KR100447907B1 - Force feedback device using hydraulic cylinder - Google Patents

Abstract

The present invention relates to a force reflecting mechanism used in a master device for teaching a teaching object such as a robot, etc., which includes a load adding means for applying a load by a fluid to an operating means operating by a force applied by a user, and A force measuring means for measuring the force acting on the operating means, a fluid load adjusting means for adjusting the magnitude of the fluid load applied by the load adding means, and a mechanism for measuring the force acting on the operating means by the user. Compared with a predetermined reference load determined by the force acting on, and if there is a difference, the output of the load adding means for canceling the difference is calculated, and the adjustment value of the fluid load adjusting means according to the calculated output Comprising a control means for calculating and adjusting the fluid load control means accordingly.

Such a force reflecting mechanism can be configured to be smaller and lighter than a conventional force reflecting mechanism by using a hydraulic device. Therefore, the force reflecting mechanism is also suitable for applications requiring small size and light weight, such as a garment type master apparatus, and improves adaptability to external environments. Can be.

Description

Force reflection mechanism using hydraulic cylinder {FORCE FEEDBACK DEVICE USING HYDRAULIC CYLINDER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force feedback mechanism, and more particularly, to a master device that teaches a teaching object such as a robot in a remote location or a virtual space or in a location that is difficult for humans to access. It relates to a mechanism for feedback (feedback) of the user to manipulate the teaching master-device).

Remote teaching devices, such as master devices, use force reflection mechanisms to increase adaptability to the external environment. These force reflection mechanisms must be able to exert enough force to constrain the movement of a person. In the conventional force reflecting mechanism, an actuator, an electric motor, an electric brake, or the like is usually configured.

Structures using electric motors are relatively bulky, heavy and consume a lot of power, making them inadequate for portable use. The use of electric brakes also makes the system more stable, but it is not suitable for systems that require lighter weights, such as garment-type master devices, because they are bulky and heavy systems such as motors.

Force reflecting mechanisms using actuators connect the actuators directly or use force transmission structures such as wires, gears or links.

Such actuators and electric brakes have a small output per weight and volume, so that the weight and volume of the force reflecting device are increased to burden the wearer to obtain an appropriate output. In addition, the force reflecting mechanism including a force transmission structure such as a gear or a link is less efficient than the mechanism for directly transmitting power and has a backlash due to the characteristics of the mechanism, and its weight cannot be ignored. Has

The present invention solves the problems of the prior art as described above, and is suitable for applications requiring small size and light weight, such as a suit-type master device, and a load sufficient to restrain human movement. Its main purpose is to provide a force reflecting mechanism that can be applied.

1 is a schematic diagram of a force reflecting mechanism according to an embodiment of the present invention.

2 is a schematic diagram showing a valve opening and closing operation of a hydraulic cylinder.

Figure 3 is a schematic diagram of a force measuring device for measuring the force acting on the operating means by the user using the micro displacement.

4 is a control conceptual diagram of the force reflecting mechanism of FIG.

5 is a schematic diagram showing an example in which the force reflecting mechanism of the present invention is applied to a linear system.

<Explanation of symbols for the main parts of the drawings>

1: cylinder

2: sensor

3: cylinder shaft

4: spring

5: load shaft

10, 31: 1st hydraulic chamber

11, 32: 2nd hydraulic chamber

12, 33: movable bulkhead

14, 34: Euro

15, 24: magnet

16, 25: Hall sensor

20: spool

21: gear

22: pinion

23: motor

The force reflecting mechanism according to the present invention includes a plurality of hydraulic chambers, a partition wall partitioning a plurality of hydraulic chambers so as to be movable, a plurality of hydraulic chambers through a flow path by a flow path for communicating the plurality of hydraulic chambers and the partition walls. A hydraulic cylinder comprising a fluid flowing therebetween; Load adjusting means for generating a load in the hydraulic cylinder and controlling the same by changing the cross-sectional area of the flow path to change the flow resistance of the fluid; A load shaft which is operated by a force applied by a user; Force measuring means for measuring a force applied to the load shaft; A cylinder shaft which connects the partition wall and the load shaft, moves the partition wall in conjunction with the load shaft, and transmits a resistance force to the load shaft according to the magnitude of the load in the hydraulic cylinder; The measurement of the force exerted by the user on the load shaft is compared with a predetermined reference load determined by the force applied to the mechanism remotely controlled from the outside, and the load in the hydraulic cylinder required to offset the difference is calculated accordingly. It is composed of a control unit for controlling the adjusting means.

The load regulating means includes a valve for opening and closing the flow path to vary the flow resistance of the fluid, a driving part controlled by the controller and operating the valve, and a sensor for measuring the opening and closing amount of the valve.

The force reflecting mechanism further includes a sensor for measuring displacement of the cylinder shaft, and the controller determines the opening / closing amount of the valve from a function relationship between the displacement measurement value of the cylinder shaft and the required load in the hydraulic cylinder calculated by the controller.

