16-899D/NUR 2840 Project Page

Walker Robot

PHASE 1

The preliminary designs are near

ing the finishing stages. Thus far, two ideas for haptic control are being investigated.

  1. Control using joystick(s). With this method, one or two joysticks will be strategically placed within or upon the walker's supporting bars. The exact placement of the joysticks will be determined by experimentation (ultimately, the location providing the most information regarding the user's motion will be selected). Each joystick will be directly interfaced to the serial ports provided on the XR4000.
  2. Control using force-sensing resistors (FSR). With this method, strategic placement of multiple FSRs will be used to determine the user's motion. One possible scheme involves embedding FSR sensors at the extremities of each grip on the supporting bars. Two more sensors will be placed at the base of each supporting bar to indicate downward (or supporting) forces. This method will require an interfacing device that will be attached to either a serial or parallel port of the XR4000.

Each method is inexpensive and is intended to produce adequate information regarding the user's motion. A mock-up of the second method was implemented using switches instead of FSRs to determine force. The device works well and will be tested once we have secured a roller-walker. The following pictures and movie demonstrate this prototype.

PHASE 2

We have recently completed the data extraction portion of this project. Taking he ideas and designs from PHASE 1, we constructed a set of handle bars from PVC pipe, force-sensing resistors, and insulation foam and attached them to a commercial roller walker. The interface circuitry used to extract pressure readings took the input from the force-sensing resistors into and voltage-follower op-amp, which was then converted into a digital signal and queried from a serial port.