Compliant mechanism

A compliant mechanism includes a first unit, a second unit, at least one elastic member and a driver for driving the elastic member to rotate through a predetermined angle. The first and second units collectively define a passage about which the second unit is rotatable relative to the first unit. The elastic member has a plate and first and second shafts which are coaxially connected to two opposite ends of the plate respectively and rotatably connected with the first and second units respectively. The elastic member is rotatable about a co-axis of the first and second shafts and elastically deformable when the second unit rotates relative to the first unit. The elastic member can change its resistance to the rotation of the second unit by rotating; therefore the compliant mechanism has a great safety upon receiving load and is widely applicable in many fields.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to compliant mechanisms and more particularly, to a compliant mechanism which is modularized and widely applicable in many fields.

2. Description of the Related Art

Service robots are developed quickly in recent years not only in function but even safety. In particular, when the robots contact, interact, and serve users, any potential injury done by the robots to the users should be avoided. Therefore, compliant mechanisms, which have the advantages of quick response and none of any damageable electronic components, have been applied in the robots to absorb and buffer the shock resulting from the external force so as to upgrade the safety of the robots.

Specifically speaking, the compliant mechanisms can be installed in the joints of the robot or the robot's loading parts for contact with the users or loading things. When the robot is about to receive a large load, the rigidity of the corresponding compliant mechanism is raised. When the robot is about to receive a small load or contact the users or fragile things, the rigidity of the corresponding compliant mechanism is lowered. As a result, the robot can function safely.

However, the conventional compliant mechanisms have specific configurations, complicated structures, or big sizes and it is difficult to modify them according to different applications. In other words, the conventional compliant mechanisms are still defective to need further improvement.

SUMMARY OF THE INVENTION

The present invention has been accomplished in view of the above-noted circumstances. It is an objective of the present invention to provide a compliant mechanism which has a modularized and hollow structure to result in a wide applicability.

To attain the above objective, the present invention provides a compliant mechanism which comprises a first unit, a second unit rotatably connected with the first unit, at least one elastic member and a driver for driving the elastic member to rotate. The first unit and the second unit collectively define a passage. The elastic member has a plate and first and second shafts which are coaxially connected to two opposite ends of the plate respectively and rotatably connected with the first unit and the second unit respectively so that the elastic member is rotatable about a co-axis of the first shaft and the second shaft, and the direction about which the elastic member rotates intersects the direction about which the second unit rotates. When the second unit rotates relative to the first unit, the elastic member is elastically deformed.

As a result, the driver can drive the elastic member to rotate about the co-axis of the first and second shafts through a predetermined angle to change the angle of the plate relative to the direction about which the second unit rotates so as to adjust the resistance of the elastic member to the rotation of the second unit relative to the first unit. Therefore, the rigidity of the compliant mechanism will vary with the posture of the elastic member. When the mechanism is set in a low rigidity manner, the elastic member can absorb an external force, which makes the second unit rotate, to avoid the device carrying the mechanism from damaging the things or the users contacting the device. When the mechanism is set in a high rigidity manner, the elastic member can resist the external force to enable the device to receive a large load, such as the load of carrying heavy things.

Besides, the direction about which the elastic member rotates may intersect the direction about which the second unit rotates for providing a good effect on the adjustment of the resistance of the elastic member. Preferably, the direction about which the elastic member rotates is perpendicular to the direction about which the second unit rotates for providing an optimum effect on the resistance adjustment.

The compliant mechanism provided by the present invention is modularized, so that only parts of the first and second units might need some modifications to adapt the mechanism to different environments and devices, which means the mechanism is widely applicable in many fields. Besides, the mechanism is hollow and provided with the passage to facilitate installation of electric wires therethrough, which causes more convenience to dispose the wires and more flexibility to design the configuration of a product having the mechanism.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS. 1-3, a compliant mechanism10, which is provided by a preferred embodiment of the present invention, comprises a first unit20, a second unit30, two drivers40, two transmission subassemblies50, a bearing subassembly60and two elastic members70.

The first unit20primarily comprises a base22and a tube24. The base22is provided with an inward side222facing the second unit30and an outward side224facing the outside of the mechanism10. The drivers40, which are motors, are fastened to the inward side222of the base22and connected with the transmission subassemblies50respectively. Each transmission subassembly50has a worm52connected with the driver40and a worm gear54engaged with the worm52. The transmission subassemblies50are located inside the tube24which is fastened to the inward side222of the base22.

