High-speed scanning is a huge challenge to the motion control of step-scanning gene sequencing stage. The stage should achieve high-precision position stability with minimal settling time for each step. The existing step-scanning scheme usually bases on fixed-step motion control, which has limited means to reduce the time cost of approaching the desired position and keeping high-precision position stability. In this work, we focus on shortening the settling time of stepping motion and propose a novel variable step control method to increase the scanning speed of gene sequencing stage. Specifically, the variable step control stabilizes the stage at any position in a steady-state interval rather than the desired position on each step, so that reduces the settling time. The resulting step-length error is compensated in the next acceleration and deceleration process of stepping to avoid the accumulation of errors. We explicitly described the working process of the step-scanning gene sequencer and designed the PID control structure used in the variable step control for the gene sequencing stage. The simulation was performed to check the performance and stability of the variable step control. Under the conditions of the variable step control where the IMA6000 gene sequencer prototype was evaluated extensively. The experimental results show that the real gene sequencer can step 1.54 mm in 50 ms period, and maintain a high-precision stable state less than 30 nm standard deviation in the following 10 ms period. The proposed method performs well on the gene sequencing stage.

高速扫描是步进扫描基因测序阶段运动控制的巨大挑战。该平台应在每个步骤的建立时间最少的情况下实现高精度的位置稳定性。现有的步进扫描方案通常基于固定步进运动控制，其具有有限的手段来减少接近期望位置的时间成本并保持高精度的位置稳定性。在这项工作中，我们着重于缩短步进运动的建立时间，并提出了一种新颖的可变步进控制方法来提高基因测序阶段的扫描速度。具体而言，可变步长控制将载物台稳定在稳态间隔内的任何位置，而不是稳定每个步长上的所需位置，从而减少了稳定时间。所产生的步长误差将在下一个步进加速和减速过程中得到补偿，以避免误差的累积。我们明确描述了步进扫描基因测序仪的工作过程，并设计了用于基因测序阶段的可变步进控制中的PID控制结构。进行仿真以检查可变步长控制的性能和稳定性。在可变步长控制的条件下，对IMA6000基因测序仪原型进行了广泛评估。实验结果表明，真实基因测序仪可在50 ms的时间内步进1.54 mm，并在接下来的10 ms的时间内保持小于30 nm标准偏差的高精度稳定状态。所提出的方法在基因测序阶段表现良好。