unwinding acceleration to the motor of each winch, a plurality of pillars, and a plurality of sheaves attached to each of the plurality of pillars, the plurality of winches being located at the lower part of each of the plurality of pillars, and the plurality of wires extending upward from each winch and being stretched across the sheaves.

This parallel wire mechanism includes a plurality of wires, a work object connected to the plurality of wires, and a plurality of winches each having a motor provided on each of the plurality of wires for unwinding and winding each of the wires, and the work object is moved by unwinding and winding each of the wires of the motor in each winch. Therefore, the work object can be moved by unwinding and winding each of the wires in the area surrounded by the plurality of wires, so that the work object can be easily moved. In addition, the entire three-dimensional space formed by the plurality of wires can be set as the movable range of the work object, so that the work object can be moved over a wide range. In addition, this parallel wire mechanism only needs to include a plurality of wires and a plurality of winches each having a motor, and the aforementioned heavy equipment such as the guide rail and arm can be eliminated, so that the parallel wire mechanism can be easily installed and rearranged. Therefore, the parallel wire mechanism can be easily installed and rearranged at a wide construction site, so that the work object can be moved over a wide area and easily. Furthermore, the force applied to the work object can be measured by a sensor, and the work object can be moved based on the measured force, so that the worker can intuitively move the work object by applying force to the work object.

The first calculation unit may also change the spring constant depending on the location of the work object. In this case, by changing the spring constant when the work object approaches a location where it is undesirable to approach, it is possible to make it difficult for the work object to approach that location. Therefore, by changing the spring constant, it is possible to generate a repulsive force that makes it difficult for the work object to approach a preset movement limit area or an obstacle, etc. As a result, even if the work object attempts to approach the movement limit area or an obstacle, etc. due to an operating error, etc., the repulsive force can prevent the approach, thereby improving the safety of work at a construction site.

The first calculation unit may also calculate the target position, the target speed, or the target acceleration by canceling the gravity of the work object, and perform the calculation without canceling a part of the gravity of the work object. In this case, the first calculation unit calculates the target position, the target speed, or the target acceleration by canceling the gravity of the work object. However, when the work object is placed on the ground or floor, the first calculation unit performs the calculation without canceling a part of the gravity of the work object. Therefore, since a part of the gravity is not canceled, a part of the gravity of the work object is applied to the ground or floor, for example, in a situation where it is desired to move a work object placed on the ground or floor. As a result, a desired load can be applied to the ground or floor, and the load can be reduced by a required amount.

According to this disclosure, it is possible to easily move a work object over a wide area in the direction in which a force is applied to the work object.

FIG. 1 is a diagram illustrating a construction site to which the parallel wire mechanism according to the present embodiment is applied. 13A and 13B are diagrams each showing a schematic diagram of a parallel wire mechanism according to a modified example. FIG. 2 is a block diagram showing the functions of the parallel wire mechanism of FIG. 1 . FIG. 2 is a block diagram illustrating various calculations performed by the parallel wire mechanism of FIG. 1. FIG. 2 is a diagram showing a schematic diagram of calculation of the wire unwinding length by the parallel wire mechanism of FIG. 1 . 13A and 13B are diagrams for explaining a potential method performed by a parallel wire mechanism according to a modified example. FIG. 7 is a block diagram illustrating various calculations performed by the parallel wire mechanism of FIG. FIG. 13 is a diagram illustrating a construction site to which a parallel wire mechanism according to a further modified example is applied.

Below, an embodiment of the parallel wire mechanism according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are given the same reference numerals, and duplicated descriptions will be omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios, etc. are not limited to those shown in the drawings.

Figure 1 shows a parallel wire mechanism 1 according to this embodiment, and a construction site A to which the parallel wire mechanism 1 is applied. The parallel wire mechanism 1 includes a plurality of wires 5 that support a work object T. In this disclosure, "work object" refers to materials used in work carried out at a construction site. The construction site A may be, for example, a place that requires special equipment or is difficult for people to enter, and even in such a place, the parallel wire mechanism 1 can freely move the work object T using the wires 5.

The parallel wire mechanism 1 is, for example, a three-dimensional suspended parallel wire mechanism installed at a construction site A as shown in FIG. 1, and moves a work object T to a desired position by balancer control, which will be described later. In other words, the parallel wire mechanism 1 can be used as a wide-area balancer device capable of moving the work object T over a wide area. For example, the work object T is moved by applying a force by being pulled or pushed by a worker M (see FIG. 2(a) or FIG. 2(b)). As an example, the worker M moves the work object T by pulling a kamikaze rope.