The second unit30comprises a disk32and two connectors34. The disk32is provided with an inward side322facing the first unit20and an outward side324facing the outside of the mechanism10. The connectors34are fastened to the inward side322of the disk32in proximity of the periphery edge of the disk32. The tube24is located between the connectors34.

The bearing subassembly60comprises a first bearing62, which is a crossed roller bearing in the embodiment and can be replaced by one or more other kinds of bearings according to different situations, an inner collar64and an outer collar66fixed at an inner rim and an outer rim of the first bearing62respectively in a tight fit manner and fastened to the tube24and the disk32respectively by bolts. Because the disk32, the bearing subassembly60and the first unit20are hollow and aligned orderly, the mechanism10is provided with a passage12penetrating the first unit20and the second unit30. As a result, the second unit30is rotatable about the passage12relative to the first unit20.

Each elastic member70has a plate72, a first shaft74and a second shaft76, which are coaxially connected to two opposite ends of the plate72respectively. The first shafts74of the elastic members70, each of which rotatably penetrates through the tube24by means of a second bearing78, are fixed at the centers of the worm gears54respectively. Each of the second shafts76of the elastic members70is rotatably disposed at one of the connectors34by means of a second bearing78. As a result, the drivers40can respectively drive the elastic members70to rotate about a co-axis of their own first and second shafts74and76, which are coaxial with each other and perpendicular to the passage12. In other words, the direction about which the drivers40drive the elastic members70to rotate is perpendicular to the direction about which the second unit30rotates.

It is to be understood the design that the rotation axis of the elastic members70perpendicularly intersects the rotation axis of the second unit30is just an optimum solution. As long as the elastic members70are rotatable to change their posture, the resistance provided by the elastic members70against the rotation movement of the second unit30is adjustable.

In aforesaid compliant mechanism10provided by the present invention, the elastic members70can be driven by the drivers40to rotate between a maximum resistance position P1(as shown inFIG. 4) and a minimum resistance position P2(as shown inFIG. 5). In other words, the resistance of the elastic members70to the rotation of the second unit30is adjustable by changing the angles of the plates72relative to the rotation axis of the second unit30, and the rigidity of the mechanism10will vary with the aforesaid resistance. When the mechanism10is set in a low rigidity state, such as the elastic members70are driven to the minimum resistance position P2, the elastic members70can absorb an external force, which makes the second unit30rotate, by elastic deformation so as to avoid a device (not shown) carrying the mechanism10from damaging the things or the users contacting the device.

When the mechanism10is set in a high rigidity state, such as the elastic members70are driven to the maximum resistance position P1, the elastic members70can resist the external force to be hardly deformed, such that the device carrying the mechanism10can receive a great load, such as the load of carrying heavy things.

It is more important that the compliant mechanism10provided by the present invention only requires slight modifications in the shapes of the disk32and the base22to adapt different environments and devices. This feature means the mechanism10is widely applicable in many fields. Besides, because the mechanism10has the passage12that facilitates arrangement of electric wires, the configuration design of a product having the mechanism10is more flexible.

It should be appreciated that each transmission subassembly50is arranged to cause speed reduction between the driver40and the elastic member70. The transmission subassembly50introduced in this embodiment, which consists of a worm and a worm gear, not only makes the rotation axis of the elastic member70perpendicular to the rotation axis of the output shaft of the driver40but also has the characteristics of high speed reduction ratio and irreversible transmission direction. The drivers40can be servo motors that can do optimal adjustments on the resistance of the elastic members70quickly. However, the driver40and the transmission subassembly50are not limited to a servo motor and the combination of a worm and a worm gear. Besides, although two elastic members70positioned opposite to each other can make the mechanism10more balanced while receiving an external force, the major characteristic of the elastic members70is the adjustable resistance, so the amount of the elastic members70is not limited. Furthermore, because of having a hollow structure like a tube as a whole, the mechanism10is convenient in arranging electronic wires and is widely applicable in many fields. However, the details of the hollow structure are not limited to those provided by the preferred embodiment of the present invention.