This project is a portable, deployable wall plotter robot. My motivation for creating a cable-driven robot for this project is in part due to a perceived need in the field of architecture. If we consider the landscape of robotics as a whole, we could generalize that there is an inverse relationship between size of workspace and accuracy of the manipulator. Architecture, especially on-site construction involves a multitude of tasks not suitable to industrial arms because of their limited workspace. Furthermore, construction tolerances are rarely so high as to require industrial levels of precision. However, aerial robotics for construction is energy expensive and far from a viable option. I therefore see wire robots as a potentially successful middle ground. I hope that through this project I'll become much more knowledgeable about wire robots and will end up with a successful proof of concept for auto-calibrating wire robots.
Parallel Robots tend to have limited workspace, due to limitations of the stroke of linear actuators. Wire robots (or cable robots, or tendon-based Steward platforms) address this by substituting actuators with cables. The flexibility of wires allows large changes in the length of the kinematic chain, for example by coiling the tendons onto a drum. This allows them to overcome the purely geometric workspace limitation factor of classical robots. Wires can be coiled by very fast drums while the moving mass of the robot is extremely low, which allows the robot to reach very high end effector speeds and accelerations.
(x0, y0) = (-1,-1) (left stepper motor)The simulation is plotting the region which satisfies the condition that each stepper can only put out positive force (i.e. pull on the string) and that force must be less than some value fmax, which is changing here.
(x1, y1) = (1,-1) (right stepper motor)
(x2, y2) = (1,1) (right counterweight)
(x3, y3) = (-1,1) (left counterweight)
force of springs fs = 1
force on stepper 1 = f0
force on stepper 2 = f1
mass*gravity term (alpha) = 0.1