Note that the present invention is not limited to the structure shown in FIG. 1 in which four wires 5 are provided, and may be a suspended parallel wire mechanism having three wires 5 as shown in the modified example of FIG. 2(a). Furthermore, it may be a two-dimensional suspended parallel wire mechanism having two wires 5 as shown in the modified example of FIG. 2(b). As an example, the worker M may move the work object T by remote control.

As shown in FIG. 1, the parallel wire mechanism 1 includes, for example, a plurality of pillars 2, a plurality of sheaves 3 attached to each of the plurality of pillars 2, a plurality of winches 6 located at the lower part of each of the plurality of pillars 2, and a plurality of wires 5 extending upward from each winch 6 and hung over the sheaves 3. The pillars 2 and sheaves 3 may be provided in advance at the construction site A, for example.

Each of the multiple sheaves 3 is attached, for example, to the upper end of each pillar 2. Also, the sheaves 3 may be attached to something other than the pillars 2. As an example, the number of sets of pillars 2, sheaves 3, wires 5, and winches 6 is four. However, the number of sets of pillars 2, sheaves 3, wires 5, and winches 6 is not limited and can be changed as appropriate as long as it is three or more. Also, instead of the example shown in FIG. 1, if the main body of the winch is provided at the top of the pillars 2, the sheaves 3 can be eliminated.

The pillars 2 are, as an example, H-shaped steel beams. However, the type of pillars 2 may be, for example, steel pipe pillars, and can be changed as appropriate. In a plan view, the multiple wires 5 extend from each sheave 3 into the area surrounded by the multiple pillars 2, and cross each other at the bundling point P. In addition, the multiple wires 5 extend diagonally downward from each sheave 3 toward the bundling point P due to the gravity of the work object T.

A work object T, which is a load, is suspended from the binding point P of the multiple wires 5 via, for example, a hook F and a string B. The work object T is, for example, a transport object (materials) to be transported at the construction site A. Note that the work object T is not limited to materials, but may also be an end effector of a robot, a camera that photographs the construction site A, or various inspection devices that inspect the construction site A, and the type of work object T can be changed as appropriate.

Figure 3 is a block diagram showing the functions of the parallel wire mechanism 1. As shown in Figures 1 and 3, each winch 6 is equipped with a motor 7 that winds up and unwinds each wire 5. By winding up and unwinding each wire 5 with each motor 7 of each winch 6, it is possible to move the work object T to a desired position within the area surrounded by multiple pillars 2.

The parallel wire mechanism 1 assists, for example, when a worker M applies force to a work object T to move it. For example, the parallel wire mechanism 1 includes multiple (e.g., four) sensors 11 provided for each wire 5, a control unit 10, and multiple winches 6 with built-in motors 7.

Each of the multiple sensors 11 measures the external force applied to the work object T. As the sensor 11, for example, a tension sensor that is provided on the sheave 3 and measures the tension of the wire 5 can be used. When using the sensor 11 that is a tension sensor provided on the sheave 3, it is possible to effectively use an existing tension sensor. The position of the sensor 11 may be near the sheave 3 or near the work object T (for example, the hook F). In addition, the external force applied to the work object T may be measured by a force sensor other than a tension sensor.

The control unit 10, for example, performs balancer control to control the movement of the work object T. Balancer control refers to control that gives virtual inertia, viscosity, and spring constant to the work object T, thereby changing the characteristics of the power assist for the work object T (for example, how light a force is required to move the work object T, and how quickly the movement of the work object T stops when the application of force to the work object T is stopped).

The control unit 10 controls the movement of the work object T, for example, by impedance control. Impedance control refers to a position and force control method for setting the mechanical impedance (inertia, viscosity, and spring constant) that occurs when an external force is applied to something to a desired value.

The control unit 10 measures the external force acting on the work object T using the sensor 11, calculates the behavior of the system including virtual inertia, viscosity, and spring constant when the external force is acting using an impedance model, and moves the work object T using the calculated values to achieve the desired impedance characteristics. Note that in this embodiment, the virtual inertia, viscosity, and spring constant calculated by impedance control may be the same as or different from the physical parameters of the work object T.

