A novel planar six-axis force and torque (F/T) sensor is proposed, inspired by a 3-RRR compliant mechanism, and having three limbs, each of which has three revolute joints. This design innovatively employs strain gauges on the top and bottom surfaces only, which reduces not only the number of required fabrication processes but also the labor costs associated with attaching strain gauges onto positions that are difficult to access. In this study, the stiffness of the planar F/T sensor associated with ${F}_{x}$ , ${F}_{y}$ , and ${T}_{z}$ are formulated using inverse kinematics and coordinate transformation methods. For ${T}_{x}$ , ${T}_{y}$ , and ${F}_{z}$ , the equivalent cantilever beam method is adopted to derive the relationships between loads and strains. Moreover, optimization is performed to determine the optimal design parameters of the F/T sensor. The calibration error using the cubic transformation matrix is 0.29% in the measurement range ${F}_{x}= {F}_{y}= {F}_{z}= \pm 100$ N, ${T}_{z} = \pm 10$ Nm, ${T}_{x}= {T}_{y}= \pm 6$ Nm.

In recent years, methods have been developed to automate vineyard operations to address the ever increased labor cost. One operation that has not been completely automated is grapevine pruning. A robotic machine for grapevine pruning needs to respond to the changing physical characteristics of the environment, and to date, no algorithm can accurately identified appropriate positions for grapevine pruning in a variety of environmental conditions. This paper presents the development of an image processing and image analysis algorithm to determine pruning position. Ten images full of canes were analyzed, and an 85% success rate for pruning positions was achieved

The geometric error motions of rotary stages greatly affect the accuracy of constructed machines such as machine tools, measuring instruments, and robots. In this paper, an embedded sensor system for real-time measurement of two radial and three angular error motions of a rotary stage is proposed, which makes use of a rotary encoder with multiple scanning heads to measure the rotational angle and two radial error motions and a miniature autocollimator to measure two tilt angular errors of the axis of rotation. The assembly errors of the grid disc of the encoder and the mirror for autocollimator are also evaluated and compensated. The developed measuring device can be fixed inside the rotary stage. In the experiments, radial error motions of two points on the axis (h = 5 mm and 60 mm) were measured and calibrated with LVDTs, and the data showed that the radial error motions of the axis were less than 20 μm, and the calibration residual errors were less than 2 μm. When intermittent external forces were applied to the stage, the change of the stage’s error motion could also be monitored accurately.