Patent Application
20190145504
The present invention relates to an actuator, and more particularly to a linear series elastic actuator in series connection that can be applied to a humanoid robot or a rehabilitation robot.
A conventional industrial robot is applied with a motor module to serve as a driving device. Because the industrial robots need speed and rigidity in operation, the industrial robot needs a driving device having a large volume. However, for rehabilitation robots, humanoid robots or prosthetic robots, the driving devices for these robots are designed to have light weight so that high torque density motors are used in these robots.
However, the conventional motor modules for rehabilitation robots are designed as those for industrial robots and mainly use brushed motors or brushless motors and have insufficient torque density. Therefore, the conventional motor modules are not applied as the driving devices for rehabilitation robots, humanoid robots or prosthetic robots. In addition, the motor module of a conventional driving device uses a belt wheel assembly or gear assembly to transmit the power to an output axle, such that the loss of the transmission of the motor torque is increased.
To overcome the shortcomings, the present invention tends to provide a linear series elastic actuator to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide a linear series elastic actuator to provide a sufficient torque density and to prevent loss of torque transmission.
The actuator has a linear driving mechanism, an output member, and an elastic member. The linear driving mechanism has a stepping motor, a thread rod assembly, and a linearly moveable member. The threaded rod assembly is connected with the stepping motor. The linearly moveable member is located at a side of the stepping motor and is connected with and driven by the thread rod assembly to reciprocatively move along a power input axis. The output member is disposed on a side of the linearly moveable member and has a capability of linearly moving along a power output axis that is co-axial with the power input axis. The elastic member is connected between the linearly moveable member and the output member to provide an elastic force along the power input axis.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
With reference to
With reference to
The output member 2A, 2B is disposed on a side of the linearly moveable member 13A, 13B and can linearly move along a power output axis a2 that is co-axial with the power input axis a1.
The elastic member 3A, 3B is connected between the linearly moveable member 13A, 13B and the output member 2A, 2B to provide an elastic force along the power input axis a2.
With reference to
The actuator A may further comprise at least one rail 16A. Preferably, two rails 16A are implemented. The rails 16A are parallel with the threaded rod 121A. The linearly moveable member 13A and the output member 2A are mounted on the rails 16A and are moveable along the rails 16A. In addition, the actuator A may further comprise a bottom base 15A. The stepping motor 10A is mounted securely on the bottom base 15A by the supporting frame 17A, and the rails 16A are mounted securely on the bottom base 15A.
The elastic member 3A comprises a spring 30A mounted around the threaded rod 121A and has two ends abutting respectively on the linearly moveable member 13A and the output member 2A.
In addition, the actuator A may further comprise a displacement sensor 5A mounted on one side of the elastic member 3A to detect a deformation of the elastic member 3A and to calculate an output force. Accordingly, the output force provided by the actuator A can be precisely controlled.
With reference to
Furthermore, the output member 2B has a movement space 22B, a first side board 23B, and a second side board 24B. The movement space 22B is defined in the output member 2B. The first side board 23B and the second side board 24B are disposed respectively at two opposite sides of the movement space 22B. The first side board 23B has a through hole 21B defined through the first side board 23B and communicating with the movement space 22B. The linearly moveable member 13B is mounted linearly moveably in the movement space 22B of the output member 2B. The sleeve 122B is connected securely with one end of the rotator 11B. The threaded rod 121B is linearly moveably mounted through the rotator 11B, the sleeve 122B, the through hole 21B in the first side board 23B and extends into the movement space 22B. The spring 30B is mounted around the threaded rod 121B, and the two ends of the spring 30B abut respectively on the linearly moveable member 13B and the first side board 23B.
In the second embodiment, a displacement sensor 5B is mounted on one side of the elastic member 3B to detect a deformation of the elastic member 3B and to calculate an output force.
The linear series elastic actuator A, B in accordance with the present invention can be applied in rehabilitation robots, humanoid robots, prosthetic robots or interactive robots and is connected with the moveable components of the robots to provide power to the robots.
With reference to
In addition, with the displacement sensor 5A mounted on a side of the elastic member 3A, the deformation of the elastic member 3A can be detected and the output force can be calculated. Accordingly, the output force in the dual directions can be precisely controlled by the displacement sensor 5A at a low cost, and the advantages of high torque density and precise control in force can be achieved.
The stepping motor 10A, 10B has the advantages of dual directional driving effect, high torque density, low in cost, and high reliability. With the low rigidity of the elastic member 3A, 3B between the linearly moveable member 13A, 13B and the output member 2A, 2B, the output force provided by the stepping motor 10A, 10B can be precisely controlled in the range of the deformation of the elastic member 3A, 3B. The linear series elastic actuator A has an excellent utility.
Furthermore, the actuator in accordance with the present invention A, B has a structure in series connection and the co-axial input and output axes a1, a2, so the structure of the linear series elastic actuator A, B is compact, simplified, reduced in volume, and light in weight. The stepping motor 10A, 10B can drive the threaded rod 121A, 121B directly and provide an output force via the co-axial linearly movable member 13A, 13B and the output member 2A, 2B to linearly move the output member 2A, 2B, such that the loss of the torque transmission of the stepping motor 10A, 10B can be effectively reduced. In addition, the elastic member 3A, 3B co-axially connects the linearly moveable member 13A, 13B with the output member 2A, 2B and can transmit force in dual directions to provide functions of energy-storing and buffering. The linear series elastic actuator A, B can be applied in rehabilitation robots, humanoid robots or prosthetic robots that need mobility, affinity between humans and the machine, and interaction between humans and the machine, and provide power sources to these robots to ensure the safety of using these robots.
Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