The control unit 10, as an example, includes a first calculation unit 12 that calculates a target position of the work object T, a second calculation unit 13 that calculates the unwinding length of each wire 5 for each motor 7, and an output unit 14 that outputs a command value for the unwinding length of the wire 5 calculated by the second calculation unit 13 to each motor 7. The first calculation unit 12 calculates virtual inertia, viscosity, and spring constant based on the force measured by the sensor 11 to calculate the target position of the work object T.

An exemplary calculation block diagram of the sensor 11, the first calculator 12, the second calculator 13, and the output unit 14 is shown in Fig. 4. In Fig. 4, τ _m indicates the measured tension of the wire 5, P _ref indicates the target output node position, f _ext,est indicates the estimated operating force, and L _ref indicates the target wire length. The sensor 11 measures, for example, the measured wire tension τ _m .

In this embodiment, the first calculation unit 12 calculates the force applied by the worker M to the work object T from the values of each sensor 11. At this time, the force due to the weight of the work object T (gravity) is cancelled by the following statics calculation. As a specific example, the first calculation unit 12 uses the measurement wire tension τ _m to perform statics calculation, dead zone processing, and calculation based on an impedance model to calculate a target output node position _Pref as a target position of the work object T. For example, the statics calculation by the first calculation unit 12 is performed by the following formula (1).

式（１）において、－ｆ_ｗｉｒｅはワイヤ駆動力（ワイヤ張力の合力）、Ｇは出力節の重力を示している。例えば、第１算出部１２による不感帯処理は下記の式（２）によって行われる。

In formula (1), -f _wire represents the wire driving force (resultant force of the wire tensions), and G represents the gravity of the output node. For example, the dead zone process by the first calculator 12 is performed by the following formula (2).

The first calculation unit 12 _{calculates the target position of the work object T as a target output node position Pref using impedance parameters (e.g., virtual mass M, virtual viscosity coefficient C, and spring constant K of the virtual spring) given in advance from the} estimated operating force _fext ,est applied to the work object T by the worker. The first calculation unit 12 may calculate a target velocity or target acceleration of the work object T instead of the target position of the work object T. When it is desired to move the work object T quickly according to the force applied by the worker M, it is preferable that the virtual viscosity coefficient C and the virtual mass M have as small values as possible. However, since the virtual viscosity coefficient C and the virtual mass M may cause vibration if they are too small, it is preferable that they have as small values as possible within a range where vibration does not occur. When it is not necessary to return to the original position when the force applied by the worker is removed, the spring constant K of the virtual spring is preferably 0.

The second calculation unit 13 calculates the target wire length L _ref of each wire 5 as the unwinding length of each wire 5 by inverse kinematic calculation from the calculated target output node position P _ref . The second calculation unit 13 may calculate the unwinding speed or unwinding acceleration of the wire 5 instead of the unwinding length of the wire 5. x1, x2, x3, and x4 in FIG. 5 respectively indicate the unwinding length x1 of the first wire, the unwinding length x2 of the second wire, the unwinding length x3 of the third wire, and the unwinding length x4 of the fourth wire among the four wires 5 suspending the work target T at the current position. As shown in FIG. 5, the second calculation unit 13 may calculate the unwinding length y1 of the first wire, the unwinding length y2 of the second wire, the unwinding length y3 of the third wire, and the unwinding length y4 of the fourth wire among the four wires 5 suspending the work target T at the target position.

The output unit 14 outputs a command value for the unwinding length of each wire 5 (for example, each of the aforementioned unwinding lengths y1, y2, y3, and y4) to each motor 7, which is the drive system. In this way, the output unit 14 outputs a command value for the unwinding length to each motor 7, and each wire 5 is unwound at a unwinding length based on the command value, making it possible to move the work object T to the desired position.

Next, the effects of the parallel wire mechanism 1 according to this embodiment will be described. As shown in Figs. 1 and 3, the parallel wire mechanism 1 includes a plurality of wires 5, a work object T connected to the plurality of wires 5, and a plurality of winches 6 provided on each of the plurality of wires 5 for unwinding and winding each of the wires 5. The work object T moves as the motor 7 in each winch 6 unwinds and winds each of the wires 5.

Therefore, the work object T can be moved by unwinding and winding each wire 5 within the area enclosed by the multiple wires 5, so that the work object T can be moved easily. In addition, the entire three-dimensional space formed by the multiple wires 5 can be the movable range of the work object T, so that the work object T can be moved over a wide range.

