Robotic Shake Table with Camera and Accelerometer Feedback
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Solution Overview
Problem
Conventional shake tables are expensive, limited in functionality, and pose challenges in accurately positioning heavy specimens, such as large boulders, for repeatable experiments, particularly when studying the dynamics of precariously balanced rocks.
Innovation Solution
A low-cost robotic shake table (Shakebot) is developed, featuring a simplified design with off-the-shelf mechanical parts and 3D-printed unique components. It includes a closed-loop stepper motor for actuation, a perception system with an accelerometer and camera for motion estimation, and a microcontroller for controlling the motion and processing perception data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-scale shake tables are used to simulate earthquakes on large structures, then measurement precision and reliability are improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent uses a tabletop shake table that replicates the essential functionality of full-scale shake tables by using sensors (accelerometers and cameras) to capture and analyze ground motion. Instead of building expensive full-scale tables, the invention creates a scaled-down copying system that provides sufficient measurement precision for research purposes through computer vision and sensor fusion techniques.
Solution Approach 2:
The patent replaces complex mechanical sensing systems with a combination of accelerometers and camera-based vision systems. The camera captures visual data of fiducial markers on the specimen, and through image processing and coordinate transformation, derives ground motion parameters without requiring complex mechanical measurement devices.
2Device complexity
If conventional tabletop shake tables are used for testing small models, then cost is reduced, but functionality and measurement precision are limited
Solution Approach 1:
The patent enhances the functionality of tabletop shake tables by integrating multiple sensing modalities (accelerometers, cameras, fiducial markers) that enable the system to perform various experiments including PBR dynamics, structural response, and ground motion characterization. The system can accommodate different specimen types and experimental configurations, making it universally applicable to diverse earthquake research needs.
Solution Approach 2:
The patent introduces fiducial markers as intermediary objects that bridge the gap between the physical specimen and the digital measurement system. These markers serve as visual references that the camera can track to derive precise position and motion data, enhancing measurement capabilities without adding complex mechanical sensors to the specimen itself.
3Reliability
If heavy boulders are repositioned for repeated PBR experiments, then experimental data completeness is improved, but operation difficulty and time consumption increase
Solution Approach 1:
The patent employs a robotic arm to perform preliminary positioning of precariously balanced rocks (PBR) specimens before each experiment. The robotic arm can precisely place and reposition heavy boulders according to predetermined coordinates, eliminating the need for manual handling and ensuring consistent initial conditions for repeated experiments. This preliminary automated positioning maintains experiment reliability while significantly reducing operational difficulty.
4Measurement precision
If proprietary hardware and software are used in conventional shake tables, then measurement precision is maintained, but cost and accessibility worsen
Solution Approach 1:
The patent segments the measurement system into independent, off-the-shelf components including standard accelerometers, consumer-grade cameras, and readily available fiducial markers. Each component can be sourced separately from commercial vendors, allowing the system to be built and maintained without proprietary hardware constraints. This segmentation maintains measurement precision through careful component selection and integration while dramatically reducing overall system cost and improving accessibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The robotic shake table provides a cost-effective, accessible, and safe platform for earthquake research and education, enabling accurate and repeatable experiments on specimens like precariously balanced rocks, with improved motion estimation and control compared to conventional tables.
Implementation Method 1
The perception system includes at least one of an accelerometer coupled to the pedestal
Implementation Method 2
a camera positioned above the pedestal to view a plurality of fiducial markers affixed to the pedestal
Data Source
AI summary
A low-cost robotic shake table and method for operating the same is disclosed. The shake table includes a chassis having a pedestal slidably coupled to two linear shafts. The shake table also includes a motion system having a stepper motor, a transmission, and a motor driver, with the stepper motor coupled to the pedestal through the transmission. The shake table includes a perception system having a camera, an accelerometer coupled to the pedestal, and a plurality of fiducial markers coupled to the pedestal, and a microcontroller communicatively coupled to the motor driver and the perception system. The microcontroller is configured to receive an input motion data, produce a set of translational velocities based upon the input motion data, and convert the set of translational velocities into a control signal that will cause the stepper motor to move the pedestal along the linear shafts according to the translational velocities.