09.1 - Project Proposal

Introduction:

Fishing is a popular leisure activity, that people of many ages and backgrounds can partake in all over the world. As a group, we will focus on the people who have trouble with operating certain objects and actions with fishing. Our team will develop an autonomous fishing robot that simplifies the fishing process by performing all tasks independently. Specifically, we are developing a robot to aid people in casting the fishing rod through multiple mechanisms through one to two actions. The casting and reel of the rod will be activated by a button and able to maneuver left and right with a joystick or controller buttons.

Description of the problem:

One of the system's mechanisms will need to be able to cast the line and therefore must move the rod in two different directions. It will move backward to prep the rod for casting, and forward to cast the line. The backward motion must be slower than the forward motion that will cast the line into the water. This variable angular velocity paired with the fact that the direction of motion must alternate makes the profile of motion difficult to accomplish with simple joints alone. A further concern is that during the forward motion, the mechanism should be imparting the greatest amount of force on the rod. This means that variable torque will be a necessary component of our mechanism as well. Looking past the casting motion, one of the mechanisms must be able to reel in the line. For this reason it will need to generate rotational motion and provide substantial torque with minimal input.

Description of Proposed Mechanism: 

To solve our problem, will we integrate three different mechanisms, all grounded to a fishing rod mount. The mount will attach to the end of a table or dock, similar to when a rod is resting on a boat. Our design will need to have two different functions, one to cast the line and one to reel it in. We will use two separate servo motors for each of these functions. The reel mechanism will resemble a four-bar linkage, with one junction grounded to the motor and one junction grounded to the reel handle. The casting mechanism will feature 2 functions, the forward-backwards whipping motion of the rod (planar motion), a 360 degree rotation of the rod to pick different areas of the water to cast. For the planar forwards/backwards whipping motion, we will use a gear train to achieve a variable speed of the forward/backwards motion coupled with a reciprocator to rotate the rod forwards and backwards. This will be detailed further in our preliminary design below. For the 360 degree rotation of the rod, we will use a slider crank connected to a servo. 

Proposed Scope of Work: 

Our proposed scope of work is to design and simulate a robotic fishing rod mechanism with a focus on the complex motion and force profiles necessary for casting. The mechanism will be capable of a controlled 360-degree rotation, emulating the natural motion of casting a line, and will include a novel linkage system to manipulate the bail for both casting and reeling. The design will need to account for the differential speeds required for the backward and forward motions of the cast, ensuring a slow preparatory draw back and a rapid, forceful forward cast. A combination of rigid and non-linear linkages will be explored to achieve the varied angular velocities needed. Analysis will be conducted on joint forces, dynamic loading, and torque requirements to support the rod during casting. Our deliverable by the end of the semester will include a comprehensive kinematic analysis, a simulation model of the casting motion, and detailed mechanical design specifications. We plan to leverage the knowledge acquired in our coursework to design a system that can be actuated with minimal user input, focusing on the mechanical complexities rather than electronic controls in this phase.

Preliminary Design Ideas: 

Our design will feature 4 different mechanisms to perform 2 different functions: Casting and Reeling. We plan to use three 360 continuous rotation servo motors, one will be used to control the Reel Mechanism and two to control the Casting mechanism. All mechanisms detailed below will be grounded to a mount for the casting rod. 

Mechanism 1: Reeling the Line

For the reel mechanism, we will use a Galloway Mechanism. This mechanism takes one full rotation of the input link and gives two full rotations of the output link. This will allow us to reel in the line faster while using less power from the motor. Another important aspect of the reel mechanism will be the torque provided to reel in a fish. This will need further analysis, but is an important design consideration. 

 Example of the Galloway Mechanism in motion (click photo to view motion):

For application purposes, we have included the following diagram to identify the inputs and outputs. 

Mechanism 2: 360 Rod Rotation

Pictured below is the base of the robot. The rod will be mounted in the center of the circle attached by two links to a rotation servo for the 360 degrees of motion. 

The casting motion will be generated by a combination of mechanisms.

Mechanism 3: Casting Motion

The mechanism that will connect to the rod is a reciprocator. However, instead of the final output being alternating lateral motion, the final output (the slot wherein the rod will fit) will be the longer portion of the elbow link pictured in the YouTube link below.

Mechanism 4:  Uniform Rotation to Variable Rotation - Casting

In order to ready the rod (move backward) and cast (whip forward) the input angular velocity to the reciprocator will need to be variable. This will be accomplished using a uniform angular velocity to variable angular velocity mechanism as demonstrated in the YouTube video below. The output or driven component will rotate on the same axle as the input to the reciprocator (Mechanism 3).