The force measuring means includes one or more springs coupled to both ends of the load shaft and the cylinder shaft, and a sensor for measuring the displacement of the spring and transmitting a corresponding signal to the controller.

The present invention will be described in detail through the embodiments shown in the accompanying drawings.

1 is a schematic diagram of a force reflecting mechanism according to an embodiment of the present invention. For example, the force reflecting mechanism is applied to the rotation system for the sake of simplicity. A sensor 1 for measuring the rotational speed of the cylinder shaft 3 of the cylinder 1 is coupled to a cylinder 1 having a closed flow path, and a load shaft is coupled to the other end to which the cylinder shaft 3 is exposed. (5, see Fig. 3) is combined. A valve is provided on the closed flow path of the cylinder 1 to interrupt the fluid flow, and may transmit a force due to the interruption of the fluid flow to the cylinder shaft 3. Therefore, the rotational force by the user and the fluid load by the hydraulic cylinder act on the load shaft 5.

2 is a schematic diagram showing a valve opening and closing operation of a hydraulic cylinder having a closed flow path. The hydraulic cylinder divides the first hydraulic chamber 10, the second hydraulic chamber 11, the first hydraulic chamber and the second hydraulic chamber, and is movable partition 12 fixed to the cylinder shaft 3, the first hydraulic chamber and the second hydraulic chamber. And a flow path 14 for connecting the hydraulic chamber, and the hydraulic cylinder includes a spool 20 for intermittent flow paths, a drive gear 21 for moving the spool 20, a drive motor 23, and positions of the spools. A load regulating means composed of a magnet 24 and a linear Hall sensor 25 for measurement is installed. The spool 20 for interrupting the closed flow path is coupled in a screw form to enable rotational and translational movement with respect to the outer frame 13 and has a gear 21 attached thereto. The gear 21 is driven by the pinion 22 attached to the motor 23 to move the spool 20.

Fig. 2 (a) shows a state where the load is the smallest when the valve is completely opened, and Fig. 2 (b) shows a state where the cylinder shaft 3 is fixed because the valve is completely shut off.

When the cylinder shaft 3 is rotated by the force acting by the user, the fluid moves from the first hydraulic chamber to the second hydraulic chamber or from the second hydraulic chamber to the first hydraulic chamber according to the rotation direction. At this time, when the spool 20 is moved to change the cross-sectional area of the flow path, the flow rate changes and a pressure difference occurs between the first hydraulic chamber and the second hydraulic chamber, thereby generating a resistance torque in the cylinder shaft 3 with respect to the movement direction. As shown in Fig. 2 (b), when the flow path is completely blocked, the fluid can no longer flow and the maximum brake torque occurs.

The moving structure of the spool can be configured in various ways, for example, a direct driving method using a shape memory alloy, a voice coil, a linear motion motor, or the like may be used.

In the example shown, the gear 21 is attached with a magnet 24 so that the displacement of the spool 20 can be measured through the Hall sensor 25. In addition, direct measurement of the spool using a laser distance measuring device, an eddy current type distance measuring sensor, and an indirect measuring method of measuring the rotational amount through the Hall sensor of the magnetic index attached to the gear is possible. .

The force transmitted by the cylinder shaft 3 appears in a form proportional to the rotational speed of the cylinder shaft and the valve opening / closing amount, but this alone does not sufficiently convey a feeling of contact with the external environment of the remote robot to the user. Thus, the force measuring means by the micro displacement shown in Fig. 3 can be used to measure the force acting on the load shaft 5. As shown in FIG. 3, one end of the spring 4 is connected to the cylinder shaft 3 and the other end of the spring 4 is connected to the final output end of the load shaft 5.

As a contact analysis method between the object and the contact object, conventional spring-damper modeling may be used to calculate the relationship between the small displacement between the object and the contact object and the force applied to the contact object. At this time, the spring constant K and the damping constant C are determined according to the material of the object and the contact object.

According to the present invention, the spring-damper dynamics at the time of contact between the remote robot and the object are appropriately corresponded to each of the spring 4-hydraulic damping of the force reflecting mechanism, thereby making it possible to actually express the contact.

Figure 3 (a) is a no-load state and (b) shows that a micro displacement occurred due to the load applied by the user. Micro-relative motion between the cylinder shaft 3 and the load shaft 5 can be generated by the tension compression of the spring 4 connecting the cylinder shaft 3 and the load shaft 5. Coil springs or leaf springs may be used as the springs connected to the load end and may be directly or indirectly attached to the load end.

The generated micro displacement is measured by the magnet 15 fixed to the load shaft 5 and the hall sensor 16 fixed to the cylinder shaft 3. Load measurements can be made in a variety of ways, for example direct or indirect measurement methods such as the use of torsion bars and strain gauges. The measured small relative displacements can be converted into forces by a generally known relationship between the forces and the displacements, which enables the measurement of the forces added by the actual user and the feedback control structure for the forces.

