Engineering Projects/Robot end effector/Howard Community College/Spring2012/p1501mjj3

Electronic Sections Expected

Problem Statement

Need to make a robot arm that will pick up objects.

Team Members

Summary

We began this section of the project with high hopes of finishing it entirely. However, this was not accomplished. But along the way we have made a great deal of progress and have set it up well for the next group. This final section we created a functioning fin ray claw that needs only a little fine tuning. Also we completed some of the motor mounts and made progress with the arduinos and programming them to run our motors almost to the desired fashion but ran into some powering issues. All in all it was a good final four weeks and we made a lot of progress.

Poster

End Effector Conclusion

Story

During the final four weeks a was accomplished. A functional fin ray claw was assembled using mostly PVC, some springs, bolts, and the flimsy plastic cutting board material. Now this was constructed to find a replacement for the original paper fin ray claw that we saw as not sturdy enough for what we were trying to accomplish. Using PVC couplings for the body and the ends of two PVC caps for the circular bases this dream came to life. The smaller circle was set below the bigger circle using bolts and having springs between them to keep the claw open. The bolts ran up into the body of the claw where they all connected to a small circular board with an eye hook in the middle. The purpose behind this is that the motor will pull up on the eye hook, contracting the springs and forcing the hand to close. It worked well, however, I feel that some softer springs would be much more effective. Then two pieces of cutting board were cut out. Both in a shape almost resembling a three legged spider. One was smaller and connected to the smaller base and a larger for the larger base. Then the legs were connected to each other using a slit in the end and it worked well. To add stability to the fingers rubber bands were used to bend the plastic and strengthen it. A lot of planning went into this portion of the project and overall we were pretty satisfied with the result. Also ran into some issues powering multiple stepper motors of that size using the arduino and the old motor shield. We had to use an external power supply and remover the jumper from the motor shield to keep the arduino safe. Had two running at once for a short period and it started over heating the board. Overall had lots of difficulties powering multiple motors at the same time.

Decision List

No formal decisions were made.

Material List

Materials Used:

1: plastic cutting boards, 6$

2: PVC coupling 2", $2

3: PVC cap 2", $2

4: PVC cap 4", $3

5: 3 1/4" by 4" bolts w/ nuts and washers, $4

6: Eye bolt, $1

7: Rubber Bands

8: Scrap Wood

9: Monster motor shield

10: External power supply

Future Materials:

1: String/chain to pull with motor for claw

2: Higher quality cutting board

3: Another monster motor shield

4: Screws

Software List

1: Autocad

2: Paint

3: Arduino

Time

36.5 hrs

Tutorials

Next Steps

The next steps with regards to building the fin ray are as follows. It is recommended to get some sort of better material for the fingers. They are pretty flimsy and not that great. Also the shape of the fingers is terrible. They need to come to more of a cone shape at the end so that your picking range is vastly improved. Maybe even add more fingers so that they can be cut at less sharp angles. Softer springs would also be recommended. Right now it takes to much force to pull the claw closed I feel like it might be a bit much for the tiny motor. Another way to help with that would be to get better bolts. The ones in there now are threaded all the way and when they are pulled through the holes it tends to snag. So if you could get some that or solid and cylindrical up until they end it may help. Either that or grind the threads off of the current ones. To further the progression on the control of multiple motors on one motor shield, you will need to try using a motor shield that can run more power like the Monster Motor shield, and have it hooked up to an external power source and try running it that way.