KR100478396B1 - Controller for hoist arrangement - Google Patents

Abstract

A human power amplifier assist device (10) includes an end-effector (14) tha t is grasped by a human operator and applied to a load (25). The end-effector (14) is suspended, via a line (13), from a take-up pulley (11), winch or dru m that is driven by an actuator (12) to lift or lower the load (25). The end- effector (14) includes a force sensor (31) that measures the vertical force imposed on the end-effector (14) by the operator and delivers a signal to a controller (20). The controller (20) and actuator (12) are structured in suc h a way that a predetermined percentage of the force necessary to lift or lowe r the load (25) is applied by the actuator (12), with the remaining force bein g supplied by the operator. The load (25) thus feels lighter to the operator, but the operator does not lose the sense of lifting against both the gravitation and inertial forces originating in the load (25).

Description

Controller for Hoist Device {CONTROLLER FOR HOIST ARRANGEMENT}

This application is directed to U.S. Provisional Application No. 60 / 134,002, filed May 13, 1999, U.S. Provisional Application No. 60 / 146,538, filed July 30, 1999 and U.S. Patent Application, July 30, 1999 Priority is claimed on provisional application 60 / 146,541, which is incorporated herein by reference.

The present invention relates to a material handling apparatus for lifting and lowering loads by a worker's manpower.

The apparatus described herein is different from the conventional material handling apparatus used by automated assembly and warehouse workers. Conventional devices include three types of material handling devices currently available on the market.

A material handling device of the kind called balancer consists of an electric winding pulley, a string wound around the pulley as the pulley rotates, and an end-effector attached to the end of the string. The end effector has a part that is connected to the article to be pulled up. As the pulley rotates, the rope is wound or unrolled to raise or lower the load connected to the end effector. In this kind of material handling system, the actuator generates a pulling force on the string equal to the gravity of the object being pulled so that the tension is in line with the weight of the object. Therefore, the only force that the operator must apply for the movement of the object is the acceleration force of the object. This force can be quite large if the weight of the object is large. Therefore, acceleration and deceleration of heavy objects are limited by the force of the operator.

There are two ways to tension a string so that it is exactly balanced with the weight of the object. First, when the system is operated at pneumatic pressure, the air pressure is adjusted so that the pulling force is in balance with the weight of the load. Secondly, when the system is electrically operated, an appropriate amount of voltage is provided to the amplifier so that the pulling force is balanced with the weight of the load. The statically set tension of the balancer is not easy to change in real time, so this kind of system is not suitable for moving objects of varying weight. This is because each object needs a different deflection force to offset its gravity. This is cumbersome because the operator must manually adjust the weight of the object or weigh it. For example, pneumatic balancers made by Zimmerman International Corporation or Knight Industries are based on this principle. The air pressure is set and controlled by the valve to maintain a constant load balance. The operator manually accesses the actuator and sets the system to the desired pressure so that a constant tension is produced in the cord. Scaflia's LIFTRONIC system machine is also a balancer, but it works electrically. When the system picks up the load, the LIFTRONIC machine gives the rope the same pulling force in the opposite direction as the weight of the object caught. This machine is superior to Zimmerman pneumatic balancers because it has an electronic circuit that initially balances the load when it is picked up by the system. Thus, the operator does not have to approach the actuator and adjust the initial tension of the string. In such a system, the weight of the load is first measured by the force sensor of the system. During these measurements, the operator should not touch the load and instead allow the system to determine the weight of the object. If the operator touches an object, measuring the tension becomes inaccurate. This causes the LIFTRONIC machine to give the rope an unequal pulling force in the opposite direction to the weight of the object caught. Unlike the auxiliary device of the present application, the balancer does not allow the worker to physically feel the force required to lift the load. Also, unlike the device of the present application, the balancer only offsets the gravity of the object at the tension of the string and is not versatile enough to be used when the load is heavy.

