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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 9, Issue 4, April 2018, pp. 594–605, Article ID: IJMET_09_04_068
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=9&IType=4
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication Scopus Indexed
DESIGN AND ANALYSIS OF HUMAN
POWERED HYBRID VEHICLE
Kuldeep Singh, Murari S Iyengar and Narahari S Iyengar
School of Mechanical Engineering, Vellore Institute of Technology, Vellore
Dr. Denis Ashok S.
School of Mechanical Engineering, Vellore Institute of Technology, Vellore
ABSTRACT
In a world that is running out of fossil fuels, harvesting human kinetic energy will
provide an immediate solution to various mechanical challenges and fuel limitations.
Also, harvesting renewable sources of energy can be the key to solving this problem.
Recent awareness of energy consumption and the environment has generated interest
in the eco-friendly transportation system in both developed and developing regions of
the world. But the mileage offered by electric vehicles is less because of high power
consumption in the initial stages. By using a pedal-assisted drivetrain system we can
reduce the consumption rate of battery power by the motor, which increases the
battery life. The delta configuration is chosen for a low turning radius. Structural and
weight analysis are performed to select the right material for the frame so as to build
a vehicle which would be lightweight but strong enough to sustain high loads exerted
by the driver during a ride. The overall design objective is to minimize the weight and
maximize the energy efficiency of the driver and motor. In this paper, a design and
development of a human powered transportation system are presented. It allows
driver to move in all types of terrain by transferring power to the drive train through
the use human powered pedal and electric powered motor. The paper mainly focuses
on the suspension and chassis design and analysis. It also provides a detailed
calculation into the power required by motor to run the vehicle.
Key words: Electric vehicle, Human power, Battery-electric car, Pedal-assisted
drivetrain and Use of human kinetic energy
Cite this Article: Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis
Ashok S, Design and Analysis of Human Powered Hybrid Vehicle, International
Journal of Mechanical Engineering and Technology, 9(4), 2018, pp. 594–605.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=9&IType=4
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
http://www.iaeme.com/IJMET/index.asp 595 editor@iaeme.com
1. INTRODUCTION
In the past few years, the rise in global temperatures attributed to the use of fossil fuelled
vehicles has triggered the need for green vehicles. Also, the lack of sources for non-renewable
fossil fuels may affect the transportation system of future generations. The main aim of the
project is to develop a hybrid human-powered vehicle. Human-powered vehicle is a vehicle
which utilizes human muscle power for propulsion. It dates back to ancient times where it was
used for various purposes, such as short-distance transportation. Since then, technology has
come a long way. While in older days, the vehicles solely relied on human power for
transportation, the hybrid vehicle integrates electrical energy into this system. The vehicle
will utilise a motor powered by batteries to reduce the energy expended by the driver.
However, it will not solely rely on the motor as the vehicle will use a pedal-assisted drive
system along with the battery powered motor for its functioning.
The inspiration for this project comes from observing the ever-rising pollution and its
harmful effects. In India, majority of the vehicles are fuelled by combustion of fossil fuels.
This trend has resulted in the release of harmful pollutants leading to the depletion of the
ozone layer and increased global warming. While the solution to this problem is electric cars,
it also gives rise to another problem – power consumption. In India, electric power
consumption rate is very high. This leads to a shortage in electric power available across the
country. The main objective of our project is to address both these issues.
2. METHODOLOGY
Figure 1 Flow chart diagram of methodology
End-user needs: A method of transportation that is eco-friendly, easily affordable and
provides good mileage.
Design objective: A low weight, easily affordable, good mileage, human powered hybrid
vehicle
Constraints: Low budget, high-power consumption by motor, low efficiency of CVT,
energy expended by driver to pedal
Metric for success: The vehicle is powered by a motor drawing energy from batteries
combined with a pedal-assisted drive train, thus improving the life of batteries, reducing
energy used by driver and offering a clean form of transportation.
Design and Analysis of Human Powered Hybrid Vehicle
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3. CONCEPT GENERATION 1. Suspension: The vehicle will utilise 3 wheels employed in a delta formation as
opposed to the delta formation. This is done so to reduce the turning radius of the
vehicle and to offer more traction for the vehicle to utilise the full capacity of the
motor.
Figure 2 Configurations of 3-wheel vehicles
1. Chassis: The body will employ a space-frame chassis which can be easily
manufactured. This type of chassis also has the benefit of low cost and good strength.
2. Transmission: The drivetrain of the vehicle will combine both human and electrical
energies. This will be done by combining the power received from the motor and
pedal in the ratio of 70:30. A CVT will be attached to the motor to improve efficiency
and ease the load on the motor.
