ExoStance

Project

• Currently, physically disablilities limit users to one option for transportation.
  • Wheelchairs themselves are difficult to navigate many situations.
  • Exoskeletons are expensive and impractical. It wears on the hardware.
• The ExoStance's light frame, and small footprint provides an effective alternative method of transportation to people with disabilities.
  • Standing up in motion.
  • Access to a vehicle without expensive modifications.
  • Affordabable over offering.

System

Methods

• This project utilizes two existing electric unicycles, Secured to either side of the frame.
• Mechanical team designed a custom frame that houses electrical components and battery between the users’ legs. The frame can be easily disassembled.
• Electronics in the frame are powered by a 12V battery that provides power to the motor drivers and actuators. And DC/DC converter that provides 5V2 and STM32 microcontroller.
• User controls movement with a joystick and four buttons.
• External Interrupts read actuator positions into a model to control:
• Actuators at the hip and the knee allowed the user to sit and stand.
• Actuators on the wheels for turn assist.
• Actuators on the side of the base control balance on uneven ground.
• Kickstand controlled by actuators provides added stability.

Conclusion

• Project Successes
  • Users are able to drive the ExoStance freely.
  • User control of position and drive mode.
  • Precise actuator control for user safety.
• Future Development
  • This was a proof of concept that will be iterated to bring to market.
  • More research on reading speed from the wheels for safety limitations.
  • Next year, the engineers will refine the controller and implement wireless user interface.
  • Next year's team will be urged to implement tilt sensing in control loops.
• Lessons Learned
  • Interpretation of sensor data.
  • Power Distribution and management.
  • Control loop with analog input and pulse-width modulation.