The second type of material handling device is similar to the balancer described above, but the operator adjusts the rate of rise and fall of the object being moved using an intermediary device such as a valve, push-button, keyboard, switch or teach pendant. do. For example, if the operator opens the valve more, the lifting speed of the object becomes higher. By using the intermediary device, the operator does not have physical contact with the load to be raised, but is cumbersome to operate the valve or the switch. The worker does not know how much he raises because his hand is not in contact with the object. Although suitable for lifting objects of varying weights, this type of system is not convenient for the operator since the operator must concentrate on the intermediate device (ie valve, push-button, keyboard or switch). The operator therefore has to concentrate more on the operation of the intermediary device than on the speed of the object, which makes the impression manipulation unnatural.

The third kind of material handling apparatus uses an end effector with a force sensor or a motion sensor. Such a device measures the force or motion of an operator and changes the speed of the actuator based on it. An example of such a device is US Pat. No. 4,917,360 to Yasuhiro Kojima. By using such and similar devices, the pulley rotates to raise the load when the operator pushes the end actuator upwards, and the pulley rotates to lower the load when the operator pushes the end actuator downward. Problems arise when the operator pushes the end effector downwards to engage the suction cup, which the controller and actuator understand this to lower the load. This causes the actuator to rotate to loosen the line more than necessary, causing "slack" in the line. Hereinafter, the term "slack" is understood to be the excess length of the string, but not to be construed to include the case where the string is not only fully taut. Slack cords can be wound around the operator's neck or hands. After slack has occurred in the rope due to this or other circumstances, the worker may press the handle upwards and the strap may be wound close to the operator's neck or hand to cause fatal injury. Slack may occur even when a suction cup is not used as a means of holding a load, and it is important to prevent slack at all times for safety. During fast movement, the operator may accidentally lift the load or touch the bottom of the end effector to place it on a peripheral device (eg conveyor belt). In pallet work, the operator uses the bottom of the end effector very often to finely adjust the position of the box that is difficult to place in place. This phenomenon causes a slack in the string because the operator pushes the end actuator downward to adjust the position of the box, where the end actuator is restricted from moving downward. In general, slack in strings can be dangerous for workers and other identical working environments. In the manual material handling apparatus of the present invention, no slack occurs in the string.

This type of force sensor device also does not allow the operator to actually feel the weight of the load being lifted. This can make the movement of goods unnatural and dangerous.

The auxiliary device of the present invention solves the problems described above with respect to three kinds of material handling devices. The hoist of the present invention is designed to provide an end tension between the operator, an actuator such as an electric motor, a computer or other type of controller for controlling the actuator, and a tension between the cord, cable, chain, rope, wire or actuator and the end actuator. Contains a different kind of line for passing. Hereinafter, the term "impression" should be understood to include the movement of both the up and down of the article. The end effector provides an interface between the operator and the object to be raised. Force transmission mechanisms, such as pulleys, drums or winches, are used to apply the force generated by the actuator to the string that transmits the pulling force to the end effector.

A signal indicative of the vertical force exerted on the end effector by the operator and measured by the sensor is transmitted to a controller associated with the actuator. In operation, the controller causes the actuator to properly rotate the pulley and move the end effector so that the operator only lifts a small, pre-programmed portion of the load while the remaining force is provided by the actuator. The actuator therefore assists the operator during the hike movement in response to the force of the operator's hand. The tension of the cord is also detected or measured, for example by the energy or current consumed by the actuator. Also, because load loading is the main factor in determining the magnitude of tension, load loading can be used to approximate the tension and vice versa. Hereinafter, it should be understood that the tension can be calculated using the load and the load can be calculated using the tension. A signal indicative of the load or string tension is transmitted to the controller, which uses the load load signal or tension signal to effectively drive the actuator according to the operator's input. This can, for example, prevent the actuator from releasing the string in the event of a zero load or tension, so that no slack (as defined above) occurs on the string even if the string is loose (i.e. not taut). do.

