Pancake Flippin Robot

  • Objective

    Build a pick-and-place robot that can pick up a small object from one position and place it somewhere else under position-control. The specific application/scenario for this robot is up to you.

  • Outcome

    Determined to make our robot have a fun application, we chose to move forward with a pancake flipping robot. The robot has four degrees of freedom for its four stages of motion.

Main Assembly CAD

Stage 1: Rotational Base

The rotational base allows for rotation of the entire robot. It is driven by a brushless motor and a timing belt drive. In order to increase the resolution of the positional accuracy, we added an extra gear stage to achieve a gear ratio of approximately 13:1. We designed the brushless motor mount and slot sensor mount ourselves. For the pulleys and gears, we downloaded starter files with the required amount of teeth and then adapted them to fit our needs by adding things like shaft collars or homing flags. Because tensioning a timing belt is crucial, we allowed for this to occur in our design in two ways. First, the brushless motor mount can be positioned wherever on the 8020. Second, we added a tensioner, made up of two ball bearings, to the 8020 (hidden in this picture underneath the orange gear) that was also mounted on a slot.

Stage 2: Vertical Linear Stage

We also needed vertical range of motion that would allow the pancake to be lifted from the griddle so that it could be flipped. In order to accomplish this, we purchased a vertical linear stage with a stepper motor. This stage mounts directly to the large pulley of the rotational base with 8020 and some simple laser cut brackets. We also designed a 3D printed mount to attach to the carriage that could hold the entire horizontal arm of the robot. In order to appropriately home this stage of motion, we used a slot sensor and designed our own flag and sensor mount.

Stage 3: Horizontal Arm

Once the spatula was at the correct level, we needed horizontal translation in order for the spatula to get under the pancake. In order to achieve this, we purchased a linear guide rail. We decided to drive the guide rail using a DC motor and cable transmission for precise control. We used a guide rail with two heads and made a mount that attached to both heads at a large distance in order to achieve stability. This mount both holds the spatula assembly and also allows for cable termination. We also designed the DC motor mount, motor and idler pulleys, and homing flag.

Stage 4: Spatula Rotation

The final stage of motion is to flip the pancake. In order to achieve this we used spur gears driven by a servo motor. We chose to use an OTS spatula so we had to make a spatula mount that attached to the shaft driven by the servo. The driven shaft is mounted to two pillow block bearings for support. We also designed the servo mount to be on slots so that we could use different sized gears in order to achieve the right flipping speed for the pancake.

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Willow (Makenzie's Version)

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