3.1. Suspension
The rear suspension uses a double-wishbone set up. The damper-spring setup will be mounted
on the lower wishbones attached to the chassis frame
Figure 3 Left: Rear suspension geometry | Right: Rear suspension assembly
3.1.1. Wheel Base and Track Width
The steering geometry is one of the most important factors to be considered while designing
the vehicle. This is influenced by the track width and wheel base. A longer wheel base
ensures that the vehicle has better stability at higher speeds as the rate of longitudinal load
transfer is low. However, the low rate of longitudinal low transfer reduces the
manoeuvrability of the vehicle. The track width too plays a similar role in the stability of the
vehicle.
After due consideration and iterations, optimum values for the wheelbase and track width
were chosen. The wheelbase was set at 2100mm with the height of the vehicle capped at
1989mm. The track width plays a more crucial role while cornering. A wide track width
ensures that the rate of lateral load transfer is low, thus lowering the chances of the vehicle
capsizing while cornering. But since the vehicle needs to be quick on corners and quite
reactive to the lateral load transfer, an optimum track width 1100mm was chosen. The width
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
http://www.iaeme.com/IJMET/index.asp 597 editor@iaeme.com
of the chassis frame was done taking into consideration the space boxes of the transmission
system.
Figure 4 Top view of rear suspension geometry
The suspension system is defined as the combination of linkages, dampers and springs
that act the connection between the body of vehicle and the ground. The main purpose of the
suspension system is three-fold: Comfort, Contact and Control.
Our vehicle suspension system focuses more on the comfort as the vehicle is a passenger
vehicle. The suspension works to maintain perfect driver conditions for the driver. This is
done for all possible manoeuvres of the vehicle. Another purpose of the suspension system
i.e. contact depends on the tires of the vehicle. The tires have to be in constant contact with
the ground to ensure that the forces generated by the transmission and brake systems are
transferred to the ground via the tires. The steering input too needs to be transferred to the
ground. To ensure this, the tires must always be in contact with the ground.
Figure 5 Front view of rear suspension geometry
The upper and lower arms transfer load from the chassis to the tires. The damper is
directly attached to the chassis frame. The damper is installed to provide critical damping for
the vehicle. To achieve critical damping ride calculations have been carried out and spring
stiffness has to be calculated. Our suspension plays role to control movements under two
situations
Accelerating and Braking situation (In this case, the load transfer along the
longitudinal axis).
Cornering situation.
Ride Comfort
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3.1.2. Predominant Factors of the Design
Figure 6 Kingpin inclination of 6 degrees
The king pin inclination plays a role in affecting the geometric variations of the steering
systems. Also the forces transmitted to the chassis depend on the king pin inclination. A
positive king pin angle gives better steering feedback to the driver. The value of this angle
must be optimum as high angles induce a negative gain on camber and a low angle reduces
the steering feel.
The scrub radius too plays a similar role. A Positive scrub radius in the front will cause
the wheel to toe out while accelerating and toe in while braking. On the rear wheel, a positive
scrub radius will cause the wheel to toe in at all times. The opposite happens with a negative
scrub radius. Hence a positive scrub radius has been used in the suspension geometry.
A camber of 0 degrees is implemented because this enables the tyres to have maximum
contact with the ground during ride. With this setup, iterations were made for different
camber values at different roll and heave while camber change values were observed
3.1.3. Load transfer calculations
The length of the A arms and the angle between each of them determines the forces that will
be experienced by them. The particular lengths were chosen as they met the requirements of
the track of the vehicle and could sustain the forces acting on them.
Table 1 Input required to calculate longitudinal load transfer during acceleration and braking
ASSUMPTIONS
Symbol Value Units
Deceleration (A) 1.2 g
Acceleration (A) 1.2 g
CG Height (h) 0.3 m
Wheelbase (L) 1.64 m
Weight on Front Axle (%Wf) 0.4 decimal
Weight on Front Axle (%Wr) 0.6 decimal
Mass of Vehicle (W) 250 kg
Longitudinal load transfer equation:
(1)
Initial front load:
(2)
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
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Initial rear load:
(3)
After load transfer (During acceleration):
(4)
(5)
After load transfer (During braking):
(6)
(7)
Table 2 Longitudinal load transfer values obtained using equations 1 to 7
RESULTS
ΔW 753.695122 N
Wfi 1373.4 N
Wri 2060.1 N
Wffa 619.704878 N
Wfra 2813.795122 N
Wffb 2127.095122 N
Wfrb 1306.404878 N
Table 3 Input required to calculate lateral load transfer during cornering
Assumptions Symbol Value Unit
Lateral Accelartion Ay 1 g m/sec^2
Total Wieght W 250 kg
Track Width Rear Tr 1.1 m
Roll Rate Front Køf 11.89089289 kgm/deg
Roll Rate Rear Kør 13.94267091 kgm/deg
CG Location From Front a 1.26 m
CG Location From Rear b 0.84 m
Rear Roll Centre Height Zrr 0.09233 m
Dist Between Cg And Roll Axis H 0.21168 m
Wheel Base L 2.1 m
CG height from Ground h 0.3 m
Lateral load transfer formula:
(
) (
) (8)
Using eq. 8 we get
After the load transfer calculations, the force calculation is carried out on the A-arms
using the force body diagrams. The CAD models are then imported into ANSYS to carry out
static structural analysis on the model. The IGES standard of the a-arm model is imported and
the model is subjected to boundary conditions for carrying out the analysis. The model is
given fixed support from one end of the A-Arms and the forces are applied to the
perpendicular surface on the other end of the A-arms. This analysis helps to determine the
factor of safety of the suspension assembly.
