Application Background
Different scenarios and devices have different requirements for speed, stability, etc. Selecting the appropriate speed planning mode for the equipment's process requirements can create more value for users and save greater costs. To meet market demands, Leadshine motion control cards offer the following four speed planning modes.
T-shaped velocity curve
It can be used to control the acceleration and deceleration of motors to ensure precise positioning; in scenarios where ultimate efficiency is required, the T-shaped speed planning mode can be selected.
S-shaped velocity curve
An S-shaped velocity curve is a motion curve used to control changes in acceleration and deceleration in motion control systems and automated equipment to achieve smooth and stable motion processes. Similar to a T-shaped velocity curve, the S-shaped velocity curve is smoother during the transition between acceleration and deceleration.
S Plus speed curve
S Plus speed curve planning is similar to S-curve planning, but S Plus allows for independent setting of acceleration and deceleration. This enables more flexible exploration of the platform's limits, allowing the equipment to achieve maximum efficiency.
Sine and cosine velocity curves
Sine and cosine velocity curves simulate the shape of a sine or cosine function. During motion, these curves exhibit acceleration and deceleration that vary in the form of a sine or cosine function, making them suitable for applications requiring sine or cosine velocity variations.
Function Introduction
NO.1
A Brief Description of Four Speed Planning Methods
NO.2
A list of commands for each speed planning mode
NO.3
Comparison chart of four speed planning modes
Comparison of T-shaped and S-shaped velocity curves
As shown in the figure above, the difference between the S-curve and the T-curve lies in whether or not the acceleration and deceleration phases are smoothed. With the same parameters, the S-curve requires more smoothing time than the T-curve, thus making it less efficient.
T-shaped and S-Puls-shaped velocity curves
Under the same parameters, the S Plus speed curve is smoother and more stable than the T-curve, achieving a shock absorption effect. Users can also adjust the Acc, Dec, and Ajerk, Djerk values according to the equipment performance to achieve maximum efficiency while maintaining a smooth effect.
Comparison of S Plus with the same ACC but different Ajerk settings
As shown in the diagram above, efficiency gradually increases with a higher jerk factor; however, at 100x, the smoothing effect is almost imperceptible. Therefore, it is necessary to adjust the jerk and acceleration values to find the optimal setting for the machine. The adjustment method will be described below.
Effects of different parameters on sine and cosine curves
The shape of the sine and cosine curves helps reduce shock and vibration, improving the platform's performance, stability, and accuracy. It is suitable for scenarios requiring sine and cosine velocity variations, such as mobile phone lens stability testing.
Instruction Call and Curve Planning
T-shaped velocity planning
T-programming functions use combinations:
dmc_set_plan_mode: Speed planning mode
dmc_set_profile_unit: Speed settings
To ensure smooth acceleration and accurate stopping of the platform during motion, a trapezoidal velocity curve is generally used to control the motion process. As shown in the figure above, the T-shaped velocity curve consists of three stages: uniform acceleration → uniform speed → uniform deceleration.
The T-shaped speed curve is the fastest and simplest to set up in speed planning, and it also has the highest efficiency. However, the T-shaped speed curve is not smooth enough. During the acceleration and deceleration phases, the rapid changes in acceleration cause equipment vibration and impact on the equipment.
S-shaped speed planning
S-shaped programming functions use combinations:
dmc_set_plan_mode: Speed planning mode
dmc_set_profile_unit: Speed settings
dmc_set_s_profile: Smoothing time settings
To address the impact of T-curve speed curves on equipment, Leadshine Control also offers S-curve speed curves, designed to improve the smoothness of platform movement. As shown in the diagram above, a smooth curve appears during acceleration and deceleration, effectively reducing the impact on the platform caused by sudden increases in acceleration. Compared to the T-curve, the S-curve is less efficient. The increased time is the set smoothing time, which users can adjust as needed.
S Plus-shaped velocity planning
S-Plus shape programming functions use combination:
dmc_set_plan_mode: Speed planning mode
dmc_set_profile_extern: Higher-order velocity profile settings
As shown in the graph, the S Plus high-order velocity curve planning almost perfectly matches the S-shape on the velocity curve. The acceleration versus time graph shows that velocity planning is divided into 7 stages. To smooth the acceleration, a smoothing time function can be set.
After equipment debugging, determine the starting speed, ending speed, maximum speed, and acceleration. Adjust the values of Ajerk and Djerk flexibly according to requirements.
If the user is more concerned about platform vibration, the jerk should be kept at 1x; if the customer has higher efficiency requirements, the jerk value should be increased. The adjustment principle is the same as when adjusting the acceleration, generally a 10x increase, until a critical value is reached where the machine will not vibrate and the efficiency will be at its maximum.
The planning of the S Plus high-order velocity curve is almost identical to the S-shape on the velocity curve. As can be seen from the acceleration versus time curve, the velocity planning is divided into 7 stages. Smoothing is performed in stages T1, T3, T5, and T7.
The advantage of high-order velocity curves lies in the ability to autonomously configure appropriate acceleration and jerk. By understanding the maximum acceleration limit of the equipment, efficiency can be maximized.
Sine and Cosine Velocity Programming
dmc_sine_oscillate_set_mode: Sets the oscillation mode.
dmc_sine_oscillate_set_cycle_num: Sets the curve output mode.
dmc_sine_oscillate_unit: Starts the sine and cosine curve operation.
Speed curve use cases
S Plus Trial Case
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ushort usCardId = 0; //Card number ushort axis = 0; //Axis number ushort mode = 2; //Speed mode double Min_vel = 0; //Minimum speed double Stop_vel = 0; //Stop speed double Max_vel = 1000; //Target speed double Tdec = 10000; //Acceleration double Tacc = 10000; //Deceleration double Ajerk = 1000000; //Acceleration double Djerk = 1000000; //Deceleration double Dist = 1000; //Target position ushort posi_mode = 0; //Set speed planning mode 0: T-shape/smooth S-shape 2: S plus shape ret = LTDMC.dmc_set_plan_mode(usCardId, axis, mode); //Set single-axis motion speed curve, acceleration interface ret = LTDMC.dmc_set_profile_extern(usCardId, axis, Min_vel, Max_vel, Tdec, Tacc, Ajerk, Djerk, Stop_vel); // Point movement ret = LTDMC.dmc_pmove_unit(usCardId, axis, Dist, posi_mode);
S Plus speed curve planning has been applied to translational sorting machines, enabling them to meet the requirements of short-stroke, rapid movement while ensuring stable platform operation without vibration and high precision, thus maximizing efficiency.
Examples of sine and cosine curves
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ushort usCardId = 0; // Card number ushort axis = 0; // Axis number ushort mode = 0; // Position and time are sine curves uint cycle_num = 1; // Output 1 cycle double Amplitude = 1000; // Sine curve amplitude double Frequency = 10; // Oscillate 10 times per second // Set sine oscillation mode ret = LTDMC.dmc_sine_oscillate_set_mode(usCardId, axis, mode); // Set the curve to output by cycle number ret = LTDMC.dmc_sine_oscillate_set_cycle_num(usCardId, axis, cycle_num); // Start sine curve operation ret = LTDMC.dmc_sine_oscillate_unit(usCardId, axis, Amplitude, Frequency);
The Leadshine 3000/5000 series motion control cards support all four speed planning modes described above. Please contact us if you require relevant speed curve planning information.
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