By this bag sharing concept, the worker has a feeling of lifting the load but is much smaller than the normally required force. The force exerted by the actuator takes into account both the gravity and the inertia forces required to move the load. Since the force exerted by the actuator is automatically determined by the force of the joule and the force exerted on the end effector by the operator, there is no need to set or adjust the attraction amplifier for loads of different weight. The attraction amplifiers do not have switches, valves, keyboards, teach pendents or push-buttons to control the lifting speed of the load. The contact force between the end effector handle coupled with the operator's hand and string force is used to determine the speed of pulling up the load. The force of the operator's hand is measured and used by the controller in cooperation with the force of the rope, giving the required angular velocity of the pulley to raise and lower the rope, thereby providing sufficient mechanical strength for the worker working on the lifting. In this way, the device follows the operator's arm movement in a "natural" manner. When an operator uses these devices to handle a load, an appropriately defined portion of the total load (sum of gravity and acceleration) is lifted by the operator. This force allows the operator to feel how much weight is lifting. Conversely, if the operator does not apply any vertical force (up or down) to the end effector handle, the actuator does not rotate the pulley at all and the load hangs without moving on the pulley.

Although the conventional apparatus described above raises a load, these apparatuses

Do not let the worker feel the impression movement physically,

Does not compensate for inertia,

No compensation for various loads,

Does not address ergonomic concerns,

It does not prevent slack in the line.

The device of the present invention does not have the above disadvantages.

1 shows a first embodiment of the present invention, which shows a human power amplifier 10. A winding pulley 11 driven by an actuator 12 is mounted directly on the ceiling, wall or overhead crane at the top of the device. A string 13 is wound around the winding pulley 11. When the pulley 11 is rotated, the rope 13 can raise or lower the article 25. The string 13 can be wound around the pulley to provide the force to raise the load, which can be any type of wire, wire, cable, belt, rope, wire string, cord, twist, string or other member. have. The row 13 has an end-effector 14 comprising a human interface subsystem 15 comprising a handle 16 and a load interface subsystem 17. Is attached, and in this embodiment this end effector 14 comprises a pair of suction cups 18. Moreover, the suction cup 18 is provided with the air hose 19 which supplies low pressure air.

In a preferred embodiment, the actuator 12 may be replaced by an electric motor with a transmission or an electric motor without a transmission. In addition, actuator 12 may be powered using other types of energy, including pneumatic, hydraulic, and other alternative forms of energy. As used in this embodiment, the transmission is a mechanical device such as a pulley and a string that increases or decreases the tensile force of the string. The pulley 11 may be replaced by a drum, winch or other mechanism capable of converting the movement provided by the actuator 12 into a vertical movement that raises or lowers the rope 13. In this embodiment, the actuator 12 powers the winding pulley 11 directly, but the winding pulley 11 is mounted at another position of the actuator 12 and powered through other transmission systems such as chain and sprocket assemblies. It may be delivered to the winding pulley (11). The actuator 12 is driven by the electronic controller 20 which receives a signal from the end effector 14 via the signal cable 21. Since there are several ways of transmitting electrical signals, the signal cable 21 can be replaced with other alternative signal transmission means (e.g. RF, light, etc.). In a preferred embodiment, the controller 20 essentially includes the following three main components.

1. Computers, analog or digital circuits with input / output capability and standard peripherals. The controller's function in this area is to process the information received from the various sensors and switches to generate a command signal to the actuator.

2. A power amplifier that transmits power to the actuator based on the computer's instructions. Typically, this power amplifier receives power from a power supply and delivers the right amount of power to the actuator. The amount of power supplied by the power amplifier to the actuator 12 is determined by the command signal calculated by the computer.

3. Logic circuit consisting of an electromechanical relay or a solid state relay that starts and stops the system according to a series of possible events. For example, a relay uses two push buttons installed on a controller or end actuator to start and end the operation of the entire system. This relay engages a friction brake in the event of a power failure or operator left the system.

