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Factao
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- TL;DR Summary
- What could be a way to transfer a rotary motion within a (micro) system that have two axial DOF, which are the yaw and the pitch (aka a wrist within a mechatronic arm)?
Hello,
As a personal project,I am currently designing a mechatronic hand, with a number of DOF similar to our hand. I've choose to transmit the axial movement of a finger through a rotary motion, because cable where causing too many backslash an other linear transmission became severely more complicated due to the wrist complexity. I need to transmit four movement trough the wrist, so here two little schema to illustrate the situation:
Here, the green vector is the orientation of the forearm and the purple one is the orientation of the hand. The rotation on the blue axis has a limit of 90 degree ,from the purple vector orientation,toward the positive and the negative y axis. The rotation on the blue one have a limit of 25 degree toward the positive z axis, and a limit of 30 degree toward the negative z axis. In other word, these schema represent the orientation of your hand from your forearm.
The motion reception part is within the hand, so it have the same orientation, and it will always keep the same position within it.
The axial actuator is a servo motor. The motion can be translated in every possible way that you may think of. The only problematic is to transmit the motion within the volume of a quater of your wrist (because there is four finger that need it, I am excluding the ring finger).
If you have an idea, I would happily listen to it. Of course, I have been working on my project, so here is two idea that seem functional. Feel free to critique them, I am creating this thread exactly for this.
1-Transmission with miter gears:
Within this system, the transmission is made by a pair of miter gears. There is a 90 degree translation within a piece that is acting as a link between the arm and the hand. Of course, this system required a spacing between the red and the blue axis. I did a prototype of this system, but it too bulky and does not look good nor practical. I am considering this one as my last resort because it is functional, despite the default. Here is an illustration of the system and a picture of the prototype:
As you see, it is bulky and does not seem to be an efficient way to accomplish the required transmission.
2-Universal joint
I've never work with those before, but it seem to be a better way to build my wrist than a bunch of gear. However, I do not know if u-joint are actually made to transmit a rotation between two shaft that does not have a predefined orientation. So here is another schema (yes, I love them too) that is explaining what I am planning to do.
However, this system seems to be too simple to work as intended and, with my inexistant knowledge concerning these u-joints, I cannot tell if this is an appropriate use of this method of transmission.
As a personal project,I am currently designing a mechatronic hand, with a number of DOF similar to our hand. I've choose to transmit the axial movement of a finger through a rotary motion, because cable where causing too many backslash an other linear transmission became severely more complicated due to the wrist complexity. I need to transmit four movement trough the wrist, so here two little schema to illustrate the situation:
Here, the green vector is the orientation of the forearm and the purple one is the orientation of the hand. The rotation on the blue axis has a limit of 90 degree ,from the purple vector orientation,toward the positive and the negative y axis. The rotation on the blue one have a limit of 25 degree toward the positive z axis, and a limit of 30 degree toward the negative z axis. In other word, these schema represent the orientation of your hand from your forearm.
The motion reception part is within the hand, so it have the same orientation, and it will always keep the same position within it.
The axial actuator is a servo motor. The motion can be translated in every possible way that you may think of. The only problematic is to transmit the motion within the volume of a quater of your wrist (because there is four finger that need it, I am excluding the ring finger).
If you have an idea, I would happily listen to it. Of course, I have been working on my project, so here is two idea that seem functional. Feel free to critique them, I am creating this thread exactly for this.
1-Transmission with miter gears:
Within this system, the transmission is made by a pair of miter gears. There is a 90 degree translation within a piece that is acting as a link between the arm and the hand. Of course, this system required a spacing between the red and the blue axis. I did a prototype of this system, but it too bulky and does not look good nor practical. I am considering this one as my last resort because it is functional, despite the default. Here is an illustration of the system and a picture of the prototype:
As you see, it is bulky and does not seem to be an efficient way to accomplish the required transmission.
2-Universal joint
I've never work with those before, but it seem to be a better way to build my wrist than a bunch of gear. However, I do not know if u-joint are actually made to transmit a rotation between two shaft that does not have a predefined orientation. So here is another schema (yes, I love them too) that is explaining what I am planning to do.
However, this system seems to be too simple to work as intended and, with my inexistant knowledge concerning these u-joints, I cannot tell if this is an appropriate use of this method of transmission.