DESIGN OF A SMART ELECTRIC POWER TILLER
BACKGROUND INFORMATION
Sand is an Agri Tech startup based in Chennai. It aims to bring forth innovative and affordable agricultural equipment and services and ease the efforts of low-income farmers. I was working as a Design Intern at Sand Bird. My primary responsibility was the design and development of Smart Electric Power Tillers which Sand Bird plans to launch in market soon.
What is a Power Tiller
Power Tiller is a two wheeled agricultural implement used for cultivation, weeding, sowing and various other agricultural activities. Two-wheeler tractor or Hand Tractor are some of the common terms used to describe a power tiller. Its direction of travel and control of field operation is done by the operator behind it. It can be effectively used to reduce the dependence of farmers on animal power. In recent times Power tillers have gained significant traction in Indian Markets. Shortage of labour along with rising wage rates, timesaving, reducing drudgery are some of the factors behind that. Tillers are generally preferred by small land holding farmers for farming operations.
MARKET SURVEY
Before starting with the design of tiller we did a market survey to understand the issues which farmers face with tillers currently available in the market.
The current operational cost of tillers is too high for farmers. So even if they somehow buy it, it's maintenance and fuel cost is too high for them.
High Operational Cost
Issues with Tillers
Awkward sitting position
The sitting position of tillers currently available in market creates large number of vibrations. Due to this farmers operate the tillers while standing which becomes tiring for them.
No Provision to transport goods
Some farmers told that current power tiller don't provide any provision for transporting goods over small distances. E.g. transporting harvest from farms to market.
Farmers operating the tillers
SOLUTION IMPLEMENTED
After understanding the pain points of farmers, the Sand Bird Team came up with following solution:
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Implement Detachable Rear Attachment
It was decided to implement a detachable rear attachment for our tiller. Farmer should be able to operate the tiller with or without it.
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Facility to operate tiller using Rear Attachment
Farmer should have all the controls to operate the tiller using rear attachment. Also a provision should be provided at the back of rear attachment so that farmer could attach various implements to it.
Implement E-Powertrain
To reduce the operational cost, it was decided to implement E- Powertrain for our tiller. This would significantly reduce the operational cost as electric charging won't be as expensive as Diesel. Also the government of India provides various subsidies on the use of Electric Vehicles which would be beneficial for farmers.
REAR ATTACHMENT DESIGN
1. Based on the inputs received, I first made a concept model for our tiller. This would be then be used for individual subsystems design.
Concept of the Electric Power Tiller
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2. For the farmer to use the detachable rear attachment for various farming and non farming operations, they would need following subassemblies in it:
a. Steering
b. Brakes
c. Ergonomic sitting position
d. Provision to transfer power from front gear box to rear attachment to power implements.
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Using these inputs I started with the design of frame for the rear attachment of our tiller.
DESIGN PROCEDURE FOR FRAME
1. Fix Wheelbase
Distance between the front and rear axle is an important factor for deciding steering geometry. Higher the wheelbase the more difficult it becomes to steer the vehicle. Whereas for brakes lower wheelbase significantly increases the braking torque required at front axle. Based on both these factors wheelbase dimensions were finalized.
2. Fix Trackwidth
Distance between the two wheels of an axle provides us the trackwidth of a vehicle. Higher the trackwidth, more stable the tiller would become for driver while moving over bumps. Also the packaging of subcomponents plays a major role in finalizing the trackwidth.
3. Finalize Driver Position
Driver position was fixed in such a way that the ergonomics was not compromised. Steering wheel and Pedal box were positioned in such a way that driver could easily operate the tiller without having much strain even if it is operated for long hours.
4. PTO Shaft Positioning
A Power Take Off Shaft (PTO Shaft) was going to be used to transmit power from front gearbox to to implements attached at the back of rear attachment. Space and mount had to be provided for this shaft. Also it was made sure that the PTO shaft won't interfere with the rear axle.
Frame Design and sketches
E - POWERTRAIN PACKAGING
1. I worked on the packaging of E Powertrain components for our tiller.
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2. The selection of components was done by E Powertrain team . MATLAB Simulink was used to calculate the total power required by tiller and based on those calculations, components were finalized.
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3. Components of E Powertrain were packaged with an aim of achieving 40:60 weight distribution between front and rear axle.
E Powertrain Packaging
Motor and Motor Controller Mounting
FINAL CAD ASSEMBLY