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3.2. Chassis Design
3.2.1. Introduction
When designing a chassis, many factors have to be taken into account. The frame being the
main component of the vehicle, the design goals for the entire vehicle have to be set. The
Human-Powered Hybrid Vehicle is a three wheeled vehicle. According to the space
constraints of other related departments, the chassis has been designed.
Upon completion of the suspension geometry, the chassis design can be initiated. Ideally,
the center of gravity is kept low and centered for the vehicle. To do so, draw out the major
components like the drive-train and driver. With the suspension points, driver and drive train
in free space, connect all the components.
The initial design is analyzed and iterated till a satisfactory result is achieved. The chassis
includes a large number of frame members which requires using Finite Element Analysis to
work out numerous equations. Thus, ANSYS Static Structural is used to analyze the chassis.
3.2.2. Torsional Rigidity
The rear mounting points are fixed in torsional rigidity test to allow the chassis to experience
maximum torsional force. A force couple is applied to the front end of the vehicle. Based on
the deflection endured by the chassis, the torsional rigidity is calculated.
Figure 7 Total deformation test of chassis
3.2.3. Considerations
Main considerations would be the, stress, deflection and Factor of Safety. When under load,
the geometry of the chassis changes which has slight effects on the handling. While this
deflection affects handling, in a way it can help improve it as it provides a feedback to the
driver. Load paths are one of the most critical aspects of a chassis. These load paths help
transfer the load from node to node without putting too much stress on any one single node.
The stresses developed can point out the critical areas that need addressing. These areas can
be redesigned by changing orientation or by providing support through reinforcement. Areas
with unnecessary members can also be identified and altered accordingly. The mass of the
chassis can increase or decrease based on the material, geometric dimensions of the members
used and the complexity of the chassis design itself.
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
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Figure 8 Left: Top of chassis | Right: Front view of chassis
By looking at the images, one can notice that the middle section of the chassis includes
wide elements. This is done for two reasons. The first reason is that the width of the chassis
allows the driver to comfortable operate the vehicle. This also significantly reduces egress
time in times of emergency. The second reason is the efficient transfer of loads which results
in efficient distribution of stresses in the chassis. Due to its large openings on the sides,
equipment can be mounted / dismounted easily. A majority of the load lies within the
boundaries of the chassis which helps maintain the center of gravity of the chassis as centered
as possible.
Figure 9 Left: Side view of chassis | Right: Isometric view of chassis
3.3. Transmission
3.3.1. Introduction
The transmission system of this vehicle has been designed keeping in mind, the speed and
acceleration requirements of various loading conditions. COMPAGE AUTOMATION BLDC
motor has been chosen to meet these requirements. According to the data sheet the motor is
capable of delivering maximum torque of 29 N-m. The power transmission is carried by a
CVT and a combination of chain sprocket.
