​

​

​

​

Animal Care Cage Processing Machine

Background

BISON. (n.d.). DC Gearmotor, Right Angle, Nameplate RPM 19, Voltage 130VDC (Model 35TW37). Retrieved May 19, 2025.

ASTM International. (2019). Standard specification for aluminum and aluminum-alloy drawn seamless tubes (ASTM B210/B210M-19a). West Conshohocken, PA: ASTM International.

​

​

`

UCSD Central Research Services facility cleans dirty mice cages from external animal research laboratories. Workers must remove bedding from cages by physically flipping the cages over a dump station before they can be properly cleaned by a conveyor belt washer. This process, which is a full-time job, exposes workers to severe allergens from mice droppings and causes repetitive strain injuries. Currently, there are no commercially available automated solutions with a satisfactory efficiency, adaptability, or price.

Fig.1. CRS cage processing facility.

​

1

​

Adrian Tong, Vicente Ibarra, Surejkrishna Melattinkara Sunil, Isaac Lin

Sponsored By: Dr. Keith Jenné, Executive Director of UCSD Animal Care Program

​

Pick up cage

Flip Cage

Dump Contents

Fig.2. Illustration of worker’s repetitive rotating motion

​

Result

Translate: Linear translators

Dump: Rotary platform

Grab: Grabber arm

Fig 4: Von Mises Stresses on Adapter

​

Aluminum 6061-S (3 in x 1in)

Max stress, 1625 psi << Yield Stress, 35,000 psi

​

Fig 3: Von Mises Stress on linear actuator mount tube.

​

Aluminum 6061-S (2 in x 1in)

Max Stress, 209 psi << Yield Stress, 13050 psi

​

​

​

​

Project Objectives

Solution: Develop an automated machine to grab cages, dump bedding, then load cages into the conveyor belt washer.

Requirements:

• Efficiency: Grab, dump, and load cages at a rate of approx. 70% of a human worker’s efficiency.
• Load: Operate for typical cage weights of small mice cages (1.5 lbs).
• Interaction: Only require human involvement to load cages into machine and start the machine.

​

Sponsor: We would like to acknowledge our sponsor Dr. Keith Jenné and his team Nestor Riveria, Hugo Rivas, and Matthew Lerche for their support. MAE Staff: We would like to acknowledge Professor Huihui Qi, Professor Nicholas Gravish, Yifei Zheng, Tom Chalfant, Stephen Mercsak, and Chris Cassidy for their guidance and support.

References

Firgelli Super-duty linear actuator

Custom grabber arm adapters: Al6061-S

Force distribution block

• Integrate automated loading to remove human interaction from the process completely.
• Integrate vision system to Identify and grip different cage sizes.
• Utilize a motorized cart to increase accessibility.
• Tune rotary motor parameters to optimize speed.

High Steel Guide Rods

Future Improvements

​

• “Dry test” was conducted to ensure the machine can perform the work cycle, in addition to a “dirty test” with animal bedding within Central Research Services.
• The machine was able to complete a full workflow cycle at the required load and interaction objectives.

​

Aluminum 6061-S tubes

Fixed floating bearing configuration

Impact on Society

BISON DC Gearmotor: Can provide up to 1000 lbf*in torque at continuous duty cycle.

8020 Aluminum extrusions: Provide rigidity and flexibility for proper alignment.

Extrusion-braced steel plates to mount platform to linear translator system.

ESS-24 Stepper Motor: Rotates ball screw with integrated step count.

Rail Blocks: Supports the rotary platform and provides smooth translation with preload for 3147 lbf-in of dynamic load per block.

Ball screw: Facilitates precise linear translation with <0.06 in. of position tolerance.

Workflow

Human Safety: Reduces human exposure to severe health hazards in an occupational environment through automation.

​

Affordability: Expands accessibility of automated cage-cleaning through robust, specialized, and cost-effective design.

​

​

​

​

​

Acknowledgements

Electrical diagram

• Limit switch homing system to prevent tolerance stack-up.
• Multi-phase Arduino codebase for step-by-step automation.
• Trapezoidal and S-curve motion profiles for motor actuation.

Final Design