The operator interface subsystem 15 is designed to measure the force of the operator, that is, the force exerted on the operator interface subsystem 15, by the operator. The load interface subsystem 17 is designed to be in contact with the load and to accommodate various holding devices. The design of this load interface subsystem depends on the load geometry and other factors related to the pulling behavior. In addition to the suction cup 18 shown in FIG. 1, hooks and grippers connected to the load interface subsystem are examples of other means. When lifting a heavy object, this article interface subsystem may include two or more suction cups.

The operator interface subsystem 15 of the end actuator 14 includes a sensor (described below) that measures the amount of vertical force exerted by the operator. If the operator's hand pushes the handle 16 upwards, the winding pulley 11 moves the end actuator 14 upwards. If the operator's hand pushes the handle 16 downward, the take-up pulley moves the end effector 14 downward. The measured hand force of the operator is transmitted to the controller 20 via the signal cable 21 (or other replaceable signal transmission means). The system of the preferred embodiment of the present invention also includes a sensor disposed proximate to the end actuator 14 while an operator-applied force that is not proximate to the end actuator 14 for estimating operator attraction. Estimation components may be used.

Using these measuring devices, the controller 20 assigns a pulley speed necessary to raise or lower the string 13 which generates enough mechanical force to assist as necessary for the operator's pulling operation. The controller 20 then supplies power to the actuator 12 via the power cable 23 to cause the pulley 11 to rotate. All of these actions take place so quickly that the operator's attempts to raise and the device's attempts to happen at the same time occur completely simultaneously. Thus, the physical movement of the operator is changed to the physical assistance of the mechanism, and the force of the mechanism is controlled directly and simultaneously by the operator. In summary, the load moves vertically because both the worker and the pulley move vertically. One of the most important characteristics of the device according to the invention is that the end effector rotates the actuator and pulley according to the hand movement of the operator up and down, and the movement of the end effector downward is restricted and the end effector is moved downward by the operator. The line does not loosen even if it is pushed.

A dead-man switch with a lever 26 on the handle 16 (described below) sends a signal to the controller 20 via a signal cable 22 (or other alternative signal transmission means). do. When the operator is holding the handle 16, the deadman switch transmits a logic signal to the controller 20 that causes the end effector to move along the operator's hand. When the operator releases the handle 16, the deadman switch transmits another logic signal to the controller 20 that causes the end effector to remain stationary. In a preferred embodiment of the invention, a friction brake 24 is installed on the actuator 12. This friction brake always engages when the operator releases the deadman switch or a power failure occurs. It is possible to use an end effector with two handles, but only one of them needs to be installed as a sensor for measuring the operator's action. When lifting a heavy object, two attraction amplifiers similar to the attraction amplifier 10 shown in FIG. 1 can be used, one for the left hand and the other for the right hand.

First, the architecture of two types of end effectors will be described in detail in consideration of the force measurement of the operator. The control algorithm then considers the operation of the system and the prevention of line slack. A flowchart is also given to illustrate the implementation of this control algorithm.

Two types of end effectors are described here. 2 is an example of an end effector 31 which measures the force of a person via a force sensor. The force sensor 31 is installed between the handle 32 and the bracket 33 and is connected to the controller 20 via the signal cable 21. The force sensor 31 has a threaded portion 34 that is screwed into the bore in the handle 32 that the operator grabs. The opposite side of the force sensor 31 is connected to the bracket 33 via the cylinder 35. The outer diameter of the cylinder 35 is slightly smaller than the inner diameter of the handle 32. This clearance enables the sliding action between the handle 32 and the cylinder 35 and is transmitted to the force of the operator in the vertical direction and to the bracket 33 and transmitted to the force sensor 31 without any resistance. The sensor 31 ensures the operator's force in a non-vertical direction that is not transmitted. If a force other than the vertical direction is transmitted to the force sensor 31, it may cause a false reading of the sensor or damage of the force sensor assembly.

The present invention solves the problems of not allowing the worker to feel the impression movement physically, compensating the inertia force, without compensating for various load loads, not dealing with ergonomic interests, and preventing slack in the strings. .

