In order to reduce cucumber harvesting cost and improve economic benefits,a cucumber harvesting robot was developed.The cucumber harvesting robot consists of a vehicle,a 4-DOF articulated manipulator,an end-effector,an upper monitor,a vision system and four DC servo drive systems.The Kinematics of the cucumber harvesting robot manipulator was constructed using D-H coordinate frame model.And the inverse kinematics which provides a foundation for trajectory planning has been solved with inverse transform technique.The cycloidal motion,which has properties of continuity and zero velocity and acceleration at the ports of the bounded interval,was adopted as a feasible approach to plan trajectory in joint space of the cucumber harvesting robot manipulator.Moreover,hardware and software based on CAN-bus communication between the upper monitor and the joint controllers have been designed.Experimental results show that the upper monitor communicates with the four joint controllers efficiently by CAN-bus,and the integrated errors of four joint angles do not exceed four degrees.Probable factors resulting in the errors were analyzed and the corresponding solutions for improving precision are proposed.
Zhang LibinWang YanYang QinghuaBao GuanjunGao FengXun Yi
A new kind of flexible pneumatic wall-climbing robot,named WALKMAN-I,was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA),a flexible pneumatic spherical joint and six suction cups. It has many characteristics of low-cost,lightweight,simple structure and good flexibility. Its operating principle was introduced. Then three basic locomotion modes,which are linear motion,curvilinear motion and crossing the orthogonal planes,were presented. The safety conditions of WALKMAN-I were discussed and built. Finally,the control system was designed and experiments were carried out. Experimental results show that WALKMAN-I is able to climb on the vertical wall surface along a straight line or a curved path,and has the ability of crossing orthogonal planes and obstacles. The maximum rotation angle reaches 90°,the maximum velocity reaches 5 mm/s,and the rotation angle and the moving velocity of WALKMAN-I can be easily controlled.
As the representation of new concept agricultural machinery,agricultural robots possess great advantages of improving agricultural productivity,enhancing production environment and solving the problem of labor shortage.Therefore,the strategy for application of agricultural robots and precision agriculture to improve the intelligence and information level of agriculture is the inevitable trend for China’s agriculture in the twentieth century.Based on the developmental status of agricultural robots in China,the agricultural robots are categorized and the performances,structures and characteristics of various agricultural robots such as vegetable grafting robots,transplanting robots,spraying robots,mowing robots,harvesting robots,grading and detecting robots are amply introduced.It can be seen that vegetable grafting robots,spraying robots,harvesting robots,grading and detecting robots have already been put into production while others are still at experimental stage.At present,there are several problems such as low popularization,great limitations,high cost and low intelligence,which greatly restrict the development of agricultural robots in China.Thus,open agricultural robot system with good expansibility,generality and flexibility should be developed and adopted to decrease its cost and shorten developing cycle.The mechanical structure of robots should also be designed as simply as possible.Finally,multi-robot system would become another important development direction of agricultural robots in the future.
