基于GPS和陀螺仪的水稻插秧机自动导航设计(8)

基于GPS和陀螺仪的水稻插秧机自动导航设计

230Y.Nagasaka et al./Computers and Electronics in Agriculture43(2004)223–234

Fig.7.Control way of turning.

throttle,the HST lever,and the attachment control lever positions were controlled according to the vehicle location.The engine throttle position is set fully open during operation and is set at the middle position in other situations.The HST lever position is set so that the vehicle travels at a speed of0.7m/s.

2.6.Turn control

At the headland,the rice transplanter moves forward and backward during a turn so as to minimize the headland space.The width of the headland is3.5m.Fig.7shows how turning is effected at the headland.When the rice transplanter reaches the edge of the?eld,it?rst stops transplanting and lifts the transplanting attachment,then the HST lever is set to the backup position and the vehicle moves backward in a straight line for a distance of40cm.After mov-ing40cm,the HST lever is set to the advance position at0.3m/s.While the rice transplanter is turning,if the yaw angle is less than160?,only the yaw angle is obtained.Under these con-ditions,the steering angle is kept at40?and the brake is applied on one side.If the yaw angle exceeds160?,the rice transplanter is moved as close as possible to the next desired path.The transplanter stops4.7m from the?eld edge.Then it moves backward.If the rice transplanter does not get suf?ciently close to the next desired path at this point,the steering is manipulated so as to get as close as possible to the desired path until it reaches2m from the?eld edge.

3.Results and discussion

The experiment was conducted two days after?ooding the?eld.The four corners of the paddy?eld were measured before operation.The size of this paddy?eld was50m×10m. The quotient obtained by dividing the?eld width by the sowing width was an odd number, so in this?eld,the automated rice transplanter moved to the opposite side of the entrance before starting operation.

Fig.8shows the path of the automated rice transplanter.In Fig.8,the in?uence of the vehicle inclination was corrected.Table2shows the summary of line-following control at a speed of0.7m/s.

The rice transplanter went forwards and backwards in the?eld three times.Path1has an RMS position error that is more than0.2m.It is thought that the?rst yaw angle offset was large.The lateral position error in Table2(a)is larger than in(b)because in the?rst

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