Brainstorming: Robotic Arm

The robotic arm is a crucial item in the Rov construction. Many of the tasks rely solely on its effective use. Having an easy to use multipurpose arm may be the key to winning the MATES competition. I have sketched out various designs as seen in Appendix I, which is at the end of this post.

The first design uses a hydraulic system. The arm is locked down in two pivot points indicated by the circle with a cross in the middle. It is then connected to a hydraulic arm that may either extend or retract. In this design creating a negative pressure and retracting the hydraulic arm closes the space between the two gripping arms. This design is simple and is useful for grabbing delicate items. It would best be used when an item must be retrieved and returned to the surface. The fact that it closes relying on a negative pressure means it is easy to keep the arm closed, however large amounts of force may not be applied as this could cause leaks that would let water into the closed system.

The second design relies on an electronic motor. This design has one stationary arm, which is shown on the left side of the drawing, and one arm connected to a geared motor. The gear allows a greater torque to be applied to the arm. This design requires greater monitoring from the control station. If care is not used the motor may easily become overworked and burn out, rendering the arm useless. This arm is best suited situations where large amounts of force are needed for short amounts of time, such as grabbing and pulling an item.

The third design also relies on a hydraulic arm, which is useful as it does not require excess energy. The arms are locked into pivot points in the middle of the arms as shown by the circles with a cross in them. This design, unlike the first one, requires a positive pressure from the control station to close the arm. This makes it easier to apply more force, although care must be taken not to create a tear or leak within the line. This is useful for grabbing items with large amounts of force and holding them for an extended period as the hydraulic line may simply be locked at the required pressure. This differs from the second design in that although they both can produce greater force, there is no risk of burning out the motor from extended use. A pressure gauge would be very useful in this design as it will make it easier to produce the required force and lower the risk of exceeding the maximum pressure of the system.

The fourth design is similar to the second in that one arm remains completely stationary. The second arm is attached by mobile rods that allow it to extend and retract. This design is shown running off a hydraulic system although it could easily be adapted to use a motor or servo. This design is also locked down in multiple locations to provide a secure base. This design is useful as it is less prone to breaking off from the main body. Its narrow profile is also useful for a situation where there is little room to maneuver the arm, such as reaching inside a hole. This same profile limits the design as it is unable to grasp large items.

While all these designs will prove effective if constructed properly, the true deciding factor will depend upon the tasks assigned. The construction of multiple arms may even be necessary to accommodate varying tasks. The use of hydraulics instead of electronics allows more energy to be focused on the motors, increasing their speed.