1 shows an embodiment of an attraction amplifier comprising an end effector according to the invention.

FIG. 2 is a cross-sectional view of one embodiment of an end effector usable in the present invention, showing a particular structure of a force sensor measuring force of an operator. FIG.

3 is a cross sectional view of one embodiment of another end actuator including a displacement detector for measuring a force exerted on the end actuator by an operator;

4 is a perspective view when the end effector of FIG. 3 is used to lift a box by an operator;

5 is a block diagram showing the force and load of a worker interacting with a component of the attraction amplifier to move the load.

FIG. 6 illustrates the problem of slack in strings that may occur in the prior art using suction cups to grasp the box.

FIG. 7A is a partial cross-sectional view of one embodiment of an end actuator including a displacement detector for measuring the force exerted by the operator on the end actuator and a force sensor for measuring the tension of the string; FIG.

FIG. 7B is a partial cross-sectional view of one embodiment of an end actuator including a displacement detector for measuring the force exerted on the end actuator by a worker and a force sensor for measuring the force associated with the weight and acceleration of the load only; .

8 schematically illustrates the use of a force sensor that can be used to measure the total force exerted on a ceiling or overhead crane by the attraction amplifier.

9 shows schematically an embodiment of an actuator comprising a mechanism for measuring the tension of a string and a motion sensor.

10A and 10B are partial cross-sectional views illustrating one embodiment of an end actuator including a displacement detector for measuring the force exerted by the operator on the end actuator and a mechanism for detecting the tension of the string.

11A and 11B illustrate an embodiment of an actuator including a switch and a mechanism for detecting the tension of a string.

12A and 12B illustrate an embodiment of an end actuator comprising a displacement detector for measuring a force exerted on the end actuator by an operator and a switch that transmits a signal when the end actuator is constrained to move downward; Drawing showing.

FIG. 13 illustrates the use of a clamp-on current sensor that can be used to detect the current consumed by an actuator. FIG.

FIG. 14 is a block diagram showing the force and load of a worker interacting with a component of the attraction amplifier to move the load while the slack of the string is prevented.

15A, 15B, 15C, and 15D are graphs showing control variable K _M values as a function of tension in hoist strings.

FIG. 16 illustrates one embodiment of an attraction amplifier that prevents slack in the string even when the end actuator is pressed down by an operator while the end actuator is restricted from moving downward;

FIG. 17 is a block diagram showing the force and load of an operator used as a feedback signal for moving the load while the slack of the string is prevented.

18A and 18B are flowcharts of software that can be used to drive a controller in practicing the present invention.

Claims (17)