The parallel wire mechanism 1 only needs to be equipped with multiple wires 5 and multiple winches 6 each having a motor 7, and does not require heavy equipment such as a crane, guide rails, or arms, so the parallel wire mechanism 1 can be easily installed and rearranged. Therefore, by easily installing and rearranging the parallel wire mechanism 1 at a wide-area construction site A, the work object T can be moved easily over a wide area.

The sensor 11 measures the external force acting on the work object T, and the work object T can be moved based on the measured force, so the worker M can intuitively move the work object T by applying force to the work object T. Furthermore, in this embodiment, the work object T can be moved without applying the weight of the work object T to the floor surface of the construction site A, so it can be used even on a deck slab under construction where there is a limit on the load capacity.

Next, the parallel wire mechanism 1 according to the modified example will be described with reference to Figs. 6 and 7. Below, descriptions that overlap with the contents of the embodiment described above will be omitted as appropriate. The parallel wire mechanism 1 according to the modified example uses a potential method to restrict the movement of the work object T outside the movable range of the work object T and to avoid an obstacle W.

The potential method is one of the path derivation techniques, and by using the potential method, it is possible to change the force pushing back the work object T depending on the distance between the target position of the work object T and places where you do not want the work object T to approach, such as obstacles W and areas outside the above-mentioned range of motion. In the potential method, a potential function is defined for the target position and the position of obstacle W, and the gradient value of the potential function is increased as it approaches obstacle W, thereby deriving a movement path to the above-mentioned target position while suppressing approach to obstacle W. With the potential method, it is possible to change the path of the work object T in real time.

For example, in the parallel wire mechanism 1 according to the modified example, the first calculator 12 calculates the virtual stiffness by using the potential method. As an example, the first calculator 12 calculates a spring constant K as the virtual stiffness by using the following formula (3) according to the position of the work object T (the value of x below).

As described above, in formula (3), the spring constant K of the virtual spring may be 0 or a value other than 0 depending on the position of the work object T. In this way, by changing the spring constant K depending on the position of the work object T, it is possible to generate a spring force against the movement of the work object T. Therefore, when the work object T approaches an obstacle W, it is possible to generate a spring force that pushes the work object T back from the obstacle W.

As described above, in the parallel wire mechanism 1 according to the modified example, the first calculation unit 12 changes the spring constant K depending on the location of the work object T. Therefore, by changing the spring constant K when the work object T approaches a location where it is not desirable to approach, it is possible to make it difficult for the work object T to approach that location.

Furthermore, by changing the spring constant K, it is possible to generate a repulsive force that makes it difficult for the work object T to approach a preset movement limit area or an obstacle W, etc. As a result, even if the work object T attempts to approach the movement limit area or an obstacle W, etc. due to an operating error, etc., the repulsive force can prevent the approach, thereby improving the safety of work at construction sites.

In the above-mentioned modified example, a distance sensor may be mounted on the work object T, which measures the distance to the obstacle W in real time, and the obstacle W may be avoided based on the measurement result of the distance sensor. In this case, as in the above, the first calculation unit 12 changes the spring constant K depending on the location of the work object T, so that contact with the obstacle W can be avoided.

Next, a further modified parallel wire mechanism 1 will be described with reference to FIG. 8. This parallel wire mechanism 1 performs wide-area load reduction tracking control. That is, in this modified example, instead of the work object T, which is the suspended load described above, the movement of the work object V, which exerts a force on the floor C, is controlled. The work object V may or may not have a self-propelled function.

For example, concrete is poured on the floor C, and the work object V is a concrete finishing robot. As an example, the weight of the work object V is 200 kg. In this modified example, the binding points of the multiple wires 5 are provided on the work object V, and the parallel wire mechanism 1 reduces the load on the floor C. This work object V, like the work object T described above, can also move freely within the area formed by the multiple wires 5.

In the parallel wire mechanism 1 according to this modified example, the first calculation unit 12 calculates the target position of the work object V without canceling part of the force (gravity) due to the weight of the work object V when performing static calculations. As a specific example, when the weight of the work object V is 200 kg and the load on the floor C is reduced to 50 kg, 150 kg is canceled.

As described above, in the parallel wire mechanism 1 according to this modified example, the first calculation unit 12 calculates the target position of the work object V without canceling a part of the gravity of the work object V. Therefore, when the work object V is placed on the floor C (the ground or the floor surface, etc.), the first calculation unit 12 performs the calculation without canceling a part of the gravity of the work object V.

