Final Takeaways 

Designing and manufacturing the robot gripping device led to several design principles for future consideration.

• CAD and analysis tools provide an easy visual aid in developing new design iterations. However, these tools are not able to substitute substitute for the manufacturing prototypes. Although a mechanism may seem to work in with these design tools, important considerations needed to be made with regard to tolerances, frictional forces, and material properties.
  
• Determining proper choices for pin joints can make or break a design. We went through several variations of hole sizes and bolt types to find a proper fit that would be nearly frictionless while maintaining a smooth consistent contact. In the end, we used shoulder bolts for most joints while sizing the holes slightly smaller. The tight press fit with the shoulder bolts along with proper lubrication gave the smoothest and tightest contact. 
• More links in a system can lead to more problems. Our overall design combined the eight bar robot gripper mechanism with a crank slider. The complexity in the number of parts can compound on itself leading to the needs for tighter tolerances and better manufacturing. In the future, it would be useful to look at methods to reduce the overall number of moving pieces.

Future Improvements

If there were more time to improve on the current design we would begin to encapsulate the mechanics along with a separate battery for the Raspberry Pi into the device. We would also improve upon the ergonomics of the current design by creating a device that would more comfortably fit in to the users hand during operation. Finally, we would experiment toggling the device with a mussel sensor instead of a switch. This would allow the user to activate the mechanism by flexing a mussel of his choice. This type of biomechanic sensor may be very convenient for a handicapped operator.

Figure 16: Completed Rope Grabber Mechanism