Crane Tether Mechanism Cole Perrault Spring 2016 ET 493 Dr. Cris Koutsougeras

Problem Certain work environment's may be prone to slips, trips and falls. Current systems use mechanical means to automatically lock. Releasing the lock may be difficult after an STF. Personnel may get suspension trauma.

Hardware Solenoid Seatbelt Tether Accelerometer Arduino ZigBee Modules Encoder

Solenoid Requires NPN Transistor TIP120 Diode for current protection 12-24V up to 6A

Encoder Use of Arduino external interrupts Implements function at each interrupt

Methodology Module One Module Two Accelerometer: to measure slip, trips, falls ZigBee: to communicate STF values Encoder: to measure the tethers rotational velocity Solenoid: to lock/unlock the tether ZigBee: to communicate STF values

Flow Chart Lock Tether Set point STF Encoder Input Accelerometer Input Velocity Conversions Lock Tether Flow Chart

Encoder

Velocity First order approximation with preset time interval Encoder to return position based on four different possible states

Angular Velocity Angular_Velocity() will be executed on interval Solenoid state determined from STF and RPM set point

Angular Velocity Determine if we are extending the tether Determine If we are reading encoder pulses Calculating RPM

Linear Velocity Scale is linear correlation of voltage offset for each -/+ g felt by sensor If free fall is detected send true value

Prototype Improvements Addition of “super positon” sensors. Determine pattern for STF Use of multiple sensors Implementation of boon sweeping

Crane Tether Mechanism Cole Perrault Spring 2016 ET 493 Ho-Hoon Lee Cris Koutsougeras