DESIGN AND ANALYSIS OF HUMAN POWERED HYBRID VEHICLE€¦ · driver to move in all types of terrain...

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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

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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


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


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



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



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)



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.



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.



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.



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:



(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



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



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

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DC Link Voltage Controller for Light Weight Electric Vehicle. International Conference

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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

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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.

DESIGN AND ANALYSIS OF HUMAN POWERED HYBRID VEHICLE€¦ · driver to move in all types of terrain...

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