so what I'm trying to do is making rheometer which measures the rheological properties of a material. Basically, there are two measuring methods available: Rotational tests and oscillatory tests. With rotational measurements, the measuring bob turns in one direction. In an oscillatory test, the measuring bob "oscillates" around the axis.

Image: https://ibb.co/zQ7dXx5

what my focus is to with oscillatory tests with set sinusoidal oscillation.

The basic principle of an oscillatory rheometer is to induce a sinusoidal shear deformation in the sample and measure the resultant stress response; the time scale probed is determined by the frequency of oscillation, ω, of the shear deformation. In a typical experiment, the sample is placed between two plates, as shown in the image2 below While the top plate remains stationary, a motor rotates the bottom plate, thereby imposing a time-dependent strain γ(t)=γ ·sin(ωt) on the sample. Simultaneously, the time-dependent stress σ (t) is quantified by measuring the torque that the sample imposes on the top plate.

image2: https://ibb.co/Ld4XQmF

So to able to do above testing I need to run the motor with sinusoidal oscillation with exact angle.Hope you get it what im trying to say? does anyone know any motor controllers that allow that kind of motion ? or any hints how do i wet my feet? cheers!!