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The Task at Hand
We are setting out to spec, design, prototype and build a set of Series Differential Compliance Actuators. We build these actuators in order that they may eventually be used in a 3D bipedal walking robot. The set of actuators will be composed of a one degree of freedom actuator and a two degree of freedom, differential actuator. In order to display the effectiveness of these actuators we will be presenting them as a part of a greater demo (or 2) which would serve to display the functionality and advantage of our actuators.
We will accomplish our tasks before Olin's graduation date in May '08.
Specific Requirements
The Actuators
We admit that the mechanical aspects of this project are unique and so must be custom designed and manufactured. We believe the same is true for the electrical portion of this project, but some research should be done to confirm that, and if we find otherwise, we will attempt to adopt as much stock hardware as possible.
- Must be acceptable for any joint on a human-proportioned 3 foot biped.
- Must present an interface to a modern PC (either USB or some other modern standard)
- Must present an appropriate communication protocol that could be used in a 18 DoF robot
- May present an interface for use with standard PWM-based technology.
- Neither actuator is more important than the other, and so both should demand high effort throughout the project.
The Demo
- Must be some application which is accomplished much better through the use of our actuator
- Must be simple enough to be done reasonably well in the allotted time
- Must be elegant enough to impress, rather than confuse (moderate to high wow factor)
- Must not prevent us from completing our goals for the actuator.
Tasks and Scheduling
Intermediate Deliverables
Before Winter Break
- A functional (but not necessarily packaged) 1 DoF SDCA (Must meet biped spec)
- A basic definition of the Demo, definitely narrowed down to a single idea.
By Mid-Semester Spring
- A nearly packaged 1 DoF SDCA (Must meet biped spec)
- A functional (but not necessarily packaged) 2 DoF SDCA (Must meet biped spec)
- A solid design for the Demo.
By Graduation
- See: Definition of Success
Preliminary Breakdown of Tasks
Context
- Define the 3D Biped Spec - Create a full set of specifications for the robot. What must the robot be able to do? How much will it need to weigh?
- Put it all together
Actuator
- Define the Actuator Spec - Translate the robot's specs into actuator specs. What must the actuator be able to do? How fast? How hard? At what weight?
- Define the M/E interface - This interface may develop over time, but should never go backward. What decisions are made about sensing that will not change?
- Design the Actuator - iterate through the design process for the actuator to create at least 2 "functional" prototypes - these will make extensive use of the cRio
- Build the final actuator - Make the final prototype, and integrate the electrical components.
Demo
- Brainstorm Demo ideas - What can we possibly make? What would be cool? Useful? New? Useless but cool and new? Classic? Funny? Entertaining?
- Narrow Down on Demo Ideas - get to 3-5 ideas
- Sketch / Model DemoBot? Ideas - What will they really look like? Concept art?
- Choose one demobot idea - what will we do.
- Design the demo idea - Run it through until you have a reasonable prototype
- Build the Demo
Simulation
- Work on impedance control simulation
- Actuator simulation
- Motor control simulation
Definition of Success
- A Packaged and polished 1 DoF SDCA
- A Packaged and polished 2 DoF differentially-jointed SDCA package
- Both actuator must successfully implement impedance control, and must be usable by anyone with a modern desktop PC.
- A robot based on our actuators which demonstrates a significant advantage of compliant actuators over traditional actuators.