3.1 Walker Project Proposal
Introduction
Wheels are great on flat ground, but they suck at stairs and rocky paths. We want to build an 6 or 8 legged walker using a "Strider" linkage because it gives a much smoother, flatter walking path than a standard circle.
Problem Statement
Many fourbar linkage walking robots are not smooth and struggle with obstacles. We want to optimize a motion profile for a combination of smoothness and obstacle avoidance.
Mechanism
Crank-rocker fourbar. Must be grashof to work with a continuous rotation motor. Need at least 4 sets of 2 four bars so the robot does not rock with every step. Additionally, we would have a rigid bar coming off of l4 to act as a foot. On the end of this bar, we could make a simple rubber/tpu end piece that serves two functions. First, it would increase friction. Second, it would give some natural compliance to the system that would allow a wider range of motion profiles to work well.
Extended Scope Mechanism:
8-legged assembly where each pair leg is a 10-bar Strider linkage that converts a single rotating crank input into a complex, high-clearance path with a nearly linear ground-contact phase.
Proposed Scope
Ideally, the final prototype of this project will be able to complete a set course of variable obstacles. While our solution may not be applicable to each and every type of obstacle that may exist for real-world applications of this technology, we intend to demonstrate the validity of such technology in interacting with unknown or variable terrain.
The analysis we will need to complete prior to fabrication of this project will of course include link and part dimensions, along with maximum step heights and widths. Depending on the motors and driver used, we will also likely need to use inverse kinematics and part specifications to calculate a preliminary walking speed for the robot.
To increase scope, i.e. address more varied obstacle types, we could increase the complexity and range of the system by adding motors and links, along with adding capabilities for turning, which has the added benefit of allowing multiple types of obstacle avoidance, since the robot could walk around obstacles rather than having to go over, which relies on step range.
Minimum Scope
6 legged
1 motor
Flat ground walking
Basic kinematic model
Extended Scope
Strider linkage
8 legged
2 motors will allow for turning??
Small obstacles clearance
Preliminary Design
This runs in a python script that allows us to quickly iterate linkage
dimensions to visually optimize our motion profile. Theoretically, we could
add more to the code in order to make the bottom of the profile as long and
flat as possible. However, the drawback to this is that the step would not be
as high, so it may be harder to go over small obstacles such as pebbles.