PROJECT PORTFOLIO
Senior Project: Rose Float Electric Drive System 2008-2009: Cal Poly, San Luis Obispo Purpose: Cal Poly San Luis Obispo has a long history as a participant in the Tournament of Roses Parade in Pasadena, CA. As a school that has a proud reputation of “learn by doing”, Cal Poly, with the support of BAE Systems, Inc., has embraced the challenge of designing the first electric drive system specifically for a Rose Parade Float. The current Rose Float utilizes a hybrid hydraulic/propane system, and requires approximately 60 kW of power to traverse the Rose Parade route. The electric drive system provides the full capability of the previous system, as well as proves to be much more reliable and efficient than the current drive-train. Task: Our team, Charged Floats, was given the task of designing a new drive system for the Cal Poly Rose Float program. The challenge is to create a system that will replace the current propane/hydraulic powered hybrid system. Our system is a more efficient and sustainable electricpowered system. It is thought that the future of energy consumption depends on our ability to efficiently store and utilize electric power. This project demonstrates the capabilities of large scale electric-powered vehicles. Our goal was to provide BAE Systems and the Cal Poly Rose Float program with a working system that can drive a 40,000-lb float at parade speeds of approximately 5 mph. (The float also needs to be transported every year from San Luis Obispo to Pomona which requires transportation speeds of up to 15 mph.)
Knowledge Applied: • Used my understanding of statics to develop a free-body diagram used to determine all the forces acting on the float. Developed a list of assumptions to simplify the system. • Utilized Excel to analyze the power consumption and to determine the size of the electric motors required to power a 40,000 lb float through the Rose Parade route. Power Analysis Free-Body Diagram:
2
Power Analysis: Parameter Float weight Tire diameter Tread thickness
Value 40,000 39 9
Units lbf in in
Speed Requirements Parade: 2 4 6 Transportation: 10 12 15
mph mph mph mph mph mph
0.89 1.79 2.68 4.47 5.36 6.71
m/s m/s m/s m/s m/s m/s
Power Required
Drag 2
101325 Pascals-N/m 293.15 K 287.05 J/kg-K 3 1.204 kg/m ρ (air) V (air speed) see speed req's above 2 S (surface area) 28 m CD (coef of drag) 1.3 (see attached) p (air) T (air) R (air)
Fd (2mph) Fd (4mph) Fd (6mph) Fd (10mph) Fd (12mph) Fd (15mph)
17.3 69.1 155 432 621 971
N N N N N N
3.88 15.52 34.93 97.02 139.71 218.30
Rolling Resistance: (took 3 to push 200lbf each at 2 in/sec) Crr (rolling resistance coef) Nf (normal force)
0.04 44,482 N (per wheel)
Frr (rolling resistance) 1779.29 N (per wheel) FrrT (total resistance) 7117.15 N 1600 lbf
lbf lbf lbf lbf lbf lbf
Conversions: start w/ mult by. mph 0.44704 0.00134 Watt N 0.22481 in 0.0254
to get m/s hp lbf m
Efficiencies: Final Drive
0.96
Tire Radius 39" diameter
0.4953 m
Gear Ratio 30 :1
(kW)
P = Σ(Fd + FrrT + n*G)*V*(1/Eff)
Speed 2 mph 4 mph
0.0% 6.6 13.4
0.5% 7.5 15.0
1.0% 8.3 16.7
Road Grade (%) 1.5% 2.0% 9.1 10.0 18.4 20.0
2.5% 10.8 21.7
3.0% 11.6 23.3
3.5% 12.4 25.0
6 mph 10 mph 12 mph 15 mph
20.3 35.2 43.2 56.5
22.8 39.3 48.2 62.7
25.3 43.4 53.2 68.9
27.8 47.6 58.2 75.1
32.7 55.9 68.1 87.6
35.2 60.0 73.1 93.8
37.7 64.2 78.0 100.0
