Trajectory-tracking control of parallel manipulators is more difficult than in the case of serial ones due to the presence of the loop-closure constraints and constraint forces resulting from them. One needs to eliminate these forces to get to the equation of motion, and then apply a control scheme. In this paper, such a control scheme is presented through application on a semi-regular Stewart platform manipulator (SRSPM). The manipulator has six degrees-of-freedom; however, it is modelled by a system of 18 coupled nonlinear ordinary differential equations (ODE) using the constrained Lagrangian formulation. The model is then linearised through feedback, and controlled by a linear PD servo scheme. Numerical simulations over a non-singular path show that the scheme is fairly accurate, at the cost of being computationally expensive. The scheme is general in nature, and as such, it is expected to work in the case of other parallel manipulators as well.