How to plot a surface in 3 dimension described by 4 parameters?

Hi all,

I'm trying to depict the control envelope of a reaction wheels system composed by 4 wheels to control the attitude of a spacecraft. I would like to change the magnitude of the torque provided by each of the 4 wheels from -1 to 1 and I would like to evaluate the torque computed with respect to the body frame. To compute the torque in body frame I use the allocation matrix A (which is 3 by 4 matrix) in such a way that T = A*[R1; R2; R3; R4] where R1-R4 is the torque of each wheel. My goal is to depict the surface (in 3 dimension) which is related to the maximum torque profile obtained activating differently each wheel. I tried to use "ndgrid" but I cannot understand the size of the output I obtain: [R1, R2, R3, R4] = ndgrid(linspace(-1,1,10), linspace(-1,1,10), linspace(-1,1,10), linspace(-1,1,10));

How can I compute the vector T in order to use each row of T with the command surf(T(1,:), T(2,:), T(3,:)) ?

Thank you all!

Matteo