2.5% 14.5 29.1 43.9 74.9 91.3 117.4
3.0% 15.6 31.3 47.2 80.5 98.0 125.8
3.5% 16.7 33.5 50.6 86.0 104.7 134.1
2.5% 199 200 202 206 210 216
3.0% 214 215 217 222 225 231
3.5% 230 231 232 237 240 246
Power Required Speed 2 mph 4 mph 6 mph 10 mph 12 mph 15 mph
(hp)
0.0% 8.9 18.0 27.2 47.1 58.0 75.8
Torque Angular Velocity ω [rad/s] 54 108 162 271 325 406
0.5% 10.0 20.2 30.6 52.7 64.7 84.1 (N·m)
30.3 51.7 63.1 81.4
P = Σ(Fd + FrrT + n*G)*V*(1/Eff) 1.0% 11.1 22.4 33.9 58.3 71.3 92.4
Road Grade (%) 1.5% 2.0% 12.2 13.4 24.6 26.8 37.2 40.6 63.8 69.4 78.0 84.7 100.8 109.1
T = P/ω Road Grade (%)
0.0% 123 124 125 130 133 139
Electric Drive System Layout:
3
0.5% 138 139 140 145 148 154
1.0% 153 154 156 160 164 170
1.5% 169 169 171 176 179 185
2.0% 184 185 186 191 194 200
RPM 517 1034 1551 2586 3103 3878
Knowledge Applied: • Used my understanding of statics to develop a free-body diagram used to determine all the forces acting on the float. Developed a list of assumptions to simplify the system. • Utilized Excel to analyze the power consumption and to determine the size of the electric motors required to power a 40,000 lb float through the Rose Parade route. Power Analysis Free-Body Diagram:
2
Power Analysis: Parameter Float weight Tire diameter Tread thickness
Value 40,000 39 9
Units lbf in in
Speed Requirements Parade: 2 4 6 Transportation: 10 12 15
mph mph mph mph mph mph
0.89 1.79 2.68 4.47 5.36 6.71
m/s m/s m/s m/s m/s m/s
Power Required
Drag 2
101325 Pascals-N/m 293.15 K 287.05 J/kg-K 3 1.204 kg/m ρ (air) V (air speed) see speed req's above 2 S (surface area) 28 m CD (coef of drag) 1.3 (see attached) p (air) T (air) R (air)
Fd (2mph) Fd (4mph) Fd (6mph) Fd (10mph) Fd (12mph) Fd (15mph)
17.3 69.1 155 432 621 971
N N N N N N
3.88 15.52 34.93 97.02 139.71 218.30
Rolling Resistance: (took 3 to push 200lbf each at 2 in/sec) Crr (rolling resistance coef) Nf (normal force)
0.04 44,482 N (per wheel)
Frr (rolling resistance) 1779.29 N (per wheel) FrrT (total resistance) 7117.15 N 1600 lbf
lbf lbf lbf lbf lbf lbf
Conversions: start w/ mult by. mph 0.44704 0.00134 Watt N 0.22481 in 0.0254
to get m/s hp lbf m
Efficiencies: Final Drive
0.96
Tire Radius 39" diameter
0.4953 m
Gear Ratio 30 :1
(kW)
P = Σ(Fd + FrrT + n*G)*V*(1/Eff)
Speed 2 mph 4 mph
0.0% 6.6 13.4
0.5% 7.5 15.0
1.0% 8.3 16.7
Road Grade (%) 1.5% 2.0% 9.1 10.0 18.4 20.0
2.5% 10.8 21.7
3.0% 11.6 23.3
3.5% 12.4 25.0
6 mph 10 mph 12 mph 15 mph
20.3 35.2 43.2 56.5
22.8 39.3 48.2 62.7
25.3 43.4 53.2 68.9
27.8 47.6 58.2 75.1
32.7 55.9 68.1 87.6
35.2 60.0 73.1 93.8
37.7 64.2 78.0 100.0
2.5% 14.5 29.1 43.9 74.9 91.3 117.4
3.0% 15.6 31.3 47.2 80.5 98.0 125.8
3.5% 16.7 33.5 50.6 86.0 104.7 134.1
2.5% 199 200 202 206 210 216
3.0% 214 215 217 222 225 231
3.5% 230 231 232 237 240 246
Power Required Speed 2 mph 4 mph 6 mph 10 mph 12 mph 15 mph
(hp)
0.0% 8.9 18.0 27.2 47.1 58.0 75.8
Torque Angular Velocity ω [rad/s] 54 108 162 271 325 406
0.5% 10.0 20.2 30.6 52.7 64.7 84.1 (N·m)
30.3 51.7 63.1 81.4
P = Σ(Fd + FrrT + n*G)*V*(1/Eff) 1.0% 11.1 22.4 33.9 58.3 71.3 92.4
Road Grade (%) 1.5% 2.0% 12.2 13.4 24.6 26.8 37.2 40.6 63.8 69.4 78.0 84.7 100.8 109.1
T = P/ω Road Grade (%)
0.0% 123 124 125 130 133 139
Electric Drive System Layout:
3
0.5% 138 139 140 145 148 154
1.0% 153 154 156 160 164 170
1.5% 169 169 171 176 179 185
2.0% 184 185 186 191 194 200
RPM 517 1034 1551 2586 3103 3878
