Remote-control Grass Cutter Operates Under 40cm-high Solar Mounting System (2)

2019/02/25 17:52
Shinichi Kato, Nikkei BP Intelligence Group, CleanTech Labo
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Continued from Remote-control Grass Cutter Operates Under 40cm-high Solar Mounting System (1)

Takes advantage of motorization

Sasaki Corp also developed grass cutters that use storage batteries as power sources, in addition to the remote-control grass cutter it commercialized.

It is an electric grass cutter intended for use on ridges between rice fields and was jointly developed with the National Agriculture and Food Research Organization (NARO), receiving a subsidy from the Ministry of Agriculture, Forestry and Fisheries (MAFF). In developing the machine, the company aimed for remote control and self-traveling on ridges with certain levels of width and strength.

Remote operation was incorporated in the electric grass cutter to ensure the safety of operators. The company said it thought remote control will be suitable for use on solar power plant sites where small animals such as mice and snakes live (Fig. 3).

Fig. 3: Remote control incorporated as measures against snakes and for other reasons (source: Sasaki)

The body height was reduced to 40cm so the machine can cut grass under mounting systems. The company emphasizes that low height is impossible when an engine is used as the power source and that low height is one of the advantages of motorization.

The machine can be used on slopes of 35° according to the specification, and it can deal with slopes of 40° or more in actual operation. This is also an advantage of motorization. If engines are used, fuel is not supplied properly on slopes with a certain degree or more in many cases so such machines usually cannot be used on such steep slopes.

The company also had a plan to incorporate self-traveling, but the plan was abandoned because the sale price would quadruple, failing to realize high cost-effectiveness.

The sale price of the electric-powered grass cutter is set to 2 million yen (approx US$18,083) for a fully equipped unit. A large amount of the price is for the storage batteries. The machine is mounted with two storage batteries as standard equipment, and the company recommends purchase of one spare battery. The suggested retail price of the battery is 300,000 yen, so the price of the batteries will be 900,000 yen including the spare battery.

Li-ion batteries made by a Canadian manufacturer are used. The company originally considered the use of storage batteries made by a domestic manufacturer, but the company eventually selected the Canadian products because none of the domestic products satisfied the specifications set by Sasaki.

The machine is designed so that it can operate for at least one hour on one of the storage batteries. Grass on 840m2 of land can be cut in one hour, while grass on 1,680m2 of land can be cut in two hours using two batteries mounted on the machine.

The company recommends the additional battery as a spare battery so that rotation is realized when the machine is always mounted with two fully charged batteries. After the first one hour of operation, the used battery is replaced with the spare battery. Then, the machine can be operated for two more hours. The removed battery is fully charged during the two hours.

The traveling unit is about 1m in length, and the attachment for grass cutting is mounted on the front side of the unit. The turning radius is small, so the machine can turn in a space 2m in diameter.

Slipping and lateral displacement are minimized because crawlers are used for traveling. The superior traveling performance, stability and operability are commitments by the company as a manufacturer of grass cutters for agricultural use.

The product was developed for solar power plants, but after its release, the company found that it can also be used in other fields and for other purposes. The company received various requests for use of the product to cut grass and transport produce in orchards, to collect coke on floors beside conveyors at steel plants and other purposes taking advantage of the characteristics of the electric machine (Fig. 4, Video 2).

Fig. 4: Product also used in orchards (source: Sasaki)

Video 2: Use of remote control grass cutter for transporting, snow removal, etc (source: Sasaki)

To use the machine for purposes other than grass cutting, the grass cutting attachment mounted on the front is removed and a different attachment is mounted according to the purpose.

This is also the advantage of motorization. If an engine is used as the power source, various changes and adjustments including rearrangement of gears are required for using the machine for other purposes. If the machine is powered by electricity, the machine can be used for other purposes without making any changes if the motor specification matches the purpose.

Maintenance operations include replacement of rotary blades on the grass cutting attachment. Brushes and wheels need to be replaced every three to four years, depending on the usage condition of the motor. The storage batteries should be charged even during winter when the machine is not used for grass cutting, etc., because natural discharge occurs due to the properties of storage batteries, according to the company.