In the controller for a hoist device, The controller receives, among other signals, a first electrical signal indicative of the force of the operator on the end effector connectable to the rope supporting the load and wound on the pulley, and a second signal indicative of the tension of the string. And an output terminal for controlling the rotational speed of the pulley as a function of a second signal. Controller for hoist device. The method of claim 1, The rotational speed of the pulley is a function of both the first signal and the second signal causing the end effector to follow the hand movements of the operator when the end actuator is not restricted to move downward. Controller for hoist device. The method of claim 1, And said controller is said second signal indicates that the tension of said string is zero and stops said pulley when said end effector is pressed down by an operator. The method of claim 1, The controller reduces the rotational speed of the pulley to prevent slack from occurring in the string when the second signal indicates a decrease in tension of the string when the end actuator is pressed down by an operator. Controller for hoist device. The method of claim 1, And the controller applies an upward deflection force to the string to raise the end effector. The method of claim 1, The output signal generated by the controller is such that the rotational speed of the pulley becomes zero when the first signal indicates the downward movement of the operator and the second signal indicates that the tension of the string is zero. A controller for a hoist device. The method of claim 1, The second signal indicates that the tension of the string is zero and the first signal indicates that the ascending speed command signal from the controller causes the tension of the string not to be zero when the operator intends to move upwards. A controller for a hoist device. The method of claim 1, When the end effector is not restricted to move downwards and the second signal indicates that the tension of the string is not zero, the output signal generated by the controller indicates that the end effector is operated by the operator according to the hand operation of the operator. And any increase or decrease in downward force results in an increase or decrease corresponding to the rate of descent of the end effector for a given load. The method of claim 1, If the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, the output signal generated by the controller causes the end effector to follow the hand movements of the operator. The increase or decrease of the load weight causes a decrease or increase corresponding to the rising speed of the end effector and an increase or decrease corresponding to the lowering speed with respect to the operator's force given on the end effector. Controller for hoist device. The method of claim 1, If the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, the output signal generated by the controller causes the end effector to follow the hand movements of the operator. The increase or decrease in the weight of the cargo requires a corresponding increase or decrease in the upward force of the operator and a corresponding decrease or increase in the downward force given to the end effector to maintain the speed of a given end effector. Hoist device controller, characterized in that. The method of claim 1, When the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, the speed command signal e generated by the controller is in the form of e = K (ff _up ). Where f is the first signal indicative of the force exerted by the operator, f _up is a constant, and K is the increase or decrease corresponding to the descending speed of the end effector for a given article given an increase or decrease in the downward force of the operator. A controller for a hoist device, characterized in that it is a transfer function selected to produce a. The method of claim 1, When the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, a speed command signal is generated by the controller as a function of the first and second signals, As the actuator rotates to cause the end effector to follow the hand movements of the operator, an increase or decrease in the weight of the load causes a decrease or increase corresponding to the rising speed of the end effector for a given operator force, at which time Increases or decreases requires increasing or decreasing corresponding to the upward force of the operator given on said end effector to maintain the speed of a given end effector. The method of claim 1, If the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, the output signal generated by the controller is e = K (ff _up ) + Q (f _R Where e is the output signal, f is the first signal representing the force of the operator, f _up is a constant, f _R is the signal representing the tension of the joule, and K and Q are the Wherein the increase or decrease is a transfer function selected to cause an increase or decrease corresponding to the rate of descent of the end effector for a given load. The method of claim 1, If the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, then the output signal is determined according to the formula e = K (ff _up ) + Q (f _R ). Generated by the controller, where e is the output signal, f is the first signal representing the force of the operator, f _up is a constant, f _R is the signal representing the tension of the joule, and K and Q are the increase in downward force of the operator Or a reduction function is a transfer function selected to cause an increase or decrease corresponding to the rate of descent of the end effector for a given load. The method of claim 1, If the end effector is not restricted to move downwards and the second signal indicates that the tension of the string is not zero, the output signal generated by the controller is e = K (ff _up ) + Q (P _L Where e is an output signal, f is a first signal representing the force of the operator, f _up is a constant, P _L is a second signal representing the force exerted on the end effector by a load, And K and Q are transfer functions wherein the increase or decrease of the downward force of the operator is selected to cause an increase or decrease corresponding to the rate of descent of the end effector for a given load. The method of claim 1, If the end effector is not restricted to move downward and the second signal indicates that the tension of the string is not zero, then the output signal is determined according to the formula e = K (ff _up ) + Q (f _R ). Generated by the controller, where e is an output signal, f is a first signal representing the force of the operator, f _up is a constant, P _L is a second signal representing the force exerted on the end effector by load, and K and Q are the transfer functions wherein the increase or decrease of the load weight is selected to cause an increase or decrease corresponding to the upward force of the operator to maintain the speed of a given end effector. The method of claim 1, The estimated tension is calculated by the formula f _R = [K _T I- (I _P α + B _P ω + T _O )] / R, where f _R is the tension of the string and I _P is all rotating parts of the actuator And the total moment of inertia of the pulley on the motor shaft, B _P is the total friction coefficient of the rotating parts and pulley of the actuator, α is the angular acceleration of the motor drive shaft, ω is the angular velocity of the motor drive shaft, K _T is the current consumed by the actuator 1 Actuator torque for amps, T _O is a constant torque due to Coulomb friction in the actuator and pulley, and R is the radius of the pulley.