Motorized Wheelchairs

Question 1

Who would use Motorized Wheelchairs?

Answer 1

• Neurological/Musculo-Skeletal Injury/Disorder: Higher SCI, strokes, CP, MS, muscular dystrophies
• Disorders that compromise cardiovascular and pulmonary systems
• Age: old people

Question 2

What are some characteristics of motorized wheelchairs?

Answer 2

• Heavier
• Different control types (joystick, toggles, head pressure, sip/puff)
  -Rear- (fast, bad turn), mid- (best turning, unsteady), or front- (good turning, slower) wheel drive

Question 3

What are the three types of batteries?

Answer 3

• Wet: use chemical reaction between lead and sulphuric acid to create electrical energy
• Gel: mixture of sulphuric acid, fumed silica, pure water, and phosphoric acid, which forms a thixotropic gel.
• AGM: Have an absorbent glass mat sandwiched between the plates, saturated with acid electrolyte, but with none free to spill.

Question 4

What are the advantages and disadvantages of wet batteries?

Answer 4

Adv: cheaper, less vulnerable to overcharging, bigger capacity

Dis: require maintenance, can leak, self-discharge

Question 5

What are the advantages and disadvantages of gel batteries?

Answer 5

Adv: No maintenance, better in low temp, longer life cycle

Dis: Expensive, less capacity

Question 6

What are the advantages and disadvantages of AGM batteries?

Answer 6

Adv: No maintenance, shock resistant, low self-discharge

Dis: higher cost, susceptible to overcharging

Question 7

Describe how joysticks work

Answer 7

Most common interface. Converts displacement to voltage.

• Proportional Movement Sensing Joystick (MSJ): uses direction and amount of movement of moveable joystick to determine direction and speed
• Isometric Joystick (IJ): uses the amount and direction on immovable joystick to determine direction and speed

Question 8

What are some alternative control mechanisms (5)?

Answer 8

• Headrest Position monitors: activated by head movement
• Sip/Puff tube: pressure applied to pneumatic tube
• Chin control: joystick but controlled with the chin
• Speech control: speech recognition systems
• Tongue Operated system: tongue touch keypad on the roof of the mouth

Question 9

Why is the tongue a good possible control system? (8)

Answer 9

• Sophisticated motor control with fine degree of control
• Fast movements, very flexible
• Connected to brain by cranial nerve (escapes high SCI)
• Non-invasive access
• Not afflicted by repetitive motion disorders
• Doesn’t fatigue easily
• Privacy advantage
• Body doesn’t influence it

Question 10

What was the iBOT?

Answer 10

High-tech mobilized wheelchair. Gyro-balanced mobility device that can drive on four or two wheels. Could climb stairs, bump up curbs, and elevate the passenger. Cost: $30,000.

Question 11

What was the Tek RMB?

Answer 11

Moving Standing Frame.

Wheelchair that allows paraplegics to stand and move around their environment. Price: $15,000