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3.3.2. Input
Table 4 Input required for transmission power calculation
Assumptions Symbol Value Unit
Radius of Wheel r 0.304 m
Mass of Vehicle M 250 kg
Max RPM N 3000 RPM
Frontal Area A 1.13 sq. metre
Max Torque by Motor Tm 29 N-m
Gradient α 4 deg
Crank Length L 170 mm
Coefficient Of Drag CD 0.9659
Rolling Coefficient µ 0.7
Average Power Produce By Human 500 watts
Air Density ρ 1.225 ⁄
Average Velocity of The Vehicle v 15 kmph
Force Exerted on Pedal By Driver Fp 200 N
Gear Ratio of Chain Sprocket i1 2
Gear Ratio of CVT i2 4
3.3.3. Formulae used
3.3.3.1. Resisting Forces
Rolling resistance:
(9)
Gradient resistance:
(10)
Aerodynamic resistance:
(11)
3.3.3.2. Power Calculation
Power consumed for climbing gradient:
(12)
Power consumed for rolling resistance:
(13)
Power consumed for aerodynamic at high speeds:
(14)
At high speed (no gradient) Total power consumed:
(15)
3.3.3.3. Torque Calculation
Total Tractive effort:
(16)
At high speed on flat road Total Tractive effort:
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
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(17)
Initial torque at wheels to move the vehicle wheel:
( ) (18)
Torque obtained from pedal:
(19)
Table 5 Transmission calculations obtained using equations 9 to 19
RESULTS
Rolling Resistance 1715
N
Gradient Resistance 539
N
Aerodynamic Resistance 11.5692
N
Power Consumed for Rolling Resistance 7134.4
watts
Power Consumed for Aerodynamic at High Speeds 48.12788
watts
Total Power Consumed 7182.528
watts
Total Tractive Effort 2265.569
N
At High Speed on Flat Road Total Tractive Effort 1726.569
N
Initial Torque at Wheels to Move the Vehicle Wheel 262.4385
Nm
Torque Produce by Pedal 34
Nm
Input Torque At CVT(Sum of Motor and Pedal Torque) 97 Nm
Final Torque Output (With Pedal) 388
Nm
From the above results, we see that the torque required to move the vehicle is 262.43
Nm. By using a combination of pedal and motor, we obtain a torque of 388 Nm. Since
the torque output is greater than the torque required, the load on the motor is decreased
and thus the power consumption rate decreases.
4. ANALYSIS
Using ANSYS Static Structural, Finite Element Analysis has been carried out to validate the
safety of our designs.
Figure 10 Left: Safety factor of rear upright | Right: Total deformation of rear upright
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Figure 11 Left: Safety factor of rear hub | Right: Total deformation of rear hub
Figure 12 Left: Safety factor of chassis | Right: Total deformation of chassis
5. CONCLUSION
Taking into consideration the various design iterations, calculations and analyses conducted,
the subassemblies are put together to deliver the final product. The final product is a three-
wheeled vehicle that runs on electric and human power. The total mass of the vehicle
including driver and luggage is 250 kg.
Figure 13 Isometric view of designed hybrid vehicle
Kuldeep Singh, Murari S Iyengar, Narahari S Iyengar and Dr. Denis Ashok S
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SCOPE OF FUTURE WORK
As research towards developing batteries with large power storage capacity, increased range
of one time usage, low weight, low cost is immense, in future the vehicle can be developed
into a hybrid type where human power can assist battery storage energy. The system can work
as a regenerative power system. A novel solution for in-house development of circuitry can be
carried in future to save cost.
The transmission system of the HPV can be further improved by use of planetary and sun
gears. Also, hydraulic transmission can be other options that can be explored for better
transmission output.
The hybrid can be developed either by using a single motor powering all wheels as in
conventional all electric cars or by using the equal number of motors as that of number of
wheels available making it a perfect all-wheel drive hybrid human powered vehicle.
More work can be carried out so that the vehicle can be converted to a fusion vehicle
completely, which means the source of energy can be from both human power and also from
other renewable sources of energy like solar energy or wind energy.
An adjustable pedal mechanism can be implemented to improve driver response and
comfort for drivers of different height and build.
REFERENCES
[1] Ahmed MortuzaSaleque, Alif Md. Asif Khan, 2017. A Variable Speed PMSM Drive with
DC Link Voltage Controller for Light Weight Electric Vehicle. International Conference
on Electrical, Computer and Communication Engineering (ECCE), pp 145-151, 16-17
Feb. 2017, DOI: 10.1109/ECACE.2017.7912896, ISBN: 978-1-5090-5627-9.
[2] Jerzy A Zoladz, Arno CHJ Rademaker, 2000. Human muscle power generating capability
during cycling at different pedalling rates. Experimental physiology, 85(01):117–124,
2000
[3] JhaAbhay K, Ahmed MortuzaSaleque, 2017, Drivetrain Design and Feasibility Analysis
of Electric Three-Wheeler Powered by Renewable Energy Sources. Proceedings of the
2017 4th International Conference on Advances in Electrical Engineering (ICAEE), 28-30
September, Dhaka, Bangladesh
[4] Julian Edgar, 2014. Design and Development of an Improved Hybrid Tricycle, the
Recumbent Bike Forum.
[5] Visakh Sasikumar, Jacob Thekkekara, Ashok Jhunjhunwala, 2016 Green Transportation
using Intelligent Solar Electric Pedal Assist Three Wheeler.
[6] N.Siva Teja, B.Yogi Anvesh, Ch.Mahesh, D.Sai Kiran and D.Satya Harsha, Design and
Analysis of Hybrid Vehicle, International Journal of Mechanical Engineering and
Technology (IJMET) Volume 8, Issue 5, May 2017, pp. 237–248.
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