Development of Solar Operated Walking Type Power Weeder

Abstract

Power weeders are most commonly used machines for removing weeds, to prevent them from competing with main crops. However, these power weeders are power by either petrol or diesel engine. With the shortage of fossil fuel, its unavailability in rural areas and for reducing emission due to burning of fossil fuel, an alternative energy powered weeder is very much required. As solar energy was very available and weeding usually carried out during daytime, hence an attempt made to develop a solar energy operated weeder for dryland. It comprised of a powering system and a blade assembly. The power source included solar photovoltaic panel, solar charge controller, battery, motor charge controller and BLDC motor. The sweep type blade was used, which is mounted behind the main frame and power was given to the rear wheels by 750 watt 48 volt BLDC motor using a chain and sprocket drive. The performance of weeder was evaluated at three different forward speed of S1, S2 and S3 is 1.0 - 1.5, 1.5 - 2.0 and 2.0 – 2.5 km/h respectively. Total weight of weeder is 88 kg and total force required to push the weeder at 2.5 km/h was 107 kg (730 watt).  Four batteries, each of size 12 V, 12 amp, powered the motor. Two solar panels were use to charge the battery, each with a power of 150 watts, and it takes 2 h to completely charge the battery while weeder is in steady state. The battery was discharge in 1.3 h in field when solar panel disconnected. With simultaneous charging and discharging of battery, this solar power system could run the weeder for 7.3 h. The developed weeder was teste in groundnut crop having 600 mm row-to-row spacing up to 30 to 40 mm depth with a field capacity of S1, S2 and S3 was 0.042, 0.059 and 0.075 ha/h. The weeding and field efficiency for S1, S2 and S3 were found to be 90.94, 84.69, 83.50% and 79.21, 83.97, 85.68% respectively. The effect of forward speed S1, S2 and S3 on Energy expenditure rate and heart rate was found to be 8.23, 9.27 and 10.34 kJ/min or 94, 98 and 50 bpm respectively. The plant damage increased with increasing forward speed of operation, Hence the developed solar operated walking type power weeder could be used successfully by the a small scale farmer for carrying out weeding operations.