Troubleshooting Jerky Motion of a Robot Arm: Expert Tips & Solutions

In summary, the speaker has designed a robotic arm with a servo motor and planetary gear box, using taper roller and deep groove bearings. However, when the motor is turned on, the arm moves in a jerky motion and the rpm is very slow. Some suggest that this may be due to unbalanced load or improper pre-loading of bearings. The speaker has also used a lamina coupling to connect the drive shaft. To resolve these issues, suggestions are given such as filling hollow pipes with concrete to prevent swinging, paying attention to the quality of the coupling, and limiting the acceleration to avoid shock waves in the mechanical system. It is also mentioned that there may be a binding problem due to misalignment or incorrect tolerances.
  • #1
GPP
1
0
Dear friends,
I have designed a robotic arm driven by servo motor via a planetary gear box.I have used taper roller bearing & deep groove bearing to hold the driven shaft.The distance between two bearings is 10 mm .When
arm.jpg
I turn ON the motor, the motion of arm is jerky.Also, I've used lamina coupling to couple the drive shaft.
The rpm of rotation is very very slow.Some say this may be due to unbalanced load or may be due to less distance between two bearings & improper pre-loading of bearings.
I've also fine tuned the motor.

Please can anyone help me to resolve this problem
 
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  • #2
GPP said:
planetary gear box.
You might want to "pre-load" the planetary.
 
  • #3
GPP said:
the motion of arm is jerky.Also, I've used lamina coupling to couple the drive shaft.

1) If the pipes are hollow, fill them up with concrete which is a "dead" material that will prevent swingings. Hollow pipes will ring, ( tubular bells ).

2) Pay attention to the quality of the coupling ( no spring effect ) and lack in the gearbox.

3) You must limit the dA(t)/dt ( A(t) being the acceleration ). This means to control the A(t) by S-curves. Say you are using a digital controller and you have a speed control loop. At the input of this control loop you could insert an array of speed elements. Changing the "soll-wert" ( must-be-value ) of the loop, the array is stepwise filled up with the new speed value. The output of this array block is the mean-value of the elements in the array at all time. The resulting response to a step in the speed function will be something like this:

images?q=tbn:ANd9GcTyr__93Avnq2su7h6HWQySRueKehVLf4_AFhIzg_Uetx6cUc1HBA.png


Following this curve, you will limit shock waves in the mechanical system.

PS: As for 3), I think something is wrong. Anyway I hope you understand the idea. :smile:
 
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  • #4
There has to be some binding problem arising from misalignment or incorrect tolerances being applied. If the arm is moving in a chattering fashion, it is moving along and experiencing static/dynamic friction as it does so. The slow rpm ( how slow/fast should it be ) could mean the motor has unaccounted torque that it has to deal with.
On paper it may look fine, but upon assembly tightening of components has thrown the paper model out the window.
 

1. What is the purpose of "Jerking of robot arm" in robotics?

The jerking of a robot arm refers to the short, sudden movements of the arm during operation. This is often used to overcome inertia and allow the arm to move faster and more accurately.

2. What causes the jerking motion in a robot arm?

The jerking motion in a robot arm can be caused by various factors such as motor speed, acceleration, and friction in the joints. It can also be a result of programming errors or mechanical issues.

3. Is jerking of a robot arm harmful to the arm's components?

Excessive jerking of a robot arm can cause wear and tear on the arm's components such as motors, gears, and joints. It is important to properly calibrate and program the arm to minimize jerking and prolong its lifespan.

4. How can jerking of a robot arm be reduced?

To reduce jerking of a robot arm, engineers can use smoother and more precise motors, optimize the arm's acceleration and deceleration, and implement advanced control algorithms. Regular maintenance and calibration can also help reduce jerking.

5. What are the safety considerations when dealing with jerking of a robot arm?

Safety is a crucial aspect when working with a robot arm, especially when it involves jerking motion. Engineers must ensure that the arm is properly secured and there are no obstacles in its path. It is also important to have emergency stop buttons and safety protocols in place to prevent any accidents or damage to the arm or its surroundings.

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