This paper proposes a novel concept for the spray painting robotic device, which is to be used in the coating process of the automotive industry. In order to realize compact design and simultaneously get better performance in terms of running speed and dynamic response, parallel kinematic mechanisms (PKMs) are introduced in this concept. In conjunction with the gantry beam, four standalone spray painting units are assigned and two kinds of PKMs (i.e. 3-RPS PKM and 5 R symmetrical PKM, R: revolute joint; P: prismatic joint; S: spherical joint) are used as the execution mechanisms of the four spray painting units. Based on this concept design, the kinematic optimization of the device is carried out by taking the motion/force transmission performance into consideration and the geometric parameters are derived. Sequentially, a prototype is developed and its performance in the coating process is investigated by a series of spray painting experiments on a Jetta car body and a SUV car body. The finished surfaces have good quality in terms of luster, uniformity, and thickness. Thus, this newly developed spray painting robotic device provides a better choice or solution for the coating task in automotive industry, and has good application prospect in this field.
A new torsional vibration–based method for the detection of engine misfires was proposed based on the discrete Fourier transform of angular acceleration of the crankshaft. By analysis of the sensitivity of the discrete Fourier transform to fluctuations in speed and load of the engine, the characteristic harmonics and characteristic discrete Fourier transforms of a cylinder were defined. Then cylinder misfires under any operating conditions were diagnosed by checking the characteristic discrete Fourier transforms of the cylinder at its characteristic harmonics. An experiment on a four-stroke, six-cylinder diesel engine showed that this method accurately identified misfire faults and the misfiring cylinders.
In this paper, a novel internal folded hardware-efficient architecture of multi-level 2-D 9/7 discrete wavelet transform (DWT) is proposed. For multi-level DWT, the unfolded structure is more extensively used compared with the folded structure, because of its low memory consumption and low time delay. However, a set of input data valid every few clock cycles caused the mismatch between clock and data in the unfolded structure. The mismatch usually needs to be solved by multi-clock or complex data adjustment, which increases the consumption of hardware resources and the complexity of the overall system. To solve the above problem of the unfolded structure, we adjust the data input timing by using a single clock domain and folding the DWT architecture of different levels in varying degrees, according to their own clock-to-data ratios. For an image of size of N × N pixels and 3-level DWT, the proposed architecture requires only 6N words temporal memory. For 3-level DWT with an image of size 512 × 512 pixels, the hardware estimation and comparison of the existing architectures show that, the hardware estimation result shows at least 30.6% area-delay-product (ADP) decrease, and at least 22.4% transistor-delay-product (TDP) decrease for S = 8, and 25.77% transistor-delay-product (TDP) decrease for S = 16.
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