## 3 Software Design of Performance Testing System for Space Harmonic Reducer  
The function of space harmonic reducer performance test software is divided into four parts: life test, precision test, backlash test and efficiency test. Test parameters can be set (including test name, test code, test serial number, sensor range, sensitivity, resolution, angle range, date, environmental conditions, etc.). These data are automatically saved in the test data file after setting is determined. In the life test, one or more controllers can be realized respectively. The life test can be divided into two types: continuous operation and swing operation. The software can realize the above two functions, and the operation parameters can be set in the software (operation time, direction, speed, swing angle, etc.). It can collect the running current of the motor in real time and save it in the form of curve. Precision and backlash testing can be divided into two modes: continuous operation testing mode and random angle testing mode. The transmission error of harmonic reducer is defined as the deviation between the expected output position and the actual output position, which is expressed as follows:  
\[\theta_{err}=\frac{\theta_{i}}{i}-\theta_{0} \tag{1}\]  
where \(\theta_{i}\) is the rotation angle of the motor shaft connected to the harmonic reducer. \(i\) is the transmission ratio of gears, and \(\theta_{0}\) is the rotation angle of the output shaft. In order to better analyze transmission errors, the error accuracy is introduced in Formula (2). \[p=\left(\theta_{i}(t)-\theta_{i}(t-1)\right)/i-\left(\theta_{0}(t)-\theta_{0} (t-1)\right) \tag{2}\]  
Similar to Formula (1), \(\theta_{i}(t)\) is the rotation angle of the input shaft connected to the reducer at time \(t\), and \(\theta_{0}(t)\) is the rotation angle of the output shaft. In continuous operation mode, the input values of each operation angle are collected by rotating 360 degrees at equal angles (e.g., 9 degrees), and the operation accuracy is calculated. Then, the backlash is calculated at corresponding points by rotating 360 degrees at equal angles in reverse. In random angle mode, an angle value can be randomly inputted to input and output the accuracy value of actual angle calculation measured by the sensor, and the backlash can be calculated after returning to the original position. The angle values of input and output are displayed in real time during the test. The test records and results are saved in Excel data format and can be invoked when querying. In order to analyze the transmission efficiency of the reducer, a formula for calculating the efficiency is introduced. The efficiency is the ratio of output power to input power. as shown in Formula (3), \(n_{0}\) and \(T_{0}\) are output speed and torque respectively, \(n_{i}\) and \(T_{i}\) are input speed and torque respectively. The \(i\) is the transmission ratio of gears. Transmission efficiency is one of the comprehensive quality indexes of harmonic gear reducer. In theory, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Name of Selected Component** & **Function** & **Number** \\ \hline Heidehan position coder & \begin{tabular}{c} Input and output angle \\ measurement \\ \end{tabular} & 12 \\ \hline German HBM Sensor & \
\begin{tabular}{c} Input and output torque \\ measurement \\ \end{tabular} & 12 \\ \hline YPD series DC current/voltage & Acquisition of DC current, \\ transmitters of Suzhou Xunpeng & DC voltage, AC current and \\ Instrument & AC voltage & 6 for each \\ \hline Yanhua Adam 3937 connection module &
\begin{tabular}{c} Automatic control of \\ connection and interruption \\ through PCI bus \\ \end{tabular} & 1 \\ \hline \hline \end{tabular}
\end{table}