SAPE Single Arm Printer Experiment June 02, 2014 12:49PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 04:15PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 04:24PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 05:23PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 09:10PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 09:18PM |
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Re: SAPE Single Arm Printer Experiment June 02, 2014 09:54PM |
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A2
Very cool!
Am I the only one that see's it evolving into a backhoe Remotely, and pragmatically dig holes in the yard, scale it up and dig a pond, or a basement, switch the backhoe out for the 3d cement extruder to finish the job! Mount a chair to it for a flight simulator The worm gear will be inherently safe if you loose power too.
Re: SAPE Single Arm Printer Experiment June 03, 2014 12:58AM |
Registered: 10 years ago Posts: 56 |
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see3d
Too Funny!
I just finished rebuilding my DIY tractor backhoe attachment last week. I never though about putting a seat on the bucket and running the joysticks out to the seat and taking it for a joy ride.
Quote
A2
Very cool!
Am I the only one that see's it evolving into a backhoe Remotely, and pragmatically dig holes in the yard, scale it up and dig a pond, or a basement, switch the backhoe out for the 3d cement extruder to finish the job! Mount a chair to it for a flight simulator The worm gear will be inherently safe if you loose power too.
Re: SAPE Single Arm Printer Experiment June 03, 2014 02:16AM |
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Re: SAPE Single Arm Printer Experiment June 05, 2014 01:37PM |
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Re: SAPE Single Arm Printer Experiment June 05, 2014 09:55PM |
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Re: SAPE Single Arm Printer Experiment June 07, 2014 03:09PM |
Registered: 10 years ago Posts: 56 |
The inverse kinematics coordinate translation is all done in the controller (ramps 1.4) . After writing the software for my GDR, the SAPE was not much more difficult. The Simpson style printer (grounded delta) is inherently more stable because of its geometry but it has the same singularities and it relies heavily on symmetry. Symmetry is a cold hearted bitch that will rob you of 6 months of your life leaving only emptiness in your soul.Quote
Feign
This does look awesome, though I'm guessing the programming to keep it level and on a g-code designated path will be a bit painful.
Also, while it looks awesome and easy to make, your Simpson-style printer looks much more stable.
Re: SAPE Single Arm Printer Experiment June 07, 2014 03:11PM |
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Re: SAPE Single Arm Printer Experiment June 07, 2014 06:15PM |
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Re: SAPE Single Arm Printer Experiment June 07, 2014 07:59PM |
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Re: SAPE Single Arm Printer Experiment May 17, 2015 06:12PM |
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Re: SAPE Single Arm Printer Experiment May 17, 2015 08:15PM |
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Re: SAPE Single Arm Printer Experiment May 27, 2015 06:05PM |
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Re: SAPE Single Arm Printer Experiment June 01, 2015 05:31AM |
Registered: 9 years ago Posts: 14 |
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Dejay
Not what you asked but I just had to share it I just bought the small (tiny) kit for a servo driven robot arm, the meArm. For 33£ / 50€ I simply could not resist! The plans are on thingieverse and there are also bigger 3D printed versions of it (see comments). The design of the arm seems to be rather smart, the servos / steppers are on the base not on the arm etc.
Not clue if a reprap firmware for these types of kinematic arms exist, but a GCode converter most likely. Maybe the links to the software for the meArm helps you find one. Not even sure how you call a robot arm like this? Is that still a parallel manipulator?
Re: SAPE Single Arm Printer Experiment June 01, 2015 04:32PM |
Registered: 9 years ago Posts: 210 |
int b = sqrt ((x * x) + (z * z)); // b = distance from the origin to the start of the gripper //Serial.write(b); float q1 = atan2( x, z ); // q1 = angle between the horizontal and the line b //Serial.print(q1,4); float q2 = acos((bic_sq - for_sq + (b * b))/(2 * bicep * b)); // q1 = angle between line b and the bicep //Serial.print(q2,4); float abi = q1 + q2; // abi = angle between horizontal and the bicep //Serial.print(abi,4); float afo = acos((bic_sq + for_sq - (b * b))/(2 * bicep * forearm)); // afo = angle between bicep and forearm
myservo0.write(abi); // sets the servo position according to the scaled value myservo3.write(afo); // sets the servo position according to the scaled value
Re: SAPE Single Arm Printer Experiment June 16, 2015 11:47PM |
Registered: 9 years ago Posts: 14 |
Quote
Dejay
Well if you can program a bit you could try adapt something like marlin. Or just use the gcode interpreter in marlin.
The inverse kinematic code for the meArm is here: [github.com]
int b = sqrt ((x * x) + (z * z)); // b = distance from the origin to the start of the gripper //Serial.write(b); float q1 = atan2( x, z ); // q1 = angle between the horizontal and the line b //Serial.print(q1,4); float q2 = acos((bic_sq - for_sq + (b * b))/(2 * bicep * b)); // q1 = angle between line b and the bicep //Serial.print(q2,4); float abi = q1 + q2; // abi = angle between horizontal and the bicep //Serial.print(abi,4); float afo = acos((bic_sq + for_sq - (b * b))/(2 * bicep * forearm)); // afo = angle between bicep and forearm
Afaik controlling servos is simpler than steppers, so instead of generating step signals until you reach the destination over time, you just set the position you want your servo to be at:
myservo0.write(abi); // sets the servo position according to the scaled value myservo3.write(afo); // sets the servo position according to the scaled value
If you've never programmed before it might seem like a daunting task but it's not black magic. You can start simple and add more functionality as you learn. Reading code written by others is always a bit of work through. But rewarding Writing code is much more fun of course! Hope this helps.
Afaik the problem with robot arms is jerk and backlash though. Limiting acceleration of the servos (starting and ending a move slow) could help though. And servos aren't precise enough (not enough steps / mm) and not repeatable enough.
I have this crazy idea that you could improve the precision though by using computer vision to track the precise location of the effector and using some kind of algorithm to compensate for backlash and jerk and arm droop. Maybe you could use an IMU for this as well. After all our human arms are highly imprecisely manufactured as well but we "learn" to use them precisely. If you could teach a robot that then you could safe a lot on "precision manufacturing". This would also be an important step for reprap "reproducability" by creating less precise but 3D printable linkages. That's just crazy talk though
Re: SAPE Single Arm Printer Experiment June 17, 2015 12:03AM |
Registered: 9 years ago Posts: 210 |