Dual-Directional Locking mechanism for precision motion controlBlind
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Mechanical Engineering
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Sami-n
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Description:
--Short Summary--Design and model an addition of a secondary dual-directional locking mechanism for maintaining a platform’s slope angle in an event of a high spike/impact load of a minimum 40Nm in a miniature space. (Length: 90mm, Width: 33mm, Height 40mm).
--Detailed Description--
The goal of this design is to maintain a platform at a user-defined slope angle given random and frequent scheduled loads/disturbances. The current design includes a worm gear set to provide some degree of holding torque (for example 2Nm) which is sufficient for loads such as a person standing on one end of the platform. However, in cases of high impact load such as a person jumping on the tip of the platform, a secondary mechanical locking mechanism (both directions) is required to prevent the platform from moving. Note that the space constraint will likely be the main challenge for this project.
The task is to add the mechanism to the existing model while staying within the given space (box). The strict dimensions of the enclosure box including the current BOM items are:
-Length: 90mm
-Width: 33mm
-Height 40mm
We currently have a working version that uses a secondary motor to engage and disengage a custom dog-clutch-like mechanism. However, due to the high added cost and space, we would like to further explore a purely mechanical design. That being said, we are open to ideas that use minimal power (100-200mA at 5V or 50-100mA at 12V), are very compact and reliable, and are cost efficient.
Please note that the user in our experiment will frequently signal the platform, that will signal the motor to precisely change the platform’s slope angle. Therefore, the dual-directional locking mechanism should not interfere with the motor’s operation when there isn’t an overload. This means the mechanism should either:
1) Stay disengaged on idle mode and only engage when a load higher than ~2Nm is experienced/detected
2) Stay engaged on idle mode and immediately (i.e. milliseconds) disengage when the motor starts rotating
Other innovative ideas that would achieve the goal are more than welcome.
Feel free to add components such as gears, clutches, shafts, linkages, torque limiters, brakes, springs, pawl sets, etc., or other parts/mechanism that you see fit while staying within the enclosure space and minimizing cost. You may also add features (extrude, cut, etc.) to the interior of the enclosure box and make reasonable modifications to the existing shafts and gears (e.g. remove the hub from the gear if you have to).
Preference will be given to off-the-shelf torque rated components that are compiled with other parts to achieve the dual-directional locking, rather than multiple complex custom-made parts.
Please provide a 3D model of your concept with an explanation of how the design functions to meet the project’s goal. Also, include the names of the additional components used in the model.
SolidWorks is preferred but it is okay to use another software given a clear presentation of the concept.
Wants:
Functionality – The design concept achieves the dual-directional locking of the platform in an event of an overload, and mechanically disengages post overload.Size – The design concept does not exceed the given enclosure space (preference will be given to the most compact design)
Cost – The additional cost of the design is minimal.
Precision – The platform does not slope more than 2 degrees in an event of an overload before the locking mechanism is engaged, and after dis-engagement.
Strength – The design can withstand an impact load of up to a minimum of 40Nm
Reliability – The mechanism should not fail to engage for impact loads that occur in a fraction of a second and will be a reliable and maintenance free assembly in line w/ other components’ lifecycles.
Don't Wants:
Use of a secondary motor to achieve desired outcome - due to power and cost limitations.Manual locking/unlocking - the system has to be fully automated.
Software:
- SolidWorks
Prepaid PrizeEntries
#11 Dual-Directional Locking Mechanism for Precision Motion Control v1a Vit G
by Vit Gean
Oct 15, 2019 13:47
#9 Dual-Directional Locking Mechanism for Precision Motion Control v1 Vit G
by Vit Gean
Oct 14, 2019 12:11
Discussion
Hey Sami,
can we remove the worm gear and use a different way to change the platform inclination using the same motor all the while staying within the dimensional limits. Also in the new design can the motor be located inside the enclosure itself.
Thanks.
can we remove the worm gear and use a different way to change the platform inclination using the same motor all the while staying within the dimensional limits. Also in the new design can the motor be located inside the enclosure itself.
Thanks.
Hello Sami.
I would like to ask what happens to the platform if the load applied is less than 40Nm.... Does it remain in it's position or does the platform tilt at any load less than 40Nm
I would like to ask what happens to the platform if the load applied is less than 40Nm.... Does it remain in it's position or does the platform tilt at any load less than 40Nm
Please check my design, thanks
Please check my entry, Thanks.
Working on it.
Hi Sami,
Thanks for your quick response. I am asking about speed and adjustment resolution in order to see if my design will work. It requires a minimum speed from the motor. Thank you,
Brett
Thanks for your quick response. I am asking about speed and adjustment resolution in order to see if my design will work. It requires a minimum speed from the motor. Thank you,
Brett
Hi Prepo, the motor operation is not a part of this project, rather a locking/braking mechanism to maintain the slope for a 40+Nm loads. The motor is only considered for proper and timely disengagement of the mechanism.
What is the speed at which the motor runs when making adjustments? And what is the smallest adjustment that It will make (1 degree? or is there no minimum?)?
I may not have correctly understood the condition of the task, but the only goal here can be to prevent the motor from overloading.
I also think that the platform cannot tilt in any direction if the motor does not rotate. With the motor stopped, it is more likely to break something, but not to change the slope of the platform, no matter how much load it has on it.
I have an idea for how the solution could look like, but as far as I can see, the loads are too big for such a small thing. The torque ratio T1/T2 = 1/40 - so, if T1=2 Nm, T2=80 Nm and the axial force on the worm gear will be 80 Nm/0,010 m=8000 N which is 800 kg. And if T1=40 Nm we get for axial force 160 000 N (16 t). Really strange.
Please don't close this job before it's timeline.
Hello Sami-n
Is this unit part of Combined Mechanism or stand alone unit?
Is this unit part of Combined Mechanism or stand alone unit?
Hi Ghufran, you may only edit the 8mm shaft connected to the platform. Nothing outside of the enclosure box can be modified.
can i use the full bottom face of platform to attach stuff?
Hi Sava, You're right. Please only refer to the torque values.
Aaah, it is the torque of the motor may be.
If a person about 750 N (75 kg) is standing on one end of the platform the torque will be 750*0,0625=46,875 Nm?
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