The feedback control structure for this force is that the contact force is generated when the slave robot in the real or virtual space starts to contact the object, and the force begins to increase as the robot enters the object. The measured or calculated force at this time is the reference force. It is the purpose of feedback control to express the signal of the user's motion as a signal that it is dangerous for the user to move the robot further to stop the robot at the appropriate moment. When the reference force is input to the controller, the rotational speed of the cylinder is sensed, and the position of the spool is calculated by a table or an empirical formula and controlled by a motor. When the spool is locked, the cross-sectional area of the flow path is reduced to make the user feel resistance. At this time, additional rotational displacement is generated in the micro displacement spring of FIG. 3, and the difference between the force applied by the user and the resistance torque acting on the cylinder shaft 3 is determined. It can be measured and fed back to compensate for the spool's position again.

The required load torque can be adjusted by controlling the opening / closing amount of the valve with the opening / closing adjustment actuator using the torque value measured by the force measuring device. The control concept of this force reflecting mechanism is shown in FIG. Adjust the force reflection sensitivity by adding an appropriate gain to the feedback torque value. Control of the opening and closing amount of the valve in the control unit may be performed by modeling the closed flow path system as a damper. The output load of the force reflecting mechanism is a difference between the required load and the frictional force of the mechanism itself, which is calculated by multiplying the damping coefficient determined by the opening and closing amount of the valve and the rotational speed measured by the cylinder shaft rotational speed sensor. . That is, a table or equation of the damping coefficient for the valve opening and closing amount can be prepared to inversely determine the valve opening and closing amount based on the required load and the measuring speed of the cylinder shaft, thereby adjusting the output of the force reflecting mechanism.

The force reflecting mechanism obtained through the present invention may be configured in the form of a force reflecting joystick, a passive joint, and the like as well as the rotating system.

An example of a linear system of force reflecting mechanism is shown in FIG. The linear system includes a first hydraulic chamber 31, a second hydraulic chamber 32, a first hydraulic chamber 31 and a second hydraulic chamber 32, and a movable partition 33 attached to the output shaft 37. Is provided, the flow path 34 connects the first hydraulic chamber 31 and the second hydraulic chamber 32, the electric valve 35 intermittent the flow path (34). The laser distance measuring sensor 36 measures the displacement of the output shaft 37, and the spring 38 connects the output shaft 37 and the external shaft 39 to form a passive joint, and is attached to the output shaft 37. The magnet 41 attached to the hall sensor 40 and the outer shaft 39 measures the relative displacement of the output shaft 37 and the outer shaft 39.

While the present invention has been described with reference to specific embodiments thereof, those skilled in the art may variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

The present invention provides a much smaller and lighter force reflecting mechanism as compared to a conventional force reflecting mechanism in reflecting the force acting on the remotely controlled mechanism as a user's force, and the force reflecting mechanism is small as a garment type master device. It can also be effectively used for applications requiring light weight and low power. The force reflecting mechanism of the present invention can also apply sufficient load to restrain human movement and increase the adaptability to the external environment, and thus can be used for various purposes including the use of the conventional force reflecting mechanism.

Claims (4)

A force reflecting mechanism for reflecting a force applied from the outside to a remotely controlled mechanism to a user who controls the apparatus, A plurality of hydraulic chambers, partition walls which partition the plurality of hydraulic chambers and are movably installed, flow paths for communicating the plurality of hydraulic chambers with each other, and flow between the plurality of hydraulic chambers through the flow paths by movement of the partition walls. A hydraulic cylinder comprising a fluid; Load adjusting means for generating a load in the hydraulic cylinder and controlling the same by changing the cross-sectional area of the flow path to change the flow resistance of the fluid; A load shaft which is operated by a force applied by a user; Force measuring means for measuring a force applied to the load shaft; A cylinder shaft which connects the partition wall and the load shaft, moves the partition wall in conjunction with the load shaft, and transmits a resistive force to the load shaft according to the magnitude of the load in the hydraulic cylinder; The measurement of the force applied by the user to the load shaft is compared with a predetermined reference load determined by the force applied to the remotely controlled mechanism from the outside, and the load in the hydraulic cylinder required to cancel the difference is calculated and Accordingly, the control unit for controlling the load adjusting means Force reflecting mechanism, characterized in that consisting of. The method of claim 1, wherein the load adjusting means is a valve for opening and closing the flow path to change the flow resistance of the fluid, a drive unit controlled by the control unit for operating the valve, and measuring the opening and closing amount of the valve Force reflecting mechanism comprising a sensor for. According to claim 2, The force reflecting mechanism further comprises a sensor for measuring the displacement of the cylinder axis, And the control unit determines the opening / closing amount of the valve from a function relationship between the displacement measurement value of the cylinder shaft and the required load in the hydraulic cylinder calculated by the control unit. The method of claim 1, wherein the force measuring means comprises one or more springs, each end of which is coupled to the load shaft and the cylinder shaft, and a sensor for measuring the displacement of the spring and transmitting a corresponding signal to the controller; Strength reflecting mechanism, characterized in that.