1. Jeremiah Harmon Greg Buzulencia
The Equalizer
Jeremiah Harmon
Greg Buzulencia

2. Topics of Interest Overall Design Description
Component by Component Description
Interface Description
Design Issues
Cost Estimates

3. Inspiration
Challenges facing cyclists today

4. The Equalizer – Summary
Electromagnetic Bicycle Trainer system.
The resistance from 1-10 can be selected using push buttons connected to the HCS12.
Resistance Level: 4
Heart Rate: bpm

5. The Equalizer - Uses Riding with others of varying skill.
A rider in a flat area can simulate hills.
Act as an indoor trainer.
Interfaced heart rate monitoring system.

6. Voltage to Current converter (DC) Magnetic Hysteresis Brake
System Block Diagram
5V Supply
12V Battery
Voltage to Current converter (DC)
Magnetic Hysteresis Brake
Micro-controller
Heart rate sensor
Push buttons
LCD screen

7. Full System Diagram

8. The Equalizer - MCU to Brake
The brake is controlled by the HCS12 with a voltage-current converter.
The converter can apply a DC current to an electromagnetic brake.
An electromagnetic hysteresis rotary brake can provide resistance against the rear wheel of the bike.

9. The Equalizer - Power
Since the bike is mobile, a lightweight 12V nickel metal-hydride rechargeable battery is used.
Power is supplied to brake (primarily), MCU and device controller.
Considerations are being taken for issues dealing with bursts of current drawn by brake.

10. Electromagnetic Brake
Applies a constant resistance against rotation of rear wheel of the bike.
Can increase the amount of power a user needs to exert on the bike by 5-40%.
The user can pick from 11 levels of resistance.
Each level provides preset resistance.

11. Electromagnetic Brake – Overview
A Magnetic Hysteresis Brake best met our project design constraints.
The hysteresis effect.
Two components –a reticulated pole structure and a steel rotor/shaft assembly.
Ball bearing can spin freely without touching – no friction
Magnetizing force creates a flux field.

12. Electromagnetic Brake – Overview
The rotor is magnetically restrained
Smooth, infinitely controllable torque loads
Torque independent of speed
Quiet operation
No wear components exist
Long, maintenance free life

13. Electromagnetic Brake – Operational Specifications
High maximum operating speed.
The maximum rotational speed was calculated using a top road speed of 40 MPH.
(40mi/h) * (5280 ft/mi) * (12 in/ft) * (1/60 hr/min) * (1/(26*) in-1) = 517 RPM
Given a 4” brake, the maximum RPM of the brake will be 3361 RPM.

14. Electromagnetic Brake – Operational Specifications
Resistance conversion table: brake torque vs total force.
Resistance level
Force (lbs)
Torque on Wheel (in-lb) 1 .5
6.5 2 13 3
1.5
19.5 4 26 5
2.5
32.5 6 39 7
3.5
45.5 8 52 9
4.5
58.5 10 65

15. Electromagnetic Brake - Schematic

16. Electromagnetic Brake – Operating Limitations

17. Rear view of brake system

18. Battery
The largest power consumer is the Magtrol HB-8-3 brake which uses 15 Watts to power itself.
Maximum current draw from the brake, assuming a top speed of 40 mph, is 750 mA.
At maximum speed (3400 RPM) for 3 hours: 3hrs x 750 mA = 2250 mAh
Other components draw an additional 50mA.
Total:
3hrs x 800mA = 2400 mAh

19. Power Consumption Problem
When the brake has a sudden current draw, power could be drawn away from other components.
Solution:
Add capacitors to maintain voltage.

20. Battery - Operational Specifications
Nominal Voltage
Minimum charging time
Minimum Life Cycles
Standard charging time
Capacity
12 V
1.2 hours
500
14 – 16 hours
1800mAh

21. Heart Rate Monitor
Heart rate monitor must be accurate but un-cumbersome for the user.
The ideal solution:
not connected to user
accurate
can remain with the bike when not in use.
Requirements met by the Salutron Model Two electrical contacts determine the user’s EKG.

22. Heart Rate Monitor
Stainless steel contacts are durable and weather-proof
Simplified wiring
The sensor is recreational, not medical, with a tolerance of 0.65%.

23. HR Monitor - Specifications
Salutron Model 4000
Power: 3 volts (+/- 2.2 mA maximum
PCB Dimensions: 1.6 x 0.75 x 0.4 inches (41 x 19 x 10 mm)
Input signals: Right and Left sensors, Vcc and Ground.
Output signals(TTL compatible):         
1.      One pulse signal per each detected heartbeat
2.      UART serial port: heart rate reported at each heart beat
3.      SPI serial port: heart rate or ECG waveform reported

24. HR and LCD Mount Diagram

25. LCD Display The LCD displays the current heart rate and resistance
The center button turns the resistance on and off
The user can scroll through modes by pressing the ‘Enter’ button and the ‘up’ or ‘down’ button
The users are defined by going to the user mode and selecting <New User> from the list of users

26. LCD – Operational Specifications
Okaya RC2004LRSASOK
Vdd = 2.7v – 5.5v max
Max Temperature = 70ºC
Min Temperature = -20ºC
Display Dimensions: 76 mm x 25.2 mm
Display Characteristics: 20 characters x 4 lines
LCD Controller: Samsung KS0066U LSI

27. LCD Diagram
Resistance Level: 4
Heart Rate: bpm

28. Device Controller
Device controller takes PWM signal from HCS12 and outputs a linearly equivalent current to the electro-magnetic brake

29. Device Controller - Specifications
LORD Rheonetic Wonderbox Device Controller Kit (RD )
Power: 12 Vdc (2 A max output)
Size: 3.5 x 2.5 x 1.1 inches
Input: 2.1 mm Female banana plug
PWM: 30 KHz unfiltered ( input )

30. Interface to HCS12
The HCS12 must have sufficient I/O interfaces for the sensors and controllers.
Heart Rate Sensor: serial connection
LCD: 13 parallel bits
Brake Controller: PWM output
Push Buttons: 3 timer ports
These ports are all available on the HCS12

31. Interface Diagram HCS12 Brake Controller PWM A SER1 B P2 P1 P0 PWM SPICR DB
CMD
Heart Rate Monitor
Buttons
LCD

32. Cost Estimates Component Product Quantity Item Cost Total cost to us
Brake
Magtrol HB-8-3 1
$174.95
Push Buttons
GC Electronics 3
$3.78
$11.34
LCD Display
Okaya RC2004LRSASOK
$25.80
$0 (Donated)
Battery w/ solder tabs
Dantona DANAA1800MMHWT 10
$3.50
$35.00
50 pin connectors
Philmore 2
$1.78
$3.56
Device controller
LORD RD
$170.00
Microcontroller with Evaluation Board
Technological Arts Adapt9S12E256 with Motorola MC9S12DP256D
$133.00 $0
Heart Rate Monitor
Salutron
$25.95
Total
$579.60
$420.80

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