vc_set_joint_velocity should take const float

[axbycc-mark]

xArm-CPLUS-SDK/include/xarm/wrapper/xarm_api.h

Line 1817 in 6f1c219

int vc_set_joint_velocity(fp32 speeds[7], bool is_sync = true, fp32 duration = -1.0);

This function and related commands take float array. This prevents the user from passing in a const float*. Since the API should not modify user input, it's better to take const float*