Therefore, since part of the gravity of the work object V is not cancelled, in a situation where it is desired to move the work object V placed on the floor C, part of the gravity of the work object V is applied to the floor C. As a result, the desired load can be applied to the floor C, and the load can be reduced by the required amount. For example, if the work object V is a concrete finishing robot, it is possible to apply only the load necessary for finishing to the top edge (surface) of the concrete after pouring, without applying all of the robot's own weight. This allows for a smooth finish without causing the top edge (surface) of the unhardened concrete to collapse due to a concentrated load of 200 kg (the robot's own weight).

The above describes the embodiments and modifications of the parallel wire mechanism 1 according to the present disclosure. However, the parallel wire mechanism according to the present disclosure is not limited to the embodiments or modifications described above, and may be modified or applied to other things without changing the gist of each claim. In other words, the configuration, function, shape, size, number and arrangement of each part of the parallel wire mechanism may be modified as appropriate without changing the gist of each claim.

For example, in the above embodiment, an example was described in which the work object T was suspended from the bundling point P of the multiple wires 5. However, the work object may be suspended at a location other than the bundling point of the multiple wires. In other words, the work object only needs to be connected to the multiple wires.

In the above embodiment, an example was described in which the parallel wire mechanism 1 was used to move the work object T at a construction site A where pillars 2 and sheaves 3 were installed. However, the configuration and type of the construction site in which the parallel wire mechanism according to the present disclosure is used can be changed as appropriate.

1...parallel wire mechanism, 2...pillar, 3...sheave, 5...wire, 6...winch, 7...motor, 10...control unit, 11...sensor, 12...first calculation unit, 13...second calculation unit, 14...output unit, A...construction site, B...string, C...floor, F...hook, K...spring constant, M...worker, P...binding point, T, V...work object, W...obstacle.

Claims (2)

A plurality of wires installed at a construction site;
a plurality of winches each provided on each of the plurality of wires and each having a motor for winding and unwinding the wire;
a work object connected to the plurality of wires and supported by the plurality of wires;
A sensor for measuring a force applied to the work object;
a first calculation unit that calculates at least one of a virtual inertia, a virtual viscosity, and a virtual spring constant based on the force measured by the sensor, and calculates at least one of a target position, a target velocity, and a target acceleration of the work object;
a second calculation unit that calculates, for each motor of each winch, at least one of an unwinding length, an unwinding speed, and an unwinding acceleration of each of the wires for moving the work object at at least one of the target position, the target speed, and the target acceleration;
an output unit that outputs at least one command value of the unwinding length, the unwinding speed, and the unwinding acceleration to the motor of each of the winches;
Several pillars and
a plurality of sheaves attached to each of the plurality of posts;
The plurality of winches are located at the lower part of each of the plurality of columns, and the plurality of wires extend upward from each of the winches and are stretched over the sheaves ,
The first calculation unit calculates a spring constant K as virtual stiffness by using the following equation (3) in accordance with the position of the work object (the value of x below):
Parallel wire mechanism. A plurality of wires installed at a construction site;
a plurality of winches each provided on each of the plurality of wires and each having a motor for winding and unwinding the wire;
a work object connected to the plurality of wires and supported by the plurality of wires;
A sensor for measuring a force applied to the work object;
a first calculation unit that calculates at least one of a virtual inertia, a virtual viscosity, and a virtual spring constant based on the force measured by the sensor, and calculates at least one of a target position, a target velocity, and a target acceleration of the work object;
a second calculation unit that calculates, for each motor of each winch, at least one of an unwinding length, an unwinding speed, and an unwinding acceleration of each of the wires for moving the work object at at least one of the target position, the target speed, and the target acceleration;
an output unit that outputs at least one command value of the unwinding length, the unwinding speed, and the unwinding acceleration to the motor of each of the winches;
Several pillars and
a plurality of sheaves attached to each of the plurality of posts;
The plurality of winches are located at the lower part of each of the plurality of columns, and the plurality of wires extend upward from each of the winches and are stretched over the sheaves ,
the first calculation unit calculates any one of the target position, the target velocity, and the target acceleration by canceling the gravity of the work object;
The first calculation unit performs the calculation without canceling a part of the gravity of the work object,
The work object is a concrete finishing robot.
Parallel wire mechanism.

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